All definitions needed for SL Environmental Systems and Societies.

Abiotic Factor

A non-living, physical factor that may influence an organism or ecosystem; i.e. temperature, sunlight,
pH, salinity, precipitation

Biochemical Oxygen Demand (BOD)

A measure of the amount of dissolved oxygen required to break down the organic material in a given
volume of water through aerobic biological activity

Biodegradable

Capable of being broken down by natural biological processes; i.e. the activities of decomposer
organisms

Biodiversity

The amount of biological or living diversity per unit area. It includes the concepts of species diversity,
habitat diversity and genetic diversity.

Biomass/Standing Crop

The mass of organic material in organisms or ecosystems, usually per unit area. Sometimes the term
"dry weight biomass" is used where mass is measured after the removal of water. Water is not
organic material and inorganic material is usually relatively insignificant in terms of mass

Biome

A collection of ecosystems sharing similar climatic conditions; i.e. tundra, tropical rainforest, desert.

Biosphere

That part of the Earth inhabited by organisms, that is, the narrow zone (a few km thick) in which
plants and animals exist. It extends from the upper part of the atmosphere (where birds, insects and
wind-blown pollen may be found) down to the deepest part of the Earth's crust to which living
organisms venture.

Biotic Factor

A living, biological factor that may influence an organism or ecosystem; i.e. predation, parasitism,
disease, competition.

Carrying Capacity

The maximum number of species or "load" that can be sustainably supported by a given environment.

01
Climax Community

A community of organisms that is more or less stable, and that is in equilibrium with natural
environmental conditions such as climate; the end point of ecological succession.

Community

A group of populations living and interacting with each other in a common habitat.

Competition

A common demand by 2 or more organisms upon limited supply of a resource; i.e. food, water, light,
space, mates, nesting sites. It may be intraspecific or interspecific.

Correlation

A measure of the association between 2 variables. If 2 variables tend to move up or down together,
they are said to be positively correlated. If they tend to move in opposite directions, they are said to
be negatively correlated.

Crude Birth Rate

The number of births per thousand individuals in a population per year.

Crude Death Rate

The number of deaths per thousand individuals in a population per year.

Demographic Transition Model

A general model describing the changing levels of fertility and mortality in a human population over
time. It was developed with reference to the transition experienced as developed countries (i.e. those
of North America, Europe, Australia) passed through the processes of industrialization and
urbanization.

Diversity

A generic term for heterogeneity. The scientific meaning of the diversity becomes clease from the
context in which it is used; it may refer to heterogeneity of species of habitat, or to genetic
heterogeneity.

Genetic Diversity

The range of genetic material present in a gene pool or population of a species.

Habitat Diversity

The range of different habitats or numbers of ecological niches per unit area in an ecosystem,
community or biome. Conseravtion of habitat diversity usually leads to the conservation of species
and genetic diversity.

02
Diversity Index

A numerical measure of species diversity that is derived from both the number of species (variety)
and their proportional abundance.

Species Diversity

The variety of species per unit area. This includes both the number of species present and their
relative abundance.

Doubling Time

The number of years it would take a population to double its size at its current growth rate. A natural
increase rate of 1% will enable a human population to double in 70 years. Other doubling times can
then be calculated approximately, that it, the doubling time for any human population is equal to 70
divided by the natural increase rate

Ecological Footprint

The area of land and water required to support a defined human population at a given standard of
living. The measure takes account of the area required to provide all the resources needed be the
population, and the assimilation of all wastes.

Ecosystem

A community of interdependent organisms and the physical environment they inhabit.

Entropy

A measure of the amount of disorder, chaos or randomness in a system; the greater the disorder, the
higher the level of entropy.

Environmental Impact Assessment (EIA)

A method of detailed survey required, in many countries, before a major development. Ideally it
should be independent of, but paid for by, the developer. Such a survey should include a baseline
study to measure environmental conditions before development commences, and to identify areas
and species of conservation importance.

Equilibrium

A state of balance among the components of a system.

Eutrophication

The natural or artificial enrichment of a body of water, particularly with respect to nitrates and
phosphates, that result in depletion of the oxygen content of the water. Eutrophication is accelerated
by human activities that add detergents, sewage or agricultural fertilizers to bodies of water.

03
Evolution

The cumulative, gradual change in the genetic characteristics of successive generations of a species
or race of an organism, ultimately giving rise to species or races different from the common ancestor.
Evolution reflects changes in the genetic composition of a population over time.

Feedback

The return of part of the output from a system as input, so as to affect succeeding outputs.

Negative Feedback

Feedback that tends to damp down, neutralize or counteract any deviation from an equilibrium, and
promotes stability.

Positive Feedback

Feedback that amplifies or increases change; it leads to exponential deviation away from an
equilibrium.

Fertility

In the context of human populations, this refers to the potential for reproduction exhibited in a
population. It may be measured as fertility rate, which is the number of births per thousand women of
child- bearing age. Alternatively it may be measured as total fertility, which is simply the average
number of children a women has in her lifetime.

Gaia

Hypothesis developed by James Lovelock and named after an ancient Greek Earth goddess. It
compares the Earth to a living organism in which feedback mechanisms maintain equilibrium.

Global Warming

An increase in average temperature of the Earth's atmosphere.

Gross National Production (GNP)

The current value if all goods and services produced in a country per year.

Greenhouse Gases

Those atmospheric gases which absorb infrared radiation, causing world temperatures to be warmer
than they would otherwise be.

Habitat

The environment in which a species normally lives.

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Halogenated Organic Gases

Usually known as halocarbons and first identified as depleting the ozone layer in the stratosphere.
Now known to be potent greenhouse gases. The most well known are chlorofluorocarbons CFC’s)

Isolation

The process by which 2 populations become separated by geographical, behavioral, genetic ore
reproductive factors. If gene flow between the 2 subpopulations is prevented, new species may
evolve.

K- Strategist

Species that usually concentrate their reproductive investment in a small number of offspring, thus
increasing the survival rate and adapting them for living in long- term climax communities.

Latitude

The angular distance from the equator (that is, north or south of it) as measured from the centre of
the Earth (in degrees).

Less Economically Developed Country

A country with low to moderate industrialization and low to moderate GNP per capita.

More Economically Developed Country

A highly industrialized country with high average GNP per capita.

Model

A simplified description designed to show the structure or workings of an object, system or concept.

Mutualism

A relationship between individuals of 2 or more species in which all benefit and none suffer.

Natural Capital

A term sometimes used by economists for natural resources. If properly managed, renewable and
replenishable resources are forms of wealth that can produce 'natural income' indefinitely in the form
of valuable goods and services.

Non- Renewable Natural Capital

Natural resources that cannot be replenished within a timescale of that same order as that at which
they are taken from the environment and used; i.e. fossil fuels.

Replenishable Natural Capital

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Non-living natural resources that depend on the energy of the Sun for their replenishment; i.e.
groundwater.

Rate of Natural Increase

The form in which human population growth rates are usually expressed: crude birth rate- crude
death rate/ 10 (inward and outward migration are ignored)

Niche

A species' share of a habitat and the resources in it. Depends on where the specie lives and what it
does.

Parasitism

A relationship between 2 species in which one species lives in or on another, gaining all or much of
its food from it.

Pollution

The addition to an environment of a substance or an agent (such as heat) by human activity, at a rate
greater than that at which it can be rendered harmless by the environment, and which has an
appreciable effect on the organism within it.

Non- Point Source Pollution

The release of pollutants from numerous, widely dispersed origins; i.e. gases from exhaust systems
in vehicles.

Point Source Pollution

The release of pollutants from a single, clearly identifiable site; i.e. a factory chimney

Population

A group of organisms of the same species living in the same area at the same time, and which are
capable of interbreeding.

Gross Productivity (GP)

The total gain in energy or biomass per unit area per unit time, which could be through
photosynthesis in primary producers or absorption in consumers.

Gross Primary Productivity (GPP)

The total gain in energy or biomass per unit area per unit time fixed by photosynthesis in green
plants.

Gross Secondary Productivity (GSP)

The total gain by consumers in energy or biomass per unit area per unit time through absorption.

06
Net Productivity (NP)

The gain in energy or biomass per unit area per unit time remaining after allowing for respiratory
losses (R).

Net Primary Productivity

The gain by producers in energy or biomass per unit area per unit time remaining after allowing for
respiratory losses (R).

Net Secondary Productivity

The gain by consumers in energy or biomass per unit time remaining after allowing for respiratory
losses (R).

Primary Productivity

The gain by producers in energy or biomass per unit area per unit time. Can refer to either net or
gross productivity.

Secondary Productivity

The biomass gained by heterotrophic organisms, through feeding and absorption, measured in units
of mass or energy per unit area per unit time.

R- Strategist

Species that tend to spread their reproductive investment among a large number of offspring so that
they are well adapted to colonize new habitats rapidly and make opportunistic use of short- lived
resources.

Sere

The set of communities that succeed one another over the course of succession at a given location.

Smog

The tern now used for any haziness in the atmosphere caused by air pollutants.

Society

An arbitrary group of individuals who share some common characteristics such as geographical
location, cultural background, historical time frame, religious perspective, value system, etc,

Soil

A mixture of mineral particles and organic material that covers the land, and in which terrestrial plants
grow.

Soil Profile

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A vertical section through a soil, from the surface down to the parent material, revealing the soil
layers of horizons.

Speciation

The process through which new species form.

Species

A group of organisms that interbreed and produce fertile offspring.

Stable Equilibrium

The condition of a system in which there is a tendency for it to return to a previous equilibrium
condition following disturbance.

Steady- State Equilibrium

The condition of an open system in which there are no changes over the longer term, but in which
there may be oscillations in the very short term. There are continuing inputs and outputs of matter
and energy, but the system as a whole remains in a more or less constant state.

Succession

The orderly process of change over time in a community. Changes in the community of organisms
frequently cause changes in the physical environment that allow another community to become
established and replace the former through competition. Often, but not inevitably, the later
communities in such a sequence or sere are more complex than those that appear earlier.

Sustainability

Use of global resources at a rate that allows natural regeneration and minimizes damage to the
environment.

System

An assemblage of parts and the relationship between them, which together constitute an entity or
whole.

Closed System

A system in which energy, but not matter, is exchanged with its surroundings.

Isolated System

A system that exchanges neither matter nor energy with its surroundings.

Open System

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A system in which both matter and energy are exchanged with its surroundings.

Trophic Level

The position that an organism occupies in a food chain, or a group of organisms in a community that
occupy the same position in food chains.

Zonation

The arrangement or patterning of plant communities or ecosystems into parallel or sub- parallel
bands in response to change, over a distance, in some environmental factor.

First Law of Thermodynamics

"Energy may be transformed from one form to another, but cannot be created or destroyed."

Second Law of Thermodynamics

"In an isolated system, entropy tends to increase spontaneously."

Static Equilibrium

The condition in which there is no change in the system over time. A static equilibrium is a condition
to which natural systems can be compared.

Transfers

The processes that move through a system and produce a change in location but not a change in
state or form.
For example: run-off of water from a leaf to the ground.

Transformations

Processes that lead to an interaction within a system in the formation of a new end product, or involve
a change of state.
For example: evaporation.

Flow

The inputs and outputs of a system.

Renewable Natural Capital

Natural resources that have a sustainable yield or harvest equal to or less than their natural
productivity; for example, food crops, timber.

Sustainable Development

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'Development that meets current needs without compromising the ability of future generations to meet
their own needs.'

Sustainable Yield

The rate of increase in natural capital which can be exploited without depleting the original stock or its
potential for replenishment.

Maximum Sustainable Yield

The largest yield (or catch) that can be taken from the stock of a species over an indefinite period.

Natural Increase Rate

The crude birth rate minus the crude death rate, excluding migration. A natural increase rate of 1%
will make the doubling time of a human population 70 years.

Pyramids

Graphical models of the quantitative differences that exist between the trophic levels of a single
ecosystem.

Pyramid of Numbers

A pyramid that represents the numbers of individual plants and animals present in a food web.

Pyramid of Biomass

A pyramid that represents the standing stock of each trophic level measured in units such as grams
of biomass per square metre (gm-2) or energy per square metre (Jm-2).
It takes into account the body size of each organism, meaning the dry mass of each organism and its
energy content must be calculated. A pyramid of biomass represents storages.

Pyramid of Productivity

A pyramid that represents the flow of energy through a trophic level and invariably show a decrease
along the food chain.

Predation

The interaction between two organisms - the predator (which has a higher trophic level) and the prey
(which has a lower trophic level). Predators differ from parasites in that they kill their prey before
eating it.

Herbivory/Grazer Interactions

The interaction between a primary consumer (herbivore) and a producer.

Soil Degradation

The decline the quantity and quality of soil.

10
Environmental Value System

A particular world view or set of paradigms which shape the way an individual or group of people
perceive and evaluate environmental issues. This will be influenced by cultural, economic and socio-
political context.

11
TOPIC 1.1: ENVIRONMENTAL VALUE SYSTEMS

Image from realgreenearth.com

What is a world view?? Maybe more importantly what is an environmental world view? What is it? This is
the "world view" or set of paradigms that shape the ways that individuals and groups approach
environmental issues. It can also be viewed as a system as there are inputs and outputs that influence it.

Views vary from people who believe the world has unending resources and humans have unending
resourcefulness (Cornucopians) to the ecocentrists who believe we are a part of nature and that we have
to change our lifestyles to prevent any further damage to the Earth.

In this unit we will look at the environmental philosophies of an individual, as with that of a community. We
will see how these philosophies are shaped by cultural, economic and socio-political context. You should
recognize this and appreciate that others may have equally valid viewpoints. You will also justify your own
personal viewpoint. This unit is 3.5 hours.

Significant ideas:

 Historical events, among other influences, affect the development of environmental value
systems (EVSs) and environmental movements
 There is a wide spectrum of EVSs, each with its own premises and implication

Big questions

 What value systems can you identify at play in the causes and approaches to resolving the issues
addressed in this topic?
 How does your own value system compare with others you have encountered in the context of
issues raised in this topic?

Knowledge and Understanding

U.1.1.1 Significant historical influences on the development of the environmental movement have
come from literature, the media, major environmental disasters, international agreements and
technological developments.

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Significant historical influences on the development of the environmental movement have come from
literature, the media, major environmental disasters, international agreements and technological
development.

Consider major landmarks, for example, James Lovelock’s development of the Gaia hypothesis;
Minamata disaster; Rachel Carson’s book
Silent Spring (1962);, Davis Guggenheim’s documentary An Inconvenient Truth (2006); Chernobyl
disaster of 1986; Fukushima Daiihi nuclear disaster of 2011; Bhopal disaster of 1984; Gulf of Mexico oil
spill of 2010; Chipko movement; Rio Earth Summit 2012 (Rio+20); Earth Day; Green
Revolution; Copenhagen Accord; recent or local events of student interest., whaling (Save the Whale),
First Nation Americans, aka American Indians or Native Americans leading to environmental pressure
groups, both local and global, the concept of stewardship and increased media coverage raising public
awareness.

Timeline:

 1948: IUCN Founded

 1952: Great Smog in London kills 4,000, caused by coal burning during cold winter
 1956: Minamata deaths from mercury pollution in food chain
 1958: Start of UN Law of the Sea
 1961: WWF Founded
 1962: Rachel Carson publishes //Silent Spring//
 1969: Cuyahoga river catches fire due to ignition of oil and chemical pollution
 1970 James Lovelock's Gaia Hypothesis
 1974: CITES started
 1977: Greenpeace " Save the Whale" campaign
 1978: Love Canal
 1979: World Climate Conference raises awareness of climate change
 1980: World Conservation Strategy; Friends of the Earth begins confrontational protests
 1984: Bhopal Disaster 3,000-4,000 die due to explosion of pesticide factory in India
 1986: Chernobyl disaster
 1991: One million tonnes of crude oil dumped into Persian Gulf at end of Gulf War
 1992 Rio Earth Summit
 1997: Kyoto Protocol
 2005: Hurricane Katrina hits US Gulf Coast
 2006: Al Gore's //An Inconvenient Truth//
 2007: Great Pacific Ocean Garbage Patch discovered
 2010: Deepwater Horizon Oil Spill
 2011: Japan- Fukushima Daiichi nuclear disaster
 2015 Paris Climate Change Conference

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U.1.1.2 An EVS is a worldview or paradigm that shapes the way an individual, or group of people,
perceives and evaluates environmental issues, influenced by cultural, religious, economic and
socio-political contexts.

This is a particular world view or set of paradigms that shapes the way an individual or group of people
perceive and evaluate environmental issues. This will be influenced by cultural (including religious),
economic and socio-political context. An environmental value system is a system in the sense that it has
inputs (for example, education, cultural influences, religious doctrine, media) and outputs (for example,
decisions, perspectives, courses of action) determined by processing these inputs.

Ecosystems may often cross national boundaries and this may lead to conflict arising from the clash of
different value systems about exploitation of resources (for example, ocean fishing and whaling).

U.1.1.3 An EVS might be considered as a system in the sense that it may be influenced by
education, experience, culture and media (inputs), and involves a set of interrelated premises,
values and arguments that can generate consistent decisions and evaluations (outputs).
An environmental value system is a system in the sense that it has;

 inputs - education,cultural influences, religious doctrine, media)

 Outputs - decisions, perspectives, courses of action determined by processing these inputs.

There is a spectrum of EVSs, from ecocentric through anthropocentric to technocentric value

systems.

14
 An ecocentric viewpoint integrates social, spiritual and environmental dimensions into a
holistic ideal. It puts ecology and nature as central to humanity and emphasizes a less
materialistic approach to life with greater self-sufficiency
 of societies. An ecocentric viewpoint prioritizes biorights, emphasizes the importance of
education and encourages self-restraint in human behaviour.
 An anthropocentric viewpoint argues that humans must sustainably manage the global
system. This might be through the use of taxes, environmental regulation and legislation.
Debate would be encouraged to reach a consensual, pragmatic approach to solving
environmental problems.

15
  A technocentric viewpoint argues that technological developments can provide solutions
to environmental problems. This is a consequence of a largely optimistic view of the role
humans can play in improving the lot of humanity.
 Scientific research is encouraged in order to form policies and to understand how
systems can be controlled, manipulated or changed to solve resource depletion. A pro-
growth agenda is deemed necessary for society’s improvement

U.1.1.4 There are extremes at either end of this spectrum (for example, deep ecologists–
ecocentric to cornucopian–technocentric), but in practice, EVSs vary greatly depending on
cultures and time periods, and they rarely fit simply or perfectly into any classification.

Deep ecology: a need for spiritual revolution to fix environmental problems is at the core of all
environmental issues. Nature is at the center, equal rights for species. (Nature before human)

Soft ecology: self-sufficiency in resource management. Ecological understand a principle for all aspect of
living. Shun large scale profit motives for action, for small-scale community orientated schemes.

Environmental managers: no radical political agenda but promote working to create change within the
existing social and political structures. Current economic growth can be sustained if environmental issues
are managed by legal means or political agreement. (Believe that the environment can be used if manage
properly)

Cornucopian: a perspective that doesn't really see environmental issues as "problems" as humans have
always found a way out of difficulties in the past. New resources and technologies will solve any
environmental problems as they are encountered. There is no need for radical agendas, socio-economic
or political reform. (Don’t care for the environment; human come first)

Different EVSs ascribe different intrinsic value to components of the biosphere.

Common Native American EVS’s

there are many EVS’s among different tribes so this is a generalization

16
  Tendency to live in communities and share property
 Subsistent economy based on trade
 Low impact technology
 Tribal law requires agreement based on consensus
 Laws are passed down by oral tradition
 Most tribes have a matrilineal (mothers) descent, extended families, and small population
densities
 Most tribes are polytheistic and animals, plants, and nature are often regarded as objects with
spirituality

Applications and skills:

A.1.1.1 Discuss the view that the environment can have its own intrinsic value.
Resources can be valued in several ways;

 Economic: Having marketable goods and services (timber, food)

 Ecological: Providing life support services (gas exchange by forests)
 Scientific: useful applications (medicines)

These are examples of resources being valued ¨instrumentally¨.

Resources can also be valued ¨intrinsically¨. This means that a resource is valued for its cultural, esthetic,
spiritual or philosophical (moral) value and are valued regardless of their potential use to humans.

Attempts are being made to acknowledge diverse valuations of nature (for example, biodiversity, and rate
of depletion of natural resources) so that they may be weighed more rigorously against more common
economic values (for example, gross national product (GNP)). However, some argue that these
valuations are impossible to quantify and price realistically. Not surprisingly, much of the sustainability
debate centers on the problem of how to weigh conflicting values in our treatment of natural capital.
A.1.1.2 Evaluate the implications of two contrasting EVSs in the context of given environmental
issues.

The societies chosen should demonstrate significant differences

 First Nation Americans and European pioneers operating frontier economics, which involved
exploitation of seemingly unlimited resources
 Buddhist and Judaeo-Christian societies and Communist and capitalist societies.

Native American Communal property (no one owns property)

 Subsistence economy
 Barter for goods
 Low impact technologies

17
  Politically come to a consensus democratically
 Laws are handed down through oral tradition
 Matrilineal decent
 Extended families and low population density
 Polytheistic and animals, plants and nature objects have a spirituality.

Buddhism believed that Judeo-Christian believes that

 Suffering exists  Nature was created by God for

 Suffering arises from mankind
attachment to desires  Man are in charge of the nature.
 Suffering ceases when
attachment to desire ceases

The philosophy is closer towards

Buddhism believe living in balance anthropocentric (having responsibility to
with nature, therefore they tend to be provide better stewardship) or Cornucopians
more ecocentric and have philosophy (we can do whatever we want to the planet
very similar to that of the deep because God gave it to us)
ecologists.

Also Buddhism's vegetarian diet

would benefit the environment as well.

Water cannon gold minining

Forty Thousand Buffalo Hides in the corral of Wright & Rath, Dodge City, Kansas
A.1.1.3 Justify your personal viewpoint on environmental issues.

18
Reflect upon where you stand on the continuum of environmental philosophies with regard to specific
issues arising throughout the syllabus

 population control
 resource exploitation
 sustainable development
 any other ideas you feel important

Key Terms
environmental paradigm socio-political communism self-reliance
values biorights cornucopians environmental anthropocentrism
technocentrism ecocentrism socialism soft ecologists frontier economics
deep ecologists capitalism democracy managers pastoralists
Minamata Rachel Carson Fukushima totalitarianism soft ecologists
Disaster (Silent Spring) Daiihi value Gulf of
Chernobyl Rio Earth Summit Nuclear Bhopal Mexico/Deepwater
David (2012) Disaster Love Canal Horizon Oil Spill
Guggenheim Chief Seattle Earth Day London Smog Copenhagen Accord
(An Wold Wildlife Ecology Kyoto Protocol Greenpeace
Inconvenient Fund United Sustainability Non-Governmental
Truth) environmentalism Nations Biocentric Organizations
Aldo Leopold enhanced stewardship Agenda 21 (NGOs)
(A Sand County greenhouse effect pesticide MEDC biodiversity
Almanac) global warming LEDC greenhouse gas
Green altruistic
Revolution
Chipko
Movement

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TOPIC 1.2: SYSTEMS AND MODELS

A system is an assemblage of parts, working together, forming a functional whole. Many types of
environmental systems exist. From cells, to people, to cars, to economies to the whole planet. Systems
occur on different scales.

The systems approach is central to the course and has been employed for a number of reasons. The very
nature of environmental issues demands a holistic treatment. In reality, an environmental system
functions as a whole and the traditional reductionist approach of science inevitably tends to overlook or,
at least, understate this important quality. Furthermore, the systems approach is common to many
disciplines (for example, economics, geography, politics, ecology). It emphasizes the similarities between
the ways in which matter, energy and information flow (not only in biological systems but in, for example,
transport and communication systems). This approach therefore integrates the perspectives of different
disciplines.

In this unit you will be introduced to the characteristics of environmental systems. Identifying some of the
underlying principles that can be applied to living systems, from the level of the individual up to that of the
whole biosphere.

This unit will take a minimum of 2.5 hours.

Significant Ideas

 A systems approach can help in the study of complex environmental issues

 The use of systems and models simplifies interactions but may provide a more holistic view
without reducing issues to single processes

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 How does a systems approach facilitate a holistic approach to understanding?
 What are the strengths and weaknesses of the systems you have examined in this section?
 What have you learned about models and how they can be used, for example, to predict climate
change? Do their benefits outweigh their limitations?

Knowledge and Understanding

U. 1.2.1 A systems approach is a way of visualizing a complex set of interactions which may be
ecological or societal.

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  Outline the concept and characteristics of systems.

image from sciencebitz.com

SYSTEM: an assemblage of parts and their relationship forming a functioning entirety or whole. There are
two major components to a system:

1. Elements - measurable things that can be linked together. Example, trees, shrubs, herbs, birds
and insects (items we can count, measure or weight
2. Processes - change elements from on form to another. These may also be called activities,
relations, or functions. Example, growth, mortality, decomposition, and disturbances (what
happens to the elements, or what the elements do)

During the 1970’s, British chemist James Lovelock and American biologist Lynn Margulis came up with
the GAIA HYPOTHESIS: That the world acts like a single biological being made up of many individual
and interconnected units (A SYSTEM ).

A systems approach is a way of visualizing a complex set of interactions which may be ecological or
societal. These interactions produce the emergent properties of the system

 Why the system as a whole is greater than the sum of its parts
 The interactions of the parts create something they could not produce independently
 ex: two forest stands may contain the same tree species, but the spatial arrangement and size
structure of the individual trees will create different habitats for wildlife species. In this case, an
emergent property of each stand is the wildlife habitat

U. 1.2.2 These interactions produce the emergent properties of the system

An emergent property is a property which a collection or complex system has, but which the individual
members do not have. A failure to realize that a property is emergent, or supervenient, leads to the fallacy
of division.
The concept of a system can be applied at a range of scales.

21
There are different scales of systems. The range must include a small-scale local ecosystem, a large
ecosystem such as a biome, and Gaia as an example of a global ecosystem. Forests contain many
small-scale ecosystems.

U.1.2.3 A system is comprised of storages and flows

All living things use energy to do everything. Ecologists trace the flow of energy through ecosystems to
identify nutritional relationships. The ultimate source of energy for nearly all living things is the sun.

Ecologists who trace energy and matter flow in ecosystems have identified a number of interesting things.
Energy flows from one organism to another as each organism is eaten by the next. These relationships
are called food chains. For example, a plant may capture the sun's energy then become food for a deer
which may then be eaten by a bear. Each organism forms a link in the chain.

U.1.2.4 The flows provide inputs and outputs of energy and matter.

Energy flows from one compartment to another in the form of carbon–carbon bonds. When one organism
eats another organism the energy that moves between them is in the form of stored chemical energy.

Inputs and outputs from systems are called flows and represented by arrows in system diagrams. The
stock held within a system is called the storage and is represented through boxes

U.1.2.5 The flows are processes that may be either transfers (a change in location) or
transformations (a change in the chemical nature, a change in state or a change in energy

22
Transfers:

 The movement of material through living organisms

 Movement of material in non-living process
 The movement of energy

Transformations

 Matter to matter
 Energy to energy
 Matter to energy
 Energy to matter

The flows are processes that may be either transfers (a change in location) or transformation (a change in
the chemical nature, a change in state or a change in energy) Transfers normally flow through a system
and involve a change in location. Transformations lead to an interaction within a system in the formation
of a new end product, or involve a change of state. Using water as an example, run-off is a transfer
process and evaporation is a transformation process. Dead organic matter entering a lake is an example
of a transfer process; decomposition of this material is a transformation process.

Transfers include

 harvesting of forest products

 fall of forest debris on the ground

Transformations include

 photosynthesis
 respiration

U.1.2.6 In system diagrams, storages are usually represented as rectangular boxes and flows as
arrows, with the direction of each arrow indicating the direction of each flow. The size of the
boxes and the arrows may be representative of the size/magnitude of the storage or flow.

23
System diagrams consist of:

 boxes show storages

 arrows show flows (inputs/outputs)

Diagram can be labelled with the processes on each arrow:

 Photosynthesis – transformation of CO2, H2o and light into biomass and oxygen O2
 Respiration – transformation of biomass into CO2 and water
 Diffusion – movement of nutrients and water
 Consumption – tissue transfer from trophic level to another

The size of the boxes and arrows in the systems diagram can be drawn to represent the magnitude of the
storage or flow.

U.1.2.7 An open system exchanges both energy and matter across its boundary while a closed
system exchanges only energy across its boundary.

 Define and use the term open system. Use examples of real systems to characterize an open
system
 Define and use the term closed system. Use examples of real systems to characterize an closed
system.

An open system is a system that regularly exchanges feedback with its external environment.
Open systems are systems, of course, so inputs, processes, outputs, goals, assessment and evaluation,
and learning are all important. Aspects that are critically important to open systems include
the boundaries, external environment and equifinality.
Healthy open systems continuously exchange feedback with their environments, analyze that feedback,

24
adjust internal systems as needed to achieve the system’s goals, and then transmit necessary
information back out to the environment.

U.1.2.8 An isolated system is a hypothetical concept in which neither energy nor matter is
exchanged across the boundary.

 Define and use the term isolated system. Use examples of real systems to characterize an
isolated system

A closed system in which there is no transfer of mass takes place across the boundaries of system
but energy transfer is possible. Other than the universe itself, an isolated system does not exist in
practice. However, a very well insulated and bounded system with negligible loss of heat is roughly an
isolated system, especially when considered within a very short amount of time.

U.1.2.9 Ecosystems are open systems; closed systems only exist experimentally, although the
global geochemical cycles approximate to closed systems.

Systems can be thought of as fitting into one of three types:

 Open systems: exchanges matter and energy

 Closed systems: exchanges only energy
 Isolated systems: neither matter nor energy and is theoretical

U.1.3.9 A model is a simplified version of reality and can be used to understand how a system
works and to predict how it will respond to change.

 Apply the systems concept on a range of scales.

25
A model is a simplified description designed to show the structure or workings of an object, system or
concept. In practice, some models require approximation techniques to be used. For example, predictive
models of climate change may give very different results. In contrast, an aquarium may be a relatively
simple ecosystem but demonstrates many ecological concepts.

Models summarize complex systems. Therefore they can lead to loss of information and
oversimplification. A model involves some approximation and therefore losses accuracy.

U.1.2.11 A model inevitably involves some approximation and therefore loss of accuracy.

 Evaluate the strengths and limitations of systems models.

Strengths:

 allow scientist to predict/simplify complex systems

 inputs can be changed and outcomes examined without having to wait for real events.
 results can be shown to scientists and the public

Limitations:

 might not be totally accurate

 environmental factors are very complex
 different models use slightly different data to calculate predictions
 rely on the expertise of people making them
 different people may interpret them in different ways
 vested interests might hijack them politically
 any model is only as good as the data goes in and these may be suspect
 different models may show different effects using the same data

Application & Skills

A 1.2.1 Evaluate the use of models as a tool in a given situation, for example, climate change
predictions.

 Evaluate the strengths and limitations of climate change models.

26
Below are 5 different climate model simulations. You should be able to discuss the strengths and
weakness of each of these models. Which model do you believe is the best for understanding climate
change? Justify your reasoning!

Concord Consortium Climate Model

Window's to the Universe Climate Model
Koshland Science Museum Climate Model
UCAR Climate Model
Java Climate Model

S 1.2.1 Construct a system diagram or a model from a given set of information.

 Construct and analyze quantitative models involving flows and storages in a system.

To make an ecosystem (diagram/ model) showing how an ecosystem works. It must contain at least three
types of each of the following: abiotic elements, plants, herbivores, carnivores, and omnivores. Organism
numbers must have the necessary resources in the ecosystem to maintain its carrying capacity.

You are expected to be able to apply a systems approach to all of the topics in this course. You should be
able to interpret system diagrams and use data to produce your own for a variety of examples.

27
Key Terms
synergy models energy ecosystem open system
Gaia hypothesis flows transfer storage energy efficiency
biosphere inputs equilibria processess flows
system outputs model assemblage stock
closed system model ecosystem matter boundaries
emergent functional isolated system
properties

28
TOPIC 1.3: ENERGY AND EQUILIBRIA

Ecosystems are dynamic interrelated collections of living and non-living components organized in self-
regulating units. An ecosystem is a unit because it has boundaries and can be distinguished from its
surroundings. The living and non-living components affect each other in complex exchanges of energy,
nutrients and wastes. It is these dynamic exchanges, both fast and slow, which provide ecosystems with
their distinct identities. Because of these distinct features ecosystems themselves represent part of the
earth’s biodiversity. The characteristic exchanges within an ecosystem are called ecosystem functions
and in addition to energy and nutrient exchanges, involve decomposition and production of biomass. The
complex interdependencies which develop within or among ecosystems often create emergent properties,
or characteristics that cannot be predicted from the component parts alone.

Open systems tend to exist in a state of balance or quilibrium. Equilibrium is important for a system as it
avoids sudden changes in a system. However, this does not mean that all systems are none changing. If
change exists it tends to exist between certain peramiters. Equilibrium states in two ways state and
steady.

Static Equilibrium is a system in a steady state because the inputs and outputs that affect it approximately
balance over a long period of time.

The laws of thermodynamics govern the flow of energy in a system. This flow of energy gives the system
the ability to do work. Systems can exist in alternative stable states or as equilibria between which there
are tipping points.
Destabilizing positive feedback mechanisms will drive systems toward these tipping points, whereas
stabilizing negative feedback mechanisms will resist such changes.

This unit will take a minimum of 3 hours.

Significant Ideas

 The laws of thermodynamics govern the flow of energy in a system and the ability to do work
 Systems can exist in alternative stable states or as equilibria between which there are tipping
points
 Destabilizing position feedback mechanisms will drive systems toward these tipping points,
whereas stabilizing negative feedback mechanisms will resist such changes

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic

29
  How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 The principle of conservation of energy can be modeled by the energy transformations along food
chains and energy production systems: what are the strengths and limitations for such models?
 How do the delays involved in feedback loops make it difficult to predict tipping points and add to
the complexity of modelling systems?
 Do the benefits of the models used to predict tipping points outweigh their limitations?
 How does sustainability reduce the change that tipping points will be reached?

Knowledge and Understanding

U 1.3.1 The first law of thermodynamics is the principle of conservation of energy, which states
that energy in an isolated system can be transformed but cannot be created or destroyed
[The use of examples in this sub-topic is particularly important so that the abstract concepts have a
context in which to be understood]

image from apesnature.homestead.com

1st: energy is neither created nor destroyed, only changes forms. This is the principle of conservation of
energy, Energy in an isolated system can be transformed but cannot be created or destroyed.

 Ex: solar radiation -> sugars -> chemical energy -> chemical energy again

(Both laws should be examined in relation to the energy transformations and maintenance of order in
living systems.)

U 1.3.2 The principle of conservation of energy can be modelled by the energy transformations
along food chains and energy production systems.

30
The principle of conservation of energy states that energy cannot be created or destroyed, i.e. in an
isolated system, the total energy before transformation is equal to the total energy transformation.
Energy can only be changed from one form to another. Energy for the functioning of an ecosystem comes
from the Sun. Solar energy is absorbed by plants where in it is converted to stored chemical energy.

U 1.3.3 The second law of thermodynamics states that the entropy of a system increases over
time. Entropy is a measure of the amount of disorder in a system. An increase in entropy arising
from energy transformations reduces the energy available to do work.

image from longpointbiosphere.com

The second law of thermodynamics states that whenever energy is transformed, there is a loss energy
through the release of heat.

Entropy of a system increases overtime. Entropy is a measure of the amount of disorder in a system. An
increase in entropy arising from energy transformations reduces the energy available to do work.

 Living systems are only maintained through constant input of new energy from the Sun
 Entropy is simply a quantitative measure of what the second law of thermodynamics describes:
the dispersal of energy in a process in our material world

U 1.3.4 The second law of thermodynamics explains the inefficiency and decrease in available
energy along a food chain and energy generation systems.

31
 This occurs when energy is transferred between
trophic levels as illustrated in a food chain When
one animal feeds off another, there is a loss of heat
(energy) in the process. Additional loss of energy
occurs during respiration and movement. Hence,
more and more energy is lost as one moves up
through trophic levels. This fact lends more
credence to the advantages of a vegetarian diet. For
example, 1350 kilograms of corn and soybeans is
capable of supporting one person if converted to
beef. However, 1350 kilograms of soybeans and
corn utilized directly without converting to beef
will support 22 people!

image from faculty.ycp.edu

U 1.3.5 As an open system, an ecosystem will normally exist in a stable equilibrium, either in a
steady-state equilibrium or in one developing over time (for example, succession), and maintained
by stabilizing negative feedback loops.
[A stable equilbrium is the condition of a system in which there is a tendency for it to return to the
previous equilibrium following disturbance]
[A steady-state equilibrium is the condition of an open system in which there are not changes over the
longer term, but in which there may be oscillations in the very short term]

32
 image from www.nature.com
As an open system, an ecosystem will normally exist in a stable equilibrium, either in a steady state
equilibrium or in one developing over time (for example Succession), and maintain y stabilizing negative
feedback loops.

 Steady-state: in open systems, continuous inputs and outputs of energy and matter, system as a
whole remains in a constant state, no long term changes. There may be oscillations in the very
short term.
 Static: no change over time; when the state of equilibrium is distributed, the system adapts a new
equilibrium; can’t occur in living systems
 Stable: the system returns to the same equilibrium after disturbances
 Unstable: system returns to a new equilibrium after disturbances

33
U 1.3.6 Negative feedback loops (stabilizing) occur when the output of a process inhibits or
reverses the operation of the same process in such a way as to reduce change—it counteracts
deviation.

Ecosystem feedback is the effect that change in one part of an ecosystem has on another and how this
effect then feeds back to effect the source of the change inducing more or less of it. These feedback
loops form the basic dynamics for regulating the state of the ecosystem.

In order for a system to maintain a steady state or average condition the system must possess the
capacity for self-regulation. Self-regulation in many systems is controlled by negative
feedback and positive feedback mechanisms.

Negative-feedback mechanisms control the state of the system by dampening or reducing the size of
the system's elements or attributes. Positive-feedback mechanisms feed or increase the size of one or
more of the system's elements or attributes over time.

Negative (stabilizing): tends to neutralize or counteract any deviation from an equilibrium and tends to
stabilize systems. The systems gets better or goes back to normal..

Resistance to drastic changes and thus stability in natural ecosystems are maintained in part by negative
feedback systems. These are familiar to you through considering the system that regulates the heat in
your home. When the temperature in your house decreases below some set point, the thermostat that
senses temperature is activated to send a "turn on" message to your furnace. Then, once the temperature
rises above another set point, the thermostat sends a message to the furnace, telling it to shut off. Thus,
the temperature in your house is maintained within bounds. This illustrates a negative feedback system.
Negative feedback systems act to maintain homeostasis within systems; that is, to keep them in a
reasonably constant state.

U 1.3.7 Positive feedback loops (destabilizing) will tend to amplify changes and drive the system
towards a tipping point where a new equilibrium is adopted.

34
 image from www.cen.ulaval.ca
Positive (destabilizing): results in a further decrease of output and the system is destabilized and
pushed into a new state of equilibrium. The situation gets worse.

Positive feedback stimulates change and it is responsible for the sudden appearance of rapid changes
within ecosystems. When part of the system increases, another part of the system also changes in a way
that makes the first part increase even more. Positive feedback is a source of instability and change as it
can drive the system outside of its equilibrium. As an example more population leads to more births, and
more births lead to an increasing population creating a compounding effect over time.

The self-regulation of natural systems is achieved by the attainment of equilibrium through feedback
systems.
Feedback links involve time lags.

image from www.nature.com

U 1.3.8 The resilience of a system, ecological or social, refers to its tendency to avoid such tipping
points and maintain stability
[Emphasis should be placed on the relationships between resilence, stability, equilibria and diversity]

35
 image from www.oceanclimatechange.org.au
Resilience is the ability of a system to return to its initial state after a disturbance
High resilience = return to equilibrium
Low resilience = enter a new state/equilibrium
Resilience is usually good but can be bad

A tipping point is a critical threshold when even a small change can have dramatic effects and cause a
disproportionately large response in the overall system. Positive feedback loops are destabilizing and
tend to amplify changes and drive the system towards a tipping point where a new equilibrium is
adopted. Most projected tipping points are linked to climate change and represent points beyond which
irreversible change or damage occurs. Increases in CO2 levels that would lead to increased global
mean temperature, causing melting of the ice sheets and permafrost. Reaching such a tipping would, for
example, cause long-term damage to societies, the melting of Himalayan mountain glaciers, and a lack of
freshwater in many Asian societies.

Positive feedback loops (destabilizing) will tend to amplify changes and drive the system towards a
tipping point where a new equilibrium is adopted. A tipping point is the minimum amount of change within
a system that will destabilize
it, causing it to reach a new equilibrium or stable state.

Systems at threat from tipping points include:

 Antarctic sea ecosystems  West African monsoon

 Arctic sea-ice  Amazon rainforest
 Greenland ice sheet  boreal forest.
 West Antarctic ice sheet  thermohaline circulation (THC)
 El-Niño-Southern Oscillation (ENSO)

U 1.3.9 Diversity and the size of storages within systems can contribute to their resilience and
affect their speed of response to change (time lags).

36
Resilience of a system will depend on its structure.

 The more diverse/complex an ecosystem, the more resilient it tends to be (more interactions
between species). The greater the species biodiversity of an ecosystem, the greater the
likelihood there is a species that can replace another if it dies (to maintain equilibrium).
 The greater the genetic diversity within a species, the greater resilience. A monoculture of wheat
or rice can be wiped out by disease if none of the plants have genetic resistance.
 Species that can shift geographic ranges are more resilient.
 The climate affects resilience. In the Arctic, regeneration/growth of plants is slow (low temps slow
down photosynthesis/cell respiration). In tropical rain forests, growth rates are fast (light, temp,
water are not limiting factors).
 The faster the rate at which a species can reproduce means recovery is faster. r-strategists (fast
reproductive rate) can recolonize the system better than K-strategists (slow reproducers).

U 1.3.10 Humans can affect the resilience of systems through reducing these storages and
diversity
[Examples of human impacts and possible tipping points should be explored].

Humans can remove or mitigate threats to the system (pollution, invasive species) – resulting in faster
recovery.

37
Humans can reduce size of storages by harvesting wood, fish and other natural resuources. Humans can
also reduce diversity by species extinction which leads to less resilience.

U 1.3.11 The delays involved in feedback loops make it difficult to predict tipping points and add
to the complexity of modelling systems.
[A tipping point is the minimum amount of change within a system that will destabilize it, causing it to
reach a new equilibrium or stable state]

Within limits an ecosystem can recover and re-establish its equilibrium. When the disturbance is too great
the ecosystem reaches a tipping point. The critical point in a situation, process, or system behold which a
significant and often unstoppable effect or change takes place. Past the tipping point the ecosystem can't
re-establish its equilibrium. Positive feedback pushes the ecosystem to a new equilibrium where there are
significant changes to biodiversity and services it provides

Applications and Skills

A 1.3.1 Explain the implications of the laws of thermodynamics to ecological systems.
Two thermodynamic laws govern the flow of energy within ecological systems. The first law states that
energy can be transformed from one form to another (e.g., conversion of solar energy to chemical energy
by photosynthesis), but cannot be created or destroyed. The second law establishes that energy
transformation processes are not 100% efficient. These laws dictate that a large proportion of the
chemical energy, approximately 90%, transferred between feeding (trophic) levels within a system is
converted to heat energy which is of limited value to the biotic portion of the system. The energy "loss"
between feeding levels results from an inefficient transfer of organic matter (e.g., gaseous, urinary and
fecal losses) and the energy required for internal maintenance of organisms (i.e., maintenance energy).
For example, only a portion of the solar energy converted into chemical energy by photosynthesis is
realized as growth because a portion is utilized in respiration. Similarly, animals utilize a large portion of
the total energy ingested for basal metabolism thereby diminishing the amount of energy available for
growth or transfer to subsequent feeding levels within the system
A 1.3.2 Discuss the resileance in a variety of systems

image from www.oceanclimatechange.org.au

38
Resilience is the capacity of an ecosystem to respond to a disturbance. Resilience is usually defined as
the capacity of an ecosystem to absorb disturbance without shifting to an alternative state and losing
function and services. Disturbances can include fires, flooding, windstorms, insect population explosions,
and human activities such as deforestation, fracking of the ground for oil extraction, pesticide sprayed in
soil, and the introduction of exotic plant or animal species.

Some disturbances can significantly affect an ecosystem and can cause an ecosystem to reach a
threshold beyond which some species can not recover. Human activities that adversely affect ecosystem
resilience such as reduction of biodiversity, exploitation of natural resources, pollution, land-use, and
anthropogenic climate change are increasingly causing changes in ecosystems, often to less desirable
conditions.

Diversity and the size of storage's withing systems can contribute to their resilience and affect their speed
of response to change (time lag)

You need discuss resilience in a variety of systems

image from www.chikyu.ac.jp

A 1.3.3 Evaluate the possible consequences of tipping points
Evaluate: Make an appraisal by weighing up the strengths and limitations.

image from ecotippingpoints.org

The resilience of a system, ecological or social, refers to its tendency to avoid such tipping points and
maintains stability. A tipping point is the minimum amount of change within a system that will destabilize
it, causing it to reach a new equilibrium or stable state.

An environmental tipping point is a part of the human-environment system that can lever far-reaching
change in the system. A change at the tipping point sets in motion mutually reinforcing feedback loops

39
that propel the system on a completely new course.

The delays involved in feedback loops make it difficult to predict tipping points and add to the complexity
of modelling systems

 Lake Eutrophication:
 Extinction of a Keystone Species: Removal of elephants from a savannah ecosystem can result
in irreversible damage to that system.
 Coral Reef Death: If ocean acidity levels increase, the reef coral dies and cannot regenerate.

You need to understand the relationships between resilience, stability, equlibria and diversity
using specific examples to illustrate interactions.

Key Terms
positive feedback negative feedback sustainability ecosystem genergy efficiency
tipping-point entropy thermodynamics equilibrium flows
resilient destabilizing energy transfer storage steady-state equilibrium
stability stabilizing equilibria energy energy transformation
diversity work transformation static stable equilibria
stability global warming transfer equilibrium complexity
monoculture albedo predator/prey unstable precautionary principle
Laws of Principle of the entropy equilibria eutrophication
Thermodynamics Conservation of Energy albedo transformations
homeostasis
keystone species

40
TOPIC 1.4: SUSTAINABILITY

image from www.ifmaoregon.org

Sustainability is a broad discipline, giving you insights into most aspects of the human world from
business to technology to environment and the social sciences. Sustainability is the study of how natural
systems function, remain diverse and produce everything it needs for the ecology to remain in balance. It
also acknowledges that human civilization takes resources to sustain our modern way of life.

We live in a modern, consumerist and largely urban existence throughout the developed world and
consume natural resources every day. In our urban centers, we consume more power than those who live
in rural settings and urban centers use a lot more power than average, keeping streets and civic buildings
lit, to power our appliances, our heating and other public and household power requirements. It is
estimated that we use about 40% more resources every year than we can put back and that needs to
change. Sustainability and sustainable development focuses on balancing between competing needs -
our need to move forward technologically and economically, and the needs to protect the environments in
which we and others live. Sustainability is not just about the environment, it's also about our health as a
society in ensuring that no people or areas of life suffer as a result of environmental legislation, and it's
also about examining the longer term effects of the actions humanity takes and asking questions about
how it may be improved.

This unit will take a minimum of 4.5 hours

Significant Ideas

 All systems can be viewed through the lens of sustainability.

 Sustainable development meets the needs of the present without compromising the ability of
future generations to meet their own needs.
 Environmental indicators and ecological footprints can be used to assess sustainability.
 Environmental impact assessments (EIAs) play an important role in sustainable development.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
through this topic?
 What have you learned about sustainability and sustainable development in this chapter?
 What are the differences between sustainability and sustainable development?
 Ecological Footprint is a model used to estimate the demands that human populations place on
the environment; what are the limitations and benefits of these models
 How do EIAs ensure that development is sustainable?

41
Knowledge and Understanding
U 1.4.1 Sustainability is the use and management of resources that allows full natural replacement
of the resources exploited and full recovery of the ecosystems affected by their extraction and
use

image from pork.org

Environmental sustainability involves making decisions and taking action that are in the interests of
protecting the natural world, with particular emphasis on preserving the capability of the environment to
support human life. It is an important topic at the present time, as people are realising the full impact that
businesses and individuals can have on the environment.

Environmental sustainability is about making responsible decisions that will reduce the negative impact
on the environment. It is not simply about reducing the amount of waste you produce or using less
energy, but is concerned with developing processes that will lead to becoming completely sustainable in
the future

Sustainability is the use of global resources at a rate that allows natural regeneration and minimizes
damage to the environment. for example, a system of harvesting resources at a rate that allows
replacement by natural growth

Some economists may view sustainable development as a stable annual return on investment regardless
of the environmental impact, whereas some environmentalists may view it as a stable return without
environmental degradation. Consider the development of changing attitudes to sustainability and
economic growth, since the Rio Earth Summit (1992) leading to Agenda 21.

42
Sustainability can be encouraged by:

 ecological land-use to maintain habitat quality and connectivity for all species.
 sustainable material cycles, (ex carbon, nitrogen, and water cycles).
 social systems that contribute to a culture of sufficiency that eases the consumption pressures
on natural capital.

International summits on sustainable development have highlighted the issues involved in economic
development across the globe, yet the viewpoints of environmentalists and economists may be very
different.

U 1.4.2 Natural capital is a term used for natural resources that can produce a sustainable natural
income of goods or services

image from permadesign.com

There are three broad classes of natural capital.

 Renewable natural capital - living species and ecosystems. They are self-producing and self-
maintaining. They use solar energy and photosynthesis. This natural capital can yield marketable
goods such as wood fiber, but may also provide unaccounted essential services when left in
place, for example, climate regulation.
 Replenishable natural capital - groundwater and the ozone layer, is nonliving but is also often
dependent on the solar “engine” for renewal.
 Non-renewable capital - fossil fuel and minerals, are analogous to inventories: any use implies
liquidating part of the stock.

Renewable: solar energy, biomass energy, wind energy, hydro-power energy and geothermal energy.

Non-renewable: fossil fuel oils, coal, nuclear and natural gas

U 1.4.3 Natural income is the yield obtained from natural resources

43
 mage from architectstrace.wordpress.com
Any society that supports itself in part by depleting essential forms of natural capital is unsustainable. If
human well-being is dependent on the goods and services provided by certain forms of natural capital,
then longterm harvest (or pollution) rates should not exceed rates of capital renewal. Sustainability means
living, within the means of nature, on the “interest” or sustainable income generated by natural capital.

This can be encouraged by:

 Ecological land-use to maintain habitat quality and connectivity for all species.
 Sustainable material cycles, (ex carbon, nitrogen, and water cycles).
 Social systems that contribute to a culture of sufficiency that eases the consumption pressures on
natural capital.

image from travel.wikinut.com

Organisms or ecosystems have value:

 Intrinsic values: values that are not determined by their potential use to human, their value is
given vary by culture, religion, etc. E.g. a statue
 Economic value-: value that are determined from the market price of the good and services a
resources produce.
 Ecological Value: value that have no formed market price but are essential to human e.g.
photosynthesis
 Aesthetic Value: no market price, similar to ecological value,(basically things that look good). E.g.
landscape

44
Organisms or ecosystems that are valued on aesthetic or intrinsic grounds may not provide commodities
identifiable as either goods or services, and so remain unpriced or undervalued from an economic
viewpoint. Organisms or ecosystems regarded as having intrinsic value, for instance from an ethical,
spiritual or philosophical perspective, are valued regardless of their potential use to humans. Therefore,
diverse perspectives may underlie the evaluation of natural capital. Attempts are being made to
acknowledge diverse valuations of nature (for example, biodiversity, rate of depletion of natural
resources) so that they may be weighed more rigorously against more common economic values (for
example, gross national product (GNP)). However, some argue that these valuations are impossible to
quantify and price realistically. Not surprisingly, much of the sustainability debate centers on the problem
of how to weigh conflicting values in our treatment of natural capital.

How can we quantify values such as aesthetic value, which are inherently qualitative?

You need to be able to explain the relationship between natural capital, natural income and
sustainability, and discuss the value of ecosystem services to a society.

U 1.4.4 Ecosystems may provide life-supporting services such as water replenishment, flood and
erosion protection, and goods such as timber, fisheries, and agricultural crops.

Ecosystems may provide life-supporting services such as water replenishment, flood and erosion
protection, and goods such as timber, fisheries, and agricultural crops.

Ecologically minded economists describe resources as “natural capital”. If properly managed, renewable
and replenishable resources are forms of wealth that can produce “natural income” indefinitely in the form
of valuable goods and services.

 marketable commodities such as timber and grain (goods)

 ecological services such as the flood and erosion protection provided by forests (services).
 non-renewable resources cannot generate wealth without liquidation of the estate.

Removing natural vegetation has a “cost”: Loss of carbon uptake, disruption of water and nutrient cycles
and even just the loss of the aesthetic value all have a cost. The difficult part of natural capital is
prescribing a “value” in economic terms to the goods and services the biosphere provides.

45
 image from www.energy4me.org
Consider how cultural, economic, technological and other factors influence the status of a resource over
time and space.

 Uranium, due to the development of nuclear technology, has only recently become a
valuable resource.
 Salt use to be more valuable than gold.

What this all means is that resources are dynamic, its status may change, it might become valuable or it
might become invaluable.

46
 image from www.trucost.com
U 1.4.5 Factors such as biodiversity, pollution, population or climate may be used quantitatively
as environmental indicators of sustainability. These factors can be applied on a range of scales,
from local to global. The Millennium Ecosystem Assessment (MA) gave a scientific appraisal of
the condition and trends in the world’s ecosystems and the services they provide using
environmental indicators, as well as the scientific basis for action to conserve and use them
sustainably

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 image from ResearchGate
The Millennium Ecosystem Assessment is a United Nations project designed to assess the
consequences of ecosystem changes for human well-being. The objective of the multiyear exercise was
to both assess the consequences of ecosystem changes for human well-being, and to establish a
scientific basis for action to conserve the sustainable use of ecosystems and their contribution to human
well-being.

Five Main Assessments:

1. Over the past 50 years, humans have changed ecosystems more rapidly and extensively than in
any comparable period of time in human history, largely to meet rapidly growing demands for
food, fresh water, timber, fiber and fuel. This has resulted in a substantial and largely irreversible
loss in the diversity of life on Earth.
2. The changes that have been made to ecosystems have contributed to substantial net gains in
human well-being and economic development, but these gains have been achieved at growing
costs in the form of the degradation of many ecosystem services, increased risks of nonlinear
changes, and the exacerbation of poverty for some groups of people. These problems, unless
addressed, will substantially diminish the benefits that future generations obtain from ecosystems.
3. The degradation of ecosystem services could grow significantly worse during the first half of this
century and is a barrier to achieving the Millennium Development Goals.
4. The challenge of reversing the degradation of ecosystem while meeting increasing demands for
services can be partially met under some scenarios considered by the MA, but will involve
significant changes in policies, institutions and practices that are not currently under way. Many
options exist to conserve or enhance specific ecosystem services in ways that reduce negative
trade-offs or that provide positive synergies with other ecosystem services.

You need to be able to discuss how environmental indicators (such as Millennium Ecosystem
Assessment) can be used to evaluate the progress of a project to increase sustainability.

48
U 1.4.6 EIAs incorporate baseline studies before a development project is undertaken. They
assess the environmental, social and economic impacts of the project, predicting and evaluating
possible impacts and suggesting mitigation strategies for the project. They are usually followed
by an audit and continued monitoring. Each country or region has different guidance on the use
of EIAs

image from A & N Technologies, Bengaluru

EIA involves production of a baseline study before any environmental development, assessment of
possible impacts, and monitoring of change during and after the development.

49
Process for identifying the likely consequence for the biophysical environment and for man’s health and
welfare of implementing particular activities and for conveying information at a stage where it can
materially affect the decision, to those for sanctioning the proposals. (long definition).

The developments that need EIA’s differ from country to country, but certain types of developments tend
to be included in the EIA process in most parts of the world.

Purpose of the EIA:

Helps the decision making process by providing information about the consequences of the environment.
Promotes sustainable development by identifying environmentally sound practice and migration
measures for development.

Used for:
Planning process that governments set out in law when large developments are considered. They provide
a documented way of examining environmental impacts that can be used as evidence in the decision
making process of any new development.

What developments used in the EIA:

 Major new road networks

 Airport/port developments
 Building power stations
 Building dams and reservoirs
 Quarrying
 Large scale housing projects.

U 1.4.7 EIAs provide decision-makers with information in order to consider the environmental
impact of a project. There is not necessarily a requirement to implement an EIA’s proposals, and
many socio-economic factors may influence the decisions made.
An environmental impact assessment (EIA) is a planning tool that provides decision makers with an
understanding of the potential effects that human actions, especially technological ones, may have on the
environment. By understanding the potential environmental effects of an action, policymakers can choose
which should proceed and which should not. Governments from around the world perform environmental
impact assessments at the national, state or provincial, and local levels. The underlying assumption of all
environmental impact assessments is that all human activity has the potential to affect the environment,
and that knowledge concerning the environmental impact of a major decision will improve that decision

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Used in many countries, the aim of EIA is to reduce the environmental impact of a project at the earliest
possible stage during the project cycle, that is, during the planning stage. Whilst EIA processes differ
between countries and projects, there are several common components:

 Screening - is an EIA required; what level of detail is required.

 Scoping - what are the issues and impacts of the project; who are the stakeholders; what is the
current state of the environment.
 Identification of alternatives - what alternatives exist.
 Impact analysis - what are the environmental, social and other related impacts of the project.
 Mitigation and impact management - how will the impacts be mitigated, reduced or managed.
 Evaluation of significance - are the impacts acceptable.
 Preparation of an Environmental Impact Statement (EIS) or report - documentation of the
proposal, impacts, impact mitigation and management options, level of significance and
concerns.
 Review of EIS - EIS is open for public comment for a sufficient period of time.
 Decision making - public comments considered and a decision made whether to accept the
proposal as is, modify the proposal or reject the proposal outright.
 Monitoring and review - develop an implementation plan; begin monitoring and review of the
project.

U 1.4.7 Criticisms of EIAs include: the lack of a standard practice or training for practitioners, the
lack of a clear definition of system boundaries and the lack of inclusion of indirect impacts.
EIA has suffered much criticism over the years including criticism about: poor public consultation
practices; poorly written reports; costly, inefficient and time consuming practices; limited scope;
information understated or omitted from reports; EIA treated as a separate process and not integrated
into the project cycle; lack of monitoring and review of terms set out in reports; and inconsistent
application. The result is a lack of confidence in the EIA process by both decision makers and the general
public.

You need to be able to evaluate the use of EIAs. Criticisms of EIAs include the lack of a standard
practice or training for practitioners, the lack of a clear definition of system boundaries, and the
lack of inclusion of indirect impacts.

U 1.4.8 An ecological footprint (EF) is the area of land and water required to sustainably provide
all resources at the rate at which they are being consumed by a given population. If the EF is
greater than the area available to the population, this is an indication of unsustainability

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 image from wwf.panda.org
The ecological footprint of a population is the area of land, in the same vicinity as the population, that
would be required to provide all the population’s resources and assimilate all its wastes. As a model, it is
able to provide a quantitative estimate of human carrying capacity. It is, in fact, the inverse of carrying
capacity. It refers to the area required to sustainably support a given population rather than the
population that a given area can sustainably support.

Ecological footprints are the hypothetical area of land required by a society, group or individual to fulfill all
their resources needs and assimilation of wastes.

As a model, it is able to provide a quantitative estimate of human carrying capacity. It is, in fact, the
inverse of carrying capacity. It refers to the area required to sustainability support given population rather
than the population that a given area can sustainably support.

Ecological footprints can be increased by:

 greater reliance on fossil fuels

 increased use of technology and energy (but technology can also reduce the footprint)
 high levels of imported resources (which have high transport costs)
 large per capita production of carbon waste (high energy use, fossil fuel use)
 large per capita consumption of food
 a meat-rich diet

Ecological footprints can be reduced by:

 reducing use of resources

 recycling resources
 reusing resources
 improving efficiency of resource use
 reducing amount of pollution produced

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  transporting waste to other countries to deal with
 improving country to increase carrying capacity
 importing resources from other countries
 reducing population to reduce resource use
 using technology to increase carrying capacity
 using technology to intensify land

Application and Skills

A 1.4.1 Explain the relationship between natural capital, natural income and sustainability

Natural capital refers to the source or supply of resources and services that are derived from nature.
Forests, mineral deposits, fisheries and fertile soil are some examples of natural capital. Air and water
purification are just two of many services.

Natural Income is the annual yield from such sources of natural capital - timber, ores, fish and plants,

53
respectively, relative to the examples above. The point at which the amount of natural income used up
reduces the capacity of natural capital to continue providing the same amount of natural income in the
future, is the point at which sustainable scale has been exceeded.

Natural resources are not the only type of natural income which flow from ecosystems. A variety of
ecosystem functions are also provided. Forests, for example, are not simply wood production units. They
also prevent soil erosion, absorb rain water and provide flood control, they provide habitat for a diversity
of plant and animal species which may serve as foods or medicines for other species, they absorb the
natural wastes of these diverse life forms, they generate oxygen and sequester carbon from the
atmosphere, they affect the microclimate of their area, they are a key component of the hydrologic cycle,
as well as providing aesthetic enjoyment and spiritual inspiration. These forest ecosystem functions
evolved to maintain the overall health of the forest environment and the creatures in it. Ecosystem
functions are another form of natural income derived from the same natural capital of the forest
ecosystem that generates timber for economic use. Ecosystem functions that have particular value to
humans are called ecosystem services

Sustainability is the rate at which a resource depletion reduces the capacity of natural capital to provide
the future natural income. As long as the draw down exceeds the rate of replenishment, the amount
available will eventually shrink to zero - sustainability is destroyed. Sustainability allows you to focus at
least as much on ecosystem services, and the natural income they provide, as on resources. Because
natural capital is excluded from economic theory and practice, these vital, life supporting sources of
natural income essential for sustainability, are considered to have no market value and are therefore
ignored.

A 1.4.2 Discuss the value of ecosystem services to a society.

image from www.constantinealexander.net

Ecosystems have value because they maintain life on Earth and the services needed to satisfy human
material and nonmaterial needs. In addition, many people ascribe ecological, sociocultural, or intrinsic
values to the existence of ecosystems and species. The Millennium Assessment recognizes these
different paradigms, based on various motivations and concepts of value, along with the many valuation
methods connected with them. Ecosystems and the provisioning, regulating, cultural, and supporting
services they provide have economic value to human societies because people derive utility from their
actual or potential use, either directly or indirectly (known as use values). People also value ecosystem
services they are not currently using (non-use values). This paradigm of value is known as the utilitarian
(anthropocentric) concept and is based on the principles of humans’ preference satisfaction (welfare).

A 1.4.3 Discuss how environmental indicators such as MA can be used to evaluate the progress of
a project to increase sustainability
Presented at UN Millennium Summit in 2000
189 Nations signed the Declaration
8 Goals to be achieved by 2015:

 Goal 1: Eradicate Extreme Poverty & Hunger

 Goal 2: Universal Primary Education
 Goal 3: Gender Equality and Empower Women

54
  Goal 4: Reduce Child Mortality
 Goal 5: Improve Maternal Healthcare
 Goal 6: Combat HIV/AIDS, malaria, and other diseases
 Goal 7: Ensure Environmental Sustainability
 Goal 8: Develop a Global Partnership for Development

A 1.4.4 Evaluate the use of EIAs.

EIA is not the only tool to achieve sustainability, the EIA process is still a very effective tool in evaluating
the sustainability of development proposals. However, to measure the extent to which EIAs substantially
address “sustainability”, the sustainability criteria must go beyond adherence to procedural requirements
and address substantive considerations such as the sustainable use of resources, poverty and inequality.

 EIA often focuses on biophysical issues (often a fault of poor terms of reference);
 Where environment, social and economic aspects are addressed, they are not always addressed
in an integrated way (EIA reports tend to present as separate chapters)
 EIA provides an opportunity to learn from experience of similar projects and avoids the (often
high) costs of subsequently mitigating unforeseen negative and damaging impacts.
 EIA Improves long-term viability of many projects

A 1.4.5 Explain the relationship between EFs and sustainability.

When humanity's ecological resource demands exceed what nature can supply, we reach ecological
overshoot
The effects: carbon-induced climate change, species extinction, deforestation, dead coral reefs and the
loss of groundwater

The human footprint has more than tripled since 1960

Key Terms
natural income intrinsic environmental impact renewable
natural capital aesthetic sustainable replenishable
sustainable yield ecological footprint carrying capacity non-renewable
natural resource biomass resource Earthshare
renewable non-renewable remanufacturing sustainable
reuse recycling scoping development
non-technical pollution development baseline study
summary sustainable The Millennium mitigation
sustainability ecological overshoot Ecosystem Environmental Impact
ecological footprint Assessment Assessment
baseline study

55
TOPIC 1.5: HUMANS AND POLLUTION

A pollutant is a substance or energy introduced into the environment that has undesired effects, or
adversely affects the usefulness of a resource. A pollutant may cause long- or short-term damage by
changing the growth rate of plant or animal species, or by interfering with human amenities, comfort,
health, or property values (wikipedia.com).

Most cases of non-point source pollution exemplify well the intractable ethical problem of the “tragedy of
the commons”. That is to say, an individual polluting a common resource suffers little themselves from
their own pollution and yet may benefit considerably in other ways.

The interactions within the environment may be changed or damaged by human activity. Today, we are
probably more conscious of the environment than ever before, but significant damage has already been
done. Many of these activities continues today. Industrial processes, burning of fossil fuels, agricultural
production, and growing population pressures all increased levels of pollution. Incidents such the
Fukashima Powerplant and Deep Water Horizon, may grab big headlines, but just as important are the
many small acts which added together increase the impact on a habitat

In this unit you will understand the concept of pollution, how pollution is formed, pollution management
strategies, This unit is 2.5 hour.

Significant Ideas

 Pollution is a highly diverse phenomenon of human disturbance in ecosystems.

 Pollution management strategies can be applied at different levels.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 What value systems can you identify at play in the causes and approaches to resolving the issues
addressed in this topic?
 How can systems diagrams be used to show the impact of pollution on environmental and social
systems?
 How do EVSs influence the choice and implementation of pollution management strategy?

Knowledge and Understanding

U 1.5.1 Pollution is the addition of a substance or an agent to an environment through human
activity, at a rate greater than that at which it can be rendered harmless by the environment, and

56
which has an appreciable effect on the organisms in the environment.
[The term pollutant and contaminant in environmental chemistry are considered more or less
synonymous]

Pollution is the release into the environmental of a substance or an agent by human activities at a rate at
which in cannot be rendered harmless.

Pollution can be natural, deliberate or may be accidental. It includes the release of substances that affect
air, water and soil, and which reduces human quality of life.

U 1.5.2 Pollutants may be in the form of organic or inorganic substances, light, sound or thermal
energy, biological agents or invasive species, and may derive from a wide range of human
activities including the combustion of fossil fuels.
Sources of pollutants are combustion of fossil fuels, domestic and industrial waste, manufacturing and
agricultural systems.
Some sources of pollutants can't be contained by natural boundaries and therefore can act either locally,
regionally or globally such as acid rain

You are expected to be able to construct system diagrams to show the impact of pollutants
U 1.5.3 Pollution may be non-point or point source, persistent or biodegradable, acute or chronic.
[Pollution which arises from numerous widely dispersed origins is described as non-point source. Point
source pollution arises from a single clearly identifiable site]
[Biodegradable means capable of being broken down by natural biological processes]

Point source pollution is generally more easily managed because its impact is more localized, making it
easier to control emission, attribute responsibility and take legal action.

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Persistent organic pollutants (POPs):

 Organic compounds that do not break down in the environmental through chemical, biological,
and light processes. Because of their persistence, POPs bioaccumulate with potential significant
impacts on human health and the environment. The effect of POPs on human and environmental
health was discussed, with intention to eliminate or severely restrict their production, by the
international community at the Stockholm Convention on Persistent Organic Pollutants in 2001.

 Many POPs are currently or were in the past used as pesticides, solvents, pharmaceuticals, and
industrial chemicals. Although some POPs arise naturally, for example volcanoes and various
biosynthetic pathways, most are man-made

Biodegradable pollutants

 Decay or breakdown of pollution that occurs when microorganisms use an organic substance as
a source of carbon and energy. The products are rendered harmless by natural processes and so
causes no permanent harm.

Acute pollutants

 Pollution of significance which occurs suddenly and should take into account worst case
discharge scenario from the facility. Typical examples are larger oil spill due to pipe rupture or a
blow out from a well.

Chronic pollutants

58
  A persistent release of a pollutant at a low concentration resulting in adverse effects on animal or
human body with symptoms that develop slowly, due to long and continuous exposure to low
concentrations of a hazardous substance. Such symptoms do not usually subside when the
exposure stops.

U 1.5.4 Pollutants may be primary (active on emission) or secondary (arising from primary
pollutants undergoing physical or chemical change).

Pollutants are classified as primary or secondary based on their characteristics while they are emitted and
physical/chemical changes they undergo while in the environment.

The pollutants emitted into the environment directly from the identifiable sources and remains unchanged
within that environment are known as primary pollutants.

The pollutants which undergo chemical changes in the environment as a result of reactions among two or
more pollutants are called secondary pollutants.

The pollutants like sulphur dioxide, nitrogen dioxide and particulates are recognized as primary pollutants
while several other air pollutants are categorized as secondary pollutants.

59
 image from www.gov.scot
U 1.5.5 Dichlorodiphenyltrichloroethane (DDT) exemplifies a conflict between the utility of a
“pollutant” and its effect on the environment.

image from www.scienceclarified.com

DDT was developed as the first of the modern synthetic insecticides in the 1940s. It was initially used with
great effect to combat malaria, typhus, and the other insect-borne human diseases among both military
and civilian populations and for insect control in crop and livestock production, institutions, homes, and
gardens.

 quick success led to the development of resistance by many insect pest species.
 persistent organic pollutants that is extremely hydrophilic and strongly absorbed by soil
 has a soil half-life range from 22 days to 30 years
 banned after the publish of Silent Spring by Rachel Carson
 Stockholm Convention banned DDT internationally for agriculture but not for disease control

Rachel Carson highlighted the dangers of DDT in her groundbreaking 1962 book Silent Spring. Carson
used DDT to tell the broader story of the disastrous consequences of the overuse of insecticides, and

60
raised enough concern from her testimony before Congress to trigger the establishment of the
Environmental Protection Agency (EPA).

Her work attracted outrage from the pesticide industry and others. Her credibility as a scientist was
attacked, and she was derided as “hysterical,” despite her fact-based assertions and calm and scholarly
demeanor. Following the hearings, President Kennedy convened a committee to review the evidence
Carson presented. The committee's review completely vindicating her findings.

The use of DDT for malaria has many pros and cons that cause environmentalists, health organizations,
and governments to fall on either side of the fence. The main questions to ask in this nuanced argument
is whether the long-term health and ecological impacts of DDT outweigh the health benefits of DDT for
malaria, and whether there are alternatives that might work better at lower cost.

Application and Skills

A 1.5.1 Evaluate the effectiveness of each of the three different levels of intervention,
with reference to Figure 3.
[With reference to figure 3, students should appreciate the advantages of employing the earlier strategies
of pollution management over the later ones, and the importance of collaboration]
Pollutants are produced through human activities and create long-term effects when released into
ecosystems. Strategies for reducing these impacts can be directed at three different levels in the
process:

Change the human activity that generates the pollutant in the first place.

 this is the most proactive/preventative strategy because the pollutant is not created (or less of it is
created) in the first place
 tends to be difficult to achieve because it’s necessary to change the behavior of people,
businesses, and/or governments

Minimize the amount of the pollutant released into the environment.

 this is the next most proactive/preventative strategy because the pollutant is controlled at the
place where it is released
 this strategy is frequently adopted by government agencies that regulate industries because
monitoring is easiest at the place of emission
 this strategy fails to fully address the problem because the pollutant is still being produced

Clean up the pollutant and the affected areas after the pollutant has been released.

 this is a reactive strategy and tends to be very expensive; it also usually takes a very long time to
implement
 Sometimes it may not be scientifically possible
 this strategy does not solve the problem

Using Figure 3 show the value and limitations of each of the three different levels of intervention.
Appreciate the advantages of employing the earlier strategies over the later ones and the importance of
collaboration in the effective management of pollution.

61
Pollution management depends on all of the individuals involved. If there are associated costs then it
becomes harder to persuade people of the benefits of pollution management.

In many LEDC's, limited infrastructures such as the removal of domestic waste can become a major
issue. Societies awareness of problems and cultural acceptances can also impact pollution
management.

62
Cultural values, political systems and economic systems will influence the choice of pollution
management strategies and their effective implementation. Real examples should be considered.

 Cultural factors: if society adopts an 'out of sight, out of mind' approaches then individuals would
be more likely to dispose pollution in a more hazardous way.
 Political: weak regulation and lack of enforcement in LEDC’s; strong corporate involvement and
lobbying in policy decisions in MEDC’s
 Economic: pollution can be promoted if the environment is seen as a free resources; the cost of
reducing or cleaning pollution would reduce the likelihoods of solving the pollution problem

You need to be able to evaluate the effectiveness of each of the three different levels of intervention. The
principles of this figure should be use through the course when addressing issues of pollution. You should
appreciate the advantages of employing the earlier strategies of pollution management over the later
ones, and the importance of collaboration.

U 1.5.2 Evaluate the uses of DDT.

[Students might demonstrate knowledge of both the anti-malarial and agricultural use of DDT]
Disadvantages of DDT Advantages of DDT

 Broad spectrum
 Lead to premature birth, low birth weight  Non-toxic
and abnormal mental development of  Highly persistent giving long lasting effect
infants  Safe if used properly
 Alternatives methods of pest control exist  Alternatives are not as effective
 Would affect other wildlife  DDT significantly reduce malaria death e.g.
 Significant ecological effects in Ecuador between 1993-1995, the
 The effects of accumulation in human increase use of DDT= 61% reduction in
tissue are not fully known malaria
 Loss and degradation of soil  250 million/year of Malaria death
 Banning of DDT equal to increase in
malaria and resurgence of mosquitoes

S 1.5.1 Construct systems diagrams to show the impact of pollutants.

63
System diagrams allow individuals to visualize
and understand how processes work and how they might be improved. A process flow
diagram visually depicts:

 Inputs of the process or activity, which include energy and other resources consumed and raw
materials and chemicals used;
 Step-by-step process flows;
 Decision points (e.g., on alternate methods);
 Process outputs, which include products or services, air emissions, noise, odor,
radiation, wastewater discharges, solid waste, and hazardous wastes.

Key Terms
non point-source pollution contamination sewage storm water
pollution crude oil domestic waste industrial combustion
point-source pollution land refinery coal mercury
agriculture waste destruction cap and trade WHO DDT
oil spill pollution pollution waste restocking
Rachel Carson strategies management emission impact
replace restore regulate EPA culture value
replanting secondary Stockholm primary acute
fossil fuel chronic Convention (1972) persistent biodegradable
malaria free cycling

64
TOPIC 2.1: SPECIES AND POPULATIONS

A population is a subset of individuals of one species that occupies a particular geographic area and, in
sexually reproducing species, interbreeds. The geographic boundaries of a population are easy to
establish for some species but more difficult for others. For example, plants or animals occupying islands
have a geographic range defined by the perimeter of the island. In contrast, some species are dispersed
across vast expanses, and the boundaries of local populations are more difficult to determine. A
continuum exists from closed populations that are geographically isolated from, and lack exchange with,
other populations of the same species to open populations that show varying degrees of connectedness.

In this unit we will focus on how species interacts with its abiotic and biotic environments, and its niche is
described by these interactions.

This unit will take a minimum of 4.5 hours.

Significant Ideas

 A species interacts with its abiotic and biotic environments; its niche is described by these
interactions.
 Populations change and respond to interactions with the environment.
 A system has a carrying capacity for a given species.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?

Knowledge and Understanding

U 2.1 1 A species is a group of organisms that share common characteristics and that interbreed
to produce fertile offspring.
[Students should address this topic in the context of valid named species, for example use Atlantic
salmon rather than fish]

That definition of a species might seem cut and dried, but it is not — in nature, there are lots of places
where it is difficult to apply this definition. For example, many bacteria reproduce mainly asexually. The

65
bacterium shown at right is reproducing asexually, by binary fission. The definition of a species as a
group of interbreeding individuals cannot be easily applied to organisms that reproduce only or mainly
asexually. A species is often defined as a group of individuals that actually or potentially interbreed in
nature. In this sense, a species is the biggest gene pool possible under natural conditions.

U 2.1.2 A habitat is the environment in which a species normally lives.

[It is useful to be aware that for some organisms, habitats can change over time as a result of migration.]

image from www.britannica.com

A habitat is an ecological or environmental area that is inhabited by human, a particular species of
animal, plant, or other type of organism. A place where a living thing lives is its habitat. It is a place where
it can find food, shelter, protection and mates for reproduction. It is the natural environment in which an
organism lives, or the physical environment that surrounds a species population.

Be aware that for some organisms, habitats can change over time as a result of migration.

U 2.1.3 A niche describes the particular set of abiotic and biotic conditions and resources to
which an organism or population responds

image from www.paulnoll.com

A niche describes the particular set of abiotic and biotic conditions and resources to which an organism or
population responds.

Describes how an organism or population responds to the distribution of resources and competitors (for
example, by growing when resources are abundant, and when predators, parasites and pathogens are
scarce) and how it in turn alters those same factors (for example, limiting access to resources by other
organisms, acting as a food source for predators and a consumer of prey).

U 2.1.4 The fundamental niche describes the full range of conditions and resources in which a
species could survive and reproduce. The realized niche describes the actual conditions and
resources in which a species exists due to biotic interactions.

66
Every organism is adapted to environmental conditions in its habitat. However, it sometimes faces
competition with other species that limits the conditions under which it can exist. Explore how competition
between species can shape an organism's niche. The role that an organism plays in nature is
called ecological niche. For an animal, that niche includes things like its behavior, the food it eats, and
whether it is active at night or in the day.. Every organism, whether an apex predator like the lion or a
bacterium living in a hippo's intestinal tract, is likely to face competition from other species.. This direct
form of competition for an ecological niche is called interspecific competition.. This ideal niche that would
exist in the absence of competition from other species is called a species' fundamental niche. However,
organisms like the lion are generally forced to play a more limited role thanks to competition. The actual
niche that a species fills in the face of interspecific competition is called its realized niche.

image from www.quia.com

U 2.1 5 The non-living, physical factors that influence the organisms and ecosystem - such as
temperature, sunlight, pH, salinity and precipitation - are termed abiotic factors

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  Biotic: All the plants, animals, algae, fungi and microbes in an ecosystem.
 Abiotic: The chemical and physical factors in an ecosystem (non living) for example: temperature,
moisture, salininty, soil type, light, air

Abiotic factors vary in the environment and determining the types and numbers of organisms that exist in
that environment.

Factors which determine the types and numbers of organisms of a species in an ecosystem are
called limiting factors. Many limiting factors restrict the growth of populations in nature. An example of
this would include low annual average temperature average common to the Arctic restricts the growth of
trees, as the subsoil is permanently frozen.

 soil temperature
 air temperature
 wind speed
 sunlight intensity
 soil nutrients
 water
 pH

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U 2.1.6 The interactions between the organisms - such as predation, herbivory, parasitism,
mutualism, disease and competition - are termed biotic factors.
Competition between members of the same species is Intraspecific competition. Individuals of the
different species, competing for the same resources is called Interspecific competition.The other
outcome is that one species may totally out compete the other, this is the principle of Competitive
exclusion.

The word symbiosis literally means 'living together,' but when we use the word symbiosis in biology, what
we're really talking about is a close, long-term interaction between two different species. There are many
different types of symbiotic relationships that occur in nature.

 predation - one species feeds on another which enhances fitness of predator but reduces fitness
of prey. Herbivory is a form of predation.
 herbivory - the act of eating plants and a herbivore is an animal that eats plants. Herbivores play
an important role in the ecology of any area, influencing plant communities and individual plant
growth. A form of predation.
 parasitism - The host provides a habitat and food for the bacteria, but in return, the bacteria
cause disease in the host. This is an example of parasitism or an association between two
different species where the symbiont benefits and the host is harmed. Not all parasites have to
cause disease.
 mutualism - A type of symbiotic relationship in which both species benefit from the relationship.
 disease - a particular abnormal condition, a disorder of a structure or function, that affects part or
all of an organism. includes organisms such as viruses, bacteria, fungi and parasites that cause
disease.
 competition - the relationship between species that attempt to use the same limited resource
(e.g. hyenas fighting with lions over a carcass or trees competing for sunlight at the top of the
canopy)

 commensalism – one species receives a benefit from another species which enhances fitness of
one species; no effect on fitness of the other species.
 symbiosis - wo species live together which can include parasitism, mutualism, and
commensalism..

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 Predator-prey relationships are often controlled negative feedback mechanisms that control population densities
U 2.1.7 Interactions should be understood in terms of the influences each species has on the
population dynamics of others, and upon the carrying capacity of the others environment.

image from www.geo.arizona.edu

A population is a collection of individual organisms of the same species that occupy some specific area.
The term "population dynamics" refers to how the number of individuals in a population changes over
time. Biologists study the interations that affect population dynamics. Understanding populations
dynamics helps biologists understand the conservation of endangered species and management of fish
and wildlife. Basic knowledge about the processes that affect population dynamics can be used to predict
future patterns of human population growth.

The abundance of environmental resources such as food, water, and space determines how population
abundance changes over time. In the presence of unlimited resources, populations grow exponentially.

Density-dependent factors:
Factors that lower the birth rate or raise the death rate as a population grows in size. They are negative

70
feedback mechanisms leading to the stability or regulation of the population.
When prey increases so does the predator, but when this occurs the prey decreases and then again the
predators decrease too causing the prey to increase again.

Density-independent factors:
Factors that affect a population irrespective of population density notably environmental change. Abiotic
factors are density-independent factors, the most important ones are the extremes of weather (droughts,
fires and hurricane) and long-term climate change.
These factors have an impact that can increase the death rate and reduce the birth rate, it all depends on
how severe the event was.

Factors which regulate population size can be divided into either INTERNAL or EXTERNAL.

 Internal: fertility rates, territory sizes

 External: predation, pressure, parasitism

The major cause of population regulation are in the environments, these can be physical or biological.
The physical class of environmental factors are water availability, nutrient availability anf so on.
Biological factors include predators, and competition.

Ways humans can cause population growth:

 increase available resources

 reduce competition
 reduce pressure from predators
 introduce animals to new areas

Ways to decline population:

 change environment, cause habitat disruption

 change the biological environment by introducing new species
 cause secondary extinctions
 overkill

U 2.1.8 A population is a group of organisms of the same species living in the same area at the
same time, and which are capable of interbreeding.

image from www.ieu.uzh.ch

A population is a group of organisms of the same species living in the same area at the same time and
capable of interbreeding. These species share a requirement for a limited resource which reduces fitness
of one or both species.

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U 2.1.9 S and J population curves describe a generalized response of populations to a particular
set of conditions (abiotic and biotic factors).
In an environment where resources become limited, populations exhibit a pattern of growth called logistic
growth. In this case, if one plots the number of individuals in the population over time, one finds a
sigmoidal, or S-shaped curve. When population abundance is low, the population grows exponentially.
However, as population size increases, resources become limited, the population growth rate slows, and
the population abundance curve flattens. The number of individuals present in the population when the
growth rate slows to zero is referred to as K, the carrying capacity. The carrying capacity is the theoretical
maximum number of individuals that the environment can support.

A "J" curve hits its carrying capacity and just continues causing a population explosion and competition
for resources.
A population curve which shows only exponential growth. It starts slow the becomes increasingly fast.

U 2.1.10 Limiting factors will slow population growth as it approaches the carrying capacity of the
system
Carrying capacity is the maximum number of organisms that an area or ecosystem can sustainably
support over a long period of time.vThere are however limiting factors including temperatures, water and
nutrient availability. The main factors are temperature and water availability. Limiting factors are factors
that limit the distribution or numbers of a particular population. Limiting factors are environmental factors
which slow down population growth.

Temperature:
There are many ways the temperature can affect species. For example some seeds only grow in

72
extremely high temperatures as it enriches the soil with nutrients and kills competition. However some are
damaged if they are too warm or too cold. Some are able to survive low temperature. Animals adapt to
the hot/ cold temperature either by burrowing under the ground to avoid heat or having cold blood in the
heat.

Water:
All plants/animals need water to survive, for plants have no water could cause the plant to not germinate
or seeds to die. No water = Death.
Application and Skills
A 2.1.1 Explain population growth curves in terms of numbers and rates

image from
http://ibguides.com/biology/notes/populations
The sigmoid graph showing the population growth of a species has three phases which are; the
exponential phase, the transitional phase and the plateau phase. At the start of the sigmoid curve we can
see the exponential phase. This is where there is a rapid increase in population growth as natality rate
exceeds mortality rate. The abundant resources available such as food for all members of the population
and diseases as well as predators are rare. As time passes, the population reaches the transitional
phase. This is where the natality rate starts to fall and/or the mortality rate starts to rise. It is the result of a
decrease in the abundance of resources, and an increase in the number of predators and diseases.
However, even though population growth has decreased compared to the exponential phase, it is still
increasing as natality rate still exceeds mortality rate. Finally, the population reaches the plateau phase.
Here, the population size is constant so no more growth is occurring. This is the result of natality rate
being equal to mortality rate and is caused by resources becoming scarce as well as an increase in
predators, diseases and parasites. These are the limiting factors to the population growth. If natality rate
starts to drop then mortality rate will drop too as more resources become available. As natality rate starts
to increase again so does mortality rate as resources become scarce. This keeps the population number
relatively stable. If a population is limited by a shortage of resources then we say that it has reached the
carrying capacity of the environment

S 2.1.1 Interpret graphical representations or models of factors that affect an organism's niche.
Examples include predator prey relationships, competition, and organism abundance over time

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Key Terms
biotic abiotic species population habitat
niche preditor community communities ecology
predation prey parasitism mutualism ecosystem
fresh water interspecific terrestrial organisms immigration
parasitism commensalism biosphere predation migration
limiting factors carrying capacity intraspecific neutralism competition
S-curve density effect ammensilism intrinsic rate herbivory
fundamental realized niche biotic potential k-selected population density
niche interactions r-selected J-curve
abiotic factors natality mortality

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biotic factors limiting factors survivorship
environmental interspecies curves
resistance

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TOPIC 2.2: COMMUNITIES AND ECOSYSTEMS

image from www.geo.arizona.edu

An ecosystem has diverse living organisms. In the study of Ecology, these living organisms are
categorized on the basis of the level of organization. So at the basic numbers level we have the
population, then we identify the species and community to which that organism belongs, how it interacts
with the ecosystem and other organisms in the ecosystem. Scientists have also studied the interaction
between different organisms and classified their interactions into different types.

This unit will take a minimum of 5.5 hours.

Significant Ideas

 The interactions of species with their environment result in energy and nutrient flows.
 Photosynthesis and respiration play a significant role in the flow of energy in communities..
 The feeding relationships of species in a system can be modelled using food chains, food webs
and ecological pyramids.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 What are the strengths and weaknesses of models of food chains, food webs, and ecological
pyramids?
 How can pyramids of productivity be used to predict the effect of human activities on
ecosystems?
 How can systems diagrams be used to show energy flow through ecosystems? What are the
strengths and weaknesses of such diagrams?

Knowledge and Understanding

U 2.2.1 A community is a group of populations living and interacting with each other in a common
habitat

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Community refers to all the populations in a specific area or region at a certain time. Its structure involves
many types of interactions among species. Some of these involve the acquisition and use of food, space,
or other environmental resources. Others involve nutrient cycling through all members of the community
and mutual regulation of population sizes. In all of these cases, the structured interactions of populations
lead to situations in which individuals are thrown into life or death struggles.

In general, ecologists believe that a community that has a high diversity is more complex and stable than
a community that has a low diversity. This theory is founded on the observation that the food webs of
communities of high diversity are more interconnected. Greater interconnectivity causes these systems to
be more resilient to disturbance. If a species is removed, those species that relied on it for food have the
option to switch to many other species that occupy a similar role in that ecosystem. In a low diversity
ecosystem, possible substitutes for food may be non-existent or limited in abundance.

U 2.2.2 An ecosystem is a community and the physical environment with which it interacts

Everything in the natural world is connected. An ecosystem is a community of living and non-living things
that work together. Ecosystems have no particular size. An ecosystem can be as large as a desert or a
lake or as small as a tree or a puddle. If you have a terrarium, that is an artificial ecosystem. The water,
water temperature, plants, animals, air, light and soil all work together. If there isn't enough light or water
or if the soil doesn't have the right nutrients, the plants will die. If the plants die, animals that depend on
them will die. If the animals that depend on the plants die, any animals that depend on those animals will
die. Ecosystems in nature work the same way. All the parts work together to make a balanced system!

Some ecosystems can cross several countries and so their conservation and ecology has an international
dimension.

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 image from naturalscience-5.blogspot.com
U 2.2.3 Respiration and photosynthesis as processes with inputs, outputs and transformations of
energy and matter.
[The details of chloroplasts, light-dependent and light-independent reactions, mitochondria, carrier
systems, adenosine tripohosphate (ATP) and specific intermediate biochemicals are not expected]

Photosynthesis should be understood as requiring carbon dioxide, water, chlorophyll and certain visible
wavelengths of light to produce organic matter and oxygen. The transformation of light energy into the
chemical energy of organic matter should be appreciated.

Respiration should be recognized as requiring organic matter and oxygen to produce carbon dioxide and
water. Without oxygen, carbon dioxide and other waste products are formed. Energy is released in a form

78
available for use by living organisms, but is ultimately lost as heat.

Photosynthesis:

inputs:

 sunlight as energy resource, carbon dioxide and water

processes:

 chlorophyll traps sunlight; energy is used to split water molecules; hydrogen from water is
combined with carbon dioxide to produce glucose.

outputs:

 glucose used as an energy source for the plant and as a building block for other organic
molecules; oxygen is released to the atmosphere through stomata.

transformations:

 light energy is transformed to store chemical energy.

Respiration:

inputs:

 glucose and oxygen

processes:

 oxidation processes inside cells

outputs:

 release of energy for work and heat

transformations:

 stored chemical energy to kinetic energy and heat

U 2.2.4 Respiration is the conversion of organic matter into carbon dioxide and water in all living
organisms, releasing energy.
[The details of chloroplasts, light-dependent and light-independent reactions, mitochondria, carrier
systems, adenosine tripohosphate (ATP) and specific intermediate biochemicals are not expected]

79
 image from www.goldiesroom.org
Respiration releases energy for cells from glucose. This can be aerobic respiration, which needs oxygen,
or anaerobic respiration, which does not.

Respiration is a series of reactions in which energy is released from glucose. Aerobic respiration is the
form of respiration which uses oxygen. It can be summarised by this equation:

glucose + oxygen → carbon dioxide + water (+ energy)

Energy is shown in brackets because it is not a substance. Notice that:

 Glucose and oxygen are used up

 Carbon dioxide and water are produced as waste products

Aerobic respiration happens all the time in the cells of animals and plants. Most of the reactions involved
happen inside mitochondria, tiny objects inside the cytoplasm of the cell. The reactions are controlled by
enzymes.

U 2.2.5 During respiration, large amounts of energy are dissipated as heat, increasing the entropy
in the ecosystem while enabling organisms to maintain relatively low entropy and so high
organization.

Respiration is a chemical reaction where food, water and oxygen is turned into energy for us to use (also
allowing us to breathe etc.)

In every reaction there are 2 types of energy; useful and wasted. the useful energy is the stuff we want
and wasted is the stuff that's just converted accidentally while making the useful energy. it's wasted
because energy can't be destroyed or created, just changed. one type of wasted energy that's created in
most reactions is thermal, or heat energy.

As respiration is a chemical reaction, there are useful energy transfers taking place, however as a
byproduct of these reactions heat energy is produced.

U 2.2.6 Primary producers in most ecosystems convert light energy into chemical energy in the
process of photosynthesis.

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[The details of chloroplasts, light-dependent and light-independent reactions, mitochondria, carrier
systems, adenosine tripohosphate (ATP) and specific intermediate biochemicals are not expected]

Primary producers, also called autotrophs, are organisms that can produce their own food. Most
autotrophs lie at the bottom of the food chain, serving as food sources for animals farther up the line.
Primary producers are self-sufficient when it comes to meals: they produce their own food using light,
carbon dioxide, water and sometimes other chemicals too.

Producers (autotrophs) are typically plants or algae that produce their own food using photosynthesis and
form the first trophic level in a food chain. Exceptions include chemosynthetic organisms that produce
food without sunlight.

U 2.2.7 The photosynthesis reaction is can be represented by the following word equation. carbon
dioxide + water yields glucose + oxygen

Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of
sugar. This process occurs in plants and some algae. Plants need only light energy, CO2, and H2O to
make sugar. The process of photosynthesis takes place in the chloroplasts, specifically using chlorophyll,
the green pigment involved in photosynthesis.

The photosynthesis reaction is can be represented by the following word equation.

carbon dioxide + water  glucose + oxygen

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U 2.2.8 Photosynthesis produces the raw material for producing biomass
[Biomass, measured in unite of mass (for example, g m-2) should be distinguished from productivity,
measured in units of flow (for example, g m-2 hr-1 or J m-2 hr-1)]

Biomass is organic, meaning it is made of material that comes from living organisms, such as plants and
animals. The most common biomass materials used for energy are plants, wood, and waste. These are
called biomass feed stocks. Biomass energy can also be a non-renewable energy source.

Biomass contains energy first derived from the sun: Plants absorb the sun’s energy through
photosynthesis, and convert carbon dioxide and water into nutrients (carbohydrates).

U 2.2.9 The trophic level is the position that an organism occupies in a food chain, or the position
of a group of organisms in a community that occupy the same position in food chains

In ecology, the trophic level is the position that an organism occupies in a food chain, or a group of
organisms in a community that occupy the same position in food chains - what it eats, and what eats it.

Ecologists look at a natural "economy of energy" that ultimately rests upon solar energy. When they look
at an ecosystem there is almost always some foundation species that directly harvests energy from the
sun, for example, grass (however in deep sea hydrothermal vents chemosynthetic archaea form the base
of the food chain)

U 2.2.10 Producers (autotrophs) are typically plants or algae that produce their own food using
photosynthesis and form the first trophic level in a food chain. Exceptions include
chemosynthetic organisms that produce food without sunlight.

82
All life depends ultimately on primary producers, the organisms which capture the energy in sunlight by
photosynthesis. On land, they are easily recognized as plants. Although marine primary production by
coral reefs, mangroves and seagrasses is relatively better-known, the vast majority of primary production
in the sea is by microscopic single-celled plants called phytoplankton. Phytoplankton account for 50% of
the oxygen produced

An example is photosynthetic plants that make their own food from sunlight (using a process
called photosynthesis) and chemosynthetic bacteria that make their food energy from chemicals in
hydrothermal vents. These are called autotrophs orprimary producers.

U 2.2.11 Feeding relationships involve producers, consumers and decomposers. These can be
modelled using food chains, food webs and ecological pyramids
[The distinction between storage of energy illustrated by boxes i energy-flow diagrams (representing the
various trophic levels), and the flows of energy or productivity often sown as arrows (sometimes of
varying widths) needs to be emphasized.]

All living things need to feed to get energy to grow, move and reproduce. But what do these living things
feed on? Smaller insects feed on green plants, and bigger animals feed on smaller ones and so on. This
feeding relationship in an ecosystem is called a food chain. Food chains are usually in a sequence, with
an arrow used to show the flow of energy. Below are some living things that can fit into a food chain

Producer: can make their own food, as they use sunlight to make food and are called the basis of every
ecosystem which helps the rest of the species through input of energy and new biomass. This all
happens through photosynthesis which is the process when the producer uses the sun for energy.

Consumer: feed on other organisms, they do not contain photosynthesis pigments so they cannot make
their own food. They have to get energy, minerals and nutrients by eating other organisms. This makes
the heterotrophs. Herbivores feed on autotrophs, carnivores on other heterotrophs and omnivores on
both.

Decomposer: get their food from the breakdown of a dead organism matter. They break down tissue and

83
release nutrients for absorption by other producers. Decomposers also improve the nutrient capacity in
the soil by breaking down the organic material.

image from en.wikipedia.org

U 2.2.12 Ecological pyramids include pyramids of numbers, biomass and productivity and are
quantitative models that are usually measured for a given area and time
An ecological pyramid is an illustration of the reduction in energy as you move through each feeding
(trophic) level in an ecosystem. The base of the pyramid is large since the ecosystem's energy factories
(the producers) are converting solar energy into chemical energy via photosynthesis. A food chain can
also depict a reduction in energy at each feeding level if the arrows, drawn between the different levels,
continue to be reduced in size.

Pyramids are graphical models of the quantitative differences that exist between the trophic levels of a
single ecosystem. A pyramid of biomass represents the standing stock of each trophic level measured in
units such as grams of biomass per square metre (g m–2). Biomass may also be measured in units of
energy, such as J m –2.
U 2.2.13 In accordance with the second law of thermodynamics, there is a tendency for numbers
and quantities of biomass and energy to decrease along food chains; therefore, the pyramids
become narrower towards the apex
[This topic should be actively linked with sub-topic 1.3 as questions will arise requiring students to use
their knowledge of thermodynamics with energy flow in ecosystems]

Energy is lost as it is transferred between trophic levels; the efficiency of this energy transfer is measured
by net production efficiency and trophic level transfer efficiency. Only 10% of the energy is transferred to
the next, so the trophic efficiency=10%.

84
Endotherms have a low NPE and use more energy for heat and respiration than ectotherms, so most
endotherms have to eat more often than ectotherms to get the energy they need for survival.

Energy transfers within food webs are determined by the first and second laws of thermodynamics..

The second law relates to the quality of energy. This law states that whenever energy is transformed,
some of the energy will lost to a less useful form. In ecosystems, the biggest losses occur as respiration.
The second law explains why energy transfers are never 100% efficient. In fact, ecological efficiency,
which is the amount of energy transferred from one trophic level to the next, ranges from 5-30%. On
average, ecological efficiency is only about 10%.

Because ecological efficiency is so low, each trophic level has a successively smaller energy pool from
which it can withdraw energy. This is why food webs have no more than four to five trophic levels. Beyond
that, there is not enough energy to sustain higher-order predators

image from goose.ycp.edu

U 2.2.14 Bioaccumulation is the build-up of persistent or non-biodegradable pollutants within an
organism or trophic level because they cannot be broken down

Include concentration of non-biodegradable toxins in food chains, limited length of food chains, and
vulnerability of top carnivores. Consider the terms biomagnification, bioaccumulation and
bioconcentration.

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  Bioaccumulation refers to how pollutants enter a food chain. It is an increase in concentration of a
pollutant from the environment to the first organism in a food chain

If a pollutant is short-lived, it will be broken down before it can become dangerous. If it is not mobile, it
will stay in one place and is unlikely to be taken up by organisms. If the pollutant is soluble in water it will
be excreted by the organism. Pollutants that dissolve in fats, however, may be retained for a long time.

Toxins such as DDT and mercury accumulate along food chains due to the decrease of biomass and
energy

U 2.2.15 Biomagnification is the increase in concentration of persistent or non-biodegradable

pollutants along a food chain
Biomagnification refers to the tendency of
pollutants to concentrate as they move from one
trophic level to the next. It is an increase in
concentration of a pollutant from one link in a food
chain to another.

We are concerned about these phenomena because

together they mean that even small concentrations
of chemicals in the environment can find their way
into organisms in high enough dosages to cause
problems. In order for biomagnification to occur,
the pollutant must be:

1. long-lived
2. mobile
3. soluble in fats
4. biologically active

U 2.2.16 Toxins such as DDT and mercury accumulate along food chains due to the decrease of
biomass and energy
In the environment, insects would encounter DDT and absorb some of it into their bodies. Often, they
would receive a sub-lethal dose, enough to impair them but perhaps not kill them. In any event, it stands
to reason that insects either dying or merely slowed down by pesticide intake would become easy targets
for birds. Upon ingestion, the DDT in the insect bodies is released and makes its way into the tissues of
the bird's body, particularly the fat deposits. Because an individual bird eats many insects, and because
the DDT does not leave the bird's body, and because DDT resists breaking down (either in the
environment or the body), it accumulates to higher levels in the bird's tissues. In other words, the DDT
that was spread out over, say 1,000 crickets will be concentrated in one bird.
U 2.2.17 Pyramids of numbers can sometimes display different patterns; for example, when
individuals at lower trophic levels are relatively large (inverted pyramids)]

86
Pyramid of numbers:
shows the number of organisms at each trophic level in a food chain. Pyramids of numbers can
sometimes display different patterns; for example, when individuals at lower trophic levels are relatively
large (inverted pyramids).

Advantage

 easy method of giving an overview

 good for comparing changes in population numbers over different times

Disadvantage

 all organisms included regardless of their size

 numbers can be too great to represent accurately

U 2.2.18 A pyramid of biomass represents the standing stock or storage of each trophic level,
measured in units such as grams of biomass per square metre (g m-2) or Joules per square metre
(J m-2)(units of biomass or energy)
[Although there is variation in the literature, for this syllabus pyramids of biomass refers to a standing crop
(a fixed point in time) and pyramids of productivity refer to the rate of flow of biomass or energy]

Pyramid of biomass:
Contains the biomass at each trophic level. A pyramid of biomass represents the standing stock or
storage of each trophic level, measured in units such as grams of biomass per square metre (g m–
2). Pyramids of biomass can show greater quantities at higher trophic levels because they represent the
biomass present at a fixed point in time, although seasonal variations may be marked.

Advantage

 overcomes the problems of pyramids of numbers

Disadvantage

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  only uses samples from populations, so it’s impossible to measure biomass exactly
 organisms must be killed to measure dry mass

U 2.2.19 Pyramids of biomass can show greater quantities at higher trophic levels because they
represent the biomass present at a fixed point in time, although seasonal variations may be
marked.
[Although there is variation in the literature, for this syllabus pyramids of biomass refers to a standing crop
(a fixed point in time) and pyramids of productivity refer to the rate of flow of biomass or energy]
Pyramid of biomass is a diagram representing the amount of biomass measured in grams of dry mass
per square metre (g m−2), found in a particular habitat at ascending trophic levels of a food chain.
Biomass decreases at each ascending level of the food chain. A pyramid of biomass is a more accurate
representation of the flow of energy through a food chain than a pyramid of numbers, but seasonal
variations in the rate of turnover of the organisms at a particular level may result in higher or lower values
for the amount of biomass sampled at a particular time than the average amount over the whole year.
U 2.2.20 Pyramids of productivity refer to the flow of energy through a trophic level, indicating the
rate at which that stock/storage is being generated

Pyramid of productivity:
Pyramids of productivity refer to the flow of energy through a trophic level,
indicating the rate at which that stock/storage is being generated. It contains the flow of energy through
each trophic level; shows the energy being generated and available as food to the next trophic level
during a fixed period of time, measured in units such as flow of biomass or energy per square metre (g m-
2 yr-1) or Joules per square metre (J m-2 yr) (units of biomass or energy).

Advantage

 shows the actual energy transferred and allows for rate of production

Disadvantages

 very difficult and complex to collect energy data as the rate of biomass production over time is
required

U 2.2.21 Pyramids of productivity for entire ecosystems over a year always show a decrease along
the food chain.
Energy flows through the food chain in a predictable way, entering at the base of the food chain,
by photosynthesis in primary producers, and then moving up the food chain to higher trophic
levels. Because the transfer of energy from one trophic level to the next is inefficient, there is less energy
entering higher trophic levels. Thus, diagrams showing how much energy enters each trophic level will
have a distinct pyramid shape.
Application and Skill
A 2.2.1 Explain the transfer and transformation of energy as it flows through an ecosystem.

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Almost all energy enters Earth's ecosystems as solar insolation. That energy is then transformed an used
by the diverse variety of organisms that make up food webs. Through
photosynthesis, producers transform sunlight into glucose, which they then use for
respiration. Chloroplasts in plant cells use sunlight to convert CO2 and water to glucose and oxygen gas.
The plants' mitochondria then use the sugars for energy to drive respiration, their cellular processes
required to stay alive.

A 2.2.2 Analyse the efficiency of energy transfers through a system.

Gross primary production is a measure of the energy that a plants transform from the sun. The fraction of
that energy that is converted into glucose reflects the gross productivity of the plant. The energy
remaining after respiration is considered the net primary production. In general, gross production refers to
the energy contained within an organism before respiration and net production the energy after
respiration. The terms can be used to describe energy transfer in both autotrophs and heterotrophs.

Energy will decrease with each increase in trophic level- second law of thermodynamics states that during
any transfer of energy, some is lost due to the tendency toward an increase in disorder (entropy). Energy
for higher trophic levels is also constrained by loss due to metabolic respiration, as well as defensive
strategies in some organisms that lowers the quality of food Energy transfer between trophic levels is
generally inefficient, such that net production at one trophic level is generally only 10% of the net
production at the preceding trophic level

A 2.2.3 Explain the relevance of the laws of thermodynamics to the flow of energy through
ecosystems
Two laws of physics are important in the study of energy flow through ecosystems. The first law of
thermodynamics states that energy cannot be created or destroyed; it can only be changed from one form
to another. Energy for the functioning of an ecosystem comes from the Sun. Solar energy is absorbed by
plants where in it is converted to stored chemical energy.

The second law of thermodynamics states that whenever energy is transformed, there is a loss energy
through the release of heat. This occurs when energy is transferred between trophic levels as illustrated
in a food web. When one animal feeds off another, there is a loss of heat (energy) in the process.

89
Additional loss of energy occurs during respiration and movement. Hence, more and more energy is lost
as one moves up through trophic levels.
A 2.2.4 Explain the impact of a persistent or non-biodegradable pollutant in an ecosystem.
This refers to how long a pesticide remains active in the environment. Some chemicals are broken down
by decomposers in the soil (they’re biodegradable) and so are not persistent, while others cannot be
broken down by microbes (they’re non biodegradable) and so continue to act for many years, and are
classed as persistent pesticides. The early pesticides (such DTT) were persistent and did a great deal of
damage to the environment, and these have now largely been replaced with biodegradable insecticides
such as carbamates and pyrethroid

image from InTech

S 2.2.1 Construct models of feeding relationships such as food chains, food webs and ecological
pyramids from given data

image from users.rcn.com

Systems diagrams can be used to show the flow of energy through ecosystems. Stores of energy are
usually shown as boxes which represent the various trophic levels Flows of energy are usually shown as
arrows (with the amount of energy in joules or biomass per unit are represented by the thickness of the
arrow).
S 2.2.2 Construct system diagrams representing photosynthesis and respiration.

90
Key Terms
biotic abiotic trophic level food chain producer
consumer decomposer biomass food web pyramid of
pyramid of biomass pyramid of carnivore herbivore numbers
bioaccumulation productivity species population omnivore
niche bio- community ecosystem habitat
predation magnification parasitism mutualism competition
non-biological toxin paradigm photosynthesis respiration top carnivore
community prey chemosynthesis aerobic anaerobic
productivity bio- energy input transfer
respiration concentration entropy output transformation
ecological pyramids ecosystem matter photosynthesis ecosystem
laws of processes DDT & Mercury Flow vs detrivores
thermodynamics autotroph Stock/Storage MRS GREN
heterotroph

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TOPIC 2.3: FLOWS OF ENERGY AND MATTER

Energy "flows" through the ecosystem in the form of carbon-carbon bonds. When respiration occurs, the
carbon-carbon bonds are broken and the carbon is combined with oxygen to form carbon dioxide. This
process releases the energy, which is either used by the organism (to move its muscles, digest food,
excrete wastes, think, etc.) or the energy may be lost as heat. The dark arrows represent the movement
of this energy. Note that all energy comes from the sun, and that the ultimate fate of all energy in
ecosystems is to be lost as heat. Energy does not recycle!!

In this unit we will seek to quantify the relative importance of different component species and feeding
relationships. This unit is a minimum of 6 hours.

Significant Ideas:

 Ecosystems are linked together by energy and matter flows.

 The Sun's energy drives these flows, and humans are impacting the flows of energy and matter
both locally and globally.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 Why are maximum sustainable yields equivalent to the net primary or net secondary productivity
of a system? Why would harvesting biomass at a rate greater than NPP or GPP be
unsustainable?
 How can systems diagrams of carbon and nitrogen cycles be used to who the effect of human
activities on ecosystems? What are the strengths and weaknesses of such diagrams?

U 2.3.1 As solar radiation (insolation) enters the Earth's atmosphere, some energy becomes
unavailable for ecosystems as this energy is absorbed by inorganic matter or reflected back into
the atmosphere

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 image from www.philica.com

Solar energy is any type of energy generated by the sun.

About 30% of the solar energy that reaches Earth is reflected back into space. The rest is absorbed into
Earth’s atmosphere. Just as the incoming and outgoing energy at the Earth’s surface must balance, the
flow of energy into the atmosphere must be balanced by an equal flow of energy out of the atmosphere
and back to space.

Clouds, aerosols, water vapor, and ozone directly absorb 23 percent of incoming solar energy.
Evaporation and convection transfer 25 and 5 percent of incoming solar energy from the surface to the
atmosphere. These three processes transfer the equivalent of 53 percent of the incoming solar energy to
the atmosphere. If total inflow of energy must match the outgoing thermal infrared observed at the top of
the atmosphere, where does the remaining fraction (about 5-6 percent) come from? The remaining
energy comes from the Earth’s surface.

The radiation warms the Earth’s surface, and the surface radiates some of the energy back out in the
form of infrared waves. As they rise through the atmosphere, they are intercepted by greenhouse gases,
such as water vapor and carbon dioxide.

Greenhouse gases trap the heat that reflects back up into the atmosphere. In this way, they act like the
glass walls of a greenhouse. This greenhouse effect keeps the Earth warm enough to sustain life.

 Almost all energy that drives processes on Earth comes from the sun.
 This is called solar radiation and is made up of visible wavelengths (light) and those wavelengths
that humans cannot see (UV and infrared).
 Some 60% of this is intercepted by atmospheric gases and dust particles. Nearly all UV light is
absorbed by ozone.
 Both ultraviolet and visible light energy (short wave) are converted to heat energy (long wave),
following the laws of thermodynamics.

U 2.3.2 Pathways of radiation through the atmosphere involve a loss of radiation through
reflection and absorption as shown in figure 4 (below)

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 image from physics.ucsd.edu

 The systems of the biosphere are dependent on the amount of energy reaching the ground, not
the amount of energy reaching the outer atmosphere. This amount varies according to the time of
day, the season, the amount of cloud cover and other factors.
 Most of this energy is not used to power living systems, it is reflected from soil, water or
vegetation or absorbed and re-radiated as heat.
 Of the energy reaching the Earth's surface, about 35% is reflected back into space by ice, snow,
water and land.
 Some energy is absorbed and heats up the land and seas.
 Of ALL the energy coming in, only about 1-4% of it is available to plants on the surface of the
Earth.

U 2.3.3 Pathways of energy through an ecosystem include: conversion of light energy to chemical
energy, transfer of chemical energy from one trophic level to another with varying efficiencies,
overall conversion of ultraviolet and visible light to heat energy by an ecosystem, re-radiation of
heat energy to the atmosphere.

image from image from en.wikibooks.org

Matter also flows through ecosystems linking them together. This flow of matter involves transfers and
transformations

The distinction between storages of energy illustrated by boxes in energy-flow diagrams (representing the

94
various trophic levels), and the flows of energy or productivity often shown as arrows (sometimes of
varying widths) needs to be emphasized. The former are measured as the amount of energy or biomass
per unit area and the latter are given as rates, for example, J m–2 day–1.

Not all solar radiation ends up being stored as biomass. Losses include:

 reflection from leaves

 light not coming in contact chloroplasts
 light of different wavelengths
 transmission of light through the leaf
 inefficiency of photosynthesis

This energy is captured by green plants which convert light to chemical energy (glucose).
The chemical energy (glucose) is then transferred from one trophic level to the next.

The percentage of energy transferred from one trophic level to the next is called the ecological efficiency
(energy used for growth (new biomass)) x 100
energy supplied
U 2.3.3 The conversion of energy into biomass for a given period of time is measured as
productivity
[You need to be able to measure biomass and productivity experimentally. You could design experiments
to compare productivity in different systems]

image from www.nature.com

Primary productivity is the gain by producers (autotrophs) in energy or biomass per unit area per unit
time. It is when solar energy is converted, it depends on the amount of sunlight the ability of the
producers to use energy to synthesize organic compounds and the availability of other things needed for
growth, like minerals and nutrients.

Primary production is highest were conditions for growth are optimal, where there are high levels of
insolation, good water supply, warm temperatures and high nutrient levels.

You can then divide primary productivity into gross and net profits.

*GROSS is the income

*NET is the incomes minus costs

Secondary productivity depends on the amount of food there is and the efficiency of the consumers
turning this into new biomass. Unlike the primary productivity net productivity involves feeding or
absorption.

U 2.3.4 Net primary productivity (NPP) is calculated by subtracting respiratory losses (R) from
gross primary productivity (GPP). NPP = GPP - R

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[The distinction between storages of energy illustrated by boxes in energy-flow diagrams (representing
the various trophic levels), and the flows of energy or productivity often shown as arrows (sometimes of
varying widths) needs to be emphasized. The former are measured as the amount of energy or biomass
per unit area dn the latter are given as rates, for example, J m-2 yr-1]
[Values for GPP and NPP should be compared from various biomes]

The amount of organic matter or biomass produced by an individual organism, population, community or
ecosystem during a given period of time is called productivity.

Primary production refers to all or any part of the energy fixed by plants possessing chlorophyll. The total
amount of solar energy converted (fixed) into chemical energy by green plants (by the process of
photosynthesis) is called 'Gross Primary Production' (GPP).

A certain portion of gross primary production is utilized by plants for maintenance (respiration energy loss)
and the remainder is called 'Net Primary Production (NPP)' which appears as new plant biomass. It is
more useful to measure Net Primary Production (NPP). The remainder of glucose produced from
photosynthesis is deposited in and around cells representing the stored dry mass. The accumulation of
dry mass is usually termed biomass. Biomass provides a useful measure of the production and use of
resources.

Use the equation NPP = GPP – R; where R = respiratory loss.

Primary production is the foundation of all metabolic processes in an ecosystem, and the distribution of
production has a key part in determining the structure of an ecosystem.

 Gross primary productivity (GPP): is gained through photosynthesis in primary producers.

 Net primary productivity (NPP): is the gain by producers in energy or biomass per unit area per
unit time remaining after allowing for respiratory losses. (Available for consumers in ecosystem)

U 2.3.5 Gross secondary productivity (GSP) is the total energy or biomass assimilated by
consumers and is calculated by subtracting the mass of fecal loss from the mass of food
consumed. GSP = food eaten - fecal loss
[The distinction between storages of energy illustrated by boxes in energy-flow diagrams (representing
the various trophic levels), and the flows of energy or productivity often shown as arrows (sometimes of
varying widths) needs to be emphasized. The former are measured as the amount of energy or biomass
per unit area dn the latter are given as rates, for example, J m-2 yr-1]
[The term assimilation is sometimes used instead of secondary productivity]

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Production also occurs in animals as Secondary Production. Importantly though animals do not use all
the biomass they consume. Unlike the primary productivity net productivity, secondary involved feeding or
absorption.

Secondary production is the generation of biomass of the consumer in a system. This is driven by the
transfer of organic material between trophic levels, and represents the quantity of new tissue created
through the use of assimilated food. Secondary production is sometimes defined to only include
consumption of primary producers by herbivorous consumers,but is more commonly defined to include all
biomass generation by heterotrophs. This is the reason only.

Use the equation NSP = GSP – R; where GSP = food eaten – faecal loss and R = respiratory loss

 Gross secondary productivity (GSP): is gained through absorption in consumers.

 Net secondary productivity (NSP): The gain by consumers in energy or biomass per unit area
per unit time remaining after allowing for respiratory losses.

U 2.3.6 Maximum sustainable yields are equivalent to the net primary or net
secondary productivity of a system.

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Maximum sustainable yield is e—Equivalent to the NSP or NPP of system. This information can be and
important number for farmers who are trying to predict how much money they will get for their product. —
Farmers are often paid by how much biomass (often measured by weight/acre) that their crop yields. —
Modern agricultural economists spend many months predicting yields which drives prices of the food you
buy.

U 2.3.7 Matter also flows through ecosystems linking them together. This flow of matter involves
transfers and transformations.

Image from www.ck12.org

Processes involving the transfer and transformation of carbon, nitrogen and water as they cycle within an
ecosystem should be described, and the conversion of organic and inorganic storage noted where
appropriate

Factors that affect the store of nutrients and their transfer are those that affect: the amount and type of weathering
overland run-off and soil erosion the amount of rainfall
U 2.3.8 The carbon and nitrogen cycles are used to illustrate this flow of matter using flow
diagrams. These cycles contain storages (sometimes referred to as sinks) and flows, which move
matter between storage
Along with energy, water and several other chemical elements cycle through ecosystems and influence
the rates at which organisms grow and reproduce. About 10 major nutrients and six trace nutrients are
essential to all animals and plants, while others play important roles for selected species (footnote 3). The
most important biogeochemical cycles affecting ecosystem health are the water, carbon, nitrogen, and
phosphorus cycles.

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The carbon cycle involves the
processes of photosynthesis
and respiration. Carbon
dioxide plays an important role
in photosynthesis. Plants use
energy from light to split water
molecules; they then use
carbon dioxide to synthesize
carbohydrates. One of the
products of this reaction is
oxygen. Photosynthesis is the
major source of oxygen in
Earth’s atmosphere. For some
1.5 billion years before green
plants were on Earth, algae
and bacteria provided the
photosynthesis needed to build
Earth’s oxygen levels to the
point that respiration of both Nitrogen Cycle
plants and animals could
occur.

Nitrogen is an element that is

often a limiting factor for plant
growth. Although atmospheric
nitrogen is abundant, it is not
in a form that plants can
readily access. The nitrogen
molecule found in the
atmosphere must be split and
recombined with atoms to
form molecules that are
soluble in water. This is called
nitrogen fixation. Typically
nitrogen is fixed in the form of
ammonium or nitrate ions.
Some of this fixing occurs in
the atmosphere due to
lightning. Most nitrogen is
fixed by bacteria. When plants
and other organisms die,
through leaching and the
activities of other bacteria the
nitrogen is returned to the
atmosphere ready to begin the
cycle again.

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U 2.3.9 Storages in the carbon cycle include organisms and forests (both organic), or the
atmosphere, soil, fossil fuels and oceans (all inorganic)

Carbon is stored in organisms and forests, the atmosphere, soil, fossil fuels, and in the oceans. —Places
where carbon is stored are called Carbon Sinks —The oceans are the largest carbon sinks, holding many
times more carbon than all the forests on earth combined. —Climate change is affecting how much
carbon the ocean can hold.

U 2.3.10 Flows in the carbon cycle include consumption (feeding), death and decomposition,
photosynthesis, respiration, dissolving and fossilization
[The roles of calcification, sedimentation, lithification, weathering and volcanoes in the carbon cycle are
not required]
The carbon cycle is one of the major biogeochemical cycles describing the flow of essential elements
from the environment to living organisms and back to the environment again. This process is required for
the building of all organic compounds and involves the participation of many of the earth's key forces. The
carbon cycle has affected the earth throughout its history; it has contributed to major climatic changes,
and it has helped facilitate the evolution of life.

Flows in the carbon cycle are divided into:

Transfers

 herbivores feeding on producers

 carnivores feeding on herbivores
 decomposes feeding on dead organic matter
 carbon dioxide from the atmosphere dissolving in rainwater.

Transformation

 photosynthesis converts inorganic material into organic matter

 photosynthesis transforms carbon dioxide and water into glucose
 respiration converts organic storage into inorganic matter
 combustion transforms biomass into carbon dioxide nd water
 fossilization transforms organic matter in dead organisms into fossil fuels

U 2.3.11 Storages in the nitrogen cycle include organisms (organic), soil, fossil fuels, atmosphere
and water bodies (all inorganic).

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Nitrogen is stored in organisms, soil, fossil fuels, atmosphere, and bodies of water. Places where nitrogen
is stored are called Nitrogen Sinks.

The nitrogen cycle, similarly to the other biochemical cycles, cycles nitrogen from storage pools into
directly usable forms and back again. The atmosphere acts as vast storage reservoir for nitrogen
because it is 78 percent nitrogen. Because of this, the atmosphere is the largest storage reservoir of
nitrogen. Nitrogen is also stored in: watershed in soil, groundwater, ocean water, sediment and plant
matter (dead and living). Human activities are increasing nitrogen's storage in groundwater. It has been
seen that groundwater in developed countries stores significantly more carbon than that of developing
countries. In nature groundwater is a fairly small and insignificant storage reservoir.

Nitrogen is contained in both inorganic and organic molecules/reservoirs. Organic reservoirs that contain
nitrogen include: amino acids, peptides, nucleic acids and proteins. Each of these molecules is vital to an
organisms survival which emphasizes the importance of the nitrogen cycle. Examples of inorganic
molecules that contain nitrogen include man-made fertilizers and ammonia. These molecules are less
important to both the survival of organisms and the nitrogen cycle itself.

U 2.3.12 Flows in the nitrogen cycle include nitrogen fixation by bacteria and lightning,
absorption, assimilation, consumption (feeding), excretion, death and decomposition, and
denitrification by bacteria in water-logged soils.
[Detailed knowledge of the role of bacteria in nitrogen fixation, nitrification and ammonification is not
required]

image from ayUCar.com

The nitrogen cycle represents one of the most important nutrient cycles found in terrestrial ecosystems.
Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids,
proteins, and nucleic acids.

Flows in nitrogen cycle are

Transfers

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  herbivores feeding on producers
 carnivores feeding on herbivores
 decomposers feeding on dead organic matter
 plants absorbing nitrates through their roots
 removal of metabolic waste

Transformations

 lightening transforms nitrogen in the atmosphere into NO3

 nitrogen-fixing bacteria transform nitrogen gas in the atmosphere into ammonium
 nitrifying bacteria transform ammonium into nitrite and nitrate
 denitrifying bacteria transform nitrates into nitrogen
 decomposers break down organic nitrogen into ammonia
 nitrogen from nitrates is use by plants to make proteins

U 2.3.13 Human activities such as burning fossil fuels, deforestation, urbanization and agriculture
impact energy flows as well as the carbon and nitrogen cycles

image from www.drmonline.ne

Human activities have greatly increased carbon dioxide levels in the atmosphere and nitrogen levels in
the biosphere. Altered biogeochemical cycles combined with climate change increase the vulnerability of
biodiversity, food security, human health, and water quality to a changing climate.

Human activities have increased atmospheric carbon dioxide by about 40% over pre-industrial levels and
more than doubled the amount of nitrogen available to ecosystems. Similar trends have been observed
for phosphorus and other elements, and these changes have major consequences for biogeochemical
cycles and climate change.

Altered biogeochemical cycles together with climate change increase the vulnerability of biodiversity, food
security, human health, and water quality to changing climate. However, natural and managed shifts in
major biogeochemical cycles can help limit rates of climate change.

Applications and Skills

A 2.3.1 Analyse quantitative models of flows of energy and matter
Storages, yields and outputs should be included in the form of clearly constructed diagrammatic and
graphical models.
A 2.3.2 Analyse the efficiency of energy transfers through a system.

102
 image from www.bbc.co.uk
Large amounts of energy are lost from the ecosystem between one trophic level and the next level as
energy flows from the primary producers through the various trophic levels of consumers and
decomposers. The main reason for this loss is the second law of thermodynamics, which states that
whenever energy is converted from one form to another, there is a tendency toward disorder (entropy) in
the system.

A 2.3.3 Discuss human impacts on energy flows, and on the carbon and nitrogen cycles.
Humans clearly disrupt many, if not all biogeochemical cycles and in the process threaten many
ecosystems. In resent years human activities have directly or indirectly affected the biogeochemical
cycles that determine climatic conditions of earth. It is imperative to mention that, managing and
understanding environmental problems caused by climate change would require an understanding of the
biogeochemical cycles. Biogeochemical cycles always involve equilibrium states: a balance in the cycling
of the element between spheres. However, overall balance may involve elements distributed on a global
scale and that is why a disruption in one cycle causes a disruption in all other cycles. Below is a summary
of how human activities have contributed to disruption of biogeochemical cycles. For impacts on specific
cycles, the reader should refer to the sites where these cycles are presented.

Use of phosphorus fertilizers: Human influences on the phosphorus cycle come mainly from the
introduction and use of commercial synthetic fertilizers. Use of fertilizers mainly has affected the
phosphorus and nitrogen cycles. Plants may not be able to utilize all of the phosphate fertilizer applied; as
a consequence, much of it is lost from the land through the water run-off. The phosphate in the water is
eventually precipitated as sediments at the bottom of the water body. In certain lakes and ponds this may
be redissolved and recycled as a problem nutrient. Animal wastes or manure may also be applied to land
as fertilizer. If misapplied on frozen ground during the winter, much of the fertilizer may be lost when ice
melts and forms runoff. In certain areas very large feed lots of animals, may result in excessive run-off of
phosphate and nitrate into streams. Other human sources of phosphate are in the out flows from
municipal sewage treatment plants. Without an expensive tertiary treatment, the phosphate in sewage is
not removed during various treatment operations. Again an extra amount of phosphate enters the water.

Mining of Fossil fuels: Humans have interfered with the carbon cycle where fossil fuels have been mined
from the earth crust. Had fossils not been discovered prior to industrial revolution, they could have
remained there until now. Carbon dioxide is number one green house gas contributing to global warming
and climate change. Additionally, clearing of vegetation that serve as carbon sinks has increased the
concentration of carbondioxide in the atmosphere.

Production of Sulphur dioxide: Human impact on the sulfur cycle is primarily in the production of sulfur
dioxide (SO2) from industry (e.g. burning coal) and the internal combustion engine. Sulfur dioxide can
precipitate onto surfaces where it can be oxidized to sulphate in the soil (it is also toxic to some plants),
reduced to sulphide in the atmosphere, or oxidized to sulphate in the atmosphere as sulphiric acid (a
principal component of acid rain). Sulphur compounds play a big role in the climate system because they
are important for the formation of clouds.

Additionally, a lot of sulphur is brought into the air by volcanic eruptions. A strong eruption can emit
particles up to the stratosphere hence leading to cooling down of the planet.

Cultivation of legumes and use of nitrogen fertilizers:

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As a result of extensive cultivation of legumes, creation of chemical fertilizers, and pollution emitted by
vehicles and industrial plants, human beings have more than doubled the annual transfer of nitrogen into
biologically available forms. Humans have significantly contributed to the transfer of nitrogen gases from
Earth to the atmosphere, and from the land to aquatic systems through four main processes:

The application of nitrogen fertilizers to crops has caused increased rates of denitrification and leaching of
nitrate into groundwater. The additional nitrogen entering the groundwater system eventually flows into
streams, rivers, lakes, and estuaries. In these systems, the added nitrogen can lead to eutrophication.

Increased deposition of nitrogen from atmospheric sources because of fossil fuel combustion and forest
burning. Both of these processes release a variety of solid forms of nitrogen through combustion.

Livestock ranching. Livestock release a large amounts of ammonia into the environment from their
wastes. This nitrogen enters the soil system and then the hydrologic system through leaching,
groundwater flow, and runoff.

Sewage waste and septic tank leaching.

S 2.3.1 Construct a quantitative model of the flows of energy or matter for given data.

S 2.3.2 Calculate the values of both GPP and NPP from given data.
Gross primary productivity (GPP): is gained through photosynthesis in primary producers.
Net primary productivity (NPP): is the gain by producers in energy or biomass per unit area per unit time
remaining after allowing for respiratory losses. (Available for consumers in ecosystem)

Primary productivity:

 where R = energy used in respiration

 NPP = GPP – R

S 2.3.3 Calculate the values of both GSP and NSP from given data.
Gross secondary productivity(GSP): is gained through absorption in consumers.
Net secondary productivity(NSP): The gain by consumers in energy or biomass per unit area per unit time
remaining after allowing for respiratory losses.

Secondary productivity:

 NSP = GSP – R

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  GSP = food eaten – faecal loss
 where R = respiratory loss

Key Terms
producers consumers decomposers photosynthesis respiration
inputs processes outputs gross solar radiation
biomass energy flow energy transfer secondary trophic level
autotroph gross productivity net productivity carbon cycle
heterotroph biochemical cycles productivity gross primary nitrogen cycle
denitrification nitrogen fixation transformations productivity assimilation
chlorophyll chloroplast nitrification net primary reflection
inorganic primary mitochondria productivity macronutrients
productivity productivity fecal matter net secondary transfers
energy insolation reflection productivity flows and
storage urbanization efficiency transformations matter hydrological sinks
fossilization nitrogen cycle nitrification
excretion fixation solar radiation energy budget
energy subsidy fossil fuels incident
deforestation energy flow
diagram
absorption
sustainable
yield
denitrification
carbon
fixation

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TOPIC 2.4: BIOMES, ZONATION AND SUCCESSION

Biomes are groups of ecosystem that have the same climate and dominant communities. They are
complex terrestrial (mostly earth's surface) systems of abiotic and biotic factors that cover a large area
and are characterized by certain soil & climate characteristics and by certain groupings of plants and
animals. Living organisms prefer certain climatic conditions. This means that animal and plants are
usually found only in regions that suit them. A polar bear, for example, will be found in a region of low
temperature and low humidity. Such a region of the biosphere is called the arctic.

In this unit we will look at the different types of biomes and the factors that influences the organisms in
those biomes. Thisi unit is a minimum of 4.5 hours

Significant Ideas

 Climate determines the type of biome in a given area, although individual ecosystems may vary
due to many local abiotic and biotic factors.
 Succession leads to climax communities that may vary due to random events and interactions
over time. This leads to a pattern of alternative stable states for a given
 ecosystem.
 Ecosystem stability, succession and biodiversity are intrinsically linked.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development
 What are the strengths and weaknesses of models of succession and zonation?
 How could the R/R ration be used to estimate whether the harvesting of a natural capital, such as
trees , is sustainable or not?

Knowledge & Understanding:

U 2.4.1 Biomes are collections of ecosystems sharing similar climatic conditions that can be
grouped into five major classes: aquatic, forest, grassland, desert and tundra. Each of these
classes has characteristic limiting factors, productivity and biodiversity.
[You are encouraged to study at least four contrasting pairs of biomes of interest, such as
temperate forests and tropical seasonal forests; or tundras and deserts; or tropical coral reefs and
hydrothermal vents; or temperate bogs and tropical mangrove forests]

106
There are two basic categories of communities: terrestrial (land) and aquatic (water). These two basic
types of community contain eight smaller units known as biomes. A biome is a large-scale category
containing many communities of a similar nature, whose distribution is largely controlled by climate

 Terrestrial Biomes: tundra, grassland, desert, taiga, temperate forest, tropical forest.
 Aquatic Biomes: marine, freshwater, tropical coral reefs, hydrothermal vents

A biome has distinctive abiotic factors and species which distinguish it from other biomes. Water,
insolation and temperature are the climate controls important when understanding how biomes are
structured, how they function and where they are found round the world. Biomes usually cross national
boundaries (biomes do not stop at a border; for example, the Sahara, tundra, tropical rainforests).

image from www.bio.miami.edu

Refer to prevailing climate and limiting factors. For example, tropical rainforests are found close to the
equator where there is high insolation and rainfall and where light and temperature are not limiting. The
other biome may be, for
example, temperate grassland or a local example. Limit climate to temperature, precipitation and
insolation. It is required that you need to be able to explain the distribution, structure and relative
productivity of tropical rainforests, deserts, tundra and one other biome. Climate should only be explained
in terms of temperature, precipitation and insolation only.

It is possible to group the biomes into 6 categories with sub-categories in each one:

 freshwater
 marine
 desert
 forest
 grassland
 tundra

Deserts: Tundra:

 found in high latitudes

 cover 20-30 percent of the land surface  days are short
 dry air  limit levels of sunlight
 high temperatures (45-49 C in day)  water may be locked up in ice, limiting
 low precipitation (250 mm yr-1) water resources

107
  low rates of photosynthesis  photosynthesis and productivity rates are
 low NPP rates low
 vegetation scarce  low temperatures
 soil rich in nutrients and can support plant  soil may be permanently frozen
that can survive there  nutrients in soil are limited

Tropical rainforest: Temperate forest:

 seasonal weather (hot summers/cold

 high temperatures (average 26 C ) winters)
 high rainfall (over 2500 mm yr -1)  2 types of tree types in forests; Evergreen +
 near the equator deciduous could be in one forest or contain
 high light levels throughout the year both trees
 all-year round growing season  rainfall average between 500-1500 mm yr-
 high levels of photosynthesis 1
 high rates of NPP throughout the year  productivity lower than rainforest
 high diversity of animals and plants  mild climate, lower average temperature /
 low levels of nutrients in the soil lower rainfal

You should study at least four contrasting pairs of biomes. Examples of contrasting biomes
include; temperate forests and tropical seasonal forests; tundra and deserts; tropical coral reefs
and hydrothermal vents; temperate bogs and tropical mangrove forests.

image from www.globalchange.umich.edu

U 2.4.2 Insolation, precipitation and temperature are the main factors governing the distribution of
biomes.

108
The distribution of biomes results from insolation, precipitation and temperature. Climate, terrain (or
geography) and ocean and wind currents also play important roles.

Insolation is measured by the amount of solar energy received per square centimeter per minute. As the
sun rotates around the sun, the position of the land masses will change resulting in various
concentrations of solar radiation over the land masses.

The atmosphere and its circulation systems determines where moisture-carrying air masses do and do
not go. The energy source of those circulatory systems are the sun. The sun's energy drives atmospheric
movements, sustains photosynthesis, and propels the seasons.

The main geographic factors are

1. the distribution of the land masses and ocean basins

2. the topography of the continents.

Plant biomes are based primarily on the distribution of the dominant vegetation.
Animal biomes are usually named after regions because their distribution is more difficult to define.

A biome's boundaries are determined by climate more than any other factor. Eg tundra is colder and has
a shorter growing season than other biomes, it has fewer kinds of vegetation. Towards the equator,
precipitation becomes increasingly important, producing temperate communities of desert, grassland and
forest in increasing order of precipitation. In the tropical and subtropical biomes which occur in the
equatorial latitudes there is a relatively smaller range of temperature during the year, and their variation is
also determined by the amount of precipitation. Thus there are not only tropical forests but also tropical
grasslands and tropical deserts. In addition, seasonal distribution is important. Some areas could be
tropical forest but that all their rain comes in just two months rather than evenly distributed

Another important factor is altitude. Changes in vegetation with increasing altitude resemble changes in
vegetation due to increasing latitude. It isn't entirely the same. For example, increasing altitude means
increasing UV. And increasing latitude usually means different amounts of light because of changing
daylength, this doesn't happen in changing altitude

109
 image from www.tes.com
U 2.4.3 The tricellular model of atmospheric circulation explains the distribution of precipitation
and temperature and how they influence structure and relative productivity of different terrestrial
biomes.
The tricellular model explains the distribution of precipitation and temperature and how they influence
structure and relative productivity of different terrestrial biomes. The tricellular model is made up of three
different air masses, these control atmospheric movements and the redistribution of heat energy. The
three air masses, starting from the equator, are called the Hadley cell, Ferrel cell and the polar cell.

The tricellular model also contains the ITCZ (Inter-tropical convergence zone), this is the meeting place of
the trade winds from both the northern hemisphere and the southern hemisphere. The ITCZ is a low
pressure area where the trade winds, which have picked up latent heat as they crossed oceans, are now
forced to rise by convection currents. These rising convection currents are then cooled adiabatically to
form massive cumulonimbus clouds.

 As substance gain heat energy, density decreases so particles rise

 As you go up in altitude air cools, becomes more dense and falls back towards earth’s surface.
 These convection currents drive the Earth’s wind patterns and affect the biomes.
 The same phenomena drives ocean currents

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 image from ask.revision.co.zw
U 2.4.4 Climate change is altering the distribution of biomes and causing biome shifts.

image from news.mongabay.com

A changing global climate threatens species and ecosystems. The distribution of species is largely
determined by climate, as is the distribution of ecosystems and plant vegetation zones (biomes). Climate
change may simply shift these distributions, but often, barriers and human presence will provide no
opportunity for distributional shifts. For these reasons, some species and ecosystems are likely to be
eliminated by climate change.

If significant climate change occur many natural populations of wild organisms will be unable to exist
within their natural ranges. Changes in temperature and precipitation, and resultant changes in vegetation
and habitat, are likely to seriously affect the suitability of the locales where species are presently found.
Thus, climate change is an additional factor threatening the survival of species

Climate changes are happening very fast, within decades, and organisms change slowly, over many
generations through evolutionary adaptation. All they can do to adapt to fast change is to move. They
moves are:

 towards the poles where it is cooler

 higher up mountains where it is cooler
 towards the equator where it is wetter

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in Africa in the Sahel region, woodlands are becoming savannas

U 2.4.5 Zonation refers to changes in community along an environmental gradient due to factors
such as changes in altitude, latitude, tidal level or distance from shore (coverage by water)
[It is important to distinguish zonation (a spacial phenomenon) from succession (a temporal
phenomenon)]
[Named examples of organisms from the pioneer, intermediate and climax communities should be
provided]

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Zonation refers to changes in community along an environmental gradient due to factors such as changes
in altitude, latitude, tidal level or distance from shore (coverage by water).

The distinct vertical layers experience particular abiotic conditions. This is particularly clear in the
distribution of plants and animals on a rocky seashore, where different species inhabit a series of
horizontal strips or belts of the shore, approximately parallel to the water's edge. In many places the strips
(zones) are sharply bounded by the differently coloured seaweeds that populate them.

The division of vegetation in relation to a successional sequence (e.g. in sand-dunes), implying that
spatial zonation may correspond to temporal processes.

Kite diagrams are a chart that shows the number of animals (or percentage cover for plants) against
distance along a transect. The distribution of organisms in a habitat is affected by the presence of other
living organisms, such as herbivores or predators that might eat them. It is also affected by abiotic factors
(physical factors) such as availability of light or water. The width of the “kite” represents the number of
species.

The kite diagram is frequently used to show zonation along a transect. A gradual change in the
distribution of species across a habitat is called zonation. It can happen because of a gradual change in
an abiotic factor. A transect is line across a habitat or part of a habitat. It can be as simple as a string or
rope placed in a line on the ground. The number of organisms of each species can be observed and
recorded at regular intervals along the transect.

U 2.4.6 Succession is the process of change over time in an ecosystem involving pioneer,
intermediate and climax communities
[It is important to distinguish zonation (a spacial phenomenon) from succession (a temporal

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phenomenon)]
[Named examples of organisms from the pioneer, intermediate and climax communities should be
provided]
Succession is a directional non-seasonal cumulative change in the types of plant species that occupy a
given area through time. It involves the processes of colonization, establishment, and extinction which act
on the participating plant species. Most successions contain a number of stages that can be recognized
by the collection of species that dominate at that point in the succession. Succession begin when an area
is made partially or completely devoid of vegetation because of a disturbance. Some common
mechanisms of disturbance are fires, wind storms, volcanic eruptions, logging, climate change, severe
flooding, disease, and pest infestation. Succession stops when species composition changes no longer
occur with time, and this community is said to be a climax community.

 Succession- change in the community structure of a particular area over time.

 Primary succession-colonization of newly created land by organisms (rock).
 Secondary succession-occurs in places where a previous community has been destroyed.
(forest/fire) It is faster than primary succession because of the presence of soil and a seed bank.
 Pioneer-earliest community of the succession.
 Climax community-the last and final community.
 The change from pioneer to climax is called a sere.
 Zonation- The arrangement or patterning of plant communities or ecosystems into bands in
response to change, over a distance, in some environmental factor.
 The main biomes display zonation with altitude on a mountain, or around the edge of a pond in
relation to soil moisture.

 The species living in a particular place gradually change over time as does the physical and
chemical environment within that area.

 Succession takes place because through the processes of living, growing and reproducing,
organisms interact with and affect the environment within an area, gradually changing it.

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  Each species is adapted to thrive and compete best against other species under a very specific
set of environmental conditions. If these conditions change, then the existing species will be
outcompeted by a different set of species which are better adapted to the new conditions.

 The most often quoted examples of succession deal with plant succession. It is worth
remembering that as plant communities change, so will the associated micro-organism, fungus
and animal species. Succession involves the whole community, not just the plants.

 Change in the plant species present in an area is one of the driving forces behind changes in
animal species. This is because each plant species will have associated animal species which
feed on it. The presence of these herbivore species will then dictate which particular carnivores
are present.

 The structure or 'architecture' of the plant communities will also influence the animal species
which can live in the microhabitats provided by the plants.

 Changes in plant species also alter the fungal species present because many fungi are
associated with particular plants.
 Succession is directional. Different stages in a particular habitat succession can usually be
accurately predicted.
 These stages, characterised by the presence of different communities, are known as 'seres'.

 Communities change gradually from one sere to another. The seres are not totally distinct from
each other and one will tend to merge gradually into another, finally ending up with a 'climax'
community.

 Succession will not go any further than the climax community. This is the final stage.

This does not however, imply that there will be no further change. When large organisms in the
climax community, such as trees, die and fall down, then new openings are created in which
secondary succession will occur.

 Many thousands of different species might be involved in the community changes taking place
over the course of a succession. For example, in the succession from freshwater to climax
woodland.

 The actual species involved in a succession in a particular area are controlled by such factors as
the geology and history of the area, the climate, microclimate, weather, soil type and other
environmental factors.

Bare, inorganic surface → stage 1 colonisation → stage 2 establishment → stage 3 competition → stage
4 stabilisation → climax community

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 Hydrosere image from
http://iboess.wikispaces.com
If primary succession starts on dry land it is a XEROSERE

If it starts in water (a pond) it is a HYDROSERE

U 2.4.7 During succession, the patterns of energy flow, gross and net productivity, diversity, and
mineral cycling change over time

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 image from en.wikipedia.org
In early stages, gross productivity is low due to the initial conditions and low density of producers. The
proportion of energy lost through community respiration is relatively low too, so net productivity is high,
that is, the system is growing and biomass is accumulating. In later stages, with an increased consumer
community, gross productivity may be high in a climax community. However, this is balanced by
respiration, so net productivity approaches zero and the production:respiration (P:R) ratio approaches
one.

A disturbance is any event, either natural or human-induced that changes the existing condition of an
ecosystem. Disturbances in forest ecosystems affect resource levels, such as soil organic matter, water
and nutrient availability, and interception of solar radiation. Changes in resource levels, in turn, affect
plants and animals over time, leading to succession. All of these have an effect of making gaps available
that can be colonised by pioneer species within the surrounding community. This adds to both the
productivity and diversity of the community.

Changes occurring during a succession

 the size of organisms increases

 energy flow becomes more complex
 soil depth, humus, water-holding capacity, mineral content and cycling increase
 Biodiversity increases and then falls as the climax community is reached
 NPP and GPP rise and then fall
 Production: respiration ratio falls

Species diversity in successions

 Early stages of succession: few species

 Species diversity increases with the succession
 Increase continues until a balance is reached between possibilities for new species to establish,
existing species to expand their range and local extinction

U 2.4.8 Greater habitat diversity leads to greater species and genetic diversity

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Biological diversity, often shortened to biodiversity, is the variation of life at all levels of biological
organization, referring not only to the sum total of life forms across an area, but also to the range of
differences between those forms. Biodiversity runs the gamut from the genetic diversity in a single
population to the variety of ecosystems across the globe.

Greater biodiversity in ecosystems, species, and individuals leads to greater stability. For example,
species with high genetic diversity and many populations that are adapted to a wide variety of conditions
are more likely to be able to weather disturbances, disease, and climate change. Greater biodiversity also
enriches us with more varieties of foods and medicines

U 2.4.9 r- and K-strategist species have reproductive strategies that are better adapted to pioneer
and climax communities, respectively.

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 image from yesitsyomoma.wordpress.com
The terms r-selection and K-selection have also been used by ecologists to describe the growth and
reproductive strategies of various organisms. Those organisms described as r-strategists typically live in
unstable, unpredictable environments. Here the ability to reproduce rapidly (exponentially) is
important. K-strategists, on the other hand occupy more stable environments. They are larger in size and
have longer life expectancies. They are stronger or are better protected and generally are more energy
efficient.

In general, communities in early succession will be dominated by fast-growing, well-dispersed species

(opportunist, fugitive, or r-selected life-histories).

As succession proceeds, these species will tend to be replaced by more competitive (k-selected) species.
They tend to inhabit relatively stable biological communities, such as late-successional or climax forests

r - selected K - Selected

Short life Long life

Rapid growth Slower growth
Early maturity Late maturity
Numerous and small offspring Fewer, but larger offspring
Little parental care or protection High parental care and protection
Little investment in individual offspring High investment in individual offspring
Adapted to unstable environment. Adapted to stable environment
Pioneers, colonizers Later stages of succession
Niche generalists Niche specialist
Prey Predators
Regulated mainly by external factors Regulated mainly by internal factors (homeostasis)
Lower trophic level Higher trophic level

U 2.4.10 In early stages of succession, gross productivity is low due to the unfavourable initial
conditions and low density of producers. The proportion of energy lost through community
respiration is relatively low too, so net productivity is higher that is, the system is growing and
biomass is accumulating

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During succession Gross Primary Productivity tends to increase through the pioneer and early wooded
stages and then decreases as climax community reaches maturity. This increase in productivity is linked
to growth and biomass.

Early seral stages are usually marked by rapid growth and biomass biomass accumulation - grasses,
herbs and small shrubs. Gross Primary Productivity is low but Net Primary Productivity tends to be be a
large proportion of GPP as with little biomass in the early seral stages respiration is low. As the
community develops towards woodland and biomass increases so does productivity. But NPP as a
percentage of GPP can fall as respiration rates increase with more biomass.

U 2.4.11 In later stages of succession, with an increased consumer community, gross productivity
may be high in a climax community. However, this is balanced by respiration, so net productivity
approaches 0 and the productivity:respiration (P:R) ratio approaches 1
Succession is the process of ecosystem recovery after some disturbance. Biomass is at maximum in the
undisturbed ecosystem; it increases up to this maximum during succession. Plant productivity also grows,
especially if the plant cover was destroyed substantially by the disturbance. Productivity of the ecosystem
as a whole (i.e. the difference between net primary productivity and its consumption by ecosystem's
heterotrophs) in the process of succession tends to zero. Biodiversity measured as the total number of
species in the ecosystem does not change. However, biodiversity measured as the number of species
having a substantial population density is lower in the undisturbed ecosystem than in the disturbed one.

U 2.4.12 In a complex ecosystem, the variety of nutrient and energy pathways contributes to its
stability.
Redundancy in ecosystem structure and function often infers stability on a system. For instance, if there
is more than one (redundant) population of microbes that convert ammonium to nitrate and a disturbance
wipes out one population, that function (nitrification) will continue to be performed by the remaining
populations.

Ecosystem stability is an important corollary of sustainability. Over time, the structure and function of a
healthy ecosystem should remain relatively stable, even in the face of disturbance. If a stress or
disturbance does alter the ecosystem is should be able to bounce back quickly

Stability has two components:

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  Resistance - the ability of the ecosystem to continue to function without change when stressed by
disturbance.
 Resilience - the ability of the ecosystem to recover after disturbance.

Factors affecting stability:

 Disturbance frequency and intensity (how often and what kind of tillage)
 Species diversity (intercropping or rotations), interactions (competition for water and nutrients
from weed species), and life history strategies (do the species grow fast and produce many seeds
or slow with few seeds)
 Trophic complexity (how many functions are represented), redundancy (how many populations
perform each function), food web structure (how do all of these groups interact)
 Rate of nutrient or energy flux (how fast are nutrients and energy moving in and out of the system
or input:output efficiency)

image from femsre.oxfordjournals.org

Climatic and edaphic (soil) factors determine the nature of a climax community. Variations in climatic
conditions and soil structure greatly effect which plant species can thrive. Human factors frequently affect
this process through fire, agriculture, grazing and/or habitat destruction.

Climatic: temperature, rainfall, winds and light availability

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Edaphic: presence of soils, pH, water holding capacity, organic matter and nutrient
Tropagraphic: attitude, slope, aspect and ground water
Biological: competition and species interaction, affection of human” fire, grazing, biomass, more k-
strategies or fewer r-strategists

U 2.4.13 There is no one climax community, but rather a set of alternative stable states for a given
ecosystem. These depend on the climatic factors, the properties of the local soil and a range of
random events that can occur over time
There is no one climax community. In fact there are many stable alternatives within an ecosystem. These
communities are dependent on:

 Climatic factors
 Soil properties
 Random events

The more complex the ecosystem, the more stable they are due to the variety of nutrient and energy
pathways.
If one collapses its overall effect is low as there are many others to takes its place.
U 2.4.14 Human activity is one factor that can divert the progression of succession to an
alternative stable state by modifying the ecosystem; for example, the use of fire in an ecosystem,
the use of agriculture, grazing pressure, or resource use (such as deforestation). This diversion
may be more or less permanent depending upon the resilience of the ecosystem.

Human activity is one factor which can divert the progression of succession to an alternative stable state,
by modifying the ecosystem, for agriculture, grazing pressure, or resource use such as deforestation. This
diversion may be more or less permanent depending upon the resilience of the ecosystem.

Human activities often simplify ecosystems, rendering them unstable, for example, North American wheat
farms versus tall grass prairie. An ecosystems capacity to survive change may depend on diversity,
resilience and inertia

U 2.4.15 An ecosystem's capacity to survive change may depend on its diversity and resilience.

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 image from femsre.oxfordjournals.org
Ecosystem resilience refers to the capacity of an
ecosystem to recover from disturbance or withstand
ongoing pressures.1 2 It is a measure of how well
an ecosystem can tolerate disturbance without
collapsing into a different state that is controlled
by a different set of processes. Resilience is not
about a single ideal ecological state, but an ever changing
system of disturbance and recovery.

Coral reef and other tropical marine ecosystems are

subject to frequent disturbances, from threats such
as cyclones, crown-of-thorns starfish outbreaks
and influxes of freshwater as well as from a range
of human activities. These events often damage,
stress or kill components of the ecosystem. Given
enough time, a resilient ecosystem will be able to
fully recover from such disturbances and become
as biodiverse and healthy as before the impact.
Similarly, a resilient ecosystem may be able to
absorb the stresses caused by these disturbances
with little or no sign of degradation

Application and Skills

A 2.4.1 Explain the distributions, structure, biodiversity and relative productivity of contrasting
biomes.
Many places on Earth share similar climatic conditions despite being found in geographically different
areas. As a result of natural selection, comparable ecosystems have developed in these separated areas.
Scientists call these major ecosystem types biomes. The geographical distribution (and productivity) of
the various biomes is controlled primarily by the climatic variables precipitation and temperature..

Most of the classified biomes are identified by the dominant plants found in their communities. For
example, grasslands are dominated by a variety of annual and perennial species of grass, while deserts
are occupied by plant species that require very little water for survival or by plants that have specific
adaptations to conserve or acquire water.

The diversity of animal life and subdominant plant forms characteristic of each biome is generally
controlled by abiotic environmental conditions and the productivity of the dominant vegetation. In general,
species diversity becomes higher with increases in net primary productivity, moisture availability, and
temperature.

Adaptation and niche specialization are nicely demonstrated in the biome concept. Organisms that fill
similar niches in geographically separated but similar ecosystems usually are different species that have
undergone similar adaptation independently, in response to similar environmental pressures. The

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vegetation of California, Chile, South Africa, South Australia, Southern Italy and Greece display similar
morphological and physiological characteristics because of convergent evolution. In these areas, the
vegetation consists of drought-resistant, hard-leaved, low growing woody shrubs and trees like
eucalyptus, olive, juniper, and mimosa.

A 2.4.2 Discuss the impact of climate change on biomes.

image from http://www.theglobaleducationproject.org

Sea ice and glaciers are melting all over the globe due to warmer temperatures. Over 60% of the world's
fresh water is stored in the ice sheets covering Antarctica. The Ross ice shelf in Antarctica alone is as
large as France. The average temperature on the Antarctic Peninsula has risen significantly since 1947.
All of the major floating ice shelves are shrinking - melting more during the summer than is being refrozen
during winter - about 8,000 sq. km have been lost since the 1950s. If the West Antarctic ice sheet to melt
due to climate warming, it could raise sea levels by 6 meters. Sea levels are already rising by 2mm a year
- faster than during the past 5,000 years Krill - small shrimp-like sea creatures that are a major food

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source for seals, whales and penguins - feed on algae found on sea ice. In Antarctica, they are
concentrated northeast of the Antarctic Peninsula - but have declined 80% since the 1970s

A 2.4.3 Describe the process of succession in a given example..

The characteristic plants which define each of the biomes constitute part of what is known as the climax
community. The types of plants that characterize each biome have evolved to the unique climatic
conditions in that part of the world. If such a community is destroyed (by fire, logging, plowing, etc.) - and
then left alone - the biome will regenerate itself over a period of time. It will go through a number of
intermediate stages until it reached the climax stage again. This process is called succession.

In a Early seral stages are highly productive but require large inputs of nutrients and also tend to lose
nutrients. Biomass increases, but there is low productivity and fluctuations in biomass are common.
These seral stages are dominated by "weedy" or "r-adapted" species which reproduce quickly, but often
die young. Most of their energy goes into reproduction. There are relatively few species in early seral
stages.

Climax seral stages are much more complex, with many species. They create a favorable environment for
many species. Biomass does not fluctuate, and decomposition rates are roughly equivalent to new
production. Nutrients are cycled efficiently, and rarely leave the ecosystem. Individual organisms are
longer-lived, since they invest more resources in themselves and less in producing offspring.

Locally, a recently cleared field is an example of an early seral stage. It is colonized by grasses and other
plants that produce many seeds, such as many annuals. These plants may live only one year, set seed,
then die. The organisms in the field will not be able to cycle all of the nutrients, and many nutrients will run
off with rainfall. On the other hand, the climax forest is characterized by trees, which are long-lived. There
are many species, and each provides living space and food resources for other plants and a host of
animals. Decomposing materials are recycled; few escape though the waters of the forest streams.

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If one farms in a rain forest, the community is moved from a climax community to an artificial community
which resembles an early seral stage. The farm field will lose a lot of nutrients, something that tropical
soils do not have in abundance. The land will be useless for farming in a few years.

A 2.4 4 Explain the general patter of change in communities undergoing succession

 The size of the organisms increases with trees, creating a more hospitable environment.
 Energy flow becomes more complex as simple food chains become complex food webs.
 Soil depth, humus, water-holding capacity, mineral content, and cycling all increase.
 Biodiversity increases because more niches (lifestyle opportunities) appear and then falls as the
climax community is reached.
 NPP and GPP rise and then fall.
 Productivity: Respiration ration falls.

A 2.4.5 Discuss the factors that could lead to alternative stable states in an ecosystem.
Ecosystems can shift from one state to another due to changes in the ecosystem. These changes are
quantities that change quickly in response to feedbacks from the system (i.e., they are dependent on
system feedbacks), such as population densities. This perspective requires that different states can exist
simultaneously under equal environmental conditions These will depend on:

 Climatic factors
 Soil properties
 Random events

You need to be able to discuss the factors which could lead to alternative stable states in an
ecosystem, and discuss the link between ecosystem stability, succession, diversity, and human
activity.
A 2.4.6 Distinguish the roles of r and K selected species in succession.
What influences survivorship rates:

 competition for resources

 adverse environmental conditions
 predator-prey relationships

Example of survivorship curve:

 curve for species where individuals survive for their potential life span, and die at the same time.
Salmons/humans (K-strategists)
 curve for species where individuals die young but who survives lives very long life turtles/ oysters.
(r-strategists)

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S 2.4.1 Analyse data for a range of biomes

image from www.nature.com

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 image from http://www.theglobaleducationproject.org
Industrial air pollution from the developed world is carried on the dominant wind currents up to the arctic.
After settling onto the tundra, snow and ice it is absorbed into the food chain. The people and creatures
there have some of the highest concentrations of toxins in their bodies of anywhere on earth.

images from
http://www.theglobaleducationproject.org
Explain the general patterns of change in
communities undergoing succession

Biodiversity is the variety of life found at all levels of biological organization, ranging from individuals and
populations to species, communities and ecosystems. A population is a group of individuals of the same
species in a given location - a group that is genetically different from other such groups. Species are
made up of one or more populations. There were an estimated 2.2 billion populations on Earth.
populations are going extinct at a rate of 32,000 per day. The loss of populations is occurring three to
eight times faster than species loss. If all of a species' populations but one are destroyed the species
technically still exists. However, all of the beneficial interrelations flowing from those populations and their
biodiversity will have been lost.

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 image from http://www.theglobaleducationproject.org

S 2.4.2 Interpret models or graphs related to succession and zonation.

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Key Terms
atmosphere hydrosphere temperature biomes savanna
desert tropical rainforest geosphere arctic tundra temperate forest
temperate global location taiga (boreal) productivity canopy
grassland structure species diversity understory evergreen
insolation latitude stratified scrub-lands broad leaf
deciduous semi arid ecotones grazing browsing
arid monospecific fertile muskegs latitude
permafrost succession fragmentation insolation primary
Coriolis Effect precipitation pioneer species r-strategy succession
zonation insolation limiting factor precipitation k-strategy
tricellular model biome shift primary gross temperature
secondary disturbance succession productivity net productivity
succession resilience climax latitude climate change
community

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TOPIC 2.5: INVESTIGATING ECOSYSTEMS

To a large extent it is the physical (abiotic) conditions within any environment that controls the plant and
thus the animal (biotic) community that develops. In terrestrial ecosystems physical conditions in the
atmosphere, at the surface and within the soils all interact to create the conditions that give rise to
vegetation that develops. To make links between the physical environment and the biotic communities,
ecologist and environmental scientist need to be able to measure the abiotic conditions.

Remember that biotic components of an ecosystems consists of all of the living organisms in the
ecosystem. Measuring the biotic component can be a challenge at times. Especially if the organism you
are trying to sample is traveling over 50km per hour. It can also be a challenge trying to find out how
many anthills are in a 100 square kilometers.

In this unit you will learn how to make dichotomous keys to identify organisms and various sampling
techniques. This unit is a minumum of 4.5 hours.

Significant ideas:

 The description and investigation of ecosystems allows for comparisons to be made between
different ecosystems and for them to be monitored, modelled and evaluate over time, measuring
both natural change and human impacts.
 Ecosystems can be better understood through the investigation and quantification of their
components.

The study of an ecosystem requires that it be named and located; for example, Deinikerwald in
Baar, Switzerland—a mixed deciduous–coniferous managed woodland.
Ecosystem ecology is the study of these and other questions about the living and nonliving components
within the environment, how these factors interact with each other, and how both natural and human-
induced changes affect how they function.

Understanding how ecosystems work begins with an understanding of how sunlight is converted into
usable energy, the importance of nutrient cycling, and the impact mankind has on the environment. Plants
convert sunlight into usable forms of energy that are carbon based. Primary and secondary production in
populations can be used to determine energy flow in ecosystems. Studying the effects of atmospheric?
CO2 will have future implications for agricultural production and food quality
Organisms in an ecosystem can be identified using a variety of tools including keys, comparison
to herbarium or specimen collections, technologies and scientific expertise.

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Proper identification of species is important to biologists if they want to compare their study area to other
regions. Knowing the organisms that live in your region can help you to learn about their function within
the ecosystem
and why it is important to protect them

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133
Sampling strategies may be used to measure biotic and abiotic factors and their change in space,
along an environmental gradient, over time, through succession, or before and after a human
impact (for example, as part of an EIA).

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Investigations in to ecosystems are very complicated since there are so many different factors that need
to be considered. We can broadly group factors influencing ecosystems in to: biotic factors are living
factors affecting an organism, such as food, competition or disease and abiotic factors, non-living
factors.

Know the methods for measuring any three significant abiotic factors and how these may vary in a given
ecosystem with depth, time or distance.

 Marine—salinity, pH, temperature, dissolved oxygen, wave action

 Freshwater—turbidity, flow velocity, pH, temperature, dissolved oxygen
 Terrestrial—temperature, light intensity, wind speed, particle size, slope, soil moisture, drainage,
mineral content.

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 image from en.wikipedia.org
Methods and changes should be selected appropriately for the human activity chosen. Suitable human
impacts for study might include toxins from mining activity, landfills, eutrophication, effluent, oil spills and
overexploitation. This could include repeated measurements on the ground, satellite images and maps.

Example of human activity

Chernobyl 1986, Russia:
Nuclear reactor blew up

 design drawback
 human errors due to poor supervision

The cause:
This caused an increase in thermal power which lead to more explosions. This contaminated soil, plants
and animals.
Respond:

 Fire fighters tried to turn it off, it took 5000 tonnes of sand, lead and clay.
 The UN gave £75 million to make it safe and it was fixed by an international team ten years later.
 People had to evacuate 30km away
 The town was cleared of everything
 15cm of soil depth was removed
 land washed away and dams were built
 wall built around it
 food was contaminated

Measurements should be repeated to increase reliability of data. The number of repetitions

required depends on the factor being measured.
Reliability, like validity, is a way of assessing the quality of the measurement procedure used to collect
data in a dissertation. In order for the results from a study to be considered valid, the measurement
procedure must first be reliable. Reliability in research data refers to the degree to which an assessment
consistently measures whatever it is measuring.

There are many forms of reliability, all of which will have an effect on the overall reliability of the
instrument and therefore the data collected. Reliability is an essential pre-requisite for validity. It is
possible to have a reliable measure that is not valid, however a valid measure must also be
reliable.Below are some of the forms of reliability that the researcher will need to address

Inter-Rater or Inter-Observer Reliability

Used to assess the degree to which different raters/observers agree when measuring the same
phenomenon simultaneously.

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Test-Retest Reliability
Compares results from an initial test with repeated measures later on, the assumption being that the if
instrument is reliable there will be close agreement over repeated tests if the variables being measured
remain unchanged.

Parallel-Forms or Alternate-Forms Reliability

Used to assess the consistency of the results of two similar types of test used to measure the same
variable at the same time.

Methods for estimating the biomass and energy of trophic levels in a community include
measurement of dry mass, controlled combustion and extrapolation from samples. Data from
these methods can be used to construct ecological pyramids.

Dry weight measurements of quantitative samples could be extrapolated to estimate total

biomass. Biomass is calculated to indicate the total energy within in a living being or trophic level. The
greater the mass of the living material the greater the amount of energy present.

Methods for estimating the abundance of non-motile organisms include the use of quadrats for
making actual counts, measuring population density, percentage cover and percentage
frequency.
Counts

 Number of species in an individual area

Density

 The number of individuals per unit area

 D=ni/A (D = density; n = number of individuals in species, A = sampling area)

Coverage

 The proportion of ground that is occupied or area covered by the plant/species

 Ci=ai/A

Frequency

 The number of times a given event occurs

Direct and indirect methods for estimating the abundance of motile organisms can be described
and evaluated. Direct methods include actual counts and sampling. Indirect methods include the
use of capture–mark–recapture with the application of the Lincoln index.

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– n1 is the number caught in the first sample
– n2 is the number caught in the second sample
– nm is the number caught in the second sample that were marked
t is impossible for you to study every organism in an ecosystem. The number of organisms can be
overwhelming. Limitations must be put on how many plants and animals you study. In order to study the
animals there are trapping methods which help obtain more samples, like:

 pitfall traps
 small mammal traps
 light traps
 tullgren funnels

Methods can also include capture–mark–release–recapture (Lincoln index) and quadrats for measuring
population density, percentage frequency and percentage cover.

Sample methods must allow for the collection of that is scientifically representative and appropriate, and
allow the collection of data on all species present. Results can be used to compare ecosystems.

IT is important to take into consideration that the marking methods are not harmful to the animal and clear
so that they do not become easy targets for prey.
Species richness is the number of species in a community and is a useful comparative measure.

Biological diversity can be quantified in many different ways. The two main factors taken into account
when measuring diversity are richness and evenness. Richness is a measure of the number of different
kinds of organisms present in a particular area. For example, species richness is the number of different
species present. However, diversity depends not only on richness, but also on evenness. Evenness
compares the similarity of the population size of each of the species present.

Species diversity is a function of the number of species and their relative abundance and can be
compared using an index. There are many versions of diversity indices, but students are only
expected to be able to apply and evaluate the result of the Simpson diversity index as shown
below. Using this formula, the higher the result (D), the greater the species diversity. This
indication of diversity is only useful when comparing two similar habitats, or the same habitat
over time.

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D is the Simpson diversity index
– N is the total number of organisms of all species found
– n is the number of individuals of a particular species
Diversity is often considered as a function of two components:

 the number of different species

 the relative numbers of individuals of each species.

When we consider ecosystems, diversity is sometimes used to mean how may different species there are
in a community.

Species diversity is best describe as a combination of richness and evenness. Ecologists have
developed various formula to measure species diversity.

When using the Simpson's diversity index, D is a measure of species richness. A high value
of D suggests a stable and ancient site, and a low value of D could suggest pollution, recent
urbanization or agricultural activity. The index is normally used in studies of vegetation but can also be
applied to comparisons of animal or species diversity.

One of the most common indices of species diversity is the Simpson’s index. In Environmental Systems
and Society we use a derivative of the index with the formula
Applications and skills:
Design and carry out ecological investigations.

Methods of Investigation

 The Scientific Method

 Planning an Investigation
 Stages of an Investigation
 Making Investigations

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Collection and Analysis

 Transformations
 Constructing Tables and Graphs
 Descriptive Statistics
 Frequency Distributions

Sampling and Data Collection

 Direct Methods
 Point Sampling
 Quadrat Sampling
 Transect Sampling
 Mark and Recapture

Sampling Animal Populations

 Indirect Methods
 Equipment and Sampling Methods
 Keying Out Species

Construct simple identification keys for up to eight species.

Keys called dichotomous keys are used to identify species. The key is written so that the identification is
done in steps. At each step two options are given based on different possible characteristics of the
organism you are looking at. You go through all the steps until the name of the species is discovered.

This is a key that divides macroinvertebrates into four categories.

For the exams you need to have at least eight species in the key you construct. This can also be shown
graphically.

Evaluate sampling strategies.

The distribution of organisms in a habitat may be affected by physical factors, such as temperature and
light. Transects and quadrats are used to collect quantitative data.
Sampling Techniques
It is not possible to survey an entire area, so small areas called samples are taken, these are two
methods used.

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Quadrat sampling takes small areas, randomly chosen from an ecosystem, these areas are bounded by
a metal frame called a quadrat. Where to place the quandrat is usually decided by dividing an area in a
grid, and then randomly selecting co-ordinates (throwing isn't scientific enough!). For instance, below
point (2,3) has been chosen to be sampled.

Quadrats are more useful for comparing species in two different areas, and for practical purposes are
used in ecosystems without tall vegetation - such as meadows or shores.
A problem is when counting plants, but they grow in clumps; this is overcome by calculating the density or
the percentage of ground covered.
A second method is transect sampling, this is used to measure the change from one area to another. It
is carried out by laying a line along an area, and then recording species the line touches, or placing a
quadrat at regular intervals.
A slightly different method is a belt transect, where two parallel lines are laid and the conditions between
these measured.

Statistical Methods
Once you have performed an ecological investigation, you will have a lot of data and need to represent
and interpret it somehow; to do this we use statistics.
One method of interpreting the mean that you may be familiar with, is the standard deviation. This is a
measure of how spread out the data is. For instance, 10, 11 ,12, 13, 14 have a mean of 12, but 1, 1, 1, 1,
56 also have a mean of 12, this is where the standard deviation is useful.
The equation for standard deviation is:

Evaluate methods to investigate the change along an environmental gradient and the effect of a
human impact in an ecosystem

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An environmental gradient is a gradual change in abiotic factors. Environmental gradients can be related
to factors such as altitude, temperature, depth, ocean proximity and soil
humidity. Species abundances usually change along environmental gradients in a more or less predictive
way. However, the species abundance along an environmental gradient is not only determined by the
abiotic factor but, also by the change in the biotic interactions, like competition.

When measuring these changes, all parts of the gradient needs to be sampled. A transect is usually
used. The simplest one is when a line of tape is layed down across the area wanted to be measured then
to take samples of all the organisms touching the tape. Many transects should be taken to obtain
quantitative data. A belt transect is used for bigger samples

Evaluate methods for estimating biomass at different trophic levels in an ecosystem

Biomass - The mass of organic matter present in organisms or ecosystems, usually per unit area.It is
taken as the mass of an organism minus the water content (dry weight biomass). This is because water
varies from organism to organism. Additionally, it has no energy nor is it organic. The process of obtaining
dry weight biomass is the same as the soil moisture process. The sample is heated at a temperature (80
degrees C) which is hot enough to evaporate the water, but not hot enough to burn tissue. This is left for
a specific period of time and re-weighed. The process is then repeated until no further weight loss is
recorded. Biomass is usually represented per unit area so that comparisons can be made between
trophic levels. Dry-weight measurements can be extrapolated to estimate total biomass.
Evaluate methods for measuring or estimating populations of motile and non-motile organisms
Calculate and interpret data for species richness and diversity
Draw graphs to illustrate species diversity in a community over time, or between communities.

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143
Key Terms
biodegradable dichotomous key biotic mitigation correlation
diversity sustainable habitat scoping species diversity
Lincoln index environmental impact diversity competition pitfall trap
small mammal trap physical recapture index diversity release
dry weight characteristics tullgren quadrats percentage
overexploration duration funnel catchable cover
species population percentage evenness
biomass density frequency
genetic diversity species relative
capture richness abundance
light traps secchi circle
density index terrestrial

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145
TOPIC 3.1: INTRODUCTION TO BIODIVERSITY

Biodiversity is the variety of all life forms on earth - the different plants, animals and micro-organisms and
the ecosystems of which they are a part.

In this unit we will see how diversity changes through succession, genetic diversity, limiting factors and
human activities.

This unit is a minimum of 2 hours,

Significant Ideas

 Biodiversity can be identified in a variety of forms, including species diversity, habitat diversity
and genetic diversity.
 The ability to both understand and quantify biodiversity is important to conservation efforts

Big questions:

 How are issues addressed in this topic of relevance to sustainability or sustainable development
 In what ways might the solutions explored in this topic alter our predictions for the state of human
societies and the biosphere some decades from now?
 Unsustainable development can lead to species extinction. Given the five mass extinctions of the
past, is this something that the human race should be concerned about?
 What effects could species extinctions have on human societies in years to come?

Knowledge & Understanding:

U 3.1.1 Biodiversity is a broad concept encompassing the total diversity of living systems, which
includes the diversity of species, habitat diversity and genetic diversity.

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The term biodiversity refers to the variety of life on Earth at all its levels, from genes to ecosystems, and
the ecological and evolutionary processes that sustain it. Biodiversity includes not only species we
consider rare, threatened, or endangered, but every living thing—even organisms we still know little
about, such as microbes, fungi, and invertebrates. Biodiversity is important everywhere; species and
habitats in your area as well as those in distant lands all play a role in maintaining healthy ecosystems.

U 3.1.2 Species diversity in communities is a product of two variables: the number of species
(richness) and their relative proportions (evenness)
[Species diversity within a community sis a component of the broader description of the biodiversity of an
entire ecosystem]

image from friendsberowravalley.org.au

Species diversity is defined as the number of species and abundance of each species that live in a
particular location. The number of species that live in a certain location is called species richness. If you
were to measure the species richness of a forest, you might find 20 bird species, 50 plant species, and 10
mammal species. Abundance is the number of individuals of each species. For example, there might be
100 mountain beavers that live in a forest. You can talk about species diversity on a small scale, like a
forest, or on a large scale, like the total diversity of species living on Earth

U 3.1.3 Communities can be described and compared through the use of diversity indices. When
comparing communities that are similar, low diversity could be indicative of pollution,
eutrophication or recent colonization of a site. The number of species present in an area is often
indicative of general patterns of biodiversity

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 A diversity index is a mathematical measure of species diversity in a community. Diversity indices
provide more information about community composition than simply species richness (i.e., the number of
species present); they also take the relative abundances of different species into account.Diversity
indices provide important information about rarity and commonness of species in a community. The ability
to quantify diversity in this way is an important tool for biologists trying to understand community
structure.Simpson's diversity index (D) is a simple mathematical measure that characterizes species
diversity in a community

U 3.1.4 Habitat diversity refers to the range of different habitats in an ecosystem or biome.

Habitat diversity is made up of several components. Perhaps the most easily recognized component of
habitat diversity is vegetative diversity. Vegetative diversity refers to the number of different species of
vegetation present. The greater the number of species, the greater the vegetative diversity. Diverse plant
communities increase the likelihood that some of the plants that serve as required food and cover species
for a particular wildlife species are present

U 3.1.5 Genetic diversity refers to the range of genetic material present in a population of a
species.

image from www.shareyouressays.com

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Each individual species possesses genes which are the source of its own unique features: In human
beings, for example, the huge variety of people's faces reflects each person's genetic individuality. The
term genetic diversity also covers distinct populations of a single species, such as the thousands of
breeds of different dogs or the numerous variety of roses.
While some individuals might be able to tolerate an increased load of pollutants in their environment,
others, carrying different genes, might suffer from infertility or even die under the exact same
environmental conditions. Whilst the former will continue to live in the environment the latter will either
have to leave it or die. This process is called natural selection and it leads to the loss of genetic diversity
in certain habitats. However, the individuals that are no longer present might have carried genes for faster
growth or for the ability to cope better with other stress factors.

U 3.1.6 Quantification of biodiversity is important to conservation efforts so that areas of high

biodiversity may be identified, explored, and appropriate conservation put in place where
possible.
The ability to assess changes to biodiversity in a given community over time is important in assessing the
impact of human activity in the community

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 image from www.bbc.co.uk
Biodiversity in a given area is dependent on many different parameters and the interrelationships
between these factors.

 diversity changes through succession

 greater habitat diversity leads to greater species and genetic diversity
 a complex ecosystem, with its variety of nutrient and energy pathways, provides stability
 human activities modify succession, for example, logging, grazing, burning
 human activities often simplify ecosystems, rendering them unstable, for example, North America
wheat farming versus tall grass prairie
 an ecosystem’s capacity to survive change may depend on diversity, resilience and inertia.

A complex ecosystem with its variety of nutrient and energy pathways provides stability. Stability lead to
diversity.

Succession increases species diversity as there are new habitats been formed and a more complex
ecosystem had been formed.

Human activities modify succession, for example, logging, grazing, burning

Greater habitat diversity leads to greater species and genetic diversity

An ecosystem’s capacity to survive change may depend on diversity, resilience(how well the system can
return to the starting position) and inertia (how hard it is to move the system to a new position)

Human activities often simplify ecosystems, rendering them unstable

Examples:

 Tropical forests -high diversity and inertia, low resilience – thin soils
 Grasslands - low diversity and inertia, high resilience – rich soils.

Application & Skills

A 3.1 1 Distinguish between biodiversity, diversity of species, habitat diversity and genetic
diversity.

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 image from www.abmi.ca
Biodiversity: The amount of biological or living diversity per unit area. It includes the concepts of species
diversity, habitat diversity and genetic diversity.

 genetic diversity: the genetic range that is present in a population of a species. Species that have
a small genetic diversity are more at risk of being wiped out by diseases. Selective breeding by
humans to domesticate animals or grow plants with specific traits has reduced the gene pool in
many species.
 species diversity: the range of species living in a specified area. An area may have a high density
of wildlife, but if they are all from a few different species then it would have a low species
diversity.
 habitat diversity: the range of different habitats in an ecosystem. Jungle or forest ecosystems are
likely to have a higher habitat diversity than desert or tundra ecosystems.

This is the total number of species living in an ecosystem. Recently attention has been focused on global
biodiversity and the extinction of species due to human activities.

Researchers have estimated that there are between 3 - 30 million species on Earth, with a few studies
predicting that there may be over 100 million species on Earth! Currently, we have identified only 1.7
million species, so we have a long way to go before we can come close to figuring out how many species
are on Earth!

There is more biodiversity within tropical ecosystems than temperate or boreal ecosystems. Tropical
rainforests have the most diversity.

The most diverse group of animals are invertebrates. Invertebrates are animals without backbones,
including insects, crustaceans, sponges, scorpions and many other kinds of organisms. Over half of all
the animals already identified are invertebrates. Beetles are some of the most numerous species.

Science has so much more to learn about the biodiversity of microscopic organisms like bacteria and
protozoa.

It is impossible to know how many species actually exist for following reasons:

 We have not explored every part of the biosphere yet.

 Most species are less than 1mm long so they are easily overlooked.
 Apart from the popular taxonomic groups like birds and mammals there are not enough experts to
identify the more obscure and "esoteric" groups.

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  Species become extinct before they have been discovered.

A 3.1.2 Comment on the relative values of biodiversity data.

[Interpreting diversity is complex; low diversity can be present in natural; ancient and unpolluted sites]

image from jncc.defra.gov.uk

In spite of many tools and data sources, biodiversity remains difficult to quantify precisely. But precise
answers are seldom needed to devise an effective understanding of where biodiversity is, how it is
changing over space and time, the drivers responsible for such change, the consequences of such
change for ecosystem services and human well-being, and the response options available. Ideally, to
assess the conditions and trends of biodiversity either globally or sub-globally, it is necessary to measure
the abundance of all organisms over space and time, using taxonomy (such as the number of species),
functional traits (for example, the ecological type such as nitrogen-fixing plants like legumes versus non-
nitrogen-fixing plants), and the interactions among species that affect their dynamics and function
(predation, parasitism, competition, and facilitation such as pollination, for instance, and how strongly
such interactions affect ecosystems). Even more important would be to estimate turnover of biodiversity,
not just point estimates in space or time

A 3.1.3 Discuss the usefulness of providing numerical values of species diversity to

understanding the nature of biological communities and the conservation of biodiversity.

image from https://courses.lumenlearning.com

A key tool used by conservation biologists to assess the effect of the disturbance is use of diversity
indices, such as the Simpson’s index. Quantification of biodiversity in this way this way is important to
conservation efforts so that areas of high biodiversity are identified, explored, and appropriate
conservation put in place where possible. Areas that are high in biodiversity are known as hotspots. They
contain large numbers of endemic species (species not found anywhere else), and so measures of
biodiversity are essential in identifying areas that should be protected against damaging human activities.
An example of a biological hotspot is Tumbes-Choco-Magdalena, an area that includes the forests of the
South American Pacific coast (from Panama to Peru and the Galapagos Islands.

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Key Terms
biodiversity genetic diversity species diversity habitat diversity population
behaviour species inbreed lithosphere gene pool
stability fertile offspring resilience diversity
succession habitat competition inertia
climax limited
community resources

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TOPIC 3.3: THREATS TO BIODIVERSITY

Image from http://en.wikipedia.org

Rate of loss of biodiversity may vary from country to country depending on the ecosystems present,
protection policies and monitoring, environmental viewpoints and stage of economic development.

In this unit we will identify the factors that lead to biodiversity loss. You will also look at case histories of
biological significance that is threatened by human activities. You should know the ecological, socio-
political and economic pressures that caused or are causing the degradation of the chosen area, and the
consequent threat to biodiversity. This unit is a minimum of 4 hours.

Significant Ideas

 While global biodiversity is difficult to quantify, it is decreasing rapidly due to human activity.
Classification of species conservation status can provide a useful tool in the conservation of
biodiversity

Big questions:

 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development.
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 What indicators can be taken to suggest that a species is a threat from extinction?
 How can the population of a species facing extinction be restored?
 What threats do biologically significant areas face and how can the extent of the environmental
impacts be limited?
 What issues arise when attempts are made to balance conservation with economic development?
What conflicts exist between exploration, sustainable development, and conservation in tropical
biomes?

Knowledge and Understanding

U 3.3.1 Estimates of the total number of species on Earth vary considerably. They are based on
mathematical models, which are influenced by classification issues and a lack of finance for
scientific research, resulting in many habitats and groups being significantly under-recorded.

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There are 8.7 million eukaryotic species on our planet — give or take 1.3 million. The latest biodiversity
estimate, based on a new method of prediction, dramatically narrows the range of 'best guesses', which
was previously between 3 million and 100 million. It means that a staggering 86% of land species and
91% of marine species remain undiscovered.

Knowing just who we share the planet with is of particular concern now because global warming,
deforestation and other signs of human development are threatening many species, which may be
essential to the functioning of ecosystems or may have inherent value in terms of developing medicines
or other products.

One of the reasons we can’t get an accurate count is that the bulk of the things that have yet to be
discovered and described are in the realm of the very small: insects, bacteria and other microbes.

Another part of the problem is that the tradition of taxonomy has been confined to the developed world for
the bulk of its existence, leaving out the enormous diversity of much of the southern hemisphere, which is
less developed on average. Species aren’t equally distributed across the Earth; they have these hotspots,

U 3.3.2 The current rates of species loss are far greater now than in the recent past, due to
increased human influence. The human activities that cause species extinctions include habitat
destruction, introduction of invasive species, pollution, overharvesting and hunting.

t has now become clear that the loss of biodiversity scientists have been reporting for the last few
decades is more than the usual fluctuations seen in ecosystems. The current extinction rate is now
approaching 1,000 times and may climb to 10,000 times during the next century, if present trends
continue.” In 2005 the Millennium Ecosystem Assessment reported that 10-30 percent of mammal, bird,
and amphibian species are threatened with extinction because of human activity.

 Natural hazards: include volcanic eruptions, earthquakes, landslides, natural fires, avalanches,
tsunami, and drought. These events are out of our control, but we could be the indirect cause of

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 them. Environmental disasters are caused by human activity, e.g. loss of tropical rainforest, oil
spills, etc…
 Habitat: habitat loss is the major cause of loss of biodiversity, which is caused by human activities
either destroying or changing natural habitats. Overpopulation has led to more and more habitats
being degrade in order to accommodate human activities like agriculture, which is needed to
support the human population. Habitat fragmentation is the process whereby large natural areas
are separated by roads, towns, fences, fields, etc...This leads to a decrease in ecological
interactions between species and the isolation of populations. This also leads to the interaction of
wild and domestic species which could spread diseases between the populations.
 Overexploitation: hunting and harvesting of food resources has led to overexploitation of the
environment. If we exceed the maximum sustainable yield of any species then the population is
no longer sustainable.
 Agriculture: has caused many environmental problems. The introduction of monoculture (growth
of one species), fertilizers and pesticides, as well as the introduction of genetically modified
species has caused instability in the environment.
 Pollution: destroys and degrades habitats. Pesticides, fertilizers, factory emissions, and oil spills,
have caused tremendous amounts of damage to the environment and climate change, which has
altered weather patterns and shifted biomes away from the equator. This has disrupted the
suitability of ecosystems to support the range of species naturally supported there. Introduction of
non-native species: has caused instability in many habitats. It disrupts natural ecological
interactions and niches, which causes great problems for the ecosystem.

image from www.usnews.com

U 3.3.4 Tropical biomes contain some of the most globally biodiverse areas and their
unsustainable exploitation results in massive losses in biodiversity and their ability to perform
globally important ecological services.

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Rainforests once covered 14 percent of the Earth's land surface, now they cover 6 percent and experts
estimate that the last remaining rainforests could be consumed in less than 40 years.

Tropical rainforests have been lost at a massive rate. Approximately 1.5 hectares of rainforest is cleared
every second. About 50% of all timber is found in tropical rainforests, and timber is the second biggest
resource after oil. Therefore the demand for and motivation to clear tropical rainforests is high. Tropical
rainforests are also relied upon for subsistence agriculture. Many will clear forest, grow crops for 2-3
years and then more to a new site, this is called shifting cultivation. This can work as long as there is
enough time for the forests to regenerate, but as population sizes increase and the demand for resources
rises too many areas are cleared before they have had time to re-grow. This leads to a gradual
degradation of nutrients and of biodiversity. It is estimated that it takes 1000 years for the biodiversity of
the primary forest to be recovered and the secondary forest that does grow up is impoverished (of lesser
quality) in many ways

You will want to consider

 the vulnerability of other systems

 the regeneration rate of tropical rainforests
 total area and species diversity
 rainforest and “green politics”

Tropical Rainforest:

 Globally 2.4 (1 hectare) acres of rainforest have been destroyed every second... it is the
equivalent of two US football fields put together.
 149 acres (60 hectares) have been destroyed a minute

 Located within many developed countries, meaning that it would face more human disturbance
 Very complex structure with high diversity
 Play an important role in reducing the effects of global warming
 Having many economic value and demands e.g. timber
 Due to human destruction, the rainforest need a long time to recover and have poor soils
 The destruction of rainforest has been regard as a key mobilser of the enivonrmental movement
and green policies

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This shows how in the past and into the future, how the Amazon rainforest has been destroyed (green
represents rainforest)

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U 3.3.5 The International Union of Conservation of Nature (IUCN) publishes data in the “Red List of
Threatened Species” in several categories. Factors used to determine the conservation status of a
species include: population size, degree of specialization, distribution, reproductive potential and
behaviour, geographic range and degree of fragmentation, quality of habitat, trophic level, and the
probability of extinction.

The conservation status of a species is an indicator of how likely it is to remain alive at present or in the
near future.

Many factors are used to assess a species' conservation status, including: the number remaining, the
overall increase or decrease in the population over time, breeding success rates and known threats.

The IUCN Red List of Threatened Species is the best-known worldwide conservation status listing and
ranking system.

Definitions of the conservation status categories are not required and the term “criteria” has been avoided
due to the complexity of the Red List classification system.

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You should be aware of the factors used to determine a species’ conservation status, and that a sliding
scale operates. You should appreciate that a range of factors are used to determine conservation status,
such as:

 population size;
 reduction in population size;
 numbers of mature individuals;
 geographic range and degree of fragmentation;
 quality of habitat;
 area of occupancy and probability of extinction.

Rating

1. Extinct
2. Extinct in Wild
3. Critically Endangered
4. Endangered
5. Vulnerable
6. Conservation Dependent
7. Near Threatened
8. Least Concern

The following factors make a species prone to extinction:

 Narrow geographical range: species lives only in one place, if it is degraded or destroyed their
habitat will be affected or gone.
 Small population size or declining numbers: smaller populations have smaller genetic diversity
and are less resilient (large predators and extreme specialists e.g. snow leopard and tiger).
 Low population densities and large territories: if species requires large area to hunt and only
meets others to breed then habitat fragmentation and degradation will greatly affect it.
 Few populations of the species: more populations of a species (in different locations) the better
the chances of survival.
 Large Bodied species: as energy decreases up the food chain, the higher the tropic level the rarer
the species (e.g. top predators). The large bodied top predators require larger ranges, have lower
population densities, need a lot of food, and are often hunted for sport or because of the threat to
humans (lion, tiger, etc…)
 Low reproductive potential: species which reproduce slowly and infrequently (e.g. whales, and
larger seabirds e.g. albatrosses which only produce one egg per pair per year).
 Seasonal migrants: long migration routes (e.g. swallows, southern Africa to Europe), hazardous
journeys, and they need both habitats. If one habitat is destroyed or degraded and then there is
no food for them. Barriers on their journeys (e.g. salmon trying swim upstream).
 Poor dispersers: species that can not move easily to new habitats are vulnerable. For example
plants rely on seed dispersal to move which can take a long time and climate change can cause
the plant to die before it can move. Flightless birds of New Zealand are almost extinct because
they can not escape hunters or fly to new islands.
 Specialized feeders or niche requirements: for example giant pandas, which eat mostly bamboo
and koalas, which eat only eucalyptus leaves, can only survive on one food resource.
 Hunted for food or sport: over-hunting or over-harvesting can eradicate species quickly,
especially if that species lives in large groups (e.g. herds of bison in North America)

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U 3.3.6 Most tropical biomes occur in less economically developed countries (LEDCs) and
therefore there is conflict between exploitation, sustainable development and conservation.

 MEDCs are able to preserve their remaining natural ecosystems as they do not rely on the
ecosystems to provide income
 MEDCs cleared the majority of the natural ecosystems in the past for agriculture and timber
 LEDCs need to balance between conservation of tropical biomes and using the land to provide
income

Application & Skills

A 3.3.1 Discuss the case histories of three different species: one that has become extinct due to
human activity, another that is critically endangered, and a third species whose conservation
status has been improved by intervention

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You will need to know the ecological, sociopolitical and economic pressures that caused or are causing
the degradation of the chosen area, and the consequent threat to biodiversity.

Extinct Species: Dodo Raphus cucullatus

 Description: Large flightless bird endemic to the island of Mauritius.

 Ecological Role: No major predators on Mauritius so dodo had no need to develop flight. Dodo
was a ground-nesting bird.
 Pressures: In 1505 Portuguese sailors used discovered Mauritius and used it as a restocking
point on their voyages to get spices from Indonesia. They ate the dodo as a source of red meat.
Later the island was used a penal colony (jail/prison) and rats, pigs and monkeys were
introduced. These ate the dodo eggs and humans killed the dodo for sport and food. Crab-eating
macaque monkeys introduced by sailors also seemed to have an impact as the stole the dodo
eggs. The later conversion of forest to plantation also destroyed their habitat. It was known to be
extinct by 1681.
 Consequences of disappearance: Island fauna impoverished by its loss.

Critically Endangered Species: Rafflesia

 Description: A tropical parasitic plant in the forests of South-East Asia, parasitic on a vine.
 Ecological Role: These plants are single sexed (male or female) and pollination must be carried
out when the plants are flowering. Therefore a male and female plant in the same area must be
ready for pollination at the same time. The seeds are then dispersed by small squirrels and other
rodents and must then reach a host vine.
 Pressures: The Rafflesia plants are vulnerable because they need very specific conditions to
survive and carry out their lifecycle. They are also vulnerable to deforestation and logging which
destroys their habitat. Humans damage them and fewer plants means less chance of breeding.
 Methods of restoring populations: In Sabah, Sarawak (Malaysia), and Sumatra (Indonesia)
sanctuaries have been established. There are also many environmental and educational
programs being set up to educate the public on this endangered species.

Recovered Species: Australian saltwater crocodile

 Description: The Australian saltwater crocodile can grow up to 5m long. It is a bulky reptile with a
broad snout. It lays up to 80 eggs each year, which take up to three months to hatch. Crocodile
take 15 years to mature. The Australian saltwater crocodile was listed as a protected species in
Australia in 1971, and is protected under CITES, which ban trade in endangered animals.
 Ecological Role: The habitat is estuaries, swamps and rivers. Nests are built on the banks in a
heap of leaves. The eggs are food for dingoes, pythons, and other small animals. Older
crocodiles eat young crocodiles, mud-crabs, sea snakes, turtle eggs and catfish. Baby crocodiles
eat tadpoles crabs and fish. It is a top predator.
 Pressures: The saltwater crocodile was exploited for its skin (leather), meat, and body parts
through illegal hunting and smuggling. It was hunted for sport and was often deliberately killed for
attacks on humans.

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  Method of Restoring Populations: To restore the crocodiles populations there was a sustainable
use policy, with limited culling of wild populations, ranching (collecting eggs and hatchlings and
raising them in captivity) and closed-cycle farming (maintaining breeding adults in captivity and
harvesting offspring at four years of age). The exploitation of farmed animals reduces the hunting
of wild crocodiles. Visitors tour areas to see wild crocodiles (ecotourism) so they are now a
valued species. This policy was supported by the Species Survival Commission (SSC) of IUCN
but was viewed by other as treating crocodiles inhumanely.

A 3.3.2 Describe the threats to biodiversity from human activity in a given natural area of
biological significance or conservation area

Factors leading to loss of diversity include:

 natural hazard events (for example, volcanoes, drought, ice age, meteor impact);
 habitat degradation, fragmentation and loss;
 agricultural practices (for example, monoculture, use of pesticides, use of genetically modified
species);
 introduction and/or escape of non-native species; pollution; hunting, collecting and harvesting.

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Rate of loss of biodiversity may vary from country to country depending on:

 the ecosystems present

 protection policies and monitoring
 environmental viewpoints
 stage of economic development

A 3.3.3 Evaluate the impact of human activity on the biodiversity of tropical biomes

As human population grows the need for agriculture, energy and development space increases with it.
Tropical rainforests cover a massive amount of the world’s tree surface, each year over 90,000 square
miles of the forests are harvested for human use. This deforestation has worried environmentalists
because of the release of carbon from the machinery and the vegetation. It is believed that deforestation
may accelerate the effects of global warming and transform the rainforest climate. Tropical Rainforests
harbor 50% of world’s biodiversity, the massive deforestation of the forest has caused the total land mass
to go 15 million km squared to about 8 million km squared, this is nearly half; it is estimated that nearly
2% of the rainforest is lost annually. Furthermore, Approximately 137 species are lost in this biome per
day, including both species of plants and animals and insects

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 image from tropicalrainforestgkaulbach

A 3.3.4 Discuss the conflict between exploitation, sustainable development and conservation in
tropical biomes

Controlling the loss of biodiversity requires international legislation The willingness to participate in
conservation initiatives varies from country to country and is very dependent on economics, social and
political views. Most tropic biomes are located in LEDC and in the countries there are conflicts between
exploration of resources and sustainability Madagascar is trying to provide its people with with resources
and conceive its natural resources

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 image from www.friendsofanimals.org

Key Terms
biodiversity vulnerbility extinction natural cause human cause
HIPPO habitat distruction framentation loss invasive species
biocontrol kudzu Asian carp starling cane toad
pollution monoculture fertilizer pesticides over hunting
over fishing tragedy of the unstainable rate of extinction mass extinction
Red List commons migratory rainforest logging
rare specialized niche endangered unknown vulnerable
restoration IUCN degradation rehabilitation diversification
extinct limited habitat species vertical ecosystem
threatened cultural extinction approach stratification approach
earth agents assemblages sedimentary premature biological
inertia ecological extinction rock extinction extinction
non-native species exotic species catastrophic trophic cascades
interbreeding agents GMOs
genetic
bottleneck

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TOPIC 3.4: CONSERVATION OF BIODIVERSITY

Image from http://en.wikipedia.org

Life has existed on Earth for over 3.5 billion years. Over 95% of the species that ever existed have gone
extinct. So why should we be concerned about current extinction rates and conserving biodiversity?

It has become clear that biodiversity is the cornerstone of our existence on Earth. It is also important to
conserve biodiversity for the sake of our own curiosity and aesthetic appreciation.

In this unit you will consider arguments for preserving species and habitats based on ethical, aesthetic,
genetic resources and commercial considerations. You will also look at the activities of intergovernmental
and non-governmental organisations in preserving and restoring ecosystems. This unit is a minimum of 4
hours.

Significant Ideas:

 The impact of losing biodiversity drives conservation efforts.

 The variety of arguments given for the conservation of biodiversity will depend on EVSs.
 There are various approaches to the conservation of biodiversity, each with associated strengths
and limitations

Big Questions:

 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 What value systems can you identify at play in the causes and approaches to resolving the issues
addressed in this topic?
 How does your own value system compare with others you have encountered in the context of
issues raised in this topic?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 How do different conservation measures (e.g. in situ and ex situ) prevent environmental impacts,
limit the extent of the environmental impacts, or restore systems in which environmental impacts
have already occurred?
 How would a technocentric view of biodiversity differ from an ecocentric one? Ho do different
EVSs affect approaches to conservation>?
 If you are from a MEDC, how would your EVS differ from that of someone from a LEDC, or from
someone who relies on the preservation of natural ecosystems for survival?
 Do you think that the conservation measures being taken today will be sufficient of preserve the
Earth's biodiversity for the future?

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Knowledge & Understanding:
U 3.4.1 Arguments about species and habitat preservation can be based on aesthetic, ecological,
economic, ethical and social justifications.

image from epa.gov

You should appreciate arguments based on ethical, aesthetic, genetic resource and commercial
(including opportunity cost) considerations. You should also appreciate life support and ecosystem-
support functions.

Habitat conservation for wild species is one of the most important issues facing the environment today —
both in the ocean and on land. As human populations increase, land use increases, and wild species
have smaller spaces to call home. More than half of Earth's terrestrial surface has been altered due to
human activity, resulting in drastic deforestation, erosion and loss of topsoil, biodiversity loss, and
extinction. Species cannot survive outside of their natural habitat without human intervention, such as the
habitats found in a zoo or aquarium, for example. Preserving habitats is essential to preserving
biodiversity.

Ecological

 Life-support service value e.g. stable climate

 Some species are keystone species, which if removed from the ecosystem can lead to many
other species becoming extinct

Economic

 Species and habitat are direct natural capital, e.g. ecotourism

 Unknown value in the potential of the species for agriculture, medicine, genetic diversity and
biotechnology

Aesthetic

 Nature can provide inspiration for all kinds of artworks

Ethical

 The idea of good stewardship (looking after the environment) and sustainable development for
the good of future generations
 Intrinsic value of the environment or right of individuals or species to exist

The values of biodiversity can be classified as either direct values or indirect values

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Direct values - can be (relatively) easily calculated

 goods harvested & destroyed for consumption (eating) or sale in a market

 generally physical commodities of some sort
 private goods - value accrues to the owner of the resource

Examples:

 food sources (‘heirloom varieties’ of many crops, i.e. corn/maize)

 natural products (medicines, textiles, fertilizers, pesticides, etc

Indirect values - more difficult to calculate

 stabilize ecosystems (negative feedback cycles)

 provide benefits but are not generally harvested/destroyed/sold
 usually services or processes which benefit everyone
 public goods - value accrues to society instead of individuals

Examples:

 ecosystem productivity (a.k.a. ecosystem services) i.e. soil aeration, pollination, fertilization,
carbon sequestration, oxygen production ,climate regulation, etc
 scientific or educational value
 biological control (another example of negative feedback)
 gene sources
 environmental monitors
 recreation and ecotourism
 human health - possible future medical applications
 rights of indigenous peoples
 intrinsic (ethical) value - biorights

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U 3.4.2 International, governmental and non-governmental organizations (NGOs) are involved in
conserving and restoring ecosystems and biodiversity, with varying levels of effectiveness due to
their use of media, speed of response, diplomatic constraints, financial resources and political
influence.

Consider the United Nations Environment Programme (UNEP) as an intergovernmental organization and
the World Wide Fund for Nature (WWF) and Greenpeace as non-governmental organizations. Compare
and contrast UNEP and WWF in terms of use of the media, speed of response, diplomatic constraints
and political influence. Consider also recent international conventions on biodiversity (for example,
conventions signed at the Rio Earth Summit (1992) and subsequent updates).

UNEP: set up the Intergovernmental Panel on Climate Change (IPCC) and drove the Montreal Protocol
for phasing out production of ozone-depleting substances.

There are also many other economic coalitions for example ASEAN, the EU, the African Union, and
OPEC, some of which are working for sustainable development and environmental protection. NGOs are
now having more of a global impact, e.g. Greenpeace, and WWF. Institutional Inertia has been a block to
change but the power of people wanting change and voting for politicians who say they will deliver it may
be able to begin to reverse the degradation of the planet.

The World Conservation Strategy (WCS)

The WCS was published by IUCN, UNEP, and WWF in 1980, which presented a joint effort and
integrated approach to conservation. Its aims were to: maintain essential ecological processes and life
support systems; and preserve genetic diversity. It called for international, national, and regional efforts to
balance development with conservation of the world’s living resources. Many countries adopted the WCS
strategies and developed their own too.

In 1982, The UN adopted the UN World Charter for Nature which focused on the following principles:
nature shall be respected; genetic viability on earth shall not be compromised; all areas on Earth are
subject to these principles; ecosystems and organisms shall be managed to achieve and maintain
optimum sustainable productivity; and nature shall be secured against degradation caused by warfare or
hostile activities.

At the UN Earth Summit in Rio in 1992, 179 heads of government signed their countries to Agenda 21.
Agenda 21 is a guide for individuals, businesses, and governments in making choices for development
that help society and the environment. It focuses on four main principles:
Social and economic dimensions: developing countries; poverty; population; and integrating environment
and development.
Conservation and management of resources: atmosphere, land, agriculture, biotechnology, toxic

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chemicals, and radioactive waste.
Strengthening the role of major groups: women, children, indigenous people, NGOs, etc..
Means of implementation: finance, technology, science, legal measures, etc…

The Un Johannesburg Summit on sustainable development in 2002 was intended to consolidate the Rio
one however little action came out of its deliberations. In 2000, however, the UN Millennium Summit was
the largest ever gathering of world leaders who agreed to set time-bound and measurable goals for
combating poverty, hunger, disease, illiteracy, environmental degradation and discrimination against
women. This became known as the Millennium Development Goals. The follow-up in 2005 at the World
Summit in New York outlined a series of global priorities for action and recommended that each country
prepare its own national strategy for the conservation of natural resources for long-term human welfare.

U 3.4.3 Recent international conventions on biodiversity work to create collaboration between

nations for biodiversity conservation.

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The Convention on Biological Diversity (CBD) was inspired by the world community's growing
commitment to sustainable development. It represents a dramatic step forward in the conservation of
biological diversity, the sustainable use of its components, and the fair and equitable sharing of benefits
arising from the use of genetic resources.

The Convention on Biological Diversity (CBD), known informally as the Biodiversity Convention, is a
multilateral treaty. The Convention has three main goals:

 conservation of biological diversity (or biodiversity);

 sustainable use of its components; and
 fair and equitable sharing of benefits arising from genetic resources

The Convention was opened for signature at the Earth Summit in Rio de Janeiro on 5 June 1992 and
entered into force on 29 December 1993.

Each of the biodiversity-related conventions works to implement actions at the national, regional and
international level in order to reach shared goals of conservation and sustainable use. In meeting their
objectives, the conventions have developed a number of complementary approaches (site, species,
genetic resources and/or ecosystem-based) and operational tools (e.g., programmes of work, trade
permits and certificates, multilateral system for access and benefit-sharing, regional agreements, site
listings, funds).

U 3.4.4 Conservation approaches include habitat conservation, species-based conservation and a

mixed approach.

The fundamental characteristics that determine a region's inherent conservation value are vulnerability,
irreplaceability and contribution towards global ecosystem services. Properly managed protected areas

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are the epicentre for sustaining the very ecosystem services on which mankind is dependent for survival.

Conservation approaches provide for:

 the development of broader constituencies for conservation and expanded possibilities to

influence decision-making;
 opportunities to add or create new value to protected areas;
 and the opportunities to manage ecosystems sustainably outside of protected areas.

Areas of particular concern include:

 species without utilitarian or economic value;

 ecological processes that do not directly benefit people; and critical ecological functions that may
be undermined in attempts to optimize a target service.

Understanding the benefits and limitations of using conservation approaches for achieving biodiversity
conservation will help ensure that the finite resources available for biodiversity conservation and
sustainable development are used as strategically and effectively as possible to maintain the multiple
components of biodiversity and to support human well-being.

image from www.toshibatec.co.jp

U 3.4.5 Criteria for consideration when designing protected areas include size, shape, edge
effects, corridors, and proximity to potential human influence.

In effect, protected areas may become “islands” within a country and will normally lose some of their
diversity. The principles of island biogeography might be applied to the design of reserves. Need to
remember that ecosystems are rarely at a stable point. They are hard to lock them or protect them from

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change. This means they are in a nonequilibrium state. Ecosystems which experience frequent or
moderate disturbance have the greatest diversity. This is an intermediate disturbance hypothesis.Most
reserves are considered to be habitat islands in a sea of developed or fragmented lands.

Appropriate criteria should include size, shape, edge effects, corridors and proximity.

 size - larger space allows for larger populations and gene pools, and a wider variety of species
 shape - round is better than all other shapes because it reduces the edge effect
 edge effects - less edge is better; edge creates differences in the structure of an ecosystem,
called an ecotone (an area where 2 habitats meet), which influences what may successfully live
there.
 corridors - provide safe passage between protected areas
 proximity - if protected areas are close to other protected areas, they are more effective than
isolated islands

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U 3.4.6 Alternative approaches to the development of protected areas are species-based
conservation strategies including: CITES, captive breeding and reintroduction programmes, and
zoos, selection of “charismatic” species to help protect others in an area (flagship species),
selection of keystone species to protect the integrity of the food web.

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CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) is an
international agreement between governments set up to protect the many species which were becoming
endangered because of international trade. Its aim is to ensure that international trade in specimens of
wild animals and plants does not threaten their survival. Governments sign up voluntarily and establish
their own national laws to monitor trade. Species are grouped according to how threatened they are by
international trade.

 Appendix І: species can not be traded internationally as they are threatened by extinction.
 Appendix ІІ: species can be traded internationally but within strict regulations.
 Appendix ІІІ: species included at the request of a country which then needs the cooperation of
other countries to help prevent the illegal exploitation.

Captive breeding, reintroduction and zoos

While captive breeding ensures that species do not go exist we can not keep every species in captivity.
The re-introduction of captive-bred species is also a complex process. Programs to re-introduce
populations or establish new ones are very expensive and difficult. Criticisms of such programmes are
that they waste money, are unnecessary, poorly run or unethical. But they are often the best chance that
a species has to avoid extinction. These programmes also create employment and promote education.
Sometimes it is impossible to reintroduce species to their native habitat because it has been destroyed, in
which case captive-breeding and zoos are there best option. Zoos are often criticized and rightly so as
animals are kept in close confinement, in small cages or treated with cruelty. But there are many benefits
to zoos as they produce employment, income for the research and protection of species, and educate the
public in order to promote sustainable development and protection of biodiversity.

Aesthetic versus ecological value

Aesthetically there are many areas of natural beauty which need to protect. The environment is a source
of income in the form of ecotourism as well as the legacy that we leave future generations. The species-
based approach focuses on specific species and not the environment as a whole. Every species has an
ecological value as it provides a service to its environment (niche) and thus a species based approach is
very important. Aesthetic importance of species is important to us as humans however the ecological
value of a species outweighs our extrinsic needs for it and we need to appreciate the intrinsic value of
every species.

Flagship species
Charismatic species selected to appeal to the public and thereby help to protect other species in an area.
These species are charismatic, recognized, popular, large and furry but may not have significant role,
They are used to ask for funds

 giant panda
 meerkats
 gorillas

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Disadvantages:

 take priority over others

 become extinct if we failed
 in conflict with ingenious people

Keystone species
Species that are vital for the continuing function of the ecosystem. Without these species the ecosystem
may collapse. Their disappearance from ecosystem has a far greater impact than to the system. They are
not proportional to their numbers/biomass. These species can be difficult to identify

 sea otter eating sea urchins

 beavers engineers dams
 elephants removing trees so grasses can grow

Mixed approach
Combining both in situ (protected areas) and ex situ (zoos) methods can be the best solution for species
conservation

You should be aware of the relative strengths and weaknesses of:

 the Convention on International Trade in Endangered Species (CITES);

 captive breeding and reintroduction programmes
 zoos and aesthetic versus ecological value

State the strength/weakness by:

 Giving at least 1 specific Evidence/Example for the strength/weakness

 Giving a brief statement why it’s a strong/weak example
 You should have a least 2 strengths and 2 weaknesses that follow this pattern

U 3.4.7 Community support, adequate funding and proper research influence the success of
conservation efforts.

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 image www.fws.gov

U 3.4 8 The location of a conservation area in a country is a significant factor in the success of the
conservation effort. Surrounding land use for the conservation area and distance from urban
centres are important factors for consideration in conservation area design.

The granting of protected status to a species or ecosystem is no guarantee of protection without

community support, adequate funding and proper research. Consider a specific local example.

Due to pressures on habitat and decline in populations some species have become vulnerable. The
legislation provides for the protection of certain species of wild plants, birds and animals. The degree of
protection could be partial (for example: prohibiting trade, closed seasons) or full, in which case the
disturbance, killing or injuring of just one of the species could constitute an offence. Their associated
breeding and sheltering places are also protected.

The list of protected species under domestic legislation is subject to a five-yearly review whereby species
can be added to, or removed from the schedules of protected species.

For each case study, be able to outline and discuss responses to the following questions:

1. Which species is the area designed to protect?

2. Why is/are the species threatened?
3. How and why has the protected area been successful?
4. What are the weaknesses (and their causes) of the protected area?
5. Describe how the criteria used to design protected areas have influenced the success of each
case study.

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 Terrestrial and marine protected areas (% of total
territorial area) in Malawi was 15.02 as of 2010. Its
highest value over the past 20 years was 15.02 in 2010,
while its lowest value was 15.02 in 1990.

malawi_biodiversity_country_profile.pdf
Download File

Application & Skills

A 3.4.1 Explain the criteria used to design and manage protected areas.
Many protected areas in the past were set up on land that no one else wanted. It may have been poor
agricultural land, not near areas of high human density, or land that was degraded in some way. This has
led to some problems in the effectiveness of protecting biodiversity. UNESCO’s Man and the Biosphere
Programme (MAB) started in 1970 which created a network of international reserves in over 100
countries.

Island biogeography refers to the isolation of species when they are placed in a protected area or
reserves. When protected areas are created there will be some decrease in biodiversity as species are
isolated from each other. The following criteria are based upon the principles of island biogeography,
where the increased protection of species is the priority.

Criteria that conservationists now use when planning a protected area or national park are:

 Size: how large should it be to protect the species?

 Numbers: how many individuals of an endangered species must be protected?
 Fragmentation: Is it better to have one larger area or many smaller ones? A large reserve will
contain sufficient numbers of wide-ranging species, minimize edge effects and provide more
habitats for more species. But several smaller reserves that are well placed may be able to
provide more diverse habitats for more diverse populations of rare species than a larger block.
 Edge effects: how to have more interior space per edge? More internal area away from human
activities. Involves decreasing the circumference-to-area ration. Edge effects occur at ecotones
(where two habitats meet and there is a change near the boundary). More species exist at

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 ecotones as species from different habitats converge leading to increased predation and
competition. Long thin reserves have a large edge effect while circular reserves have the least.
 Shape: What is the best shape? Often determined by physical features (e.g. mountains)
 Proximity: How close is it to other reserves? How close is it to humans or human activities?
 Corridors: Should reserves be joined by corridors? Corridors are strips of protected land which
link reserves. These allow individuals to move freely from reserve to reserve and therefore
increase the size of the gene pool and allow for seasonal migration. There are disadvantages as
diseases are more easily spread and it makes hunting/poaching easier in these corridors, which
are harder to protect than reserves.

Some reserves have buffer zones, which are areas around the core reserve which is transitional. Some
farming, extraction of natural resources, e.g. selective logging can take place here. The core of the
reserve (centre) is left undisturbed and organisms should be safer this way.
A 3.4.2 Evaluate the success of a given protected area.
Sichuan giant panda sanctuary

Location: Sichuan Province, China. About 900 000 hectares of national reserves which are the habitat for
the giant panda as well as red panda and snow and clouded leopards. It is a World Heritage Site.
Habitat: there are about giant 1600 pandas living there and approximately 6000 plant species. But the
pandas habitat is shrinking as people fell the bamboo forests and degrade the habitat.

History: In the 1960s errors were made in trying to protect the pandas and many were caged in hopes
that they would breed in captivity. Captive breeding is more successful now as pandas are house in larger
areas.
Actions taken: Human populations have now been moved out of the reserves and laws on gun use
tightened. Panda numbers have now started to increase but are not yet out of trouble. Educating the
public has been very important and ecotourism has assisted greatly in funding the research and
protection of the giant panda, and the reserve as a whole.
Concerns: as the giant panda has a specialized diet of almost entirely bamboo, it means that their habitat
is limited. If the bamboo goes they will starve.

image from Travelneu.com

A 3.4.3 Evaluate different approaches to protecting biodiversity.
The preservation approach, which aims at setting aside National Parks to exclude human activities except
for tourism. Through this approach, direct use of natural resources in the park for commercial or
subsistence purposes is prohibited. This type of approach is often referred to as the “protectionism
approach” or “the fines and fences” approach. The preservation approach aims at excluding human
activities considered inimical to the objectives of conserving biodiversity in National Parks. The

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preservation approach was the most dominant approach until the 1980s, but in some National Parks, it
has now been substituted by the second approach called the community-based conservation approach
that allows people (especially those that neighbor National Parks) to benefit socially or economically from
parks

The community-based conservation approach involves initiatives aimed at conserving biodiversity in the
park but also letting local people benefit from the park [6]. Some of the initiatives involved in the
community-based conservation approach include signing of resource use agreements such as in the
Rwenzori Mountains National Park which allow local people who neighbor National Parks to have access
to specific resources from the park for subsistence use. In other cases, local people are given money for
infrastructural development, such as in Integrated Conservation and Development Initiative in Korup
National Park in Cameroon [8]. And in other National Parks such as Pendjari National Park in Benin, local
people are given a percentage of revenue generated from tourism activities in the park.

Key Terms
species habitat aesthitic intergovernment NGOs
UNEP WWF Greenpeace Rio Earth Summit island
community CITE captive ethical biogeography
stewardship genetic breeding natural selection life support
ecotourism resource gene pool ecoterrorism intrinsic value
ecotone nutrient cycling water zonation corridors
gradual edge edge effect purification migration abrupt change
buffer zone corridors reserve ecological process invasive species
minimum viable biodiversity forest interior reintroduction historic range
pop. security scale flagship species zoo
seed bank botanical captive intervention
in situ garden breeding
ex situ keystone
species
SLOSS

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TOPIC 4.1: INTRODUCTION TO WATER SYSTEMS

Image from goodmenproject.com

Only a small fraction (2.6% by volume) of the Earth’s water supply is fresh water. Of this, over 80% is in
the form of ice caps and glaciers, 0.6% is groundwater and the rest is made up of lakes, soil water,
atmospheric water vapour, rivers and biota in decreasing order of storage size.
Irrigation, industrialization and population increase all make demands on the supplies of fresh water.
Global warming may disrupt rainfall patterns and water supplies. The hydrological cycle supplies humans
with fresh water but we are withdrawing water from underground aquifers and degrading it with wastes at
a greater rate than it can be replenished.

In this unit we will look at the increased demand for fresh water, inequity of usage and political
consequences, methods of reducing use and increasing supplies. This unit is 3 hours.

Significant ideas:
 The hydrological cycle is a system of water flows and storage that may e disrupted by human
activity
 The ocean circulation system (ocean conveyor belt) influences the climate and global distribution
of water (matter and energy)

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 Many horological cycles cross international boundaries. How does this affect the management of
water?
 Identify the solutions to the impacts of agriculture, deforestation and urbanization on the
hydrological cycle
 Can agriculture, deforestation and urbanization allow for the natural functioning of the
hydrological cycle?
 In what ways may population growth and human activities have an impact on the hydrological
cycle of the future?

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Knowledge and Understanding
U 4.1.1 Solar radiation drives the hydrological cycle

Earth's water is in constant motion as water at the surface exchanges places with the gaseous moisture
and water droplets found in the atmosphere. As the sun warms the Earth, liquid water found in lakes and
oceans on the planet's surface evaporates. Moisture within the atmosphere eventually cools and
condenses, until liquid water or snow falls back to the Earth as precipitation. Runoff from rain eventually
finds its way back to lakes and oceans, completing the most direct version of the water cycle.

The water cycle is able to move 495,000 cubic kilometers of moisture through the atmosphere each year.
Without the sun's heat, there would be no evaporation to power the cycle. The heat of the sun is
responsible for the formation of clouds and weather patterns. Without heat from the sun to drive the water
cycle, there could be no weather, and all of Earth's water would exist in a frozen state

U 4.1.2 Fresh water makes up only a small fraction (approximately 2.6% by volume) of the Earth's
water storages

Only a small fraction (2.6% by volume) of the Earth’s water supply is fresh water. Of this, over 80% is in
the form of ice caps and glaciers, 0.6% is groundwater and the rest is made up of lakes, soil water,
atmospheric water vapour, rivers and biota in decreasing order of storage size. Precise figures are not
required.

The degree to which water can be looked at as renewable or non-renewable depends on where it is found
in the hydrological cycle. Renewable water resources are renewed yearly or even more frequently,
however groundwater is non-renewable resource

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U 4.1.3 Storage's in the hydrological cycle include organisms, soil and various water bodies,
including oceans, groundwater (aquifers), lakes, rivers, atmosphere, glaciers and ice caps

The water cycle is dynamic and always active, but that doesn’t mean every molecule of water is
constantly moving through the system. In fact, water is stored in various parts of the cycle, often referred
to as reservoirs. These might be as large as water in the oceans, or, on a smaller scale, water can be
‘trapped’ in an iceberg or a lake. Much more water is in storage than actively moving through the water
cycle.

How long water spends in each reservoir is called ‘residence time’. These are some estimated average
residence times, but it’s important to remember that some water will spend much longer or shorter time
than this.

U 4.1.4 Flows in the hdrological cycle include evapoevaporation, sublimation, evaporation,

condensation, convection (wind-blown movement), precipitation, melting, freezing, flooding,
surface runoff, infiltration, percolation, and stream-flow or currents

As water moves through the cycle, it changes state from liquid (rainwater, seawater) to gas (water
vapour) and back to liquid. Liquid can also freeze and become solid (ice or snow). This natural process
removes some of the water’s impurities, constantly refilling Earth’s fresh water supplies – it is our planet’s
way of recycling water.

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 1. Evaporansportation - water evaporates from plants, mainly through their leaves. This gets
water vapor back into the air.
2. Sublimation - the conversion between the solid and the gaseous phases of matter, with no
intermediate liquid stage. Used to describe the process of snow and ice changing into water
vapor in the air without first melting into water.
3. Evaporation - the process of changing water from liquid to gas. Only fresh water makes its way
up to the clouds, as ocean water leaves behind salt, minerals and metals when it evaporates.
4. Condensation - the process of changing water from gas to liquid.. As water vapour rises, it
becomes cooler and changes back into tiny liquid water droplets. These merge together to form
clouds.
5. Advection - Transport of an atmospheric property by the wind. This horizontal transport or
transfer of a quality such as heat and cold from one point to another. Advective transfers occur
either in the oceans by currents of seawater or by large-scale movement in the atmosphere
where humidity (atmospheric moisture) is another important property. In both cases a major
example is the transport of cold air or water masses from the polar regions to lower latitudes.
6. Precipitation - when rain, snow, sleet or hail falls from the sky. Depending on the air
temperature, water can take a liquid form (rain), or a solid form (snow, sleet or hail).
7. Melting - the process by which ice or snow changes into water
8. Freezing - the process by which water changes from liquid to solid

image from www.eoearth.org

U 4.1.5 Human activities such as agriculture, deforestation and irrigation have a significant impact
on surface runoff and infiltration

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image from en.wikipedia.org
Agriculture has been the cause of significant modification of landscapes throughout the world. Tillage of
land changes the infiltration and runoff characteristics of the land surface, which affects recharge to
ground water, delivery of water and sediment to surface-water bodies, and evapotranspiration. All of
these processes either directly or indirectly affect the interaction of ground water and surface water

Applications of pesticides and fertilizers to cropland can result in significant additions of contaminants to
water resources. Some pesticides are only slightly soluble in water and may attach to soil particles
instead of remaining in solution; these compounds are less likely to cause contamination of ground water.
Other pesticides, however, are detected in low, but significant, concentrations in both ground water and
surface water

Point sources of contamination to surface-water bodies are an expected side effect of urban
development.Point sources of contamination to ground water can include septic tanks, fluid storage tanks,
landfills, and industrial lagoons. If a contaminant is soluble in water and reaches the water table, the
contaminant will be transported by the slowly moving ground water. If the source continues to supply the
contaminant over a period of time,

Deforestation leads to the decreasing of interception and infiltration, because there are not trees to trap
rainfall. It is easily to increase the amount of surface runoff and increase the storm runoff in rivers. The
erosive power is enhanced by the running water. Because there are few trees, lesser roots of vegetation
bind the soil particles. This makes to the increase of soil erosion. Moreover, sediment yields in rivers
increase. The river is silted up. Finally, the river is risk to be flooded. This is the result of the raise of
riverbed and reducing carrying capacity of the channel.

U 4.1.6 Ocean circulation systems are driven by differences in temperature and salinity. The
resulting difference in water density drives the ocean conveyor belt, which distributes heat round
the world, and thus affects climate

image from www.sciencedaily.com

Mass flows of water, or currents, are essential to understanding how heat energy moves between the
Earth’s water bodies, landmasses, and atmosphere. The ocean covers 71 percent of the planet and holds
97 percent of its water, making the ocean a key factor in the storage and transfer of heat energy across
the globe. The movement of this heat through local and global ocean currents affects the regulation of

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local weather conditions and temperature extremes, stabilization of global climate patterns, cycling of
gases, and delivery of nutrients and larva to marine ecosystems

image from www.windows2universe.org

image from www.indiana.edu

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189
 image from www.dailymail.co.uk
Application and skills
A 4.1.1 Discuss human impact on the hydrological cycle
Irrigation, industrialization and population increase all make demands on the supplies of fresh water.
Global warming may disrupt rainfall patterns and water supplies. The hydrological cycle supplies humans
with fresh water but we are withdrawing water from underground aquifers and degrading it with wastes at
a greater rate than it can be replenished.

Consider the increased demand for fresh water, inequity of usage and political consequences, methods
of reducing use and increasing supplies. A case study must be explored that covers some of these issues
and demonstrates either sustainable or unsustainable water use.

The demand of water has increased in both MEDCs and LEDCs, as populations are increasing as well as
agriculture changing and expanding industry. MEDCs need more water as they wash more often, water
their gardens, and wash their cars.

Managing water

This can be reached by:

 making new buildings water efficient (rainwater for sanitation and showers)
 fitting new homes with more water-efficient appliances (dishwashers and toilets)
 expand metering to encourage households to use water more efficiently
 in some rural areas drought resistant crops should be planted to reduce the need for irrigation
 organic fertilizers cause less pollution and bio-control measures can be used to reduce crop pests

CASE STUDY

Water shortages in Southwest United States:

Resource managers in the Colorado River Basin are preparing for an unprecedented scenario: By 2015,
water in Lake Powell is likely to drop to a level that will trigger mandatory cuts in water deliveries to

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California, Arizona and Nevada.

About 36 million people in seven states and 20 Native American nations rely on Colorado River water,
which is collected in reservoirs like Lake Powell. In addition, diversions from the river irrigate 4 million
acres of land, producing about 15 percent of the nation's crops. Water deliveries to California, Arizona
and Nevada would be cut by 750,000 acre-feet — about 244,500,000,000 gallons of water. An acre-foot
of water is about 325,853 gallons, equal to the average annual household use in the U.S.

If farmers in Arizona and Southern California have to find more expensive replacement water, it would
affect food prices across the country.
Construct and analyse a hydrological cycle diagram

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TOPIC 4.2: ACCESS TO FRESH WATER

Image from environment.nationalgeographic.com

Our water resources are under pressure. More reliable information is still needed regarding the quality
and quantity of available water, and how this availability varies in time and from place to place. Human
activities affect the water cycle in many ways, which needs to be understood and quantified to manage
water resources responsibly and sustainably.
It has become evident that:

 Changes in climate are affecting water availability

 Pollution, water diversions and uncertainties about the abundance of water are threatening
economic growth, environment, and health.
 Underground water is often being overexploited and polluted.
 To augment water supply, traditional techniques – such as rainwater collection – are now being
supplemented by newer technologies like desalination and water reuse.
 Political support is needed to improve information collection that can in turn enable better
decision making about the management and use of water.

Significant Ideas

 The supplies of freshwater resources are inequitably available and unevently distriuted, which
can lead to conflict and concerns over water security
 Freshwatre resources can be sustainabily managed using a variety of different approaches

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 Tow what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 How does a systems approach help in our understanding of unequal access to water resources?
 To what extent are there solutions for increasing greater access to freshwater resources?
 Outline the opportunities and barriers to managing freshwater resources sustainably.
 Suggest how and why, access to freshwater resources is likely to change in the future.

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Knowledge and Understanding
U 4.2.1 Access to an adequate freshwater supply varies widely

image from freshwaterwatch.thewaterhub.org

Water is an important part of our daily lives and not just for drinking: when we wake up, we might take a
shower, or sip coffee or tea; quench our thirst with all types of beverages; water our gardens; wash the
laundry and the dishes; and by the end of the day, the average person in a Western society has
consumed some 150–200 litres of freshwater.. The household water consumption is a mere teaspoonful
in a bathtub when compared with the amount of water used by agriculture and industry. The USA alone
uses more than 500 billion litres of freshwater every day to cool electric power plants, and roughly the
same amount is needed to irrigate crop fields.

In striking contrast, more than one billion people in developing nations do not have access to safe
drinking water and two billion do not have adequate sanitation

12 Facts About Water In Developing Countries (From UN reports)

1. 884 million people in the world lack access to safe water supplies.
2. More than 840,000 people die each year from water-related disease.
3. Almost 2 in 3 people who need safe drinking water survive on less than $2 a day.
4. In many developing countries, millions of women spend several hours a day collecting water from
distant, often polluted sources.
5. Every minute a child dies of a water-related disease.
6. Tackle a campaign to make the world suck less.
7. Diarrhea caused by inadequate drinking water, sanitation, and hand hygiene kills an estimated
842,000 people every year globally, or approximately 2,300 people per day.
8. More than 1/2 of all primary schools in developing countries don't have adequate water facilities
and nearly 2/3 lack adequate sanitation.
9. Clean water is one aspect of improving sustainable food production in order to reduce poverty
and hunger.
10. More than 80% of sewage in developing countries is discharged untreated, polluting rivers, lakes
and coastal areas.
11. By 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity, and
two-thirds of the world's population could be living under water stressed conditions.
12. Every $1 spent on water and sanitation generates $8 as a result of saved time, increased
productivity and reduced health care costs.

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image from www.unep.org

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U 4.2.2 Climate change may disrupt rainfall patterns and further affect this access

Temperature and moisture are among the key variables that determine the distribution, growth and
productivity, and reproduction of plants and animals. Changes in climate can influence species in a
variety of ways, but the most completely understood processes are those that link moisture
availability with intrinsic thresholds that regulate productivity and reproduction. The changes in climate
that are anticipated in the coming decades will have diverse effects on moisture availability, ranging from
alterations in the timing and volume of streamflow to the lowering of water levels in many wetlands, the
expansion of thermokarst lakes in the Arctic, and a decline in mist water availability in tropical mountain
forests.

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U 4.2.3 As populations, irrigation and industrialization increase, the demand for fresh water
increases

image fromwww.cgenarchive.org
Irrigation, industrialization, and population increase all make demands on the supplies of fresh water.
Global warming may disrupt rainfall patterns and water supplies. The hydrological cycle gives humans
fresh water but we are taking up so much water from the underground aquifers that there is no time for it
to replenish.

The demand of water has increased in both MEDCs and LEDCs, as populations are increasing as well as
agriculture changing and expanding industry. MEDCs need more water as they wash more often, water
their gardens, and wash their cars. This means that the increasing use of water is making the demands
higher. Water is not an infinite resource and has to be controlled more carefully, and new water resources
need to be found.

Water can be managed if individuals and communities make changes and this should be supported by

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the government. Water should not be over used or wasted so that it is insured it can be enough for
everyone.

This can be reached by:

 making new buildings water efficient (rainwater for sanitation and showers)
 fitting new homes with more water-efficient appliances (dishwashers and toilets)
 expand metering to encourage households to use water more efficiently
 in some rural areas drought resistant crops should be planted to reduce the need for irrigation
 organic fertilizers cause less pollution and bio-control measures can be used to reduce crop pests

As populations grow, greater demands are made on water resources. Water resources are now becoming
a limiting factor in many societies, and the availability of water for drinking, industry and agriculture need
to be considered. Many societies now are dependent on groundwater which is non-renewable. As
societies develop, water needs to be increased. The increased demand for water can lead to inequity of
use and political consequences. When water supplies fail, populations will be forced to take dramatic
steps, such as mass migration. Water shortages may also lead to civil unrest and wars.

 India has 4% of the world’s freshwater, but 16% of its population. Demand will probably exceed
supply by 2020, as urban water demand is expected to double and industrial demand to triple.
Hydrologists calculate that 43% of precipitation never reaches rivers or aquifers, and water tables
are falling rapidly as 21 million wells abstract water.
 China has 8% of the world’s freshwater but must meet the needs of 22% of the world’s
population. Two-thirds of Chinese cities do not have enough water all year round, and national
water supplies are likely to reach stress levels by 2030. China uses irrigation to produce 70% of
its food, mostly in the north and northeast, where the Yellow River and major aquifers are running
dry. Huge engineering projects transfer water to this area from the water-rich south.

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 image from www.unep.org
U 4.2.4 Freshwater supplies may become limited through contamination and unsustainable
abstraction

image fromwww.freshwatersystems.com
Humans must drink potable water. In HICs water can be purified, for example in the Lea Valley, London,
where wastewater is cleaned and used to recharge aquifers. Contaminated water carries diseases such
as cholera, which is one of the diseases responsible for the high infant mortality rates in LICs. The 7th
Millennium Development Goal (MDG7) aims to reduce by half the proportion of people without
sustainable access to safe drinking water. This goal can be achieved through reliable supplies and waste
treatment technology.

With a warmer climate, droughts and floods could become more frequent, severe and long-lasting.
Droughts can have devastating effects on agriculture, livestock and water supplies, causing famine,
malnutrition and the displacement of populations from one area to another. The land may become starved
of nourishment or contaminated with mineral salts, so that even when it does rain the ground cannot
support much vegetation growth. With climate change expected to reduce rainfall in some places and
cause drought in others, some regions could become ‘economic deserts’, of no use to people or
agriculture.

The Pearl River in China is highly polluted.

 The Delta, which accounts for 10% of China’s GDP, has undergone rapid urbanisation. The rapid
growth of cities has contributed to environmental degradation in the Delta.
 Polluted water is killing crops in the Pearl River Delta.

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  Cities are rich enough to treat the water but they do not allow farmers to use the treated water, so
people are forced to drink the polluted water. Those who do fall sick.
 9,000 tonnes of heavy metals, 66,000 tonnes of nitrates and ammonia and 60,000 tonnes of
petrol are deposited into the sea every year by the river.
 The World Bank has approved a US$96 million loan to reduce water pollution.
 Guangzhou has built 30 water treatment plants which aim to cut sewage by 85%.

U 4.3.5 Water suppies can be enhanced through reservoirs, redistribution, desalination, afrtifical
recharge of aquifers and rainwater harvesting schemes. Water conservation (including grey-water
recycling) can help to reduce demand but often requires a change in attitude by the water
consumers

Most water-short regions of the world with dry climates have long-standing water conservation traditions.
These are being maintained or supplemented with demand-management practices. To meet increased
demands, water resource management practitioners are augmenting the limited natural water supply with
desalination, water reuse, enhanced groundwater recharge and inter-basin transfers.

Rainwater harvesting
Rainwater has been collected for thousands of years in many parts of the world. Today, this technique is
used in Asia to replenish underground supplies. It is relatively inexpensive and has the advantage of
allowing local communities to develop and maintain the required structures themselves.

Diverting Surface Water

Diverting surface water into the ground can help reduce losses from evaporation, compensate for
variations in flow, and improve quality. Middle East and Mediterranean regions are applying this strategy.

Dams and Reservoirs

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Dams and reservoirs have been built to store water for irrigation and drinking. Moreover dams can
provide power and help control floods, but they can also bring about undesirable social and
environmental impacts.
Transferring water between river basins can also help alleviate shortages. China, for instance, already
has major interbasin links, and is planning more. The impact of these projects on people and the
environment must be monitored closely.

Wastewater
Wastewater is now reused for different purposes in many countries, especially in the Middle East, and
this practice is expected to grow. Worldwide, non-potable water is used for irrigation and industrial
cooling. Cities are also turning to water re-use to supplement drinking water supplies, taking advantage of
progress in water treatment. More...

Desalination
Desalinated water – seawater and other salty water that has been turned into freshwater – is used by
cities and by industries, especially in the Middle East. The cost of this technique has dropped sharply, but
it relies heavily on energy from fossil fuels and hence raises waste management and climate change
issues. More...

U 4.3.6 The scaricity of water resources can lead to conflict between human populations,
particularly where sources are shared

When the demand for water overtakes supply and several stakeholders wish to use the same resource,
there is a potential for conflict. Competing demands for water for irrigation, power generation, domestic
use, recreation and conservation can also create tension both between and within countries.

The Middle Eastern water conflicts are exacerbated by low seasonal rainfall and growing population
sizes. In the western part of this region, Israelis, Syrians, Jordanians, Lebanese and Palestinians are in
dispute over shrinking water supplies. Security of water supplies was not the cause of the Arab-Israeli
War, but was a contributory factor. Water in this region comes from two sources: the River Jordan (and its
lakes) and three important aquifers. The division of these water resources between the neighbouring
states is an ongoing challenge. In the eastern part of the region, Turkey plans to build dams to store and
use water in the headwaters of the Tigris and Euphrates Rivers. This is strongly opposed by Syria and
Iraq, where reduced water supplies threaten to hold back economic development and food production.

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Treaties
The River Danube is a trans-boundary source, but international agreement has stopped conflicts.

 The Danube flows through 17 countries, and rises in the Black Forest Mountains in Germany and
flows for 2,850km to the Black Sea.
 It provides drinking water for 10 million people and the International Commission for the
Protection of the Danube River, comprising 13 member states and the EU, was set up in 1998 to
promote and coordinate sustainable and equitable water management, including conservation,
improvement and rational use of the water of the river, its tributaries and groundwater sources.

The River Nile is over-used, so conflict in the near future is likely.

 The Nile flows through 10 countries for 6,700km, draining more than 3 million km2, about one-
tenth of the entire African landmass, and is formed by three major tributaries, the White Nile, the
Blue Nile and the Atbara.
 The primary problem facing the Nile and the countries has to do with the scarcity and over-use of
the water.
 Before dams were built on the river, the discharge at Aswan varied widely throughout the year.

Application and Skils

A 4.2.1 Evaluate the strategies that can be used to meet an increasing demand for fresh water

Around the world, human activity and natural forces are reducing available water resources. Although
public awareness of the need to better manage and protect water has grown over the last decade,
economic criteria and political considerations still tend to drive water policy at all levels. Science and best
practice are rarely given adequate consideration.
Pressures on water resources are increasing mainly as a result of human activity – namely urbanisation,
population growth, increased living standards, growing competition for water, and pollution. These are
aggravated by climate change and variations in natural conditions.

Using water resources sustainably is challenging because of the many factors involved, including
changes in climate, the natural variability of the resource, as well as pressures due to human activity. At
present, most water policy is still driven by short-term economic and political concerns that do not take
into account science and good stewardship. State-of-the-art solutions and more funding, along with more
data on water resources, are needed especially in developing nations. To assess the state of our water
resources, we must fully appreciate the roles of different parts of the water cycle – such as rain, meltwater
from glaciers, and so on. Otherwise, it remains difficult to develop adequate protection and mitigation
strategies.

Poor water quality and unsustainable use of water resources can limit the economic development of a
country, harm health and affect livelihoods. On a positive note, more sustainable practices are starting to
be adopted. When managing water resources, more attention should be paid to increasing existing
natural resources and reducing demand and losses. The traditional response to rising demand for water

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was to store surface water in reservoirs, divert flow to dry regions and withdraw groundwater. Now these
methods are increasingly supplemented by water reuse, desalination and rainfall harvesting. Certain
regions are even going to the extreme of exploiting non-renewable groundwater resources.

Some countries have programs to reduce demand and losses from urban water distribution systems but
more efforts are necessary. However, this will involve changes in behaviour requiring education and
political commitment. Such efforts to conserve water and reduce demand are not only useful in regions
where water is in short supply, they can also bring economic benefits in wetter regions.

A 4.2.2 Discuss, with reference to a case study, how shared freshwater resources have given rise
to international conflict

image from www.ipa.udel.edu

As demand for water hits the limits of finite supply, potential conflicts are brewing between nations that
share transboundary freshwater reserves. More than 50 countries on five continents might soon be
caught up in water disputes unless they move quickly to establish agreements on how to share
reservoirs, rivers, and underground water aquifers. The articles and analysis below examine international
water disputes, civil disturbances caused by water shortages, and potential regulatory solutions to diffuse
water conflict.

Case Study
At the heart of tensions between India and Bangladesh is the water supply from the River Ganges.

 For most of its 2,500km length, the Ganges flows through India, but the last part of its course
takes it through Bangladesh before passing into the Bay of Bengal.
 In 1974 India opened the huge Farakka Barrage, just 11km from the Bangladeshi border. Further
upstream, a series of dams divert water into irrigation systems and many of India’s largest cities
use the river to carry wastewater from domestic and industrial sources.
 Bangladesh is being deprived of much-needed water and has to suffer the effects of India’s
pollution of the river.
 The reduced flow of the river is affecting irrigation and food production. Fish stocks and the
fishing industry are declining. Navigation and water-borne trade are becoming harder because of
lower river levels, which are also increasing salinization. The delta is eroding because less silt is
being carried and deposited. Seawater incursion is increasing as the delta dries out.

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image from www.popsci.com

203
Key Terms
pollution over population water diversion rainwater collection
desalination potable water stream-flow thermokarst
irrigation individualization cholera drought
flooding contamination heavy metals salt pans
saline brine reservoir redistribution
aquifer waste-water grey-water black-water
effluent recharge scarcity sustainable
freshwater surface water degradation evaporation
drought resistant drip irrigation xeroscape dissolved oxygen
water wars

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4.3: AQUATIC FOOD PRODUCTION SYSTEMS

The demand for aquatic food is increasing dramatically worldwide and at the same time there is a
pressure for more efficient production and distribution systems to deliver healthy and safe food also
taking into account the environmental and sustainability issues throughout the entire aquatic food value
chain.

This unit is a minimum of 4.5 hours.

Significant Ideas:

 Aquatic systems provide a source of food production.

 Unsustainable use of aquatic ecosystems can lead to environmental degradation and collapse of
wild fisheries.
 Aquaculture provides potential for increased food production.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?:
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 How far does a systems approach help our understanding of aquatic food production systems?
 Compare and contrast the environmental impact of capture fisheries and aquaculture
 to what extent can fisheries be manages sustainably?
 Outline the likely pressures on, and potential solutions for the world fisheries in decades to come.

Knowledge & Understanding:

U 4.4.1 Demand for aquatic food resources continues to increase as human population grows and
diet changes.

Global demands for food from aquatic environments are expected to increase in future decades, because
these foods will help to meet the needs and preferences of a growing human population. Median
projections suggest global population growth of 2.4 billion, to over 9.7 billion, by 2050. Food demand is

205
expected to rise even faster than population growth, owing to the emergence of a larger proportion of
‘middle-class’ people who have greater spending power and typically consume more animal protein than
people with lower incomes

image from www.fao.org

U 4.4.2 Photosynthesis by phytoplankton supports a highly diverse range of food webs.

The most abundant life forms in the ocean are plankton; most are so small that you can't even see them.
The first link in all marine food chains are the phytoplankton, or 'plant' plankton, which use sunlight to
make sugars from carbon dioxide and water (photosynthesis). Because they need sunlight, they can only
live in the photic zone. Through photosynthesis, phytoplankton make food for themselves and give off
oxygen, which is a waste product for them but essential for all animals on Earth. Phytoplankton produce
all the food at the bottom of the ocean food chain, so they are called primary producers. Most of the
photosynthesis on Earth happens in the oceans and phytoplankton produce a large share of the oxygen
in the air we breathe

U 4.4.3 Aquatic (freshwater and marine) flora and fauna are harvested by humans.

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Sustainable fishing guarantees there will be populations of ocean and freshwater wildlife for the future.
Aquatic environments are home to countless species of fish and invertebrates, most of which are
consumed as food. (Others are harvested for economic reasons, such as oysters that produce pearls
used in jewelry.) Seafood is respected all over the world, in many diverse cultures, as an important
source of protein and healthy fats. For thousands of years, people have fished to feed families and local
communities.

U 4.4.4 The highest rates of productivity are found near coastlines or in shallow seas, where
upwellings and nutrient enrichment of surface waters occurs.

Boundary ecosystems are characterized by the presence of large plants. In the open water of the ocean
and large lakes the basic production of living material (primary production) is carried out by microscopic
algae (phytoplankton) floating freely in the water. At the bottom there is not enough light to allow growth
of large, attached plants. In boundary ecosystems much of the area is shallow enough for light to reach
the bottom and permit large plants to grow. Phytoplankton is also present, but the large plants give the
boundary systems their special character

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U 4.4.5 Harvesting some species, such as seals and whales, can be controversial.

The relationship between humans a marine mammals is a special, but sometimes controversial one. It is
culturally diverse and politically influential and is based on attitudes ranging from spiritual reverence to
fondness of taste. Our relationship with whales and seals in particular have profoundly influenced recent
human history.

U 4.4.6 Ethical issues arise over biorights, rights of indigenous cultures and
international conservation legislation.

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image from www.fao.org
The principal ethical issues in fisheries relate broadly to human and ecosystem well-being. The most
important ones being poverty; the right to food; legislation and overfishing and ecosystem degradation.

Fisheries constitute an important source of livelihood for millions of people. Nearly 35 million fishers are
directly engaged in fishing and fish farming as a full-time or part-time occupation (FAO, 2002). Fishers are
particularly concentrated in developing countries, where about 95 percent of the world's fishers live.

The state of world fisheries presents us with pressing ecological, economic, social and political
challenges with significant ethical implications. For example, the depletion of a nation's fishery resources
represents a moral failure by society to maintain the natural environment and its productivity. It
compromises food security, threatening vulnerable communities in particular, and reduces the livelihood
opportunities of future generations. The contamination, by pollution, of an otherwise extremely healthy
source of food, reducing food safety and threatening human health, is another indication of moral failure
in relation to both present and future generations.

U 4.4.6 Developments in fishing equipment and changes to fishing methods have lead
to dwindling fish stocks and damage to habitats.

image from NOAA.

In the past, fishing was more sustainable because fishermen did not have the resources or the
technology to tread into the deeper waters at far flung locations. Their vessels were small with limited
capacities for stocking fish and the absence of technology like sonar restricted their fish-hunting
activities. The United Nations Food and Agriculture Organisation (FAO) estimates that 91.1% of the
world’s fisheries are either fully exploited or overexploited. With the introduction of modern industrial
fishing techniques the industry has reached a crushing over-capacity that has already decimated a vast
range of global fish populations. Today, however, fishing is a multimillion dollar industry with well-
equipped ships and hi-tech facilities that enable fishermen to explore new shores and deeper waters to
keep up with the increasing demand for seafood.

Once a fish stock is over-fished to the point of collapse, it is very difficult for it to recover.

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210
U 4.4.7 Unsustainable exploitation of aquatic systems can be mitigated at a variety of levels
(international, national, local and individual) through policy, legislation and changes in consumer
behaviour.

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image from www.ocean-law.org
There are many international agreements in place, however. There are 17 Regional Fisheries
Management Organizations (RFMOs), composed of nations that share economic interests in a particular
area. When member nations agree to RFMO regulations, they are bound by these rules, which may
include catch limits and specifications on the types of gear used. Evidence suggests these regulations
have led to decreased bycatch (such as dolphins in tuna nets), but maintaining healthy fish stocks has
remained a challenge. Enforcing fishing regulations on the high seas is extremely difficult, but member
nations have worked to address the problem of illegal fishing and prevent illegally caught seafood from
being imported.

One organization that has demonstrated enforcement success is the North Pacific Anadromous Fish
Commission (NPAFC), which exists primarily to preserve salmon stocks. Member nations are Canada,
Japan, South Korea, Russia, and the United States. The commission prohibits catching salmon on the
high seas, which is primarily accomplished using drift nets. Drift nets float freely in ocean currents, usually
near the sea’s surface. They are used to catch schooling fish like salmon and sardines. Unfortunately,
these nets result in a lot of bycatch, ensnaring seabirds, marine mammals, and other non-targeted
species.

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U 4.4.8 Aquaculture has grown to provide additional food resources and support economic
development and is expected to continue to rise.

image from www.bq-magazine.com

Aquaculture is the farming, breeding, rearing, and harvesting of plants and animals in all types of water
environments including ponds, rivers, lakes, and the ocean. Aquaculture produces all sorts of fish,
shellfish, and seaweeds including food fish, sport fish, bait fish, ornamental fish, crustaceans, mollusks,
algae, sea vegetables, and fish eggs. Aquaculture also includes the production of fish and shellfish
released into the wild to rebuild wild populations.
Approximately half the seafood eaten worldwide is farm-raised. Because harvest from wild fisheries has
peaked globally, aquaculture is widely recognized as a necessary way to meet the seafood demands of a
growing population. As a result, aquaculture is the fastest growing form of food production in the world.

U 4.3 9 Issues around aquaculture include: loss of habitats, pollution (with feed, antifouling
agents, antibiotics and other medicines added to fish pens), spread of diseases and escaped
species (some involving genetically modified organisms).

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image from www.seafoodwatch.org
Like any form of industrial production, aquaculture has environmental impacts. The major impacts for the
aquaculture industry include: using more fish than they produce, disease and parasite transfer, the
introduction and spread of exotic species, chemical pollution, habitat destruction for farm siting or due to
farm activities, and the killing of predators that prey on the farmed species.

Social impacts are also considered to be a major impact of aquaculture production and there are
numerous conflicts around the world. The major conflicts include: traditional livelihood and community
displacement and abusive labor practices. In some cases in the impacts have been extreme and people
have ended up being killed in the conflicts. Social impacts are mainly driven by export driven commodity
production like shrimp, where companies seek to maximize profits by exploiting poor countries who have
poor regulations.

Applications and skills:

A 4.3.1 Discuss, with reference to a case study, the controversial harvesting of a named species.

image from motherboard.vice.com

The whaling controversy is the international environmental and ethical debate over whale hunting. The
debate has focused on issues of sustainability and conservation as well as ownership and national
sovereignty.

A 4.3.2 Evaluate strategies that can be used to avoid unsustainable fishing.

image from howtoconserve.org

The central strategy is to protect and restore marine fisheries, which in turn support fishing livelihoods
and supply meals to millions of people around the world.
Depending on the fishery, strategies can:

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  Increase the estimated biomass of severely distressed stocks.
 Prevent further declines in and/or increase the biomass of stocks facing moderate distress.
 Reduce bycatch of non-target species or juvenile age cohorts of target stocks.
 Where possible and relevant, protect and restore critical marine habitat such as mangroves and
coral reefs.

image from www.bloomberg.org

A 4.3.3 Explain the potential value of aquaculture for providing food for future generations.

About 567 aquatic species are currently farmed all over the world, representing a wealth of genetic
diversity both within and among species. Aquaculture is practiced by both some of the poorest farmers in
developing countries and by multinational companies. Eating fish is part of the cultural tradition of many
people and in terms of health benefits, it has an excellent nutritional profile. It is a good source of protein,
fatty acids, vitamins, minerals and essential micronutrients. Aquatic plants such as seaweed are also an
important resource for aquaculture as they provide nutrition, livelihood and other important industrial
uses.

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Eighty percent of current aquaculture production is derived from animals low in the food chain such as
herbivorous, omnivorous fish and mollusks.

image fromsharkresearch.rsmas.miami.edu378 × 193Search by image

A 4.3.4 Discuss a case study that demonstrates the impact of aquaculture.

Depletion and Salinization of Potable Water; Salinization of Agricultural Land: Pumping of groundwater to
supply freshwater to shrimp farms has resulted in depletion and, sometimes, salinization of local water
supplies, causing water shortages for coastal communities. There have also been many reports of crop
losses after agricultural land has become salinized by effluent water pumped out from shrimp farms onto
land.

Human Rights Abuses: There has been large scale displacement of families to make way for shrimp
farms in some developing countries, contributing to landlessness and food insecurity. Non-violent protests
against the industry have frequently been met with threats, intimidation and violence. Protesters have
been murdered in at least 11 countries, including an estimated 150 people in Bangladesh alone.

Key Words
carrying capacity suspended solids overfishing aeration
ammonia fisheries cage culture dissolved oxygen
nitrogenous wastes algae bloom phytoplankton raceway
spawning urea turbidity hatchery
wild fish game fish ornamental fish fisheries
fish stock sustainability maximum sustainable UNFAO
SOFIA FIP yield total allowable catches
International Court of polyculture Marine Stewardship biorights
Justice aquaculture Council
GMOs

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TOPIC 4.4: WATER POLLUTION

image from www.renewedlivinginc.com

Over two thirds of Earth's surface is covered by water; less than a third is taken up by land. As Earth's
population continues to grow, people are putting ever-increasing pressure on the planet's water
resources. In a sense, our oceans, rivers, and other inland waters are being "squeezed" by human
activities—not so they take up less room, but so their quality is reduced. Poorer water quality means
water pollution.

This unit is a minimum of 4.5 hours.

Significant Ideas:

 Water pollution, both to groundwater and surface water, is a major global problem, the effects of
which influence human and other biological systems.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 To what extent can water pollution be considered as a system?
 Are the existing solutions to pollution likely to cope with current levels of water pollution?
 Which is the lesser evil - less food production or eutrophication? How are the linked?
 How is water pollution likely to change in the next decades? Give reasons for your answers.

Knowledge & Understanding:

U 4.4.1 There are a variety of freshwater and marine pollution sources.

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image frompostconflict.unep.ch
Industrial waste:
Industries produce huge amount of waste which contains toxic chemicals and pollutants which can cause
air pollution and damage to us and our environment. They contain pollutants such as lead, mercury,
sulphur, asbestos, nitrates and many other harmful chemicals. Many industries do not have proper waste
management system and drain the waste in the fresh water which goes into rivers, canals and later in to
sea. The toxic chemicals have the capability to change the color of water, increase the amount of
minerals, also known as Eutrophication, change the temperature of water and pose serious hazard to
water organisms.

Sewage and wastewater:

The sewage and waste water that is produced by each household is chemically treated and released into
sea with fresh water. The sewage water carries harmful bacteria and chemicals that can cause serious
health problems. Pathogens are known as a common water pollutant; The sewers of cities house several
pathogens and thereby diseases. Microorganisms in water are known to be causes of some very deadly
diseases and become the breeding grounds for other creatures that act like carriers. These carriers inflict
these diseases via various forms of contact onto an individual. A very common example of this process
would be Malaria.

Mining activities:
Mining is the process of crushing the rock and extracting coal and other minerals from underground.
These elements when extracted in the raw form contains harmful chemicals and can increase the amount
of toxic elements when mixed up with water which may result in health problems. Mining activities emit
several metal waste and sulphides from the rocks and is harmful for the water.

Marine dumping:
The garbage produced by each household in the form of paper, aluminum, rubber, glass, plastic, food if
collected and deposited into the sea in some countries. These items take from 2 weeks to 200 years to
decompose. When such items enters the sea, they not only cause water pollution but also harm animals
in the sea.

Accidental Oil leakage:

Oil spill pose a huge concern as large amount of oil enters into the sea and does not dissolve with water;
thereby opens problem for local marine wildlife such as fish, birds and sea otters. For e.g.: a ship carrying
large quantity of oil may spill oil if met with an accident and can cause varying damage to species in the
ocean depending on the quantity of oil spill, size of ocean, toxicity of pollutant.

Burning of fossil fuels:

Fossil fuels like coal and oil when burnt produce substantial amount of ash in the atmosphere. The
particles which contain toxic chemicals when mixed with water vapor result in acid rain. Also, carbon
dioxide is released from burning of fossil fuels which result in global warming.

Chemical fertilizers and pesticides:

Chemical fertilizers and pesticides are used by farmers to protect crops from insects and bacterias. They

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are useful for the plants growth. However, when these chemicals are mixed up with water produce
harmful for plants and animals. Also, when it rains, the chemicals mixes up with rainwater and flow down
into rivers and canals which pose serious damages for aquatic animals.

Leakage from sewer lines:

A small leakage from the sewer lines can contaminate the underground water and make it unfit for the
people to drink. Also, when not repaired on time, the leaking water can come on to the surface and
become a breeding ground for insects and mosquitoes.

Global warming:
An increase in earth’s temperature due to greenhouse effect results in global warming. It increases the
water temperature and result in death of aquatic animals and marine species which later results in water
pollution.

Radioactive waste:
Nuclear energy is produced using nuclear fission or fusion. The element that is used in production of
nuclear energy is Uranium which is highly toxic chemical. The nuclear waste that is produced by
radioactive material needs to be disposed off to prevent any nuclear accident. Nuclear waste can have
serious environmental hazards if not disposed off properly. Few major accidents have already taken place
in Russia and Japan

U 4.4.2 Types of aquatic pollutants include floating debris, organic material, inorganic plant
nutrients (nitrates and phosphates), toxic metals, synthetic compounds, suspended solids, hot
water, oil, radioactive pollution, pathogens, light, noise and biological pollutants (invasive
species).

Suspended Matter
Some pollutants do not dissolve in water as their molecules are too big to mix between the water
molecules. This material is called particulate matter and can often be a cause of water pollution. The
suspended particles eventually settle and cause a thick silt at the bottom. This is harmful to marine life
that lives on the floor of rivers or lakes. Biodegradable substances are often suspended in water and can
cause problems by increasing the amount of anaerobic microorganisms present. Toxic chemicals
suspended in water can be harmful to the development and survival of aquatic life.

Toxic Metals
Toxic Metals and solvents from industrial work can pollute rivers and lakes. These are poisonous to many
forms of aquatic life and may slow their development, make them infertile or even result in death.

Pesticides
Pesticides are used in farming to control weeds, insects and fungi. Run-offs of these pesticides can cause
water pollution and poison aquatic life. Subsequently, birds, humans and other animals may be poisoned
if they eat infected fish.

Oil
Petroleum is another form of chemical pollutant that usually contaminates water through oil spills when a
ship ruptures. Oil spills usually have only a localised affect on wildlife but can spread for miles. The oil
can
cause the death of many fish and stick to the feathers of seabirds causing them to lose the ability to fly.2.
Fertilizer
Some wastewater, fertilizers and sewage contain high levels of nutrients. If they end up in water bodies,
they encourage algae and weed growth in the water. This will make the water undrinkable, and even clog
filters. Too much algae will also use up all the oxygen in the water, and other water organisms in the
water will die out of oxygen starvation.

Synthetic compounds

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Many industries and farmers work with chemicals that end up in water. These include chemicals that are
used to control weeds, insects and pests. Metals and solvents from industries can pollute water bodies.
These are poisonous to many forms of aquatic life and may slow their development, make them infertile
and kill them.

Microbial Pollution
Microbiological pollution is the natural form of water pollution that is caused by microorganisms in
uncured water. Most of these organisms are harmless but some bacteria, viruses, and protozoa can
cause serious diseases such as cholera and typhoid. This is a significant problem for people in third world
countries who have no clean drinking water and/or facilities to cure the water.

U 4.4.3 A wide range of parameters can be used to directly test the quality of aquatic systems,
including pH, temperature, suspended solids (turbidity), metals, nitrates and phosphates.

Direct measurement is performed by monitoring the level of the pollutant itself, e.g. nitrates in a lake or
temperature levels in a lake or stream. An indirect method would monitor the effects of the pollutants on
other factors, e.g. dissolved oxygen, B.O.D., presence or absence of indicator species

Indirect measurement involves the monitoring and measurement of organisms in the ecosystem and
more specifically indicator species or index species. These are species that by virtue of their abundance
or absence will indicate the level of pollution in that ecosystem. For example: leafy lichens on trees if the
air is unpolluted

Marine—salinity, pH, temperature, dissolved oxygen, wave action

Freshwater—turbidity, flow velocity, pH, temperature, dissolved oxygen

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U 4.4.4 Biodegradation of organic material utilizes oxygen, which can lead to anoxic conditions
and subsequent anaerobic decomposition, which in turn leads to formation of methane, hydrogen
sulfide and ammonia (toxic gases).

Biodegradability is the ability of organic substances and materials to be broken down into simpler
substances through the action of enzymes from microorganisms. If this process is complete, the initial
organic substances are entirely converted into simple inorganic molecules such as water, carbon dioxide
and methane.

Changes to the organic matter load can affect organic matter concentrations in the water. The breakdown
of organic matter can result in low dissolved oxygen (e.g. hypoxia or anoxia) in the water (eutrophication).
Sediment oxygen demand is higher when production is higher. Algal (both macroalgae and microalgae)
blooms and increased plant growth occur in areas with increased nutrients and high light availability.

Changes to the organic matter concentrations in the water of a wetland can result in: eutrophication a loss
of sensitive species. The breakdown of organic matter can result in low dissolved oxygen (e.g. hypoxia or
anoxia) in the water (eutrophication). Animals that are sensitive to low dissolved oxygen and cannot move
to areas with better conditions may die, often in mass mortality events.

U 4.4.5 Biochemical oxygen demand (BOD) is a measure of the amount of dissolved oxygen
required to break down the organic material in a given volume of water through aerobic biological
activity. BOD is used to indirectly measure the amount of organic matter within a sample.

The biochemical oxygen demand is a measure of the total demand for oxygen by living and chemical
components in a water body. The greater the amount of polluting organic matter, the more microbes are
required to break it down. (So, high dissolved oxygen, high levels of pollution)

Measuring BOD is a very useful when examining the health of water, e.g. stream, rivers and lakes. BOD
is essentially the amount of dissolved oxygen required to break down organic materials in a given volume
of water through aerobic activity. Essentially it is a measure of oxygen uptake in water.

How to calculate BOD

 Determined by the number of aerobic organisms and their rate of respiration.

 The greater the amount of organic pollutant in the water the more microbes are required to break
it down. Hence, there is a positive relationships between pollutant level and BOD

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How to measure BOD?

 Take a sample of water at measure volume

 Measure the oxygen level
 More the sample in a dark place at 20 degree for five days
 After five days re-measure the oxygen level
 BOD is the difference between the two measurement

What does this mean?

 High BOD indicates there are many organisms using oxygen for respiration
 Low BOD indicates relatively few organisms needing oxygen for respiration
 High BOD - low DO levels - high pollutant levels, especially nitrate & phosphate
 Low BOD - high DO levels - low pollutant levels

U 4.4.6 Some species can be indicative of polluted waters and can be used as indicator species.
Biological indicators are aquatic plant and animal life that are susceptible to specific types and levels of
pollutants. Many organisms require a specific range of physical and chemical parameters to flourish in a
surface water.The level of pollution in water can be indicated by the species living there.Typically,
unpolluted water will contain a greater diversity of organisms than polluted water. Polluted water will
support larger numbers of tolerant organisms and have less diversity.

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U 4.4.7 A biotic index indirectly measures pollution by assaying the impact on species within the
community according to their tolerance, diversity and relative abundance.

Biotic index is a scale 1-10 that gives a measure of the quality of an ecosystem by the presence and
abundance of the species living in it. The Trent Biotic Index is based on the fact that certain species tend
to disappear and the species diversity decreases as the organic pollution in a water course increases.
The scale corresponds to the four basic water quality (Excellent, Good, Fair or Poor).

Using this index and indicator species is another indirect method of measuring pollution. The pollutant are
not measured directly but their effect on biodiversity is measured.

 Aquatic macroinvertebrates are often used as an indicator species. They have some general
characteristics that make them very useful to assess stream health.
 abundant and found in water bodies throughout the world
 not extremely mobile.
 carry out part or all of their life cycle within the stream or river.

The biotic index works by assigning different levels of tolerance to pollution to the different types of
organisms. The types of macroinvertebrates found during sampling are grouped as:

1: Pollution intolerant: These organisms are highly sensitive to pollution. (e.g., stonefly or alderfly larva)

2: Semi-Pollution intolerant: These organisms are sensitive to pollution. (e.g.. dragonfly larva or crawfish)

3: Semi-Pollution tolerant: These organisms will be found in clean and slightly polluted waterways. (e.g.,
snails or black fly larva)

4: Pollution tolerant: These organisms will be found in polluted, as well as clean aquatic ecosystems (e.g.,
leechs,bloodworms)

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U 4.4.8 Eutrophication can occur when lakes, estuaries and coastal waters receive inputs of
nutrients (nitrates and phosphates), which results in an excess growth of plants and
phytoplankton.
In eutrophication, increased amounts of nitrogen and/or phosphorus are carried into streams, lakes and
groundwater causing nutrient enrichment. This lead to rapid growth of algae, accumulation of dead
organic matter, high rate of decomposition and lack of oxygen. The role of positive feedback should be
noted in these processes.

Process(Positive Feedback):

1. Increase in inputs of nutrients (nitrates and phosphates) which enter the lake
2. Increase in algae productivity in the lake
3. Massive increase in algae
4. Increase in dead organic matter due to increase in decomposer as there are more algae for food
5. Higher rate of decomposition as the decomposers respiration
6. Increase in oxygen demand but decline in oxygen level
7. Death of organisms

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 image from www.bbc.co.uk

The consequences of marine eutrophication is very simple to explain. The quiet unseen changes of the
body of water caused by algae and plants suffocates many of the organisms as we said before. Not only
does eutrophication kill other species but the organisms that happen to survive in the water with few
oxygen change. Their bodies that were originally used of their surroundings evolve and adapt to the low
oxygen level. They were once edible to eat, but as their body changes, so does the human reactions
toward it. Many of the fishes that change, they become poisonous to our bodies causing either weakness,
blurred vision, burning muscles, difficulty breathing, memory loss, organ damage, and even death.
Impact includes

 Death of aerobic organisms

 Increased turbidity
 Loss of macrophytes
 Reduction in length of food chains

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  Loss of species diversity.

Human activities worldwide have caused the nitrogen and phosphorus content in may waters to double.

U 4.4.9 Dead zones in both oceans and fresh water can occur when there is not enough oxygen to
support marine life.

image from www.teachoceanscience.net

In coastal marine environments, “Dead Zones” are regions where oxygen concentrations are very low.
This condition of oxygen deficiency, known as hypoxia, is caused by an interaction between biological,
chemical and physical factors. In the absence of sufficient oxygen, animals and plants either die or leave
the dead zone

U 4.4.10 Water pollution management strategies include:

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 1. reducing human activities that produce pollutants (for example, alternatives to current
fertilizers and detergents)
2. reducing release of pollution into the environment (for example, treatment
of wastewater to remove nitrates and phosphates)
3. removing pollutants from the environment and restoring ecosystems (for example,
removal of mud from eutrophic lakes and reintroduction of plant and fish species).

You need to apply the model in Figure 3 in the evaluation of the strategies.

Minimize the amount of nutrients being released into the system by:

 limiting production/use of detergents containing phosphates

 alternative methods of enhancing crop growth
 create buffer zones between agricultural land and water sources
 regulating and reducing at point of emission
 prevent animal waste from leaching into groundwater and rivers/streams

Treat the polluted area by:

 pumping air into the water source

 divert or treat sewage properly
 dredge (dig up) contaminated sediments
 physically remove algae blooms
 reintroduce plant and fish species
 pumping mud from eutrophic lakes

image from pubs.usgs.gov

Application & Skills
A 4.4.1 Analyse water pollution data
Water quality monitoring is a crucial aspect to protecting water resources. Agencies must monitor lakes,
streams, rivers and other types of water bodies to assist them in determining water quality condition.
From these monitoring activities, water quality monitoring data is generated. Without this data, water

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resource managers cannot know where pollution problems exist, where we need to focus our pollution
control energies or where we've made progress

A 4.4.2 Explain the process and impacts of eutrophication.

A major problem with the use of fertilisers occurs when they're washed off the land by rainwater into rivers
and lakes. The resulting increase of nitrate or phosphate in the water encourages algae growth, which
forms a bloom over the water surface. This prevents sunlight reaching other water plants, which then die.
Bacteria break down the dead plants and use up the oxygen in the water so the lake may be left
completely lifeless

The main effects caused by eutrophication can be summarized as follows:

1. Species diversity decreases and the dominant biota changes

2. Plant and animal biomass increase
3. Turbidity increases
4. Rate of sedimentation increases, shortening the lifespan of the lake
5. Anoxic conditions may develop

Because of the high concentration of organisms in a eutrophic system, there is often a lot of competition
for resources and predator pressure. This high degree of competition and the sometimes-high chemical
or physical stress make high the struggle for survival in eutrophic systems. As a result the diversity of
organisms is lower

A 4.4.3 Evaluate the uses of indicator species and biotic indices in measuring aquatic pollution.
Biomonitoring involves the use of indicators, indicator species or indicator communities.
Macroinvertebrates, fish, and/or algae are often used. Certain aquatic plants have also been used as
indicator species for pollutants including nutrient enrichment. There are advantages and disadvantages to
each. Macroinvertebrates are most frequently used. Biochemical, genetic, morphological, and
physiological changes in certain organisms have been noted as being related to particular environmental
stressors and can be used as indicators.

The presence or absence of the indicator or of an indicator species or indicator community reflects
environmental conditions. Absence of a species is not as meaningful as it might seem as there may be
reasons, other than pollution, that result in its absence (e.g., predation, competition, or geographic
barriers which prevented it from ever being at the site). Absence of multiple species of different orders
with similar tolerance levels that were present previously at the same site is more indicative of pollution

228
than absence of a single species. It is clearly necessary to know which species should be found at the
site or in the system.

image from www.biomagazine.gr

A 4.4.4 Evaluate pollution management strategies with respect to water pollution.
Changing human activities
Possible measures to reduce nitrate loss (based on the northern hemisphere) include the
following.

 Avoid using nitrogen fertilizers between mid-September and mid-February when soils are wet and
fertilizer is most likely to be washed through the soil.
 Do not apply nitrogen just before heavy rain is forecast (assuming that forecasts are accurate).
 Use less nitrogen if the previous year was dry because less will have been less lost. This
is difficult to assess precisely.
 Do not plough up grass as this releases nitrogen.
 Use steep slopes for permanent pasture grass or woodland; use flat land above slopes for arable
crops. This minimizes the greater risk of wash from steep land.
 Incorporate straw – straw decay uses nitrogen, with up to 13 per cent less nitrogen lost – it also
locks up phosphorus.

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  Direct drilling and minimal cultivation reduces nitrogen loss by up to a half. Less disturbance
means less conversion of nitrogen to nitrate but straw has to be burnt.

Regulating and reducing the nutrient source

Public campaigns in Australia have encouraged people to:

 use zero- or low-phosphorus detergents

 wash only full loads in washing machines
 wash vehicles on porous surfaces away from drains or gutters
 reduce use of fertilizers on lawns and gardens
 compost garden and food waste
 collect and bury pet faeces.

Clean-up strategies
Once nutrients are in an ecosystem, it is much harder and more expensive to remove them than it would
have been to tackle the eutrophication at source. The main clean-up methods available are:

 precipitation (e.g. treatment with a solution of aluminium or ferrous salt to precipitate phosphates)
 removal of nutrient-enriched sediments, for example by mud pumping
 removal of biomass (e.g. harvesting of common reed) and using it for thatching or fuel.

Key Terms
eutrophication fertilizer nitrates phosphates algae bloom
leaching runoff organic nutrients positive feedback point source
non-point source dissolved BOD decomposition effluent
dead zone oxygen lake aeration ephiphytic plankton
macrophytes detergents zooplankton turbidity aeration
phosphate aerobic secchi circle oxygen meter biotic index

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stripping sediment direct salinity anaerobic
pH temperature monitoring marine recovery zone
ppm light intensity biotic marine indirect
ppt turbidity point source biochemical monitoring
wave action freshwater aquatic oxygen demand aerobic
fresh water drainage invertibrates indicator species clean zone
dissolved oxygen

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TOPIC 5.1: INTRODUCTION TO SOIL SYSTEMS

Image from Food Tank

We tend to take the soil around us for granted. It is much more than mud, clay or dirt. All the food that we
consume depends ultimately upon soil. Plants grow and depend on the soil. We either eat plants that
grow directly in the soil or the animals that eat the plants.
Soils are the part of the lithosphere where life processes and soil forming processes both take place.

In this unit we will look at the soil system, soil water, soil formation and the consequences of soil
degradation.

This unit is a minimum of 3 hours

Significant Ideas

 The soil system is a dynamic ecosystem that has inputs, outputs, storages and flows.
 The quality of soil influences the primary productivity of an area..

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extend of the environmental impacts, or restoring systems in
which environmental impacts have already occurred:
 What value systems can you identify at play in the cases and approaches to resolving the issues
addressed in this topic?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 How does the systems approach help our understanding of soils and soil processes?
 With respect to soils, how might the environmental value systems of a large scale commercial
farmer differ from that of a traditional subsistence farmer?
 How might the pressure on soils change over the next 20 years? Give reasons to support your
answer.

Knowledge & Understanding:

U 5.1.1 The soil system may be illustrated by a soil profile that has a layered structure (horizons).

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Soils are major components of the world's ecosystems.Soil forms the Earth’s
atmosphere, lithosphere (rocks), biosphere (living matter) and hydrosphere (water). Soil is what forms the
outermost layer of the Earth’s surface, and comprise weathered bedrock (regolith), organic matter (both
dead and alive), air and water.

The soil interacts with the atmosphere, lithosphere, biosphere and hydrosphere.

 The water cycle moves through the soil by infiltration and water may evaporate from the surface.
 The atmosphere may contain particulate matter that is deposited on the soils and particles may
blow up into the atmosphere.
 Rocks in the lithosphere weather to form soils, and soils at depth and pressure may form rocks.
 Plants in the biosphere may extract nutrients from the soils and dead plants may end up forming
parts of the soil.

Soils are important to humans in many ways:

 soil is the medium for plant growth, which most of foods for humans are grown in
 soil stores freshwater, 0.005% of world’s freshwater
 soil filters materials added to the soil, keeping quality water
 recycling of nutrients takes place in the soil when dead organic matter is broken down
 soil is the habitat for billions of micro-organisms, as well as other larger animals
 soil provides raw material in the forms of peat, clay, sands, gravel and minerals

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 image from en.wikipedia.org
Soil Horizons.

 O) Organic matter: Litter layer of plant residues in relatively undecomposed form.

 A) Surface Soil: Layer of mineral soil with most organic matter accumulation and soil life. This
layer eluviates (is depleted of) iron, clay and calcium, organic compounds, and other soluble
constituents. When eluviation is pronounced, a lighter colored "E" subsurface soil horizon is
apparent at the base of the "A" horizon. A-horizons may also be the result of a combination of soil
bioturbation and surface processes that separates fine particles from biologically mounded
topsoil. In this case, the A-horizon is regarded as a "biomantle".
 B) Subsoil: This layer accumulates iron, clay, aluminum and organic compounds, a process
referred to as illuviation.
 C) Parent Rock: Layer of large unbroken rocks. This layer may accumulate the more soluble
compounds.
 R) Bedrock: The parent material in bedrock landscapes. This layer denotes the layer of partially
weathered bedrock at the base of the soil profile. Unlike the above layers, R horizons largely
comprise continuous masses of hard rock that cannot be excavated by hand. Soils formed in
situ will exhibit strong similarities to this bedrock layer. These areas of bedrock are under 50 feet
of the other profiles.

U 5.1.2 Soil system storages include organic matter, organisms, nutrients, minerals, air and water.

image from www.eoearth.org

Soil has matter in all three states:

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  organic and inorganic matter form the solid state
 soil water(from precipitation, groundwater and seepage) form the liquid state
 soil atmosphere forms the gaseous state

U 5.1.3 Transfers of material within the soil, including biological mixing and leaching (minerals
dissolved in water moving through soil), contribute to the organization of the soil

image from www.senninger.com

Translocation involves the movement of soil-forming materials through the developing soil profile.
Translocation occurs by water running through the soil transferring materials from upper to lower portions
of the profile. Burrowing animals like earth worms, ants, etc., move soil materials within the profile.
Burrowing animals create passage ways through which air and water can travel promoting soil
development.

U 5.1.4 There are inputs of organic material including leaf litter and inorganic matter from parent
material, precipitation and energy. Outputs include uptake by plants and soil erosion.

image from www.gov.mb.ca

Inputs

1. Weathering
Rock weathering is one of the most important long-term sources for nutrients. However, this process adds
nutrients to ecosystems in relatively small quantities over long periods of time. Important nutrients
released by weathering include:
Calcium, magnesium, potassium, sodium, silicon, iron, aluminum, and phosphorus.

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2. Atmospheric Input
Large quantities of nutrients are added to ecosystems from the atmosphere. This addition is done either
through precipitation or by a number of biological processes.
Carbon - absorbed by way of photosynthesis.
Nitrogen - produced by lightning and precipitation.
Sulfur, chloride, calcium, and sodium - deposited by way of precipitation.

3. Biological Nitrogen Fixation

Biological nitrogen fixation is a biochemical process where nitrogen gas from the atmosphere is
chemically combined into more complex solid forms by metabolic reactions in an organism. This ability to
fix nitrogen is restricted to a symbiotic associations with legumes and other microorganisms.

Outputs

1. Erosion
Soil erosion is probably the most import means of nutrient loss to ecosystems. Erosion is very active in
agricultural and forestry systems, where cultivation, grazing, and clearcutting leaves the soil bare and
unprotected. When unprotected, the surface of the soil is easily transported by wind and moving water.
The top most layers of a soil, which have an abundance of nutrient rich organic matter, are the major
storehouse for soil nutrients like phosphorus, potassium, and nitrogen.

2. Leaching
Leaching occurs when water flowing vertically through the soil transports nutrients in solution downward
in the soil profile. Many of these nutrients can be completely lost from the soil profile if carried into
groundwater and then horizontally transported into rivers, lakes, or oceans. Leaching losses are,
generally, highest in disturbed ecosystems. In undisturbed ecosystems, efficient nutrient cycling limits the
amount of nutrients available for this process.

3. Gaseous Losses
High losses of nutrients can also occur when specific environmental conditions promote the export of
nutrients in a gaseous form. When the soil is wet and anaerobic, many compounds are chemically
reduced to a gas from solid forms in the soil. This is especially true of soil nitrogen.

U 5.1.5 Transformations include decomposition, weathering and nutrient cycling.

The transformation and movement of materials within soil organic matter pools is a dynamic process
influenced by climate, soil type, vegetation and soil organisms. All these factors operate within a
hierarchical spatial scale. Soil organisms are responsible for the decay and cycling of both macronutrients
and micronutrients, and their activity affects the structure, tilth and productivity of the soil.

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 image from earthonline.com
U 5.1.6 The structure and properties of sand, clay and loam soils differ in many ways, including
mineral and nutrient content, drainage, water-holding capacity, air spaces, biota and potential to
hold organic matter. Each of these variables is linked to the ability of the soil to promote primary
productivity
Soil structure affects aeration, water-holding capacity, drainage, and penetration by roots and seedlings,
among other things. Soil structure refers to the arrangement of soil particles into aggregates (or peds)
and the distribution of pores in between. It is not a stable property and is greatly influenced by soil
management practices.

Primary productivity of soils depend on

 mineral content
 drainage
 water-holding capacity
 air spaces
 biota
 potential to hold organic matter

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 soil texture and percolation image from soils.ifas.ufl.edu

Consider mineral content, drainage, water-holding capacity, air spaces, biota and potential to hold organic
matter, and link these to primary productivity.

Soil structure depends on:

 Soil texture ( the amount of sand and clay )

 dead organic matter
 earthworm activity

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For optimum structure, variety of pure sizes are required to allow root prevention, free drainage and water
storage. Pore spaces over 0.1 mm allow roots growth, oxygen diffusion and water movement where as
pore spaces below 0.5 mm help store water.

Application & Skills

A 5.1.1 Outline the transfers, transformations, inputs, outputs, flows and storages within soil
systems.

There are four basic processes that occur in the formation of soils,

 inputs - physical movement of material within soil.

 outputs - occur both from the surface and from the deep subsoil. Water lost by evapotranspiration
 translocations - translocation of materials within the soil profile is primarily due to gradients in
water potential and chemical concentrations within the soil pores.
 transformations - change of some soil constituent without any physical displacement.

The two driving forces for these processes are climate (temperature and precipitation) and organisms,
(plants and animals). Parent material is usually a rather passive factor in affecting soil processes because
parent materials are inherited from the geologic world. Topography (or relief) is also rather passive in
affecting soil processes, mainly by modifying the climatic influences of temperature and precipitation.

A 5.1.2 Explain how soil can be viewed as an ecosystem.

Soil is the link between the air, water, rocks, and organisms, and is responsible for many different
functions in the natural world that we call ecosystem services. These soil functions include: air quality and
composition, temperature regulation, carbon and nutrient cycling, water cycling and quality, natural
"waste" (decomposition) treatment and recycling, and habitat for most living things and their food. We
could not survive without these soil functions.

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Billions of organisms inhabit the upper layers of the soil, where they break down dead organic matter,
releasing the nutrients necessary for plant growth. The micro-organisms include bacteria, actinomycetes,
algae and fungi. Macro-organisms include earthworms and arthropods such as insects, mites and
millipedes. Each group plays a role in the soil ecosystem and can assist the organic farmer in producing a
healthy crop. Micro-organisms can be grouped according to their function: free-living decomposers
convert organic matter into nutrients for plants and other micro-organisms, rhizosphere organisms are
symbiotically associated with the plant roots and free-living nitrogen fixers.

image from asknature

A 5.1.3 Compare and contrast the structure and properties of sand, clay and loam soils, with
reference to a soil texture diagram, including their effect on primary productivity.

Soil structure depends on:

 Soil texture ( the amount of sand and clay )

 dead organic matter
 earthworm activity

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For optimum structure, variety of pure sizes are required to allow root prevention, free drainage and water
storage. Pore spaces over 0.1 mm allow roots growth, oxygen diffusion and water movement where as
pore spaces below 0.5 mm help store water.

Clay:

 fertile in temperate locations

 in tropical areas clay is permeable and easily penetrated by roots
 nutrient deficient / easily leached in tropics

The more clay present in soil the higher the force needed to pull a plough.

Different soil types have different levels of primary productivity:

 sandy soil – low

 clay soil – quite low
 loam soil – high

Primary productivity of soil depends on:

 mineral content
 drainage
 water-holding capacity
 airspaces
 biota
 potential to hold organic materials

*Shrinking limit: state which the soil passes from having a moist to a dry appearance.

*Plastic limit: occurs when each ped is surrounded by a film of water sufficient to act as a lunricant.

*Liquid limit: occurs when there is sufficient water to reduce cohesion between the peds.

*Field capacity: maximum amount of water that a particular soil can hold.

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TOPIC 5.2: TERRESTRIAL FOOD PRODUCTION
SYSTEMS AND FOOD CHOICES

Image from www.learner.org

The food systems that humans depend on for survival follow the same paths and rules as all ecological
food chain. All food chains conform to both the first and second laws of thermodynamics.

World food production differences in productivity and distribution around the world. Socio-political,
economic
and ecological influences can have a significantly effect on the global food supply.

In this unit we will look at the global food supply and how agriculture exerts a set of impacts upon the
environment.

This unit is a minimum of 6 hours.

Significant Ideas:

 The sustainability of terrestrial food production systems is influenced by sociopolitical, economic

and ecological factors.
 Consumers have a role to play through their support of different terrestrial food production
systems.
 The supply of food is inequitably available and land suitable for food production is unevenly
distributed among societies, and this can lead to conflict and concerns.

Big questions:

 Which strengths and weaknesses of the systems approach and of the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts. limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 What value systems are at play in the causes and approaches to resolving the issues addressed
in this topic?
 How are the issues addressed in this topic relevant to sustainability or sustainable development?
 How can systems diagrams be used to show the impact of farming methods on natural systems?
What are th e limitations of such diagrams?
 How can the choice of farming systems prevent environmental impacts, or limit the extent of
environmental impacts?

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  How do EVSs influence the choice of farming systems?
 What are the issues relating to sustainable terrestrial food production? Is sustainable agriculture
possible?

Knowledge & Understanding

U 5.2.1 The sustainability of terrestrial food production systems is influenced by factors such as
scale; industrialization; mechanization; fossil fuel use; seed, crop and livestock choices; water
use; fertilizers; pest control; pollinators; antibiotics; legislation; and levels of commercial versus
subsistence food production.

There are many factors that affect food production. The post-war ‘second agricultural revolution’ in
developed countries, and the ‘green revolution’ in developing nations in the mid-1960s transformed
agricultural practices and raised crop yields dramatically, but the effect is levelling off and will not meet
projected demand

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At the same time, many other factors are having severe impacts on food production: water stress and
desertification is reducing the amount of arable land; many pests are becoming resistant to insecticides,
but many of the most effective chemical agents are now banned under environmental regulations;
underdeveloped infrastructure means that losses increase further during transport and storage;
consumption patterns are changing and developing nations such as India and China have an increased
appetite for meat, and climate change is bringing new microbial diseases to food-growing regions along
with more extreme and unpredictable weather patterns.

Increases in global populations and changes in diet have put pressure on terrestrial food production
systems. Arable land is becoming limited due to increasing human settlements and urbanization. Soils
are becoming degraded through intensive farming. Increased agriculture has led to the loss of biodiversity
as native habitats have been cleared.

U 5.2.2 Inequalities exist in food production and distribution around the world

The United Nations Food and Agriculture Organization estimates that nearly 870 million people of the 7.1
billion people in the world, or one in eight, were suffering from chronic undernourishment in 2010-2012.
Almost all the hungry people, 852 million, live in developing countries, representing 15 percent of the
population of developing counties. There are 16 million people undernourished in developed countries.
Chronic under-nourishment, during childhood leads to permanent damage: stunted growth, mental
retardation, and social and developmental disorders. Many are also suffering from malnutrition (enough
energy but not enough essential nutrients).

In many MEDCs, the cost of food is relatively cheap and people choose food based on preference not
nutritional need. Seasonal foods have almost disappeared as foods are readily available all year round.
Modern technology and transport systems mean that foreign foods can be bought in almost any market.
In LEDCs, many populations struggle to produce enough food to sustain them. Arable land is scarce.
There may also be political agendas as well as simple environmental limitations on food production.
Crops that are grown are often exported for profit (cash cropping) and not for the local communities.
Arable land is in finite supply.

There are large differences in food production in the world but distribution is the problem. Countries like
USA, Canada, and Australia produce more food than they need but who should pay for it to be distributed
to poorer countries in need such as Bangladesh, Sudan and Ethiopia. The political angle attached to this
means that perhaps the receiving country maybe in the others debt, and prone to exploitation. Who
decides who gets this food? These are issues that revolve around the topic of food distribution.

The diets of MEDCs and LEDCs, differ as well. MEDCs average calorie intake is about 3314 whereas
LEDCs is only about 2666 per day. As we adapt more and more of the net primary productivity on Earth
to human needs, use and degrade more land, demand more meat, we must be reaching our limits.

Agriculture in the LEDCs are in contrast and have low levels of technology, lack of capital and high levels
of labour."

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Cause in imbalance food distribution

 Ecological: some climate and soils are better for food production
 Economic: advance technology and money can overcome ecological limitation (transportation of
water)
 Socio-political: underinvestment in rural area and rapid area in LEDC; poor human health weaken
available labor force

U 5.2.3 Food waste is prevalent in both LEDCs and more economically developed countries
(MEDCs), but for different reasons.

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As countries develop and consumption increases so does the amount of waste per capita, and pollution
becomes a greater problem. There are global, national and local strategies in place to reduce levels of
waste and minimize impact on the environment.
Global waste production

The amount and type of waste produced varies between countries.

MEDCs have higher levels of consumption, so many produce more waste than LEDCs. Ireland and the
USA produce over 700 kg of waste per person per year. In LEDCs the figure is around 150 kg per person
per year. This difference is due to different levels of consumption; it is also more common to reuse items
in LEDCs.

As a country becomes more wealthy, the demand for consumer items increases. This means that items
are replaced more frequently - leading to larger quantities of waste. For example, mobile phones and
computers that still work may be discarded for a newer version.

In LEDCs waste production is lower because:

 Less is bought because people are typically on lower incomes

 Less packaging is used on products
 Disposable items (eg razors, plastic plates and nappies) are used less
 Lower literacy levels means there is less production of written material

246
 image from www.fao.org

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U 5.4.4 Socio-economic, cultural, ecological, political and economic factors can be seen to
influence societies in their choices of food production systems

image from www.eufic.org

Social influences on food intake refer to the impact that one or more persons has on the eating behavior
of others, either direct or indirect, either conscious or subconscious. The relationship between low socio-
economic status and poor health is complicated and is influenced by gender, age, culture, environment,
social and community networks, individual lifestyle factors and health behaviors.

There are clear differences in social classes with regard to food and nutrient intakes. Low-income groups
in particular, have a greater tendency to consume unbalanced diets and have low intakes of fruit and
vegetables.

Education level and income determine food choices and behaviors that can ultimately lead to diet-related
diseases. The origins of many of the problems faced by people on low incomes emphasizes the need for
a multidisciplinary approach to targeting social needs and improving health inequalities.

U 5.2.5 As the human population grows, along with urbanization and degradation of soil
resources, the availability of land for food production per capita decreases.
As the world population continues to grow in almost all continents, great pressure is being placed on
arable land, water, energy, and biological resources to provide an adequate supply of food while
maintaining the integrity of our ecosystem. As the world population grows, the food problem will become
increasingly severe. The most venerable will be population in developing countries. The per capita
availability of world grains, which make up 80 per cent of the world’s food, has been declining for the past
25 years. Certainly with a quarter million people being added to the world population each day, the need
for grains and all other food will reach unprecedented levels.

248
U 5.4.6 The yield of food per unit area from lower trophic levels is greater in quantity, lower in cost
and may require fewer resources

image from www.sciencemusicvideos.com

Most food chains do not have a fourth or fifth trophic level, because energy is not sufficient to sustain
fourth or fifth trophic level. As you progress a trophic level only a percentage is passed on to the next
organism (approximately 10%- as a result of the energy required to maintain homeostasis), so it would
not be efficient to eat an animal that would give you a small biomass.

More people on Earth could be supported for a given area of land farmed if individuals eat lower on the
food chain. Eating primary producers instead of eating herbivores could support the same number of
people as at present, but with less land degradation because we wouldn't need to have so much land in
production. These consequences of a change in our diets result from the basic thermodynamic principles
outlined above.

The UN's Food and Agriculture Organization (FAO) estimates that ~ 30% of the ice-free land surface area
of Earth is directly or indirectly involved in livestock production!

249
Eating lower on the food chain, one or more of the following benefits would be likely:

 Not as much land and other resources raising grain to feed to animals.
 Overgrazing on public and private range lands could decrease.
 Would not have to farm or graze marginal lands as intensively
 More people in the world could receive an adequate diet
 Less fossil fuel energy (and associated emissions of CO2) would be required to produce our
food.

image from rsif.royalsocietypublishing.org

250
U 5.4.7 Cultural choices may influence societies to harvest food from higher trophic levels.

image .sustainablecitiesinstitute.org
Most food is harvested from low trophic levels (producers and herbivores). Systems that produce crops
are more energy efficient then those which produce livestock. This is because energy is greater in
proportion in the low trophic levels. Even though it is efficient to use arable systems, many cultures still
use livestock as part of their farming system. Taste and cultural demand play a major role in this and the
animals also provide a source protein which is essential for the human diet. Animals are also used as
working animals in some cultures.

U 5.4.8 Increased sustainability may be achieved through: altering human activity to reduce meat
consumption and increase consumption of organically grown and locally produced terrestrial
food products, improving the accuracy of food labels to assist consumers in making informed
food choices, monitoring and control of the standards and practices of multinational and national
food corporations by governmental and intergovernmental bodies, planting of buffer zones
around land suitable for food production to absorb nutrient runoff.
Farming must feed more people more sustainable. Advances in agricultural science and technology have
contributed to remarkable increases in food production since the mid-twentieth century. Global agriculture
has grown 2.5–3 times over the last 50 years. This has let food production keep pace with human
population growth so that, overall, there are enough calories produced per capita. However, progress
toward reducing hunger is variable across the world

Application & Skills

251
A 5.2.1 Analyse tables and graphs that illustrate the differences in inputs and outputs associated
with food production systems.
Terrestrial farming systems can be divided into several types

 Commercial farming in which farming is for profit. This usually involves one crop
 Subsistence farming in which food is produced only to feed the farmer and family. No sale for
profit

Commercial and subsistence farming can be intensive or extensive

 Intensive farms generally take up a small area of land but aim to have very high outputs per unit
area of land
 Extensive farms are usually large in comparison to the money and labor put into them

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 image from bhsagriculture.wikispaces.com
A 5.2.2 Compare and contrast the inputs, outputs and system characteristics for two given food
production systems.

The systems selected should be both terrestrial or both aquatic. In addition, the inputs and outputs of the
two systems should differ qualitatively and quantitatively (not all systems will be different in all aspects).

The pair of examples could be North American cereal farming and subsistence farming in some parts of
South-East Asia, intensive beef production in the developed world and the Maasai tribal use of livestock,
or commercial salmon farming in Norway/Scotland and rice-fish farming in Thailand. Other local or
global examples are equally valid.

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Factors to be considered should include:

 inputs, such as fertilizers (artificial or organic); water (irrigation or rainfall); pest control (pesticides
or natural predators); labour (mechanized and fossil-fuel dependent or physical labour); seed
(genetically modified organisms—GMOs—or conventional); breeding stock (domestic or wild);
livestock growth promoters (antibiotics or hormones vs organic or none)
 outputs - outputs, such as food quality, food quantity, pollutants (air, soil, water), consumer
health, soil quality (erosion, degradation, fertility); common pollutants released from food
production systems include fertilizers, pesticides, fungicides, antibiotics, hormones and gases
from the use of fossil fuels; transportation, processing and packaging of food may also lead to
further pollution from fossil fuels system characteristics—selective breeding, genetically
engineered organisms, monoculture versus polyculture, sustainability,
 system characteristics - such as diversity (monoculture versus polyculture); sustainability;
indigenous versus introduced crop species socio-cultural—the Maasai cattle equals wealth and
quantity is more important than quality;
 environmental impact—pollution (air, soil, water); habitat loss; biodiversity loss; soil erosion or
degradation; desertification; disease epidemics from high-density livestock farming
 socio-economic factors - arming for profit or subsistence, for export or local consumption, for
quantity or quality; traditional or commercial farming.

Example of compare and contrast from http://yesitsyomoma.wordpress.com

Terrestrial Systems:

Intensive Charolais beef production in France:

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In Western Europe the Charolais beef is one of the beef brands chosen. Through selective breeding and
genetic engineering bloodlines that puts weight on exist but has a low fat cover. Charolais lives under
controlled conditions, they are fed with high proteins and treated with antibiotics to make sure they are
healthy. Lots of energy is used in transporting and processing the finished meat.

Cattle raised outdoors however grown on single monoculture ( cultivation of a single crop on a farm or in
a region or country) grass land in large fields with a high stock rate. To keep the productivity of these
fields going, large amounts of fertilizer are used.

This intensified farming e the 1940′s with the aim of producing cheaper meat has led to habitat loss as
they have been removed to make bigger fields and cases of Eutrophication have increased as excess
use of fertilizers and large amounts of slurry produced in the system enter water courses. Fear of causing
antibiotic resistance in human bacteria through bioaccumulation.

Inputs:

 energy for food distribution

 food supplements
 selective breeding and genetic engineering (system characteristics)
 indoor rearing
 fertilizers to maximize grass production
 antibiotics and hormones

Outputs:

 cheap meat (socio-cultural)

 habitat destruction to make bigger fields (environmental impact)
 antibiotic resistance
 Eutrophication

Nomadic cattle grazing of the Himba:

The Charolais beef production can be contrasted with the Nomadic cattle grazing of the Himba. The
Himba people are from North West Namibia, they survive by being Nomadic hunters/grazers. They also
have a tight bond with the cattle they graze. During the dry seasons the Himba move their cattle from
area to area until the grass is used up until the raining season, they go to better pastures. Cattle to the
Himba are very important as they provide; meat, milk, skins and even dung for fires. Prestige between the
Himba is seen by how many cattle they have, not the size of the cattle. The cattle during the dry season
may start competing with herbivores. This has increased especially with global warming drought periods.
This can lead to soil erosion as extra grazing pressure removes the grasses that hold the top soil
together.

Input:

 nomadic grazing moving from place to place so land has a chance to recover
 cattle survive on low grade natural forage with no supplements
 during drought cattle die as grass disappears adding patches of nutrients to the soil
(environmental impact)

Outputs:

 Himba cattle provide meat, milk and fuel (dung)

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  owning cattle gives status in community (socio-cultural)
 during drought times Himba cattle compete with wild grazers for food this can lead to soil erosion
as well as food shortage (environmental impact)"

image from www.arctic.uoguelph.ca

Compare and contrast these in terms of their trophic levels and efficiency of energy conversion. There is
no need to consider individual production systems in detail. In terrestrial systems, most food is
harvested from relatively low trophic levels (producers and herbivores).

In aquatic systems, perhaps largely due to human tastes, most food is harvested from higher trophic
levels where the total storages are much smaller. Although energy conversions along the food chain may
be more efficient in aquatic systems, the initial fixing of available solar energy by primary producers tends
to be less efficient due to the absorption and reflection of light by water.

The Second Law of Thermodynamics states that energy goes from a concentrated form (like the sun) to a
dispersed form (like heat), the availability of energy to do work therefore diminishes on the system
becomes increasingly disorder. It explains how energy transformations in living systems can lead to loss
of energy from the system. The order in living systems is only maintained by constant input of new energy
from the sun.

We get to see from the second law of thermodynamics that energy conversion through food chains is
inefficient and that energy is lost by respiration and waste production at each level within the food web.

Energy in sunlight -> producer (90% energy lost) -> primary consumer (9% energy lost) -
> secondary consumer (0.9% energy lost)

100% -> 10% -> 1% -> 0.1%

Terrestrial farming systems are divided into two types:

 Commercial farming: for profit, often monoculture

 Subsistence farmer: produces only enough to feed their family with no sell for profit

Both commercial and subsistence can be intensive or extensive farms

 Intensive farms: take a small area of land for a high input

 Extensive farms: large in comparison to the money and labour put into it

A 5.2.3 Evaluate the relative environmental impacts of two given food production systems.

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Food production and the supply chain can have wide-ranging positive and negative impacts on the
environment. Negative impacts include escalating water and land use, soil erosion and degradation
through loss of fertility or desertification, loss of biodiversity, and intensive use of energy (for production,
notably for fertiliser manufacture, and for supply, especially in transport and refrigeration) with associated
greenhouse gas emissions

Factory farming reduces the amount of land needed for meat production, however, these farms are a
serious air and water pollutant. The waste of these animals ends up in the nature and poses a constant
risk of drinking water contamination and seriously affects the air quality of the nearby areas. One solution
for the problem with animal waste lays in its use for production of biofuel which can then be used for
production of electricity but this practice is the exception rather than the rule.

Mass meat production has shown main contributors to carbon dioxide emissions which in turn are the
main cause of the climate change. The meat industry is estimated to be responsible for about 9 percent of
total carbon dioxide emissions which are a result of emissions of various gases from the farms as well as
from the microbial activities after application of animal waste as fertilizers.

Animal husbandry poses a serious threat to the local ecosystems and biodiversity due to the use of the
land for grazing and animal feed production. As much as one quarter of the Earth’s surface is used for
grazing and about one third of arable land is used to produce animal feed. As a result, the wildlife species
struggle with lack of habitat, while some are even threatened with extinction.

A 5.2.4 Discuss the links that exist between sociocultural systems and food production systems.

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This could be illustrated through the use of examples, such as: the way in which the low
population densities and belief systems of shifting cultivators links with the ecosystem of “slash and burn”
agriculture; the relationship between high population densities, culture, soil fertility and the
wetrice ecosystem of South-East Asia; the link between the political economy of modern urban society,
corporate capitalism and agro-ecosystems.

There are many factors that come into consideration as to the method and level of sustainability of food
production methods. Population density/size, culture, soil fertility, and method of agriculture are some of
these factors.

Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then
abandoned and allowed to revert to their natural vegetation while the cultivator moves on to another plot.
The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more
commonly, when the field is overrun by weeds. The length of time that a field is cultivated is usually
shorter than the period over which the land is allowed to regenerate by lying fallow.

Of these cultivators, many use a practice of slash-and-burn as one element of their farming cycle. Others
employ land clearing without any burning, and some cultivators are purely migratory and do not use any
cyclical method on a given plot. Sometimes no slashing at all is needed where regrowth is purely
of grasses, an outcome not uncommon when soils are near exhaustion and need to lie fallow.

One land-clearing system of shifting agriculture is the slash-and-burn method, which leaves only stumps
and large trees in the field after the standing vegetation has been cut down and burned, its ashes
enriching the soil. Cultivation of the earth after clearing is usually accomplished by hoe or digging stick
and not by plough.

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 image from www.technologyreview.com
A 5.2.5 Evaluate strategies to increase sustainability in terrestrial food production systems.

 Altering human activity

 Local produce
 Food Labels

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  Monitoring multi-nationals
 Buffer zones (nutrient run-off)

Key Terms
food production food terrestrial aquatic producers
herbivores distribution environmental slash and burn biodiversity
nitrates socio-cultural impact subsistence monoculture
mixed crops E.coli shifting cultivation growth hormones pesticides
herbicides GMO antibiotics agribusiness
fertilizer organic

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TOPIC 5.3: SOIL DEGRADATION AND
CONSERVATION

Image from www.denichsoiltest.com

We tend to take the soil around us for granted. It is much more than mud, clay or dirt. All the food that we
consume depends ultimately upon soil. Plants grow and depend on the soil. We either eat plants that
grow directly in the soil or the animals that eat the plants.
Soils are the part of the lithosphere where life processes and soil forming processes both take place.

In this unit we will look at the soil system, soil water, soil formation and the consequences of soil
degradation.

This unit is a minimum of 3 hours.

Significant Ideas:

 Fertile soils require significant time to develop through the process of succession.
 Human activities may reduce soil fertility and increase soil erosion.
 Soil conservation strategies exist and may be used to preserve soil fertility and reduce soil
erosion.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 What value systems can you identify at play in the causes and approaches to resolving the issues
addressed in this topic?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 How might ecocentrists and technocentrists differ over methods of soil conservation?
 Could there be new methods of food production that may help feed the world's growing
population?

Knowledge & Understanding:

U 5.3.1 Soil ecosystems change through succession. Fertile soil contains a community of
organisms that work to maintain functioning nutrient cycles and that are resistant to soil erosion.

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The amount of time required for soil formations varies from soil to soil. Some soils develop more quickly
than others. Phases of erosion and deposition also keep soils in a changing state.

Organic matter releases releases acids and returns nutrients to the soil.

Animals help break down organic matter, mix the soil, aerate the soil and add faces to the soil.

U 5.3.2 Human activities that can reduce soil fertility include deforestation, intensive grazing,
urbanization and certain agricultural practices (such as irrigation and monoculture).

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 This shows that the soil degradation’s damage is world wide and occurs over 15% of the world’s total area.
Soil degradation is the decline in quantity and quality of soil. It is also erosion by wind and water,
biological degradation (loss of humus and plant or animal life), physical degradation (loss of structure,
changes in permeability), chemical degradation (acidification, declining fertility, changes in pH, salinity)

image from www.uwec.edu

Human activities such as overgrazing, deforestation, unsustainable agriculture and irrigation cause
processes of degradation. These include soil erosion, toxification and salinization. Desertification
(enlargement of deserts through human activities) can be associated with this degradation.

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 Many forms and causes of degradations
U 5.3.3 Commercial, industrialized food production systems generally tend to reduce soil fertility
more than small-scale subsistence farming methods.
A significant amount of chemical and energy input is required in commercial and industrialized food
production systems. This is achieved through the application of synthetic chemicals, genetically modified
organisms, and a number of other industrial products. This method usually alters the natural environment,
deteriorates soil quality, and eliminates biodiversity. The goal of commercial and industrialized food
production systems is to maximize the potential yield of crops.. In maintaining a conventional system,
biodiversity, soil fertility, and ecosystems health are compromised.

Sustainable agriculture is a more holistic approach to farming than conventional in that it relies
on ecological processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs
with adverse effects Sustainable agriculture is a natural way to produce food and has a number of social,
economic, and environmental benefits.
U 5.4.4 Reduced soil fertility may result in soil erosion, toxification, salination and desertification.
Many poor farming and forestry operations encourage erosion. Erosion accelerates when sloping land is
ploughed and when grass is removed from semi-arid land to begin dry-land farming. It accelerates when
cattle, sheep and goats are allowed to overgraze and when hillside forests are felled or cut
indiscriminately. While there are isolated instances of deserts being reclaimed by irrigation or of new
forests being planted, man, in the majority of instances, degrades the soil when he begins agricultural
operations.

Poor management practices can also lead to low organic matter. This will result in poor water infiltration,
poor water drainage, saturated soil, or compaction. These practices will limit the ability of water to infiltrate
the soil causing an increase in the soil salinity and the soil’s ability to buffer salt.

Desertification is the accumulated result of ill-adapted land use and the effects of a harsh climate. Human
activities that represent the most immediate causes are:

 over-cultivation exhausts the soil,

 overgrazing removes the vegetation cover that protects it from erosion

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  deforestation destroys the trees that bind the soil to the land and poorly drained irrigation systems
turn croplands salty.
 the lack of education and knowledge
 the movement of refugees in the case of war, the unfavorable trade conditions of developing
countries and other socio-economic and political factors enhance the effects of desertification.

Due to the lack of alternative survival strategies, farmers tend to relentlessly exploit natural resources
(food crops, water for drinking and washing, firewood) to the point that they are often over-exploited and
cannot regenerate naturally. Soil nutrients and organic matter begin to diminish as intensive agriculture
removes quantities of nutrients greater than the soil’s natural regeneration capacities. As a consequence,
the soil is unable to recover, as it does during fallow periods, resulting is an ever-increasing spiral of
environmental degradation and poverty, the principal causes of desertification.

U 5.3.5 Soil conservation measures include soil conditioners (such as organic materials and lime),
wind reduction techniques (wind breaks, shelter belts), cultivation techniques (terracing, contour
ploughing, strip cultivation) and avoiding the use of marginal lands.

image from kids.britannica.com

Strategies for combating soil degradation is not so common or widespread and to reduce this risk farmers
are encouraged and informed about the processes and conservation methods.

Farmers are in the need of beginning with extensive management practices like organic farming,
afforestation, pasture extension, and benign (gracious) crop production. However to make this work
policies need to be put into place.

Consider conservation measures:

 soil conditioners (for example, use of lime and organic materials)

 wind reduction techniques (wind breaks, shelter belts, strip cultivation)
 cultivation techniques (terracing, contour plowing)
 efforts to stop plowing of marginal lands
 Trickle drip is a slow release of water from pipes under the surfaces which can reduce the loss of
evaporation

There are several methods farmers can use to reduce or prevent erosion.

 Mechanical methods are used to reduce water flow including bunding, terracing, and contour
ploughing. The goal is to prevent and slow down the movement of rain water down the slopes.

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  Vegetation cover methods use roots of crops to help bind the soil and decrease the action of wind
and rain on the soil surface. Increased organic on the soil surface allows the soil to hold more
water and reduce the mass, movement and erosion and stabilizing the soil structure.
 Soil husbandry is used to prevent damage to the soil structure. Care is taken to reduce the use of
heavy machinery especially on wet soils and ploughing on soils that are sensitive to erosion.

The three main ways of managing salt-affected soils is by:

 flushing the soil with water and leaching the salt away
 using gypsum and calcium sulfates to replace sodium ions on the clay and colloids
 reduction in evaporation losses to reduce the upward movement of water in the soil

Both socio-economic and ecological factors have been ignored and integrated approach to soil
conservation is needed, non-technological factors like population pressure, social structures, economy
and ecological factors can determine the appropriate technical solutions.

Application & Skills

A 5.3.1 Explain the relationship between soil ecosystem succession and soil fertility.
First, lichens, which grow on rock, appear in a destroyed region. The lichens help break down the rock.
Then, as lichens die and decompose, and weathering breaks apart rock, soil begins to form. As soil
becomes richer, small plants like mosses and ferns appear, and the lichens start to disappear. The soil
continues to become richer as plants continue to die and decompose, and flowering plants and grasses
appear, bringing insects to the region. In time, shrubs and small trees cover the region, creating a suitable
habitat for reptiles, birds, and mammals. As the shrubs and trees grow, smaller plants die from lack of
sunlight and add more organic material to the soil. Eventually, the shrubs and trees die because taller
trees cover the region. This all happens gradually over a long period of time.

image from ecology-project.weebly.com

A 5.3.2 Discuss the influences of human activities on soil fertility and soil erosion.
Soil is a non-renewable resource that once it is eroded it is not renewed. Soil erosion is the permanent
change of the main characteristics of soil that could see it lose its fertility, pH, colour, humus content or
structure. Soil erosion occurs naturally by wind or harsh climatic conditions but human activities include
overgrazing, overcropping and deforestation.

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Overgrazing occurs when farmers stock too many animals such as sheep, cattle or goats on their
land. The animals damage the soil surface by eating the vegetation and either digging into wet soil or
compacting dry soil with their hooves.

Overcropping is when the land is being continuously under cultivation and is not allowed to lie fallow
between crops. This constant farming of the land reduces the soils ability to produce valuable humus for
soil fertility as it is constantly being ploughed or stripped for crop growth. The soil becomes drier and less
fertile.

Deforestation is the cutting down of large areas of forests leaving an open, exposed
landscape. Deforestation occurs for many reasons such as the sale of wood, charcoal or as a source of
fuel, while cleared land is used as pasture for livestock, plantations of commodities, and settlements. The
removal of trees without sufficient reforestation has resulted in damage to habitat, biodiversity loss and
aridity (drying of soil).

A 5.3.3 Evaluate the soil management strategies of a given commercial farming system and of a
given subsistence farming system.

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 image from en.wikipedia.org
The North American Prairies and Commercial Farming

The problems occurred were increasing salinity, soil erosion and loss of soil fertility. Farmers managed to
reduce salinity and erosion, to reduce salinity summer fallowing or leaving bare soil for long periods were
stopped or reduced. Snow fences or barriers enabled snowdrifts to pile up which provide water then they
melt in.

And to reduce erosion is used contour ploughing- along the contour lines instead of up and down slopes
traps soil and water. Strip Cropping – growing as flax and tall wheatgrass at right angles to the wind.

Key Terms
deforstation unsustainable weathering deposition mass movement
desertification wind breaks degradation leaching drainage
lime slope shelter belts soil erosion overgrazing
contour plowing porosity waterlog strip cultivation toxificiation
relief wind erosion calcification acidificiation terracing
soil texture field capacity duff shrinking limit sheet wash
gullying plastic limit

268
TOPIC 6.1: INTRODUCTION TO THE ATMOSPHERE

image from NASA

Earth is the only planet in the solar system with an atmosphere that can sustain life. The blanket of gases
not only contains the air that we breathe but also protects us from the blasts of heat and radiation
emanating from the sun. It warms the planet by day and cools it at night.

This unit is a minimum of 2 hours.

Significant Ideas:

 The atmosphere is a dynamic system that is essential to life on Earth.

 The behaviour, structure and composition of the atmosphere influence variations in all
ecosystems

Big questions:

 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 Can there ever be a stable climate?
 To what extent are human influences on climate greater?

Knowledge and Understanding

U 6.1.1 The atmosphere is a dynamic system (with inputs, outputs, flows and storages) that has
undergone changes throughout geological time.

The atmosphere is the result of energy from the sun producing the movements or currents in the
atmosphere. This energy, the Earth's movement relative to the sun, and the components of the
atmosphere and of the Earth's surface maintain the long-term climate, the short-term weather, and the
temperature conditions. These provide conditions fit for the forms of life found on Earth. The condition of
the physical world affects and is affected by the life present. The entire system is called the

269
biogeochemical system. Living organisms (biotic components) have transformed the
atmospheric composition of the Earth and vice versa throughout history.

James Lovelock, author of Gaia, proposes that the atmosphere owes its current composition to feedback
from living systems. He remarks that life on Earth requires a particular atmospheric composition, and this
composition is in turn maintained by the interaction between biological systems and the atmospheric
system.

U 6.1.2 The atmosphere is a predominantly a mixture of nitrogen and oxygen, with

smaller amounts of carbon dioxide, argon, water vapour and other trace gases.

image from National Climate Assessment

The Earth's atmosphere is composed primarily of nitrogen and oxygen, as well as some argon. There are
also several
other trace gases, meaning they occur in very small amounts.

The major constituents are oxygen (O2) and nitrogen (N2). Other components such as argon, CO2, NO,
and O3 are
produced in minute quantities in natural processes. However, industrial and other technological human
activities (such as automobile traffic) have begun to increase the amounts of materials such as CO2 by
amounts that are beginning to make a difference in the balance of circulation and radiation absorption in
the troposphere. Effects of these changes range from local atmospheric problems, like smog, to problems
of much greater scale, such as global climate change.

 Nitrogen - 78% - Dilutes oxygen and prevents rapid burning at the earth's surface. Living things
need it to make proteins. Nitrogen cannot be used directly from the air. The Nitrogen Cycle is
nature's way of supplying the needed nitrogen for living things.
 Oxygen - 21% - Used by all living things. Essential for respiration. It is necessary for combustion
or burning.
 Argon - 0.9% - Used in light bulbs.
 Carbon Dioxide - 0.03% - Plants use it to make oxygen. Acts as a blanket and prevents the
escape of heat into outer space. Scientists are afraid that the burning of fossil fuels such as coal
and oil are adding more carbon dioxide to the atmosphere.
 Water Vapor - 0.0 to 4.0% - Essential for life processes. Also prevents heat loss from the earth.
 Trace gases - gases found only in very small amounts. They include neon, helium, krypton, and
xenon.

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U 6.1.3 Human activities impact atmospheric composition through altering inputs and outputs of
the system. Changes in the concentrations of atmospheric gases—such as ozone, carbon dioxide,
and water vapour—have significant effects on ecosystems.
Most scientists believe that human activity is altering the composition of the atmosphere by increasing the
concentration of greenhouse gases (GHGs). The recent attention given to the greenhouse effect and
global warming is based on the recorded increases in concentrations of some of the greenhouse gases
due to human activity. Of particular interest are water vapor, carbon dioxide, methane, nitrous oxide,
chlorofluorocarbons, and ozone. With the exception of chlorofluorocarbons, all of these gases occur
naturally and are also produced by human activity.

image from National Climate Assessment

U 6.1.4 Most reactions connected to living systems occur in the inner layers of the atmosphere,
which are the troposphere (0–10 km above sea level) and the stratosphere (10–50 km above sea
level).

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 image from NASA Earth Observatory
The atmosphere consists of five layers: the troposphere, the stratosphere, the mesosphere, the
thermosphere, and the
exosphere. The thickness of these layers is slightly different around the globe, and also varies according
to temperature
and season. In this discussion, we will focus primarily on the troposphere and the stratosphere because
they are the
most affected by anthropogenic (or man-made) pollutants.

The troposphere is the layer closest to the Earth's surface. It is a layer of air approximately 10 to 15
kilometers thick that
is constantly in motion. The conditions in this layer determine practically all of the Earth's weather
patterns. It derives its name from the Greek word "Tropos," meaning "turning" or "mixing." The constant
motion in this layer is significant in discussing air quality because it results in the dispersion of pollutants.
In one respect this dispersion is considered
beneficial because it has the effect of diluting pollutants, which can reduce harmful impacts on a local
level. On the other hand, this dispersion also results in the movement of air pollutants (and therefore air
pollution problems) from areas of high pollution production to areas of lower production. For example,
pollutants produced in an industrialized and heavily populated city often adversely impact smaller
communities and ecosystems in a large surrounding area.

The stratosphere is the layer just above the troposphere. It is approximately 40 kilometers thick and is
composed mostly of dry stable air. In contrast to the troposphere, pollutants in the stratosphere do not
disperse, and tend to remain in the atmosphere for long periods of time.

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U 6.1.4 Most clouds form in the troposphere and play an important role in the albedo effect of the
planet.

Albedo is a measure of the reflectivity of a surface. The albedo effect when applied to the Earth is a
measure of how much of the Sun's energy is reflected back into space. More water vapour in the
atmosphere means more cloud formation. More clouds lead to increased albedo of the earth.

Different parts of the Earth have different albedos. For example, ocean surfaces and rain forests have low
albedos, which means that they reflect only a small portion of the sun's energy. Desert's, ice, and clouds,
however, have high albedos; they reflect a large portion of the sun's energy. Over the whole surface of
the Earth, about 30 percent of incoming solar energy is reflected back to space. Because a cloud usually
has a higher albedo than the surface beneath it, the cloud reflects more shortwave radiation back to
space than the surface would in the absence of the cloud, thus leaving less solar energy available to heat
the surface and atmosphere.

273
 image from www.climate.be
U 6.1.5 The greenhouse effect of the atmosphere is a natural and necessary
phenomenon maintaining suitable temperatures for living systems.

The term 'Greenhouse Effect' is commonly used to describe the increase in the Earth's average
temperature that has been recorded over the past 100 years. However, without the 'natural greenhouse
effect', life on Earth would be very different to that seen today.

The Earth receives its life sustaining warmth from the Sun. On its way to the Earth's surface most of the
heat energy passes through the Earth's atmosphere, while a smaller proportion is reflected back into
space. Without a greenhouse effect, radiation from the Sun (mostly in the form of visible light) would
travel to Earth and be changed into heat, only to be lost to space.

The energy warms the Earth's surface, and as the temperature increases, the Earth radiates heat energy
(infrared energy) back into the atmosphere. As this energy has a different wavelength to that coming from
the sun, some is absorbed by gases in the atmosphere.

Role of greenhouse gases

 Maintain mean global temperature

274
  Normal and necessary condition for life on Earth
 allow short wavelengths of radiation such as visible light and UV too pass through to the Earth's
surface, but they trap the longer wavelengths such as infrared radiation

image from Delaware Department of Natural Resources & Environmenta

Applications and Skills
A 6.1.1 Discuss the role of the albedo effect from clouds in regulating global average temperature.
Clouds have a major role in reflecting some of the Sun's radiation back into space. The proportion of
incident radiation reflected by a substance is called its albedo. The albedo of low thick clouds such as
stratocumulus is about 90 percent. The albedo of high thin clouds such as cirrus may be as low as 10
percent. The albedo could vary with the wavelength of the radiation, but for clouds it does not as
evidenced by the fact that they are white under white light. At sunrise and sunset the incident light is red,
orange or yellow and the clouds reflect this light without modification. The albedo of clouds for infrared
radiation is likely the same for visible light. There are two sides, top and bottom, to clouds that may be
involved in the reflection of radiation.

The albedo effect has a significant impact on our climate. The lower the albedo, the more radiation from
the Sun that gets absorbed by the planet, and temperatures will rise. If the albedo is higher, and the Earth
is more reflective, more of the radiation is returned to space, and the planet cools.

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A 6.1.2 Outline the role of the greenhouse effect in regulating temperature on Earth
The ‘greenhouse effect’ is an atmospheric heating phenomenon in which the Earth experiences rise in
temperature because certain gases (water vapor, carbon dioxide, nitrous oxide, and methane) in the
atmosphere allow incoming sunlight to pass through but trap heat radiated from the earth’s surface. If
these gases wouldn’t trap heat in the atmosphere, the temperature of the earth would be about 33
degrees centigrade colder on average. Because how these gases warm our planet, they are called as
greenhouse gases and the effect they create in the atmosphere is called as greenhouse effect.

When the thermal radiation (or heat) arrives from the sun, some of it is bounced from the surface of the
Earth by the ozone layer (which is the reason we can safely walk out in the sun, is this prevents the most
dangerous radiation from the sun getting through the atmosphere), leaving only some heat to make it
through to heat the Earth. This heat then rises back through the atmosphere, but most of it gets trapped
by the greenhouse gases, which causes it to remain in the Earth’s atmosphere.

276
 image from Keeping World Environment Safer and Greener

Key Terms
atmosphere troposphere mesosphere thermosphere
ozone greenhouse effect ionosphere biosphere
radiation reflection conduction convection
albedo effect water vapor shortwave radiation longwave radiation
greenhouse gases global warming climate change

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TOPIC 6.2: STRATOSPHERIC OZONE

image from http://en.wikipedia.org/wiki/Ozone_layer

The ozone layer is the part of the Earth's atmosphere which contains relatively high concentrations of
ozone (O3). "Relatively high" means a few parts per million - much higher than the concentrations in the
lower atmosphere but still small compared to the main components of the atmosphere. Although the
concentration of ozone in the ozone layer is very small, it is vitally important to life because it absorbs
biologically harmful ultraviolet (UV) radiation from the Sun. The "thickness" of the ozone layer - that is, the
total amount of ozone in a column overhead - varies by a large factor worldwide, being in general smaller
near the equator and larger as one moves towards the poles. It also varies with season, being in general
thicker during the spring and thinner during the autumn.

In this unit unit we will look at how human activities have resulted in the depletion of the ozone layer and
the roles of government and non-government agencies in controlling the restricting ozone depleting
substances.

This unit is a minimum of 2.5 hours.

Significant Ideas:

 Stratospheric ozone is a key component of the atmospheric system because it protects living
systems from the negative effects of ultraviolet radiation from the Sun.
 Human activities have disturbed the dynamic equilibrium of stratospheric ozone formation.
 Pollution management strategies are being employed to conserve stratospheric ozone.

Big questions:

 To what extent have the solutions emerging form this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts or restoring systems in
which environmental impacts have already occurred?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic after your predictions for the state of
human societies and the biosphere some decades from now?
 Why has the Montreal Protocol been so successful? Will it continue to be successful?
 Outline the links between stratospheric ozone and sustainability/sustainable development.
 What are the greatest threats to stratospheric ozone likely to be, and from where, in the decades
to come?

Knowledge and Understanding

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U 6.2.1 Some ultraviolet radiation from the Sun is absorbed by stratospheric ozone causing the
ozone molecule to break apart. Under normal conditions the ozone molecule will reform. This
ozone destruction and reformation is an example of a dynamic equilibrium.

image from www.chemhume.co.uk

Ozone plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering
action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would
reach the Earth's surface. Ultraviolet radiation is absorbed during the formation and destruction of ozone
from oxygen. You do not need to memorise chemical equations is not required.

from http://www.ucar.edu/learn/1_6_1.htm
U 6.2.2 Ozone depleting substances (including halogenated organic gases such
as chlorofluorocarbons—CFCs) are used in aerosols, gas-blown plastics, pesticides, flame
retardants and refrigerants. Halogen atoms (such as chlorine) from these pollutants increase
destruction of ozone in a repetitive cycle, allowing more ultraviolet radiation to reach the Earth.
Halogenated organic gases are very stable under normal conditions but can liberate halogen atoms when
exposed to ultraviolet radiation in the stratosphere. These atoms react with monatomic oxygen and slow
the rate of ozone
re-formation. Pollutants enhance the destruction of ozone, thereby disturbing the equilibrium of the ozone
production system

How ozone is depleted by CFC’s:

1. UV radiation breaks off a chlorine atom from a CFC molecule.

2. The chlorine atom attacks an ozone molecule (O3), breaking it apart and destroying the ozone.
3. The result is an ordinary oxygen molecule (O2) and a chlorine monoxide molecule (ClO).
4. The chlorine monoxide molecule (ClO) is attacked by a free oxygen atom releasing the chlorine
atom and forming an ordinary oxygen molecule (O2).

279
The chlorine atom is now free to attack and destroy another ozone molecule (O3). One chlorine atom can
repeat this destructive cycle thousands of times.

image from www.esrl.noaa.gov

image from kennuncorked.com

U 6.2 3 Ultraviolet radiation reaching the surface of the Earth damages human living tissues,
increasing the incidence of cataracts, mutation during cell division, skin cancer and other
subsequent effects on health.

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 image from www.eoearth.org
Effects of UV on living organisms

 Increase in mutation rates in DNA causing cancer

 Can cause eye cataracts
 Can damage the ability to carry out photosynthesis in plants and phytoplankton
 Reduces primary production and therefore total productivity
 Damage to immune system

U 6.2.4 The effects of increased ultraviolet radiation on biological productivity include damage to
photosynthetic organisms, especially phytoplankton, which form the basis of aquatic food webs.
UV-B radiation has been shown to be harmful to living organisms, damaging DNA, proteins, lipids and
membranes. Plants, which use sunlight for photosynthesis and are unable to avoid exposure to enhanced
levels of UV-B radiation, are at risk. UV-B impairs photosynthesis in many species. Overexposure to UV-
B reduces size, productivity, and quality in many of the crop plant species that have been studied (among
them, many varieties of rice, soybeans, winter wheat, cotton, and corn). Similarly, overexposure to UV-B
impairs the productivity of phytoplankton in aquatic ecosystems. UV-B increases plant's’ susceptibility to
disease. The effects also include mutation and subsequent effects on health and damage to
photosynthetic organisms, especially phytoplankton and their consumers such as zooplankton.
U 6.2.5 Pollution management may be achieved by reducing the manufacture and release of
ozone-depleting substances. Methods for this reduction include:

 recycling refrigerants
 developing alternatives to gas-blown plastics, halogenated pesticides, propellants and
aerosols
 developing non-propellant alternatives.

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  Replace the old fridge with the existing "greenfreeze" technology which does not deplete the
ozone
 Recycle old CFC coolants from old fridges and air conditioners
 Protection from excess UV e.g. sunglass and sun block
 Alternatives to gas-blown plastics
 Alternative propellants
 Alternatives to methyl bromide (bromomethane).

U 6.2.6 UNEP has had a key role in providing information, and creating and
evaluating international agreements, for the protection of stratospheric ozone.

United Nations Environment Programme (UNEP) in forging international agreements

 ITIHC (International Trade in Harmful Chemicals)

 air pollution
 contamination of international waterways
 provide information to countries and public on disadvantages of pollution
 brought together 24 countries in 1987 to sign the initial Montreal Protocol on Substances that
Deplete the Ozone Layer

U 6.2.7 An illegal market for ozone-depleting substances persists and requires consistent
monitoring.
The black market in ozone-depleting substances (ODS) is a direct consequence of international
agreement on targets to reduce and phase-out the production and consumption of such chemicals. The
illegal trade in CFCs is undermining the ‘Montreal Protocol on Substances that Deplete the Ozone Layer’.

Reasons for the illegal trade:

 ODS substitutes are often costlier than CFCs

 Updating equipment to enable use of alternative chemicals is expensive
 The lifetime of CFC containing equipment is long
 Penalties in may countries are small.

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As a result of the decline in the production and use of CFCs, and the continuation of CFC production in
developing countries, the lure of illegal trade in CFCs is obvious. Significant volumes of illegal imports of
CFCs into Western Europe have been reported, even though production in Western Europe ceased at the
end of 1994. Unfortunately, the Montreal Protocol currently does not require countries to implement
controls against illegal trade, although they have been urged to install verification programs to reduce
illegal trade in ODCs.

image from Bloomberg

U 6.2.8 The Montreal Protocol on Substances that Deplete the Ozone Layer (1987) and subsequent
updates is an international agreement for the reduction of use of ozone-depleting substances
signed under the direction of UNEP. National governments complying with the agreement made
national laws and regulations to decrease the consumption and production of halogenated
organic gases such as chlorofluorocarbons (CFCs).
1997 Montreal Protocol

 international agreement on the emission of ozone-depleting substances

 froze production and consumption of CFC’s with goal of zero production by year 2000
 LEDC’s granted a longer time to implement the treaty
 China and India have not met their quotas under the MP because of their rapid economic growth
and high demand for refrigeration & AC’s
 good example of a successful international cooperative effort to alter human impact on the
environment

Evaluate the use of ozone-depleting substances, and study the relative effectiveness of these
agreements and the difficulties in implementing and enforcing them. Be familiar with what steps national
governments are taking to comply with these agreements.

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Applications and skills:
A 6.2.1 Evaluate the role of national and international organizations in reducing the emissions of
ozone-depleting substances.
UNEP (United Nations Environment Programme), forges international agreements, studies the
effectiveness of these agreements, and the difficulties implementing and enforcing them.

The Montreal Protocol (1987), which is an international agreement on reduction of emission of ozone-
depleting substances.

The signatories agreed to freeze production of many CFCs and halons and strongly reduce consumption
and production of these substances by 2000.

Most countries followed the rules but China and India continued to produce and use huge amounts of
CFCs.

But they have since both agreed to phase out the use of CFCs.

Key Terms
zooplankton gas-blown plastics methyl bromide UNEP Montreal
phytoplankton chlorofluorocarbon halogenated organic ozone Protocol
stratosphere composition gases lapse rate troposphere
layered structure thermosphere ultraviolet (UV) freone mesosphere
polar thinning positive feedback radiation chlorine methyl
non-point source bromide
photodissasociation

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TOPIC 6.3: PHOTOCHEMICAL SMOG

image from www.igbp.net

Air pollution is the introduction of particulates, biological materials, or other harmful materials into
the Earth's atmosphere, possibly causing disease, death to humans, damage to other living organisms
such as food crops, or the natural or built environment.
It is estimated that more than 1 billion people are exposed to outdoor air pollution annually. Urban air
pollution is linked to up to 1 million premature deaths and 1 million pre-native deaths each year. Urban air
pollution is estimated to cost approximately 2% of GDP in developed countries and 5% in developing
countries. Rapid urbanisation has resulted in increasing urban air pollution in major cities, especially in
developing countries. Over 90% of air pollution in cities in these countries is attributed to vehicle
emissions brought about by high number of older vehicles coupled with poor vehicle maintenance,
inadequate infrastructure and low fuel quality.

In this unit we will look at the factors involved in the formation of urban air pollution and strategies to
control air pollution.

This unit is a minimum of 3 hours.

Significant Ideas

 The combustion of fossil fuels produces primary pollutants that may generate secondary
pollutants and lead to photochemical smog, the levels of which can vary by topography,
population density and climate.
 Photochemical smog has significant impacts on societies and living systems.
 Photochemical smog can be reduced by decreasing human reliance on fossil fuels.

Big questions:

 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 Outline the solutions to ground-level ozone. Why is there still ground-level ozone?
 Comment on the links between sustainability and photochemical smog
 Suggest how photochemical smog is likely to change in the decades to come.

Knowledge and Understanding

U 6.3.1 Primary pollutants from the combustion of fossil fuels include carbon monoxide, carbon
dioxide, black carbon or soot, unburned hydrocarbons, oxides of nitrogen, and oxides of sulfur.

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When fossil fuels are burned, two of the pollutants emitted are hydrocarbons (from unburned fuel) and
nitrogen monoxide (nitric oxide, NO). Nitrogen monoxide reacts with oxygen to form nitrogen dioxide
(NO2), a brown gas that contributes to urban haze. Nitrogen dioxide can also absorb sunlight and break
up to release oxygen atoms that combine with oxygen in the air to form ozone.

All these will mean the burning of fossil fuels and release of nitrogen monoxide which then through some
process from ozone

1. NO2 + Sunlight --> NO + O

2. O + O2 --> O3
3. O3 + NO --> O2 + NO2

Ozone is a toxic gas and an oxidizing agent. It damages crops and forests, irritates eyes, can cause
breathing difficulties in humans and may increase susceptibility to infection. It is highly reactive and can
attack fabrics and rubber materials

Sources are:

 Transport
 Cooking
 Dust from construction sites and roads
 Heating
 Power generation

U 6.3.2 In the presence of sunlight, secondary pollutants are formed when primary pollutants
undergo a variety of reactions with other chemicals already present in the atmosphere.
Secondary air pollutants are produced in the air by the interaction of two or more primary pollutants or by
reaction with normal atmospheric constituents, with or without photoactivation. Secondary pollutants are
not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere.

Examples of a secondary pollutant include ozone, which is formed when hydrocarbons (HC) and nitrogen
oxides (NOx) combine in the presence of sunlight; NO2, which is formed as NO combines with oxygen in
the air; and acid rain, which is formed when sulfur dioxide or nitrogen oxides react with water.

Smog is a mix of primary and secondary pollutants. Tropospheric ozone is the main pollutant

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U 6.3.3 Tropospheric ozone is an example of a secondary pollutant, formed when oxygen
molecules react with oxygen atoms that are released from nitrogen dioxide in the presence of
sunlight.

Ozone occurs naturally at ground-level in low concentrations. The two major sources of natural ground-
level ozone are hydrocarbons, which are released by plants and soil, and small amounts of stratospheric
ozone, which occasionally migrate down to the earth's surface. Neither of these sources contributes
enough ozone to be considered a threat to the health of humans or the environment.

Tropospheric ozone can act both as a direct greenhouse gas and as an indirect controller of greenhouse
gas lifetimes. As a direct greenhouse gas, it is thought to have caused around one third of all the direct
greenhouse gas induced warming seen since the industrial revolution.

The ozone that is a byproduct of certain human activities becomes a problem at ground level. With
increasing populations, more automobiles, and more industry, there's more ozone in the lower
atmosphere. Since 1900 the amount of ozone near the earth's surface has more than doubled. Unlike
most other air pollutants, ozone is not directly emitted from any one source. Tropospheric ozone is
formed by the interaction of sunlight, particularly ultraviolet light, with hydrocarbons and nitrogen oxides,

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which are emitted by automobiles, gasoline vapors, fossil fuel power plants, refineries, and certain other
industries.

image from Climate Change and Food Security

U 6.3.4 Tropospheric ozone is highly reactive and damages plants (crops and forests), irritates
eyes, creates respiratory illnesses and damages fabrics and rubber materials. Smog is a complex
mixture of primary and secondary pollutants, of which tropospheric ozone is the main pollutant.

image from capita.wustl.edu

Ozone affects plants in several ways. High concentrations of ozone cause plants to close their stomata.
These are the cells on the underside of the plant that allow carbon dioxide and water to diffuse into the
plant tissue. This slows down photosynthesis and plant growth. Ozone may also enter the plants through
the stomata and directly damage internal cells.

Rubber, textile dyes, fibers, and certain paints may be weakened or damaged by exposure to ozone.
Some elastic materials can become brittle and crack, while paints and fabric dyes may fade more quickly.

When ozone pollution reaches high levels, pollution alerts are issued urging people with respiratory
problems to take extra precautions or to remain indoors. Smog can damage respiratory tissues through

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inhalation. Ozone has been linked to tissue decay, the promotion of scar tissue formation, and cell
damage by oxidation. It can impair an athlete's performance, create more frequent attacks for individuals
with asthma, cause eye irritation, chest pain, coughing, nausea, headaches and chest congestion and
discomfort. It can worsen heart disease, bronchitis, and emphysema.

U 6.3.5 The frequency and severity of smog in an area depends on local topography, climate,
population density, and fossil fuel use.

Photochemical smog is a mixture of about one hundred primary and secondary pollutants formed under
the influence of sunlight. Ozone is the main pollutant. The frequency and severity of photochemical
smogs in an area depend on:

 local topography - low lying areas

 climate - high air pressure areas
 population density - number of vehicles
 fossil fuel use

U 6.3.6 Thermal inversions occur due to a lack of air movement when a layer of dense, cool air is
trapped beneath a layer of less dense, warm air. This causes concentrations of air pollutants to
build up near the ground instead of being dissipated by “normal” air movements.
Temperature inversions occur when cold air is trapped under warm air. Cold air does not move or sinks in
from surrounding hills.

Precipitation cleans the air and winds disperse the smog. Thermal inversions trap the smogs in valleys
(for example, Los Angeles, Santiago, Mexico City, Rio de Janeiro, São Paulo, Beijing) and concentrations
of air pollutants can build to harmful and even lethal levels.

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 image from apesnature.homestead.com
U 6.3.7 Deforestation and burning, may also contribute to smog.

image from Common Dreams

The primary way trees are burned is by slash-and-burn agriculture. The trees are cut down and then
burned to clear the land for farming. Biomass from other biomes, like savannah, is also burned to clear
farmland. The pollutants are much the same as from burning fossil fuels: CO2, carbon monoxide,
methane, particulates, nitrous oxide, hydrocarbons, and organic and elemental carbon.

Burning forests increase greenhouse gases in the atmosphere by releasing the CO2 stored in the
biomass and also by removing the forest so that it cannot store CO2 in the future. As with all forms of air
pollution, the smoke from biomass burning often spreads far and pollutants can plague neighboring states
or countries.

Smog caused by the fires has generated headlines and a diplomatic flare-up between Indonesia and its
neighbors in southeast Asia. It’s a threat to human health and has disrupted flights in the region. At the
same time, burning trees and peatlands are pumping heat-trapping gases into the atmosphere

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U 6.3.8 Economic losses caused by urban air pollution can be significant.

Poor air quality is one of the most serious environmental problems in urban areas around the world,
especially in developing countries. Adverse health effects from short and long term exposure to air
pollution range from premature deaths caused by heart and lung disease to worsening of asthmatic
conditions and can lead to reduced quality of life and increased costs of hospital admissions.

In Mexico City, such economic damages due to air pollution are estimated at $1.5 billion per year. In
Jakarta, 14,000 deaths, about 2 per cent of annual deaths, in the cities could be avoided every year if
particulate could be kept at the level recommended by the WHO. The researchers asserted that the
health effects of air pollution are massive. It causes huge economic losses in terms of loss of current
workforce, treatment cost, employment loss and so on. (New Age, January 1, 2004)

Air pollution also reduces food production and timber harvests, because high levels of pollution impair
photosynthesis. In Germany, for example, about US$4.7 billion a year in agricultural production is lost to

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high levels of sulphur, nitrogen oxides, and ozone.

The World Health Organisation estimates that about 700,000 deaths annually could be prevented in
developing countries if three major atmospheric pollutants - carbon monoxide, suspended particulate
matter, and lead - were brought down to safer levels. The direct health cost of urban air pollution in
developing countries was estimated in 1995 at nearly US$100 billion a year. Chronic bronchitis along
accounted for around US$40 billion).

image from South China Morning Post

U 6.3.9 Pollution management strategies include:

 altering human activity to consume less fossil fuels—example activities

 include the purchase of energy-efficient technologies, the use of public or shared transit,
and walking or cycling
 regulating and reducing pollutants at the point of emission through government regulation
or taxation
 using catalytic converters to clean the exhaust of primary pollutants from car exhaust
 regulating fuel quality by governments adopting clean-up measures such as reforestation,
regreening, and conservation of areas to sequester carbon dioxide

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 image from www.mech.hku.hk
Measures to reduce fossil fuel combustion should be considered, for example, reducing demand for
electricity and private cars and switching to renewable energy. Refer to clean-up measures, for example,
catalytic converters.

Management Strategies

Cause

 Cars, buses and taxis - Reduce demand for private cars through public transport, promote cycle
and bus lanes, restrictions and tolls for car entry to urban areas, promote cleaner fuels and hybrid
or electrical models
 Electricity - Reduce consumption of electricity through building design, small scale green power
on city buildings e.g. solar, wind, locale power stations away from urban areas.
 Enforcement - greater enforcement of emissions standards
 Clean-up - re-forestation, re-greening, conservation areas
 Public information

Release and transfer

 Cars, buses and taxis - Monitor and regulate exhaust emissions

 Electricity and industry - Use cleaner fuels and clean up emission

Effects

 Smog prevention - Design and plan city building to promote natural cooling and circulation,
promote opening up and cleaning up of covered water courses to allow evaporative cooling
 Health - Raise awareness of conditions and effects of breathing polluted air, promote pollution
related health checks ups, activated charcoal masks and provide public access to pollution
monitoring

Things to consider in evaluation:

 Most urban pollution comes from transport , particularly private cars

 80% of the car pollution comes from 30% of the cars
 Diesel engines in trucks and buses produce more particulates

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  Restriction and tools can make car use expensive
 There may be cultural resistance to public transport
 Monitoring and regulating is complicated and expansive
 Groups like WHO set international standards but national standards vary

Application and Skills:

A 6.3.1 Evaluate pollution management strategies for reducing photochemical smog.

image from www.tohoku-epco.co.jp

Key Terms
nitrogen dioxide photochemical topography thermal catalytic
nitrogen smog tropospheric inversion converter
monoxide hydrocarbons ozone pollution smog
VOC nitrogen oxide PAN nitrogen cycle fossil fuels
emissions

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TOPIC 6.4: ACID DEPOSITION

image from acidrainisbad.webs.com

Acid rain is a broad term referring to a mixture of wet and dry deposition (deposited material) from the
atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors, or
chemical forerunners, of acid rain formation result from both natural sources, such as volcanoes and
decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO2) and nitrogen
oxides (NOx) resulting from fossil fuel combustion.

When sulfur dioxide and nitrogen oxide emitted by cars and factories combine with moisture in the air,
acid rain is formed. Acid rain, which often falls far from the source of pollution, kills trees, makes lakes
unfit for fish, and even dissolves the stone in buildings and monuments. Rocky areas with thin topsoil are
particularly apt to be damaged by acid rain.

In this unit we will look at the formation of acid rain, its effects on the ecosystem and strategies to reduce
acid rain formation.

This unit is a minimum of 2.5 hours.

Significant Ideas:

 Acid deposition can impact living systems and the built environment.
 The pollution management of acid deposition often involves cross-border issues.

Big questions:

 To what extent have the solutions emerging form this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 To what extent is acidification yesterdays problem? Why has acidification declined in certain
regions?
 Examine the relationship between acidification and sustainability

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  In what ways is acidification likely to change over the next decades?

Knowledge and Understanding

U 6.4.1 The combustion of fossil fuels produces sulfur dioxide and oxides of nitrogen as primary
pollutants. These gases may be converted into secondary pollutants of dry deposition (such as
ash and dry particles) or wet deposition (such as rain and snow).
[The use of chemical symbols, formula or equations is not required]

image from www.doeaccimphal.org

Refer to the conversion of sulfur dioxide and oxides of nitrogen (NOx) into the sulfates and nitrates of dry
deposition and the sulfuric and nitric acids of wet deposition. Knowledge of chemical equations is not
required.

Acid deposition can be either wet or dry:

 Wet deposition - acidic rain, snow, or other precipitation

 Dry deposition - acidic gas or dry particles, not mixed with water

Primary pollutants - those directly emitted by a factory or automobile, such as...

 SO2 - sulfur dioxide

 NO and NO2, usually identified as NOx

Secondary pollutants - primary pollutants react with other substances in the atmosphere and create
different pollutants, such as...

 H2SO3 - sulfurous acid

 H2SO4 - sulfuric acid
 HNO3 - nitric acid

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 image from www.physicalgeography.net
U 6.4.2 The possible effects of acid deposition on soil, water and living organisms include:

 direct effect—for example, acid on aquatic organisms and coniferous forests

 indirect toxic effect—for example, increased solubility of metal (such as aluminium ions)
on fish
 indirect nutrient effect—for example, leaching of plant nutrients.

Acid rain directly affects the chemical and pH balances in ground water. The excess aluminum created by
acid rain makes aquatic environments such as the sea, lakes, and streams, toxic. The animals that can
withstand the imbalance of the water's natural minerals might survive, but quickly lose their food source
as the weaker creatures die off.

Acid rain leaches calcium out of the soil when it is absorbed by the earth. This directly affects the mineral
levels of the soil and the creatures, such as snails, that rely on that calcium for shell growth.
Consequently, snails die off and birds, which eat them for calcium, lay eggs with shells that are weak and
brittle and therefore fail to hatch.

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Acid rain directly impacts forest ecosystems and their inhabitants. Acid rain damages leaves as it falls.
Acid rain runoff from the trees and forest floors infiltrates the forest's water supplies; runoff that doesn't
enter the water supply is absorbed by the soil.

Acid rain is dangerous to humans. The same sulphate and nitrate particles that directly affect the soil and
water pH balances can cause serious damage to the respiratory system if inhaled deeply. A damaged
respiratory system means decreased oxygen in the blood supply, which eventually damages the heart.

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 image from www.globalchange.umich.edu

image from Ace Geography

U 6.4.3 The impacts of acid deposition may be limited to areas downwind of major industrial
regions but these areas may not be in the same country as the source of emissions.
Refer to areas downwind of major industrial regions that are adversely affected by acid rain and link them
to sources of sulfur dioxide and nitrogen dioxide emissions. Consider the effect of geology (rocks and

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soils) on water acidity
through buffering.

 Acid precipitation falls back to Earth rather than entering stratospheric jet stream
 most areas are downwind of pollution sources
 Canadian forests damaged by coal-fired power plants in USA
 Scandinavian and German forests damaged by British coal plants

image from greenfieldgeography.wikispaces.com

U 6.4.4 Pollution management strategies for acid deposition could include:

 altering human activity—for example, through reducing use, or using alternatives to, fossil
fuels; international agreements and national governments may work to reduce pollutant
production through lobbying
 regulating and monitoring the release of pollutants—for example, through the use of
scrubbers or catalytic converters that may remove sulfur dioxide and oxides of nitrogen
from coal-burning powerplants and cars.

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  Reducing use of fossil fuels
 Reduce the number of cars
 Switch to low sulfur fuel
 Remove sulfur before combustion
 Remove sulfur from waste gases
 Wet scrubbing
 Dry scrubbing

U 6.4.5 Clean-up and restoration measures may include spreading ground limestone in acidified
lakes or recolonization of damaged systems—but the scope of these measures is limited.
Use of limestone or lime, a process called liming, is a practice that people can do to repair the damage
caused by acid rain to lakes, rivers and brooks. Adding lime into acidic surface waters balances the
acidity. It’s a process that has extensively been used, for instance in Sweden, to keep the water pH at
optimum. Even though, liming is an expensive method and has to be done repeatedly. Furthermore, it
only offers a short-term solution at the expense of solving the broader challenges of SO2 and NOx
emissions and risks to human health. Nevertheless, it helps to restore and allow the survival of aquatic
life forms by improving chronically acidified surface waters.

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Application and Skill
A 6.4.1 Evaluate pollution management strategies for acid deposition.
[Reference to Figure 3 Pollution Management]
Measures to reduce fossil fuel combustion should be considered, for example, reducing demand for
electricity and private cars and switching to renewable energy. Refer to clean-up measures at “end of
pipe” locations (points of emission). Consider the role of international agreements in effecting change.
The cost-effectiveness of spreading ground limestone in Swedish lakes in the early 1980s provides a
good case study.

Replace

 switch to renewable energy sources (reduce fossil fuel use)

 increase energy efficiency (better light bulbs and appliances)
 more public transportation (fewer automobiles on the road)
 use low-sulfur fuels

Regulate

 install ‘scrubbers’ on smokestacks of coal-fired power plants to remove SO2

 catalytic converters installed on automobiles (required by law in the US, Canada, and Europe)

Restore

 add lime to acidified lakes and streams

 add lime to forestry plantations (why not natural forests?)
 UN Convention on Long-Range Transboundary Air Pollutants (LRTAP) - 1979; subsequently
amended and modified by US, Canada, and Europe

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Thing to consider when evaluating

 Acid deposition travels with wind and water vapor in the atmosphere
 The additional environmental impacts of cleaning up emissions e.g. mining, baking and
transporting of limestone
 Monitoring and identify sources may be difficult, as they are often non-point
 Intergovernmental agreements often require proof and appropriate compensation

Key Terms
acidification acid precipitates sulfur dioxide organisms acid deposition
wet deposition dry deposition primary secondary nitric acid
direct effects toxic effects pollutant pollutant replace
regulate catalytic nutrient effect restore aluminium ion
nutrient effect converters scrubbers burnt tree toxic effect
lichen hydrogen ion pH geological effect lime
public transport indicator species water cycle fossil fuels
combustion sulfur fuels

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TOPIC 7: ENERGY CHOICES AND SECURITY

image from www.inflexwetrust.com

The current cycle of global warming is changing the rhythms of climate that all living things
have come to rely upon. What will we do to slow this warming? How will we cope with the
changes we've already set into motion? While we struggle to figure it all out, the face of the
Earth as we know it—coasts, forests, farms, and snow-capped mountains—hangs in the balance.

In this unit you will evaluate the role of greenhouse gases, the effects of rising global
temperatures and the arguments associated with global warming. This issue involves the
international community working together to research and reduce the effects of global warming.
This unit is a minimum of 4 hours.

Significant Ideas:

 There is a range of different energy sources available to societies that vary in their
sustainability, availability, cost and socio-political implications.
 The choice of energy sources is controversial and complex. Energy security is an
important factor in making energy choices.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring
systems in which environmental impacts have already occurred
 What value systems can you identify at play in the causes and approaches to resolving the
issues addressed this topic?
 How does your own value system compare with others you have encountered in the
context of issues raised in this topic.
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state
of human societies and the biosphere some decades from now?
 How does the systems approach help our understanding of energy choices and security?
 Why do countries lack energy security?

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  Why do some societies continue to use fossil fuels despite the damage they do to the
environment?
 How do environmental value systems affect the choice of energy supply:
 Compare your environmental value systems with at least two other value systems in
relation to energy consumption
 To what extent are global energy choices sustainable?
 How might energy choices evolve in the next decade?

Knowledge and Understanding

U 7.1.1 Fossil fuels contribute to the majority of humankind’s energy supply, and they vary
widely in the impacts of their production and their emissions; their use is expected to
increase to meet global energy demand.

Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried
dead organisms, containing energy.

Fossil fuels were formed from the dead and decaying remains of prehistoric living
organisms millions of years ago. Intense heat and pressure inside the different layers of earth
transformed these dead remains into modern day's fossil fuel reserves. The fossil fuels are energy
rich carbon compounds and hydrocarbons such as coal, natural gas and petroleum.
The technological advances in the 20th century made possible the extraction of fossil fuels from
the earth commercially viable. All our modern transportation and industry development process
have been made possible because of the discovery and extraction of fossil fuels. More than three
quarters of the world's energy consumption comes from fossil fuels. Of this approximately, 40%
of fossil fuels are used in petroleum form, 15 % in natural gas form and 8 % in coal form. Fossil
fuels are the main backbone of the industrialization but they have contributed to the burden of
environmental pollution significantly. This has resulted in greenhouse gases, acid rain and global
climate change. The massive demand for fossil fuels has resulted in depletion of their deposits at
an alarming rate..

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 image from Forbes
U 7.1.2 Sources of energy with lower carbon dioxide emissions than fossil fuels
include renewable energy (solar, biomass, hydropower, wind, wave, tidal and geothermal)
and their use is expected to increase. Nuclear power is a low carbon low-emission non-
renewable resource but is controversial due to the radioactive waste it produces and the
potential scale of any accident.

Fossil fuels are nonrenewable, that is, they draw on finite resources that will eventually dwindle,
becoming too expensive or too environmentally damaging to retrieve. In contrast, the many types
of renewable energy resources are constantly replenished and will never run out.

Renewable energy plays an important role in reducing greenhouse gas emissions. When

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renewable energy sources are used, the demand for fossil fuels is reduced. Unlike fossil fuels,
non-biomass renewable sources of energy (hydropower, geothermal, wind, and solar) do not
directly emit greenhouse gases.

Renewable energy resources are all sustainable as there is no depletion of natural capital. These
resources can be large-scale for a whole country or small-scale for houses or communities.

Nuclear power is also considered a renewable energy source. It emits no greenhouse gases,
acidic gases, or particulates - linked to, respectively, global warming, environmental
degradation. The energy output of nuclear fission is the highest of any option today. This reduces
both the use of natural resources. However, nuclear power poses numerous threats to people and
the environment and point to studies in the literature that question if it will ever be a sustainable
energy source. These threats include health risks and environmental damage from uranium
mining, processing and transport, the risk of nuclear weapons proliferation or sabotage, and the
unsolved problem of radioactive nuclear waste.

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U 7.1.3 Energy security depends on adequate, reliable and affordable supply of energy that
provides a degree of independence. An inequitable availability and uneven distributions of
energy sources may lead to conflict.

image from North Atlantic Treaty Organization

Energy security as the uninterrupted availability of energy sources at an affordable price. Energy
security has many aspects: long-term energy security mainly deals with timely investments to
supply energy in line with economic developments and environmental needs. On the other hand,
short-term energy security focuses on the ability of the energy system to react promptly to
sudden changes in the supply-demand balance.

Access to cheap energy has become essential to the functioning of modern economies. However,
the uneven distribution of energy supplies among countries has led to significant vulnerabilities.
The Ukraine-Russia gas dispute in January 2009 caused the largest natural gas supply crisis in
Europe’s history. With increasingly integrated electricity grids, blackouts can cascade and affect
multiple economies simultaneously.

U 7.1.4 The energy choices adopted by a society may be influenced by

availability; sustainability; scientific and technological developments; cultural attitudes;
and political, economic and environmental factors. These in turn affect energy security and
independence.
The choice of energy sources that a nation or society uses is very much dependent upon several
factors. These include available energy resources, population size, historical energy use, needs of
industry, available technology and political direction.

MEDCs have higher energy demands than LEDCs, as they depend on energy for transport,
heating, air-conditioning, cooking and all other aspects of their lives

 Availability of the supply - domestic or international.

 Technology developments - does it already exist? Is there potential?

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  Politics - can lead to conflict over supplies or choice to use domestic supplies at increased
prices to reduce risk.
 Economics - cheaper to import or produce
 Cultural Attitudes - love of the SUV
 Sustainability
 Environmental Considerations - is it dangerous?

U 7.1.5 Improvements in energy efficiencies and energy conservation can limit growth
in energy demand and contribute to energy security.

image from US Gas and Electric

Energy efficiency has proved to be a cost-effective strategy for building economies without
necessarily increasing energy consumption. Energy efficiency, is the goal to reduce the amount

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of energy required to provide products and services. Reducing energy use reduces energy costs
and may result in a financial cost saving to consumers if the energy savings offset any additional
costs of implementing an energy efficient technology. Reducing energy use is also seen as a
solution to the problem of reducing greenhouse gas emissions.

 Enhanced environmental standards

 Reduced energy use and emission of carbon dioxide
 Reduction of waste
 Improved efficiency of walls and windows
 Energy-efficient appliances
 Improved building material

Applications and Skills

A 7.1.1 Evaluate the advantages and disadvantages of different energy sources.

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A 7.1.2 Discuss the factors that affect the choice of energy sources adopted by
different societies.
Factor that could affect the choice of energy

Availability

 Resources within or near to a country are better than those further away. The choice of
what energy source should be used is different to countries. Some have large oil, coal and
gas reserves. That makes fossil fuels an obvious choice for an energy source. The
generation of energy also depends on its availability, economy, cultural, environmental
and technological factors. When an energy resource is available and close, it is easier and
efficient to use.

Economic

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  If an energy source is more expensive than others, it would reduce the likelihood of it
been chosen. Globally, renewable energy sources are not used as much. These resources
are still not ready to meet current demands. Renewable sources can be used more if the
production prices of the non-renewable sources are increased. This may better the
environment as higher costs of the fossil fuels means that peoples view will change.
Peoples interest in renewable resources has led to an increased demand for renewable and
non-pollution sources. This leads to a greater investment and research into more
alternatives or improvements.

Cultural

 Culture fears based on the fear of nuclear accidents and waste, have made it quite
unpopular to choose. Cultural and tradition means that non-renewable resources are
favored, and the places with renewable energy resources are limited.

Environmental

 If an energy source is harmful to the environment, some societies might not choose
it. e.g Chernobyl disaster would cause USSR unlikely to choose nuclear energy.

Technological

 Higher technology may require expensive training of the workforce

A 7.1.3 Discuss the factors which affect energy security.

1. Physical – exhaustion of reserves or disruption of supply lines

2. Environmental – Protests about environmental change caused by exploitation of
energy resources
3. Economic – sudden rises in costs of energy forcing increased imports of higher-priced
energy
4. Geopolitical – political instability in energy-producing regions

The energy security of a country can be measured using the ‘Energy Security Index’ (ESI).

This is based upon:

 Availability – the amount of a country’s domestic oil and gas supplies and its level of
reliance on imported resources
 Diversity – the range of energy resources used
 Intensity – the degree to which the economy of a country is dependent on oil and gas

The higher the index, the lower the risk and therefore the greater the energy security
A 7.1.4 Evaluate the energy strategy of a given society.

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Energy use in Sweden is largely based on renewable energy. Thanks to cutting-edge technology
and a wealth of natural assets, Sweden is in the front line as the world embarks on a shift to more
sustainable energy systems. Few countries consume more energy per capita than Sweden, yet
Swedish carbon emissions are low compared with those of other countries. According to the
latest statistics from the International Energy Agency (IEA), the average Swede releases 4.25
tonnes of carbon dioxide (CO₂) per year into the atmosphere, compared with the EU average of
6.91 tonnes and the US average of 16.15 tonnes. Sweden has found a way to reduce emissions
while the economy is growing.

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Key Terms
greenhouse gas solar wind hydro geothermal
tidal renewable non-renewable nuclear bio-fuel
actual supply potential supply rate of consumption economic deplition time
reserve production mineral resource deplition
energy security thermal efficiency government
subsidy

Classroom Materials
Energy Sources Project

Case Studies

France's Energy Change - Natural Gas Europe 3 Feb 2014

How 11 Countries Are Leading The Shift To Renewable Energy
Useful Links

Fossil Fuels vs Renewable Energy from Ecology

Peak Oil Clock - Deans Corner
Fossil Fuel Formation
This interactive animation explains how photovoltaic panels convert sunshine to electricity.
Energyville Game - Chevron
In The News

Harvesting ‘limitless’ hydrogen from self-powered cells - BBC Science and Environment News
20 September 2011
Himalayas could become the Saudi Arabia of solar - New Scientist Technology News 18
October 2011
Nuclear Power in France - World Nuclear Association Feb 2014
Here’s an article about natural gas production and populations of pronghorn antelope and elk in
Wyoming, USA - New Scientist Environment News 4 May 2012
Plastics To Oil - NPR March 19, 2012
Inside the Fukashima Power Plant - BBC News 7 November 2013
Light From Plastic Bottles - wimp.com
Who Pays for Green of Germany - BBC News 27 February 2013
The use of palm oil for biofuel and as biomass for energy - Friends of the Earth
Port Augusta ‘busting a gut’ to reinvent itself as a solar city when coal-fired power is switched
off” - Guardian on Mar.23, 2016,
International Mindedness

 Choice of energy sources can have impacts at both local and global level as emissions of
greenhouse gases can contribute to global climatic change.
 Political and economic situations around the world can affect energy security and choice
of options.

TOK:

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  The choice of energy sources is controversial and complex—how can we distinguish
between a scientific claim and a pseudoscience claim when making choices?

Video Clip
Fossil fuels have powered human growth and ingenuity for centuries. Now that we're reaching
the end of cheap and abundant oil and coal supplies, we're in for an exciting ride. While there's a
real risk that we'll fall off a cliff, there's still time to control our transition to a post-carbon future.
Energy is neither created nor destroyed — and yet the global demand for it continues to increase.
But where does energy come from, and where does it go? Joshua M. Sneideman examines the
many ways in which energy cycles through our planet, from the sun to our food chain to
electricity and beyond.
Today, we consume a truly vast amount of energy - with demand continuing to skyrocket at an
alarming rate. We know that producing this energy has significant environmental impacts and
emitting so much carbon dioxide into the atmosphere could cause catastrophic climate change
How much land mass would renewables need to power a nation like the UK? An entire country's
worth. In this pragmatic talk, David MacKay tours the basic mathematics that show worrying
limitations on our sustainable energy options and explains why we should pursue them anyway
Blind Spot is a documentary film that illustrates the current oil and energy crisis that our world is
facing. Whatever measures of ignorance, greed, wishful thinking, we have put ourselves at a
crossroads, which offer two paths with dire consequences.
Bill Gates talks about the future of energy usage and his investments in alternatives to fossil
fuels.
Anything with the word nuclear next to it usually comes with a fair bit of misunderstanding.
Hopefully this video demystifies the process of how nuclear fuels are turned into electricity and
how we can use them in combination with renewables in order to reduce greenhouse gas
emissions and the effects on the climate that come with high levels of them.
For the Baltic States, the pursuit of energy independence is about more than reliable energy
sources – it’s about political freedom. In today’s security context, many dimensions of energy
security have become increasingly important.
This episode stars Nobel Peace Prize-winner Muhammad Yunus, who founded the Grameen
Shakti organization in Bangladesh distributes small solar systems and portable bio-gas systems
to rural Bangladeshis, empowering women and the poor in the process
The United Kingdom: Case Study

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TOPIC 7.2 CLIMATE CHANGE - CAUSES AND
IMPACTS

image from www.inflexwetrust.com

The current cycle of global warming is changing the rhythms of climate that all living things have come to
rely upon. What will we do to slow this warming? How will we cope with the changes we've already set
into motion? While we struggle to figure it all out, the face of the Earth as we know it—coasts, forests,
farms, and snow-capped mountains—hangs in the balance.

In this unit you will evaluate the role of greenhouse gases, the effects of rising global temperatures and
the arguments associated with global warming. This issue involves the international community working
together to research and reduce the effects of global warming.
This unit is a minimum of 5.5 hours.

Significant ideas:

 Climate change has been a normal feature of the Earth's history,. but human activity has
contributed to recent changes
 There has been significant debate about the causes of climate change
 Climate change causes widespread and significant impacts on a global scale.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic? How does a systems approach help our understanding of climate
change.
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred? Evaluate the success of the Kyoto Protocol
in stabilizing global climate change
 What value systems can you identify at play in the causes and approaches to resolving the issues
addressed in this topic? Explain why there are still uncertainties regarding global climate change
 How does your own value system compare with others you have encountered in the context of
issues raised in this topic? Evaluate measures of mitigation and adaption.
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development? Can sustainable development be achieved without a solution to global climate
change
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now? Outline the obstacles to tackling
global climate change.
 How does a systems approach help our understanding of climate change?

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  To what extent do we already know the solutions to climate change?
 How will we find them/why have they not been implemented?
 Why are some sectors of society in denial of climate change? do you agree with them? Give
reasons to support your answer.
 Examine the links between climate change and sustainability.
 Is climate change inevitable? Whey?

Knowledging and Understanding

U 7.1.1 Climate describes how the atmosphere behaves over relatively long periods of time,
whereas weather describe the condition in the atmosphere over a short period of time.

image from National Weather Service

Weather is the daily result of changes in temperature, pressure, and precipitation in the atmosphere.

 Varies from place to place

 Can only be predicted about 5 days out

Climate is the average weather pattern over a long period of time for a particular location on Earth.

 Can show long term trends.

Difference is TIMESCALE!

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 image from Common Sense Evaluation
U 7.2.2 Weather and climate are affected by oceanic and atmospheric circulatory systems

image from Ohio State University

The world’s ocean is crucial to heating the planet. While land areas and the atmosphere absorb some
sunlight, the majority of the sun’s radiation is absorbed by the ocean. Particularly in the tropical waters
around the equator, the ocean acts a as massive, heat-retaining solar panel. Earth’s atmosphere also
plays a part in this process, helping to retain heat that would otherwise quickly radiate into space after
sunset.

The ocean doesn't just store solar radiation; it also helps to distribute heat around the globe. When water
molecules are heated, they exchange freely with the air in a process called evaporation. Ocean water is
constantly evaporating, increasing the temperature and humidity of the surrounding air to form rain and
storms that are then carried by trade winds, often vast distances. In fact, almost all rain that falls on land
starts off in the ocean. The tropics are particularly rainy because heat absorption, and thus ocean
evaporation, is highest in this area.

Ocean Systems

 specific heat capacity

 surface ocean currents
 Coastal margins

Atmospheric circulatory systems

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  air motion
 pressure variations
 gneral circulation models

image from National Ocean Service - NOAA

U 7.2.3 Human activities are increasing levels of greenhouse gases (GHGs, such as carbon
dioxide, methane and water vapor) in the atmosphere, which leads to

 an increase in the mean global temperature

 increased fequency and intensity of extreme weather events
 the potential for long term changes in climate and weather patters
 rise in sea level.

Water, CO2, methane and chlorofluorocarbons (CFCs) are the main greenhouse gases. Human activities
are increasing levels of CO2, methane and CFCs in the atmosphere, which may lead to global warming.

Human contribution

 Burning of fossil fuel which release carbon dioxide

 Deforestation affects earth’s ability to absorb carbon dioxide
 Agriculture increase the methane level
 Use of fertilizers lead to higher nitrous oxide

The greenhouse effect is a normal and necessary condition for life on Earth. Consider carbon dioxide
(CO2) levels in geological times.

Role of greenhouse gases

 Maintain mean global temperature

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  Normal and necessary condition for life on Earth
 allow short wavelengths of radiation such as visible light and UV too pass through to the Earth's
surface, but they trap the longer wavelengths such as infrared radiation

The systems diagram below was produced by the UN’s IPCC and does an excellent job of showing the
inputs, outputs, and relationships among human activities, climate change processes, climate
characteristics, and threats to human populations and ecosystems. I recommend studying it extensively.

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 Image from http://www.suratclimatechange.org
U 7.2.4 the potential impacts of climate change may vary from one location to another and may be
perceived as either adverse or beneficial. These impacts may include changes in water
availability, distribution of biomes and crop growing areas, loss of biodiversity and ecosystem
services, coastal inundation, ocean acidification and damage to human health,.
Consider the potential effects on the distribution of biomes, global agriculture and human societies.
Appreciate that effects might be adverse or beneficial, for example:

 biomes shifting
 change in location of crop growing areas

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 changed weather patterns which can increase drought and cyclones and the possibility of heavier
precipitation events in most areas.
 coastal inundation (due to thermal expansion of the oceans and melting of the polar ice caps) and
possibility of water shortage
 human health (spread of tropical diseases).
 agriculture may shift towards the poles
 human health can be affected by the spreading of tropical diseases
 extinction of species in wild as many could not adapt to sudden climate change

image from en.wikipedia.org

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U 7.2.5 Both negative and positive feedback mechanisms are associated with climate change and
may involve very long time lags
Feedback mechanisms play a key role in controlling the Earth's atmosphere. Changes to these
mechanisms will have an impact on the climate

Positive feedback

 melting of polar ice lowers albedo

 increased carbon dioxide released from increased biomass decomposition
 tropical deforestation increases warming and drying
 increases forest cover decreases albedo

Negative feedback

 increased evaporation in low latitudes due to high levels of precipitation

 increasein carbon dioxide in atmosphere leads to increased plant growth

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 image from blogs.nottingham.ac.uk
Any feedback mechanisms associated with global warming may involve very long time lags.

U 7.2.6 There has been significant debate due to conflicting EVSs surround the issue of climate
change..

Sometimes conflicting arguments surround the issue of global warming. Note the complexity of the
problem and the uncertainty of global climate models. Be aware of the concept of global dimming due to
increased levels of atmospheric pollution.

Why?

 Greenhouse gases can be produce by natural: volcanic activity; release of methane by animals
and peat bogs; sunspot activity

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  Earth’s tilt and variation in orbit around the sun leads to seasonal and regional changes in
temperatures
 Ocean currents can lead to warming or cooling
 Global dimming: the cooling effects of air pollution

Complexity of the Problem:

 On a huge scale: atmosphere, the oceans and the land

 Not all feedback mechanisms are fully understood
 Many impact and processes are long-term

Uncertainty of climate models

 How much is the planet warming

 Where will the impacts of global warming be felt most acutely

You should explore different viewpoints in relation to your own. Consider the different view of 'ecocentric',
'authropocentric' and 'technocentric'.

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U 7.2.7 Global climate models are complex and there is a degree of uncertainty regarding the
accuracy of their predictions.

image from Phys.org

Climate models are mathematical representations of the interactions between the atmosphere, oceans,
land surface, ice – and the sun. This is clearly a very complex task, so models are built to estimate trends
rather than events. For example, a climate model can tell you it will be cold in winter, but it can’t tell you
what the temperature will be on a specific day – that’s weather forecasting. Climate trends are weather,
averaged out over time - usually 30 years. Trends are important because they eliminate - or "smooth out"
- single events that may be extreme, but quite rare.

 an issue on a large scale

 interactions between atmosphere, oceans and land
 natural as well as antrhopogentic forces
 not all feedback mechanisms understood
 long-term impact not known

Applications and skills:

A 7.2.1 Discuss the feedback mechanisms that would be associated with the change in mean
global temperture

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Oceans absorb CO2 from the atmosphere as they warm up, they release CO2 back into the atmosphere
and absorb less phytoplankton (producers) photosynthesize faster in warm water

 Positive feedback mechanism: more atmospheric CO2 → warmer temperatures → less CO2
absorbed & more released by oceans → more atmospheric CO2
 Negative feedback mechanism: warmer oceans → faster photosynthesis by phytoplankton →
more CO2 absorbed for photosynthesis → lower atmospheric CO2 → lower temperatures,
slowing global warming

Clouds - different cloud types interact with heat differently:

 daytime clouds cool the area under them

 nighttime clouds trap heat and act as an insulating layer
 high thin cirrus clouds trap heat
 low thick cumulus and cumulonimbus clouds have a cooling effect
 Negative feedback: higher temperature→ more evaporation → more clouds → clouds block &
reflect incoming solar radiation → lower temperatures
 Positive feedback: higher temperatures → more evaporation → more clouds → more heat
trapped → high temperatures

Pollution -

 positive feedback: aerosols → more clouds formed → trap heat → warmer temperatures → more
evaporation → more clouds → more heat trapped
 positive feedback: black soot (particulates) falls on ice → dark color absorbs more heat → ice
melts faster → more dark water/ground exposed → warmer temperatures → more melting →
repeats
 negative feedback: aerosols → more clouds → reflect more heat → lowers temperatures

Forests -

 positive feedback: forests absorb

Polar Ice -

 positive feedback: ice melts → exposes more dark water → warmer water melts more ice →
exposes more water → more melting → repeats

• Tundra -
• Atmospheric CO2 -

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A 7.2.2 Evaluate contrasting viewpoints on the issue of climate change

 Viewpoint 1: We can reduce human carbon emissions 90% within the next few decades with
current technology, but a lack of political and industrial leadership is preventing us from doing so.
(The George Monbiot viewpoint.)
 Viewpoint 2: Global warming and climate change are already happening as a result of human
activities, even though we don’t fully understand the degree of warming or the complete
mechanisms by which the changes take place. (The Al Gore and IPCC viewpoint.)

 Ecocentric:
 Anthropocentric:
 Technocentric:

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Key Terms
carbon trading solar radiation time lags permafrost polar ice caps
thermal coastal inundation methane carbon pollution
expansion mean global climate dioxide methane
greenhouse effect temperature radiant energy carbon nitrous oxide
gas model greenhouse gases fossil fuel footprint deforestation
CFC positive feedback renewable water vapor IPCC
carbon tax tropospheric heating CO2 effect combustion migration
global dimming general circulation anaerobic activity correlation renewablemass
negative model coral bleaching ice albedo transit
feedback carbon offset scheme thermal expansion acidification
carbon trading heatwave

Classroom Materials
Climate Feedback Loops
Global Warming Reading
Rising Temps Case Study
Young People Sue Over Climate Change
Review Common Misconceptions
Climate and Malaria

Useful Links
Greenhouse effect - Sumanis
Factors Affecting Global Climate - Nature
Four ways to look at global carbon footprints - an infographic from National Geographic magazine
Common questions about climate change from the United Nations Environment Program (1997)
The Issue of Global warming - This is the above UNEP site converted to a MS Word document for offline

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viewing.
How reliable are CO2 measurements? - Skeptical Science
Review on the Economics of Climate Change - BBC News
Feedback Effects - BBC News
Climate Change Around The World - BBC
UN Framework Convention on Climate Change - UN
Global Warming Effects Simulation - National Geographic
Investigating carbon offsets - Carbon Footprint
Investigating carbon offsets - Environmental Research WEb
Understanding Global Dimming - NOVA
Global Warming - Take Part
Cause and Effect of Global Warming - S-Cool
The Great Global Warming Swindle - wagtv

Topic 6: The issue of global warming, part 1 - NicheScience

Topic 6: The issue of global warming, part 2 - NicheScience
Topic 6: The issue of global warming, part 3 - NicheScience

Click to Run
In The News
Young people are suing governments over climate change - Gold Coast Bulletin, March 2016
Scientists develop CO2 sequestration technique that produces ‘supergreen’ hydrogen fuel - Maybe a
way to fulfill growing energy needs and combat global warming at the same time? from LabManager.com
Massive Antarctic Glacier Uncontrollably Retreating, Study Suggests - LiveScience Jan 2014
Acidic oceans dissolving shells of marine organisms - The Register 26 November 2012
Carbon Trading Causes Increase in Greenhouse Gas Emissions - New York Times 8 August 2012.
Scientists Concerned About Effects of Global Warming on Infectious Diseases - Science Daily, 22 May
2007
Polar Ice Loss Quickens, Raising Seas - BBC Science and Environment News 9 March 2011
Penguin and Krill Populations Decline due to Climate Change - Discovery News 11 April 2011
Global carbon emissions reach record, says IEA - BBC Science and Environment News 30 May 2011.
Species flee warming faster than previously thought - BBC Science and Environment News 20 August
2011
Why the warming climate makes animals smaller - New Scientist 23 September 2011
Marine life shifts as temperatures change - New Scientist 24 September 2011
Global Warming: Runaway temperature increase unlikely - Summit County Voice 25 November 2011
China report spells out “grim” climate change risks - Reuters 17 January 2012
Ocean currents and their role in global climate change - The Register 30 January 2012
Plant study flags dangers of a warming world - NewsDaily Science News 2 May 2012

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This is a great article about agroforestry in the Sahel - Scientific American 28 January 2011
Indigenous people have much of the knowledge needed to adapt to climate change - Trust.org 24 April
2012

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Check out our data visualization blog.
International Mindedness:

 The impacts of the climate change are global and require coordinated international action.

TOK:

 There has been considerable debate about the causes of climate change-does our interpretation
of knowledge from the past allow us to reliably predict the future?

Video Clip
This multi-part film examines the politicization of climate change over the last several decades
This short film/ documentary-esque video asks the contemporary ethical question of: "Given the general
scientific consensus that anthropogenic (human induced) climate change is real, are we ethically obliged
to take action to stop it?"
Controversial Danish economist Bjørn Lomborg explains why it's important to question orthodox opinion --
even the widespread fear of global warming.
The Great Global Warming Swindle, A great documentary by the BBC that exposes the politics behind
this shameful manipulation of the people of the world. Originally broadcasted March 8, 2007 on British
Channel 4.

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TOPIC 7.3: CLIMATE CHANGE – MITIGATION AND
ADAPTATION

Image from www.inflexwetrust.com

Climate change is one of the most complex issues facing us today. It involves many dimensions –
science, economics, society, politics and moral and ethical questions – and is a global problem, felt on
local scales, that will be around for decades and centuries to come. Carbon dioxide, the heat-trapping
greenhouse gas that has driven recent global warming, lingers in the atmosphere for hundreds of years,
and the planet (especially the oceans) takes a while to respond to warming. So even if we stopped
emitting all greenhouse gases today, global warming and climate change will continue to affect future
generations. In this way, humanity is “committed” to some level of climate change.

This unit is 3.5 hours.

Significant ideas:

 Mitigation attempts to reduce the causes of climate change

 Adaptation attempts to manage the impacts of climate change.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic? How does a systems approach help our understanding of climate
change?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?: Evaluate the success of the Kyoto Protocol
in stabilizing global climate change
 What value systems can you identify at play in the causes and approaches to resolving the issues
addressed in this topic? Explain why there are still uncertainties regarding global climate change
 How does your own value system compare with others you have encountered in the context of
issues raised in this topic? Evaluate measures of mitigation and adaptation.
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development? Can sustainable development be achieved without a solution to global climate
change?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now? Outline the obstacles to tackling
global climate change
 How do models and systems approach help our understanding of climate mitigation and
adaptation?
 How far do we already know the answers to climate mitigation and adaptation?

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  In what ways do different people/societies consider climate mitigation and adaptation?
 What do you think is the best way forward? Justify your answer
 Which is more sustainable - mitigation or adaptation?
 How might the solutions to climate change evolve in the future?

Knowledge and Understanding:

U 7.3.1 Mitigation involves reduction and/or stabilization of GHG emissions and their removal from
the atmosphere
Because we are already committed to some level of climate change, responding to climate change
involves a two-pronged approach:

Reducing emissions of and stabilizing the levels of heat-trapping greenhouse gases in the atmosphere
(“mitigation”);
Adapting to the climate change already in the pipeline (“adaptation”).

Mitigation – reducing climate change – involves reducing the flow of heat-trapping greenhouse gases into
the atmosphere, either by reducing sources of these gases (for example, the burning of fossil fuels for
electricity, heat or transport) or enhancing the “sinks” that accumulate and store these gases (such as the
oceans, forests and soil). The goal of mitigation is to avoid significant human interference with the climate
system,

Adaptation – adapting to life in a changing climate – involves adjusting to actual or expected future
climate. The goal is to reduce our vulnerability to the harmful effects of climate change (like sea-level
encroachment, more intense extreme weather events or food insecurity).
U 7.3.2 Mitigation strategies to reduce GHGs in general may include:

image from www.riskmanagementmonitor.com

Management strategies

 Global—intergovernmental and international agreements (for example, Kyoto Agreement and

subsequent updates), carbon tax and carbon trading, alternative energy sources
 Local—allow students to explore their own lifestyle in the context of local greenhouse gas
emissions, preventive and reactive.
 Personal: grow your own food and use energy-efficient products

Mitigation (Preventive measures)

 Carbon taxes - require emitters to pay a free for every ton of greenhouse gases emitted,
 Carbon trading - countries or companies emitting above the target level can buy carbon storage
credits from clean developments or reforesting degraded land in other countries
 Cap and trade - permits to pollute above certain level are sold on the free market, any
organization that is under allocation can make profit by selling the extra permits

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  Lifestyle changes - individual actions to reduce climate change including choices of transport,
energy use and consumer goods and services

Geoengineering

 Solar radiation management - releasing atmospheric sulfates on a scale equivalent to large

volcanic eruption or cloud seeding using sea water
 Carbon dioxide reduction - development of technologies to extract greenhouse gases from the
atmosphere and store them

Reduction of emissions of nitrogen oxides and methane from agriculture

 reduce chemical fertilizer use

 reduce intensive livestock farming

Alternatives to fossil fuels

 photovoltaic cells
 wind power
 DESERTEC project
 hydroelectric
 solar
 geothermal
 tidal

Adaptation

 Building design - improved air conditioning and circulation in building in the temperate zone
 Emerging diseases - monitoring and control of spreading tropical diseases
 Coastal management - improved sea defenses or managed retreat from low lying coastal areas

U 7.3.2 Mitigation strategies for carbon dioxide removal (CDR techniques) include:

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  protecting and enhancing carbon sinks through an management, for example, through the UN
collaborative program on reducing emissions from deforestation and forest degradation in
developing countries (UN-REDD)
 using biomass as a fuel source
 using carbon capture and storage (CCS)
 enhancing carbon dioxide absorption by the oceans through either fertilizing oceans with
compounds of nitrogen, phosphorus and iron to encourage the biological pump, or increasing
upwellings to release nutrients to the surface.

U 7.3.3 Even if mitigation strategies drastically reduce future emissions of GHGs, past emissions
will continue to have an effect for decades to come
The estimate of 40 years for climate lag, the time between the cause (increased greenhouse gas
emissions) and the effect (increased temperatures), has profound negative consequences for humanity.
However, if governments can find the will to act, there are positive consequences as well.

With 40 years between cause and effect, it means that average temperatures of the last decade are a
result of what we were thoughtlessly putting into the air in the 1960’s. It also means that the true impact of
our emissions over the last decade will not be felt until the 2040’s
U 7.3.4 Adaptation strategies can be used to reduce adverse affects and maximize any positive
effects Examples of adaptations include flood defenses, vaccination programs, desalinization
plants and planting of crops in previously unsuitable climates.

 Egypt - Sea-level rise - Adoption of National Climate Change Action Plan integrating climate
change concerns into national policies; adoption of Law 4/94 requiring Environmental Impact
Assessment (EIA) for project approval and regulating setback distances for coastal infrastructure;
installation of hard structures in areas vulnerable to coastal erosion.
 Sudan - Drought - Expanded use of traditional rainwater harvesting and water conserving
techniques; building of shelter-belts and wind-breaks to improve resilience of rangelands;
monitoring of the number of grazing animals and cut trees; set-up of revolving credit funds.
 Botswana - Drought - National government programmes to re-create employment options after
drought; capacity building of local authorities; assistance to small subsistence farmers to increase
crop production.
 Bangladesh - Sea-level rise; salt-water intrusion - Consideration of climate change in the National
Water Management Plan; building of flow regulators in coastal embankments; use of alternative
crops and low-technology water filters.
 Philippines - Drought; floods - Adjustment of silvicultural treatment schedules to suit climate
variations; shift to drought-resistant crops; use of shallow tube wells; rotation method of irrigation
during water shortage; construction of water impounding basins; construction of fire lines and
controlled burning; adoption of soil and water conservation measures for upland farming.

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U 7.3.5 Adaptive capacity varies from place to place and can be dependent on financial and
technological resources. MEDCs can provide economic and technological support to LEDCs
There are many obstacles to a low-carbon world. Technological, economic, and political. Political
obstacles are found nationally and internationally.

Carbon dioxide imposes high costs on society but those who emit the carbon dioxide do not pay for the
social costs that they cause.

The effectiveness of reducing carbon dioxide emissions and the implications for economic growth and
national development, vary depending on the level of development of the country in question. MEDCs
have greater economic resources to help solve the problem
U 7.3.6 There are international efforts and conferences to address mitigation and adaptation
strategies for climate change; for example the Intergovernmental Panel on Climate Change (IPCC),
National Adaptation Programmes of Action (NAPAs) and the United Nations Framework
Convention on Climate Change (UNFCCC)
Rio Earth Summit

 1992 countries developed a framework to address climate change

 stabilize greenhouse gas concentrations to a level that would prevent dangerous anthropogenic
interference with the climate system

Kyoto Protocol

 international and intergovernmental meeting in 1997

 called for the stabilization of greenhouse gas emissions by 5%
 countries allocated certain amounts of carbon dioxide to emit
 resulted in the idea of carbon trading
 use of alternative energy sources
 essential that LEDCs are brought into the agreement

IPCC (Intergovernmental Panel on Climate Change

 assessing the science related to climate change

 set up by WHO and UNEP
 carbon emissions will ultimately have to fall to zeor
 global poverty can only be reduced by halting global warming
 carbon emissions, mainly from fossil fuels, are currently rising to record levels

NAPA (National Adaptation Programme of Action

 focuses on urgent and immediate needs

 synthesis of availabel inromation
 assessment of vulnerabiity to current climate and extreme events
 identification of key adaptation measures as well as criteria for prioritizing activities
 section of a prioritized short list of activities.

UNFCCC (United Nations Framework Convention on Climate Change)

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went into effect 1994 but failed to slow down greenhouse gas emissions
encouraged MEDCs to lead the way in climage change mitigation

Application and skills:

A 7.3.1 Discuss mitigation and adaptation strategies to deal with impacts of climate change
Adaptation: live with the consequences of climate change

 protect cities from storm surges

 protect crops form drought

Mitigation: reducing or stabilizing greenhouse gas emissions

 regulations
 recycling
 energy-efficient products

A 7.3.2 Evaluate the effectiveness of international climate change talks

You should evaluate these strategies with regard to their effectiveness and the implications for MEDCs
and LEDCs of reducing CO2 emissions in terms of economic growth and national development.

 A full ratified Kyoto Protocol would achieve a reduction of warming by around 0.5 degree
 Concerns about fair target setting between MEDCs and LEDCs continue to cause disagreement
 International agreements affect large number of people
 Countries may not sign or agree to international agreements
 Concerns about the economic cost and impacts on development are widespread
 Carbon storage in ecosystems are not well understood and difficult to monitor
 Simulated volcanic eruptions are unpredictable and could damage the ozone layer
 Adaptation methods do not require international co0operation
 Emission mitigation attempts over two decades appear to have failed

Key Terms
carbon trading solar radiation time lags permafrost polar ice caps
thermal Kyoto Protocol methane carbon pollution
expansion coastal inundation climate dioxide methane
greenhouse effect mean global radiant energy carbon nitrous oxide
gas model temperature fossil fuel footprint deforestation
CFC greenhouse gases renewable water vapor IPCC
carbon tax positive feedback CO2 effect combustion migration
global dimming tropospheric heating anaerobic activity correlation renewablemass
negative general circulation coral bleaching ice albedo transit
feedback model thermal expansion acidification
carbon trading carbon offset scheme heatwave

Classroom Materials
Petition(KyotoProtocal) Case study
Personal Viewpoint and Global Warming
Case Study Research Responses GCC

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Poles Apart on Climate Change article

Useful Links
UNEP climate change mitigation
IPCC mitigation and adaptation
Global Change report
NASA
Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability

In The News
Could climate change cause humans and animals to SHRINK? Mammals became smaller due to global
warming 54 million years ago - MailOnline 15 March 2017

International-mindedness:

 The impacts of climate change are global and require global mitigation

TOK:

 There is a degree of uncertainty in the extent and effect of climate change-how can we be
conficent of the ethical responsibilities that may arise from knowledgte when that knowledgte is
often provisional or incomplete

Video Clip
This animated video produced by the Wisconsin Educational Communications Board distinguishes the
roles of mitigation and adaptation in responding to climate change. The video offers examples of actions
that humans can take as individuals and a society to adapt to and mitigate the impacts of climate change
on natural and built environments.
Climate change has already had clear impacts on natural and human systems. Over the coming decades,
based on the various scenarios of emission of greenhouse gases, the range with which climate can
change is quite wide, and depends on policy decisions that we take now

The GEF Small Grants Programme supports projects that address climate change mitigation, which is
reducing or avoiding the emission of greenhouse gases; and climate change adaptation, which is
assisting communities, especially in developing countries to become better able to cope with the negative
impacts of climate change.
The IPCC has produced a video on its Fifth Assessment Report (AR5).
The impacts of climate change destroy people's livelihoods and homes. They damage our infrastructure
and disrupt communication and trade. Moreover, climate change is endangering development successes
and the poor and marginalized are often affected the most. Even if we were to stop emissions instantly,
the world would not stop warming immediately due to the amount of gases we have already emitted.
That's why we must do both: reduce greenhouse gas emissions and adapt to inevitable climate change.
But how can we adapt, considering that the precise extent and form of climate change aren't known?

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TOPIC 8.1: HUMAN POPULATIONS DYNAMICS

Image from www.udupitoday.com

A population describes a group of individuals of the same species occupying a specific area at a specific
time. Some characteristics of populations that are of interest to biologists include the population density ,
the birthrate , and the death rate . If there is immigration into the population, or emigration out of it, then
the immigration rate and emigration rate are also of interest. Together, these population parameters, or
characteristics, describe how the population density changes over time.

Demography is the study of the statistical characteristics of human populations, e.g. total size, age and
sex composition ad changes over time with variations in birth and death rates.

In this unit we will measure population density, look at various population models.

This unit is a minimum of 5 hours.

Significant Ideas:

 A variety of models and indicators are employed to quantify human population dynamics
 Human population growth rates are impacted by a complex range of changing factors.

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 What value systems can you identify at play in the causes and approaches to resolving the issues
addressed in this topic?
 How does your own value system compare with others you have encountered in the context of
issues raised in this topic?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 How do models help our understanding of human dynamics?
 To what extent have population policies been effective in their aims?
 How do environmental value systems affect population dynamics? Give examples to support your
answer.

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  What are your views on these?
 Examine the relationship between population dynamics related to sustainable development.

Knowledge and understanding:

U 8.1.1 Demographic tools for quantifying human population include crude birth rate (CBR) crude
death rate (CDR), total fertility rate (TFR), doubling time (DT) and natural increase rate (NIR)

Image from permaculturenews.org

Birth rates:

 CBR- Crude birth rate is the number of live births per 1000 people in a population.
 Total number of births/total population X 1000 = CBR.
 CBR does not calculate the age and sex structure of the population.

Fertility:

 TFR- Total fertility rate is the average number of births per woman of child-bearing age.

GFR- General fertility rate is the number of births per thousand woman aged between 15-49 years old.

ASBR- Age-specific birth rate is the number of births per 1000 women of any specific year group.

Doubling times:

 This is the time it takes for a population to double in size.

 Doubling time=70/percentage growth rate.

Death rates:

 CDR- Crude death rate is the number of deaths per thousand people in population.
 It is a poor indicator as populations with many old people (MEDCs) have higher CDRs than
countries with more younger populations. (Ex: Denmark 11% and Mexico 5%)
 CDR= number of deaths/total population X 1000.

ASMR- Age-specific mortality rates is the number of deaths per 1000 women of any age group.

 ASMR= number of deaths/1000 women of any specific age group.

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IMR- Infant mortality rates is the number of deaths of children under 1 years old per 1000 live births.

Natural Increase:

 NIR- Natural increase rate is the CDR from the CBR.

 CBR-CDR=NIR. This excludes migration.
 A NIR of 1% will make a double of a population in 70 years. The doubling time is 70 divided by
the NIR.

U 8.1.2 Global human population has followed a rapid growth curve, but there is uncertainty as to
how this may be changing.

Exponential growth or geometric growth is when the population is growing, and there are no limiting
factors slowing the growth. The impacts of exponential growth are huge amount of extra resources
needed to feed, house, clothe and look after the increasing number of people.

The world’s population is increasing very fast, this is due to many factors such as education, health,
poverty, place of residence, and social class. Population growth is more common in Less economically
developed countries ( LEDCs ) as they are less educated, and believe they need more children to help
them make a living and take care of them in the future. Around 95% of population growth is happening in
the LEDCs.

Governments have tried to reduce the population growth rate by proving health care as well as education
and through policies e.g. China: One-child policy

More economically developed countries (MEDCs) believe they cannot raise children with a low income
which means they only have children if it does not affect their standard of living. This shows us one more
time that reducing birth rates in LEDCs can only be done by improving the standard of living in those
countries.

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U 8.1.3 As human population grows, increased stress is placed on all of the Earth's systems.

image from https://www.pik-potsdam.de

Like all living organisms, humans exploit their surroundings for resources. Before the beginning of
agriculture about 10,000 years ago, small groups of humans wandered across large areas, hunting and
gathering just enough food to stay alive. Population numbers were kept low because of the difficulty of
finding food.

Fossil Fuels
The burning of fossil fuels leads to an increase in sulfur dioxide in the atmosphere, which causes acid
rain. Acid rain has devastating consequences on biodiversity as many plants and animal species cannot
survive these conditions. As the rain becomes more acidic, biodiversity decreases.
Sewage

If untreated sewage is released into rivers it provides food for bacteria, which will increase in numbers
and use up the oxygen supply of the water. This results in a decrease in species diversity since only
species that can live in areas with low oxygen concentrations will survive.

Deforestation

This can result in habitat destruction, a reduction in soil fertility and poor soil structure leading to a
decrease in biodiversity.

Desertification

This decreases biodiversity as only species that can survive in a dry habitat will remain in these areas.

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Grazing

At low grazing intensities the biodiversity of grassland is low because a few species of plants such as
grasses are able to out-compete the others and dominate the ecosystem. As the grazing intensity
increases the biodiversity increases as the dominant plant species are kept in check by grazers and the
weaker competitors are therefore also able to grow. At very high grazing intensities the biodiversity
decreases because only plants with adaptations to tolerate the effects of grazing are able to survive.

Pesticides

Pesticides can have adverse effects on the environment if they are not biodegradable and they can
accumulate in the bodies of organisms over time. Due to the animals at each level in a food chain eating
large numbers of the organisms from the level below in the food chain, the concentration of pesticide in
the bodies of organisms increases at higher levels of food chains. This can result in the toxicity of the
pollutant reaching fatal levels in the organisms at the top of the food chain.

image from https://www.researchgate.net

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U 8.1.4 Age-gender pyramids and demographic transition models (DTM) can be used in the
prediction of human population growth. The DTM is a model that shows how a population
transitions from a pre-industrial stage with high CBRs and CDRs to an economically advanced
stage with low or declining CBRs and low CDRs.
The shapes of the pyramids are following:

 Expanding (stage 1) – high birth rates; rapid fall in each upward age group due to high death
rates; short life expectancy.
 Expanding (stage 2) – high birth rates; fall in death rates as more living to middle age; slightly
longer life expectancy.
 Stationary (stage 3) – declining birth rate; low death rate’ more people living to old age.
 Contracting (stage 4) – low birth rate; low death rate; higher dependency ratio; longer life
expectancy.

DTM- Demographic transition model shows us that countries progress through recognized stages in the
transition from LEDC to MEDC. It suggests that death rates fall before birth rates and that the total
population expands

While many of the more economically developed countries (MEDCs) have a declining population size,
that of many of the less economically developed countries (LEDCs) is rising rapidly. The position of
various countries on the demographic transition model reflects their development stages.

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U 8.1.5 Influences on human population dynamics include cultural, historical, religious, social,
political and economic factors.

 Some agriculture cultures see that having more children help with working the land. While other
cultures where women are employed and education have low birth rates.
 Religious believes include family planning. Most religions are pro-natalists.
 Social pressures are put on many women in more traditional societies to have children
 Governments may be pro-natalist or anti-natalists
 Availability of clean water, sanitation, adequate housing, reliable food supply, diseases,
healthcare, occupation, civil conflicts

U 8.1.6 National and international development policies may also have an impact on human
population dynamics.

Many policy factors influence human population growth. Domestic and international development policies
(which target the death rate through agricultural development, improved public health and sanitation, and
better service infrastructure) may stimulate rapid population growth by lowering mortality without
significantly affecting fertility.

Some analysts believe that birth rates will come down by themselves as economic welfare improves and
that the population problem is therefore better solved through policies to stimulate economic growth.

Education about birth control encourages family planning. Parents may be dependent on their children for
support in their later years and this may create an incentive to have many children.

Urbanization may also be a factor in reducing crude birth rates. Policies directed towards the education of
women, enabling women to have greater personal and economic independence, may be the most

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effective method for reducing population pressure.

Development, policies and cultural influences on human population dynamics and growth
Policies: banning abortion or China's one-child policy. Philippines have passed a Reproductive Health Bill.
Japan/Sweden/Russia have pro-natal as ageing increases and populations decline.
Development: UN Millennium development goals e.g. end extreme hunger and poverty
Earth Overshoot day: which remind people when we exhaust our ecological budget
Culturally: religion important factor e.g. Catholicism, wealth as in poorer families children can add to
family income, if children look after parents in old age then fertility rate may be higher, tradition as in Islam
for large families.

Application and Skills

S 8.1.1 Calculate values of CBR, CDR, TFR, DT and NIR
Birth rates:

 CBR- Crude birth rate is the number of live births per 1000 people in a population.
 Total number of births/total population X 1000 = CBR.
 CBR does not calculate the age and sex structure of the population.

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Fertility:

 TFR- Total fertility rate is the average number of births per woman of child-bearing age.

Doubling times:

 DT time it takes for a population to double in size.

 DT=70/percentage growth rate.

Death rates:

 CDR- Crude death rate is the number of deaths per thousand people in population.
 It is a poor indicator as populations with many old people (MEDCs) have higher CDRs than
countries with more younger populations. (Ex: Denmark 11% and Mexico 5%)
 CDR= number of deaths/total population X 1000.

Natural Increase:

 NIR- Natural increase rate is the CDR from the CBR.

 CBR-CDR=NIR. This excludes migration.
 A NIR of 1% will make a double of a population in 70 years. The doubling time is 70 divided by
the NIR.

A 8.1.1 Explain the relative values of CBR, CDR, TFR, DT and NIR
Higher young = lower death rate
Social class - more poor people, higher death rate
Occupation - some hazardous
Place of residence - urban = higher death rate

The NIR was 1.3 % during the first decade of the 21st century, hit its all-time high of 2.2 % in 1963, slowly
fell throughout the latter part of the century, and has declined sharply during the past decade. Although
the NIR is lower now than in the 1960’s, the number of people being added to the population is still larger
because there is a larger base number to multiply the percentage with. Virtually 100% of the natural
increase is located in LDC’s, primarily sub-Saharan Africa. The TFR has dropped dramatically in MDC’s,
normally hovering around 2, and has exceeded 6 in some African countries. Just as the NIR, TFR, CBR,
and CDR, the IMR is also highest in LDC’s, again primarily in Sub-Saharan Africa. Only life expectancy
and doubling time are higher in MDC’s.

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A 8.1.2 Analyse age-gender pyramids and diagrams showing demographic transition models.

image from en.wikipedia.org

Population pyramids are structures which show any measurable characteristic of the population; like sex,
age, language, religion and occupation.

 a wide base indicates a high birth rate

 narrowing base suggests falling birth rate
 straight or near vertical sides reveal a low death rate
 concave slopes characterize high death rates
 bulges in the slope indicate immigration or in-migration
 deficits in the slope indicate emigration or out-migration or age-specific or sex-specific deaths
(epidemics, war)

Low Birth and Death Rates: High Birth and Death Rates:

Birth rates decline because: People want children: ( High Birth rates)

 children are very costly  for labour

 the government looks after people through  to look after them in old age
pensions and health services  to continue the family name
 more women want their own carreer  prestige
 there is a more widespread use of family  to replace children who have died
planning
 as the infant mortality rate decreases there
is no need of child replacement

People die from: (High Death rates)

Death rates decline because:

 lack of clean water

 clean water  lack of food
 reliable food supply  poor hygiene and sanitation

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  good hygiene and sanitation  overcrowding
 lower population densities  contagious disease
 better vacations and healthcare  poverty
 rising standards of living

A 8.1.3 Discuss the use of models in predicting the growth of human populations.

This might include computer simulations, statistical and/or demographic tables for LEDCs and MEDCs,
age/sex pyramids and graphical extrapolation of population curves..

Many factors affect population growth. National or regional change in population count migration whereas
a global population change does not even consider migration.

Factors influencing birth rates include: population age-structure, women status, type of economy, wealth,
religion, social pressure, educational status, availability of contraceptives, desire for children, and the
need for governmental policies such as child benefits. It is very difficult to predict the populations birth
rate changes in all of these factors.

Death rate is influenced by: age-structure of the population, availability of clean water, sanitation,
adequate housing, reliable food supply, prevalence of disease, provision of healthcare facilities, type of
occupation, natural hazards, civil conflict/war, and chance factors. This is also difficult to predict changes
for as there is too many factors.

Changing projections:

It has always been predicted that the world was not going to have enough food supply for everyone since
the late 1700′s. In the 1990′s there were warnings about having a population explosion. It has been
predicted that the population over 60 will increase and that the working population will have to work
harder to keep the elderly alive, unless there is something done about it.

This has been discussed between academics and politicians. They keep coming to these 3 conclusions:

1. Those who think this is all just a scare story which can be changed/fixed with some changes to
the retirement ages and pension policies.
2. Those who preach and doom, (poverty in old age, healthcare rationing, intergenerational warfare
as young/old fight for scarce resources)
3. Those in between 1+2 who try and come up with reasonable ideas to reduce the impact of global
greying.

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Biggest part of the solution lies in:

1. expanding the shrinking population of workers by increasing retirement age and persuading
women to work.
2. increasing productivity of the labour force.
3. persuading people to save more for their retirement.

A 8.1.4 Explain the nature and implications of growth in human populations

The human population is growing exponentially using much of the the Earth’s finite resources, such as
fossil fuels and minerals. As a result, the amount of waste and pollution is also on the rise. Certain living
organisms act as indicator species, and their presence or absence shows the level of pollution in the air
or water. Human populations are in the form of a J-curve currently peaking at 9 billion. Due to the
increased population large amounts of resources needed to fuel population growth.

A 8.1.5 Analyse the impact that national and international development policies can have on
human population dynamics and growth
Population policies are determined by government actions. Pro-natalist policies are in favor of increasing
the birth rate and anti-natalists policies attempt to limit the birth rate.

Many areas of Europe have a low fertility rate because of the following reasons: education. In 1939, the
French passed the “Code de la famille”, a complex piece of pro natalist legislation. The pro natalist
methods in the policy included:

 Offering cash incentives to mothers who stayed at home to care for children.
 Subsidizing holidays.
 Banning the sale of contraceptives (repealed in 1967).

China instilled an anti natalist policy to help combat population explosion. Imbalances between population
and available resources were steadily increasing. China has 7% of the world’s agricultural land and 23%
of the world’s population.
The idea was to encourage economic development and improve the standard of living for the population.

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  1953 - First modern census takes place in China. The population comes in as 583 million.
 Between 1953 and 1964 the population increased by 112 million as Mao Zedong encouraged
larger families in an attempt to make China stronger.
 Attempts to slow down population growth were started in the 1970s using the slogan “Later,
longer, fewer”. People were encouraged to limit families to two children.
 1979 - One child policy introduced.

A 8.1.6 Discuss the cultural, historical, religious, social, political and economic factors that
influence human population dynamics.

 Some agriculture cultures see that having more children help with working the land. While other
cultures where women are employed and education have low birth rates.
 Religious believes include family planning. Most religions are pro-natalists.
 Social pressures are put on many women in more traditional societies to have children
 Governments may be pro-natalist or anti-natalists
 Availability of clean water, sanitation, adequate housing, reliable food supply, diseases,
healthcare, occupation, civil conflicts

Key Terms
exponential growth population limiting factors crude birth rate crude death rate
immigration clock doubling time LEDC MEDC
TFR emigration fertility mortality carrying
GDP IMR reproductive post reproductive capacity
demographic pre modernize urbanize population
transition reproductive immigration emigration pyramid
natural increase rate pre industrial population
Ester Boserup geometric curve
growth Thomas
age-sex Malthus
pyramid
While many of the more economically developed countries (MEDCs) have a declining population size,
that of many of the less economically developed countries (LEDCs) is rising rapidly. The position of
various countries on the demographic transition model reflects their development stages.

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TOPIC 8.2: RESOURCE USE IN SOCIETY

Image from tjameschawke.wordpress.com

Ecologically minded economists describe resources as “natural capital”. If properly managed, renewable
and replenishable resources are forms of wealth that can produce “natural income” indefinitely in the form
of valuable goods and services.
This income may consist of marketable commodities such as timber and grain (goods) or may be in the
form of ecological services such as the flood and erosion protection provided by forests (services).
Similarly, non-renewable resources can be considered in parallel to those
forms of economic capital that cannot.

In this unit we will look at the three classes of natural capital, understand how cultural, economic,
technological and other factors influence the status of a resource.

This unit is a minimum of 4 hours.

Significant Ideas

 The renewability of natural capital has implications for its sustainable use
 The status and economic value of natural capital is dynamic

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extent have the solutions emerging from this topic been directed at preventing
environmental impacts. limiting the extend of the environmental impacts, or restoring systems in
which environmental impacts have already occurred/
 What value systems can you identify at play in the causes and approaches to resolving the issues
addressed in this topic?
 How does your own value system compare with others you have encountered in the context of
issues raised in this topic?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 How do models and/or a systems approach help our understanding of resource use in society?

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  Why do people use non-renewable resources rather than renewable resources?
 How do environmental value systems influence the use of renewable and non-renewable
resources?
 What are your views on this?
 Outline the relationship between renewable and non-renewable resources and sustainability.
 How do you think society is likely to change in the coming years? Give reasons for your answer.

Knowledge and Understanding:

U 8.2.1 Renewable natural capital can be generated and/or replaced as fast as it is being used. It
includes living species and ecosystems that use solar energy and photosynthesis, as well as non-
living items, such as groundwater and the ozone layer.

Ecosystems may provide life-supporting services such as water replenishment, flood and erosion
protection, and goods such as timber, fisheries, and agricultural crops.

Ecologically minded economists describe resources as “natural capital”. If properly managed, renewable
and replenishable resources are forms of wealth that can produce “natural income” indefinitely in the form
of valuable goods and services.

 marketable commodities such as timber and grain (goods)

 ecological services such as the flood and erosion protection provided by forests (services).
 non-renewable resources cannot generate wealth without liquidation of the estate.

Removing natural vegetation has a “cost”: Loss of carbon uptake, disruption of water and nutrient cycles
and even just the loss of the aesthetic value all have a cost. The difficult part of natural capital is
prescribing a “value” in economic terms to the goods and services the biosphere provides.

U 8.2.2 Non-renewable natural capital is either irreplaceable or can only be replaced over
geological timescales; for example, fossil fuels, soil and minerals.

Non-renewable natural capital exist in finite amounts on Earth. Once consumed/used, they are not
replaced. Non-renewable resources may have solar radiation as an energy source, but usually only

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indirectly. Minerals and fossil fuels are classic examples of non-renewable resources. These are
considered nonrenewable resources in that their use is not sustainable because their formation takes
billions of years.

U 8.2.3 Renewable natural capital can be utilized sustainably or unsustainably. If renewable

natural capital is used beyond its natural income this use becomes unsustainable.

image from en.wikipedia.org

Sustainability is living, within the means of nature, on the ”interest” or sustainable income generated by
nature capital. So using the global resources at the rate that allows natural regeneration and minimizes
damage to the environment.

Some economists may view sustainable development as a stable annual return on investment regardless
of the environmental impact, whereas some environmentalists may view it as a stable return without
environmental degradation. Consider the development of changing attitudes to sustainability and
economic growth, since the Rio Earth Summit (1992) leading to Agenda 21.

Sustainability can be encouraged by:

 ecological land-use to maintain habitat quality and connectivity for all species.
 sustainable material cycles, (ex carbon, nitrogen, and water cycles).
 social systems that contribute to a culture of sufficiency that eases the consumption pressures
on natural capital.

International summits on sustainable development have highlighted the issues involved in economic
development across the globe, yet the viewpoints of environmentalists and economists may be very
different.

U 8.2.4 The impacts of exaction, transport and processing of a renewable natural capital may
cause damage, making this natural capital unsustainable.

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image from architectstrace.wordpress.com
Any society that supports itself in part by depleting essential forms of natural capital is unsustainable. If
human well-being is dependent on the goods and services provided by certain forms of natural capital,
then long-term harvest (or pollution) rates should not exceed rates of capital renewal. Sustainability
means living, within the means of nature, on the “interest” or sustainable income generated by natural
capital.

This can be encouraged by:

Ecological land-use to maintain habitat quality and connectivity for all species.
Sustainable material cycles, (ex carbon, nitrogen, and water cycles).
Social systems that contribute to a culture of sufficiency that eases the consumption pressures on natural
capital.

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U 8.2.5 Natural capital provides goods (such as tangible products) and services (such as climate
regulation) that have value. This value may be aesthetic, cultural, economic, environmental,
ethical, instrinsic, social, spiritual or technological.

image from travel.wikinut.com

Organisms or ecosystems have value:

 Intrinsic values: values that are not determined by their potential use to human, their value is
given vary by culture, religion, etc. E.g. a statue

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  Economic value-: value that are determined from the market price of the good and services a
resources produce.
 Ecological Value: value that have no formed market price but are essential to human e.g.
photosynthesis
 Asethic Value: no market price, similar to ecological value,(basically things that look good). E.g.
landscape

Organisms or ecosystems that are valued on aesthetic or intrinsic grounds may not provide commodities
identifiable as either goods or services, and so remain unpriced or undervalued from an economic
viewpoint. Organisms or ecosystems regarded as having intrinsic value, for instance from an ethical,
spiritual or philosophical perspective, are valued regardless of their potential use to humans. Therefore,
diverse perspectives may underlie the evaluation of natural capital. Attempts are being made to
acknowledge diverse valuations of nature (for example, biodiversity, rate of depletion of natural
resources) so that they may be weighed more rigorously against more common economic values (for
example, gross national product (GNP)). However, some argue that these valuations are impossible to
quantify and price realistically. Not surprisingly, much of the sustainability debate centers on the problem
of how to weigh conflicting values in our treatment of natural capital.

How can we quantify values such as aesthetic value, which are inherently qualitative?

U 8.2.6 The concept of a natural capital is dynamic. Whether or not something has the status of
natural capital, and the marketable value of the capital varies regionally and over time and its
influenced by cultural, social, economic, environmental, technological and political factors.
Examples include cork, uranium and lithium.

image from www.energy4me.org

The value of resources changes over time and with various other factors. During the Stone Age, fossil
fuels were worthless because the internal-combustion engine had not yet been invented, but arrowheads
were very valuable because they allowed people to hunt and therefore eat. In modern times, we need
fossil fuels to maintain many of the processes in society (communication, transportation, electricity
production), so that fossil fuels have a high economic value now, but because we've developed many
different ways to get enough food to eat, the arrowheads are no longer economically valuable.

Resources can also be valued in several different ways, some of which overlap:
economic value - have a marketable good or service which people are willing to pay for

 scientific & technological value - useful for valious applications in society (i.e. plant compounds
used to produce medicines); this could be considered a subset of economic value
 ecological value - makes it possible to live; without these services, human and other life on Earth
would die out
 intrinsic value - valued for religious, cultural, or social reasons

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Resources may have different dollar values assigned to them depending on the value that is being
measured. Some values are pretty straightforward to measure (i.e. the market value of a mineral traded
on global exchanges) while others are more difficult to calculate (How much is a 'beautiful view' worth?).

Application and Skills

A 8.2.1 Outline an example of how renewable and non-renewable natural capital has been
mismanaged
Resource depletion is an economic term referring to the exhaustion of raw materials within a region. Use
of resources beyond their rate of replacement is considered to be resource depletion.

Renewable Natural Capital

 African forests are significantly shrinking. Trees and vegetation cover are being cut down for
various uses. Most of the people use firewood as the energy source. Also, most of people’s
livelihood depends on forests as well as land, leading to the increased deforestation. Generally it
is one the environmental challenges in Malawi and developing countries at large. For example in
Malawi about 10,000 ha.forests were being deforested annually between 1981 to 1985. This
number continues through today.

Non-renewable Natural Capital

At present, the most important energy sources used by the Indian population are non-renewable sources
of energy. Indian economy is largely based on fossil fuels, minerals and oil. The value increases because
of the large demand, but the supply is decreasing. This has resulted in more efforts to drill and search
other territories. The environment is being abused and this depletion of resources is one way of showing
the effects. The consumption of petroleum has multiplied itself almost thirty times in the post-
independence era

A 8.2.2 Explain the dynamic nature of the concept of natural capital.

Cultural, economic, technological and other factors influence the status of a resource over time and
space. For example, uranium, due to the recently become a valuable resource. What this all means is
that resources are dynamic, its status may change, it might become valuable.

 different society value resources differently

 increase in demand may increase the value of a resource
 Supply of resources may influence the value of a resource

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Key Terms
natural capital natural income rate of harvest renewable non-renewable
fossil fuel replenishable economic value ecological value aesthetic value
sustainability goods dynamic intrinsic value recreational
optional value existence values regeneration harvesting processing
packaging marketing

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TOPIC 8.3: SOLID DOMESTIC WASTE

image from www.scrd.ca

Domestic solid waste, commonly known as trash or garbage (US), refuse or rubbish(UK) is a waste
type consisting of everyday items that are discarded by the public. The organic waste potions consist of
food and kitchen waste, yard trimmings or other garden waste. Inorganic waste consists of paper,
corrugated cardboard, plastic, glass, wood, and metal products such as drink cans.

In this unit we will look at your contribution to domestic waste as well as the waste contributed by our
community. We will also look at different management strategies in dealing with domestic waste.

This unit is a minimum of 3 hours.

Significant Ideas

 Solid domestic waste (SDW) is increasing as a result of growing human populations and
consumption
 Both the production and management of SDW can have significant influence on sustainability

Big questions:

 What strengths and weaknesses of the systems approach and the use of models have been
revealed through this topic?
 To what extend have the solutions emerging from this topic been directed at preventing
environmental impacts, limiting the extent of the environmental impacts, or restoring systems in
which environmental impacts have already occurred?
 What value systems can you identify at play in the causes an approaches to resolving the issues
addressed in this topic?
 How does your own value system compare with others you have encountered in the context of
issues raised in this topic?
 How are the issues addressed in this topic of relevance to sustainability or sustainable
development?
 In what ways might the solutions explored in this topic alter your predictions for the state of
human societies and the biosphere some decades from now?
 How do models and/or a systems approach help our understanding of solid domestic waste/
 Evaluate the alternatives for the disposal of solid domestic waste.
 How do environmental value systems influence the disposal of solid domestic waste?
 What are your views on this?
 Examine the relationship between solid domestic waste and sustainability
 How is solid domestic waste likely to change over the next few decades? Give reasons for your
answer.

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Knowledge and Understanding:
U 8.3.1 There are different types of SDW, the volume and composition of which changes over time
[SDW includes household wast such as paper, glass, metal, plastics, organic (kitchen or garden)
packaging, construction debris, and clothing]

Solid waste can be classified into different types depending on their source:

 Household waste is generally classified as municipal waste,

 Industrial waste as hazardous waste, and
 Biomedical waste or hospital waste as infectious waste.

This material can be made up of:

 paper
 glass
 metal
 plastics
 organic waste (kitchen or garden)
 packaging

Garbage: the four broad categories:

 Organic waste: kitchen waste, vegetables, flowers, leaves, fruits.

 Toxic waste: old medicines, paints, chemicals, bulbs, spray cans, fertilizer and pesticide
containers, batteries, shoe polish.
 Recyclable: paper, glass, metals, plastics.
 Soiled: hospital waste such as cloth soiled with blood and other body fluids.

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 image from Shanghai American School
U 8.3.2 The abundance and prevalence of non-biodegradable pollution (such as plastic, batteries
or e-waste) in particular has become a major environmental issue.

image from https://www.pinterest.com/aquaventuremlt/save-our-oceans

As we become more technologically advanced, we produce materials that can withstand extreme
temperatures, are durable and easy to use. Plastic bags, synthetics, plastic bottles, tin cans, and

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computer hardware- these are some of the things that make life easy for us.

Non-biodegradable waste is a type of waste that can not be broken down into its base compounds by
micro-organisms, air, moisture or soil in a reasonable amount of time. Non-biodegradable waste is an
environmental concern, as it threatens to overwhelm landfills and create disposal problems.

image from Scientific & Academic Publishing

U 8.3.3 Waste disposal options include landfills, incineration, recycling and composting

There are eight major groups of waste management methods, each of them divided into numerous
categories. Those groups include source reduction and reuse, animal feeding, recycling, composting,
fermentation, landfills, incineration and land application. You can start using many techniques right at
home, like reduction and reuse, which works to reduce the amount of disposable material used

 Landfills - Throwing daily waste/garbage in the landfills is the most popularly used method of
waste disposal used today. This process of waste disposal focuses attention on burying the
waste in the land.
 Incineration/Combustion - a type disposal method in which municipal solid wastes are burned at
high temperatures so as as to convert them into residue and gaseous products. The biggest
advantage of this type of method is that it can reduce the volume of solid waste to 20 to 30
percent of the original volume, decreases the space they take up and reduce the stress on
landfills.
 Recovery and Recycling - process of taking useful discarded items for a specific next use. These
discarded items are then processed to extract or recover materials and resources or convert them
to energy in the form of useable heat, electricity or fuel.
 Composting - a easy and natural bio-degradation process that takes organic wastes i.e. remains
of plants and garden and kitchen waste and turns into nutrient rich food for your plants.

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U 8.3.4 There are a variety of strategies that can be used to manage SDW (reference to figure 3)
influenced by cultural, economic, technological and political barriers. There strategies include

 altering human activity - for example, through a reduction of consumption and composting of food
waste
 controlling the release of pollutant - governments create legislation to encourage recycling and
reuse initiative and impose taxes for SDW collection and on disposable items
 reclaiming landfills, using SDW for waste to energy programs implementing initiatives to remove
plastics from the Great Pacific garage patch (clean-up and restoration)

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Pollution management strategies that should be considered are recycling, incineration, composting and
landfill.

Cause
Reduce - Reduce packaging
Reuse - Choose second hand materials or reusable containers
Recycle - Choose materials that can be recycled
Composting - Organic can be composted at source. Choose biodegradable materials

Effect
Incineration - Easy and Quick. Releases greenhouse gases such as methane which could be used for
powering but can produce toxic pollutants
Landfill - Might pollute groundwater through leeching. We are facing less available space
Sealed landfill - Prevent leeching but higher costs. There is limited space
Composting - Can turn organic wastes into resources

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Application and skills:
A 8.3.1 Evaluate SDW disposal options
Strategies for dealing with SDW:
Recycling:

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  materials are collected, separated, and processed first. Success depends on how much energy
and raw materials are required to produce the material in the first place.
 plastics
 glass can be melted and re-shaped into new bottles or jars indefinitely; this requires less energy
than making new bottles and jars
 paper
 metals (aluminum is most common and cost-effective material for recycling; steel is also
frequently recycled)
 creates green jobs
 requires public buy in
 not always cost effective
 high initial capital
 products may not be as durable.

Incineration

 SDW burned at very high temperatures

 can be used to produce electricity (‘waste-to-energy’ plants)
 may produce dioxins and heavy metal deposits from materials burned
 takes up much less space than landfills
 ash often used to build roads
 composting
 nutrients returned to soils in agriculture, parks, or home gardens
 already used on large-scale basis in many MEDC farming systems
 tricky problem with composting human waste from sewage systems
 air pollution
 ash still needs to be disposed of
 requires high amount of initial capital

Landfill

 primary way SDW is disposed of

 may have every category of SDW, including hazardous materials
 initially cheap, but costs increasing rapidly as sites fill up
 good sites difficult to find
 must be lined to prevent leachate infiltrating ground or surface water sources
 methane from decomposition may be captured for energy production
 risk of health problems
 releases greenhouse gases
 expensive to develop new sites

Composting

 reduces amount of waste in landfills

 can be done in house
 creates fertile soils
 if done incorrectly, can attract pests
 requires public buy in

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A 8.3.2 Compare and contrast pollution management strategies for SDW
A 8.3.3 Evaluate, with reference to figure 3, pollution management strategies for SDW by
considering recycling, incineration, composting and landfills.
[Students should consider the amount and source of non-biodigradable pollution generated within a
chosen locality and how it is managed]
Human activity

 reduce consumption
 compost food waste
 reduce packing
 reuse clothes/goods

Controlling release

 separate wastes into different types

 legislate recycling
 education about recycling
 tax SDW

Clean-up and Restoration

 reclaim landfills
 use incineration for energy production
 collect plastics/discarded from the environment

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Key Terms
solid domestic incineration landfill composting recycling
waste composting vericomposting wasteful leachate
upcycling hazardous mercury methane community
humus waste chemicals organic waste
diseases sanitary
landfill

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TOPIC 8.4 HUMAN POPULATION CARRYING
CAPACITY

Image from elcorreodiario.wordpress.com

By examining carefully the requirements of a given species and the resources available, it might be
possible to estimate the carrying
capacity of that environment for the species. This is problematic in the case of human populations for a
number of reasons. The range of resources used by humans is usually much greater than for any other
species. Furthermore, when one resource becomes limiting, humans show great ingenuity in substituting
one resource for another. Resource requirements vary according to lifestyles, which differ from time to
time and from population to population. Technological developments give rise to continual changes in the
resources required and available for
consumption.

In this unit we will look at how human populations regularly import resources from outside their immediate
environment, which enables them to grow beyond the boundaries set by their local resources and
increases their carrying capacity. While importing resources in this way increases the carrying capacity for
the local population, it has no influence on global carrying capacity. All these variables make it practically
impossible to make reliable estimates of carrying capacities for human populations.
This unit is a minimum of 4 hours.

Significant Ideas:

 Human carrying capacity is difficult to quantify

 The EF is a model that makes it possible to determine whether human populations are living
withing carrying capacity.

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Big Questions:

 How useful are the systems approach and the use of models in the study of carrying capacity and
ecological footprints?
 To what extent are solutions directed at preventing environmental impacts, limiting the extent of
the environmental impacts, or restoring systems likely to be most successful in the management
of pollution?
 Outline contrasting value systems in the development of population policies
 How does your own value system compare with others you have encountered with regard to
resource use?
 Can human use of resources every lead to sustainable development?
 How far is it possible for human society to live in balance with the biosphere>?
 How do models and/or a systems approach help our understanding of carrying capacity?
 Why are some carrying capacities larger than others?
 What can be done to reduce carrying capacities?
 How do environmental value systems influenced carrying capacities?
 What are your views on how best to reduce carrying capacities?
 Examine the relationship between carrying capacity and sustainability
 How might carrying capacities change in the decades to come. Justify your answer.

Knowledge and Understanding

U 8.4.1 Carrying capacity is the maximum number of species, or "load", that can be
sustainability supported by a given area.

image from http://lifeboat.com/images/carrying.capacity.of.earth.jp

For a given region, carrying capacity is the maximum number of individuals of a given species that an
area's resources can sustain indefinitely without significantly depleting or degrading those resources.
Determining the carrying capacities for most organisms is fairly straightforward. For humans carrying
capacity is much more complicated. The definition is expanded to include not degrading our cultural and
social environments and not harming the physical environment in ways that would adversely affect future
generations.

Thomas Malthus believed that thee was finite optimum population size in relation to food supply and that
an increase in population above this point would lead to a decline the the standard of living, war, famine

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and disease.

Esther Boserup believed that people have the resources to increase food production. The greatest
resource is knowledge and technology.

U 8.4.2 It is possible to estimate the carrying capacity of an environment for a given species;
however, this is problematic in the case of human populations for a number of reasons
[Because carrying capacity for human populations is difficult to calculate, it is also difficult to estimate the
extent to which they are approaching or exceeding carrying capacity, although
environmental indications (Topic 1.4) may help in this respect]
By examining carefully the requirements of a given species and the resources available, it might be
possible to estimate the carrying capacity of that environment for the species. This is problematic in the
case of human populations for a number of reasons.

 The range of resources used by humans is usually much greater than for any other species
 When one resource becomes limiting, humans show great ingenuity in substituting one resource
for another.
 Resource requirements vary according to lifestyles, which differ from time to time and from
population to population.

Technological developments give rise to continual changes in the resources required and available for
consumption.

Human populations also regularly import resources from outside their immediate environment, which
enables them to grow beyond the boundaries set by their local resources and increases their carrying
capacity. While importing resources in this way increases the carrying capacity for the local population, it
has no influence on global carrying capacity. All these variables make it practically impossible to make
reliable estimates of carrying capacities for human populations.

3 Models of a Population Growing and Approaching Carrying Capacity

image from yesitsyomoma.wordpress.com

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 image from studyblue.com
U 8.4.3 EF is the area of land and water required to support a defined human population at a given
standard of living. The measure of an EF takes into account the area required to provide all the
resources needed by the population, and the assimilation of all wastes.

image from Venngage

Human beings have an enormous impact on the natural environment, and ultimately on each other. The
way we chose to house, clothe, shelter, and meet the needs for vital resources such as food, energy, and
water, not only affect the long-term availability of those resources but well-functioning Earth systems such
as climate systems, hydrological cycles, nutrient cycles in the atmosphere, hydrosphere, and lithosphere,
and the maintenance of a diverse biosphere. But equally significant is the fact that some of our personal
and collective choices have an enormous impact on the way human beings interact in cooperative and
competitive modes, including the increasingly global search for renewable and non-renewal resources
and global efforts to extract benefits from distant locations and in the process limit the extent of
environmental degradation.

The Ecological Footprint accounts for the flows of energy and matter to and from any defined economy
and converts these into the corresponding land/water area required for nature to support these flows.

The ecological footprint of a population is the area of land, in the same vicinity as the population, that
would be required to provide all the population’s resources and assimilate all its wastes. As a model, it is
able to provide a quantitative estimate of human carrying capacity. It is, in fact, the inverse of carrying
capacity. It refers to the area required to sustainably support a given population rather than the population
that a given area can sustainably support.

Ecological footprints are the hypothetical area of land required by a society, group or individual to fulfill all
their resources needs and assimilation of wastes.

As a model, it is able to provide a quantitative estimate of human carrying capacity. It is, in fact, the

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inverse of carrying capacity. It refers to the area required to sustainability support given population rather
than the population that a given area can sustainably support.

Ecological footprints can be increased by:

 greater reliance on fossil fuels

 increased use of technology and energy (but technology can also reduce the footprint)
 high levels of imported resources (which have high transport costs)
 large per capita production of carbon waste (high energy use, fossil fuel use)
 large per capita consumption of food
 a meat-rich diet

Ecological footprints can be reduced by:

 reducing use of resources

 recycling resources
 reusing resources
 improving efficiency of resource use
 reducing amount of pollution produced
 transporting waste to other countries to deal with
 improving country to increase carrying capacity
 importing resources from other countries
 reducing population to reduce resource use
 using technology to increase carrying capacity
 using technology to intensify land

Standard of living is the result of the interaction between physical and human resources and can be
expressed as:

Standard of living: (natural resources X technology) / population

U 8.3.4 EF is a model used to estimate the demands that human populations place on the
environment.
The Environmental Footprint measures the types of products or services provided by the global hectares,
for example, in terms of goods from crop lands, animal products, fish, forest products, built up areas, and
energy and water use. Such analyses identify which areas are placing the greatest strains on
ecosystems, and can help set policy priorities. Growth in animal products and energy use, especially of
fossil fuels, are two areas that are rapidly increasing these strains.

The Ecological Footprint is not a precise measure of ecological sustainability. While it is perhaps the best
estimate to date, it is important to recognize its limitations. In general, the Footprint underestimates the
impact of human activities on the biosphere. Any applications of the Footprint methodology must keep
this perspective in mind. Because it focuses on renewable resources, the Footprint provides limited
information about most non-renewable resources and their impact on ecosystems (with the exception of
fossil fuel impacts which it partially addresses)

Factors used to calculate ecological footprint

 Bio-productive land: land used for food and materials

 Bio-productive sea: sea area used for human consumption
 Energy land: land required to support renewable energy instead of non-renewable energy

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  Built land: land that is used for development of roads and buildings
 Biodiversity land: land required to support non-human species
 Non-productive land: land: us and deserts, salt marshes, etc.

Factors ignored when calculating the ecological footprint which influence the amount of land a population
needs to support itself:

 the land or water required to provide and aquatic and atmospheric resources
 land or water needed to assimilate wastes other than carbon dioxide
 land used to produce materials imported into the country to subsidize arable land and increase
yields
 replacement of productive land lost through urbanization

If everyone on Earth had the same lifestyle as the ones in the MEDCs, many Earths would be needed to
support the global population.

The EF is a model that provides a way round the dilemma of human carrying capacity. Instead of focusing
on a given environment and trying to calculate the carrying capacity it provides, it focuses on a given
population (with its current rate of resource consumption) and estimates the area of environment
necessary to sustainability support that particular population. The size of this area is compared wit the
area available to the population, then gives an indication of whether the population is living sustainable
and within the carrying capacity provided.

image from Tunza Eco-generation

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 click on the image to calculate your EF
U 8.4.5 EFs may vary significantly by country and be individual and include aspects such as
lifestyle choices (EVS), productivity of food production systems, land use and industry. If the EF
of a human population is greater than the land area available to it, this indicates that the
population is unsustainable and exceeds the carrying capacity of that area
The average US ecological footprint is 50% larger than the average person in most European countries in
part because the US has more suburban sprawl, less public transportation, and uses more energy and
water per person than most other developed countries. However, the 50% larger footprint does not
necessarily mean a 50% better quality of life. For example:

 A person who walks or takes public transportation has a smaller footprint than someone who
commutes alone fifty miles to and from work in a car (especially if that car only gets 15 miles to
the gallon)
 A vegetarian has a smaller footprint than someone who eats a lot of meat
 A house or office park with a small amount of lawn has a smaller ecological footprint than a house
or office park with acres of lawn treated weekly with chemicals and water.

When we look at the footprint of the average person in a MEDC, it is clear that we would exceed the
carrying capacity of the earth if in the future, other populations adopted this average lifestyle. Even with
the current world population count it is clear that patterns of consumption in MEDCs are not sustainable,
and projected future populations make it dramatically less so.

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 image from http://pthbb.org/natural/footprint/
U 8.4.6 Degradation of the environment, together with the consumption of finite resources, is
expected to limit human population growth
Clearly, human numbers can not continue to increase indefinitely. Natural resources are already severely
limited, and there is emerging evidence that natural forces already starting to control human population
numbers through malnutrition and other severe diseases. More than 3 billion people worldwide are
already malnourished, and 3 billion are living in poverty; grain production per capita started declining in
1984 and continues to decline; irrigation per capita declined starting in 1978 and continues; arable land
per capita declined starting in 1948 and continues; fish production per capita started declining in 1980
and continues; fertilizer supplies essential for food production started declining in 1989 and continues to
do so; loss of food to pests has not decreased below 50% since 1990; and pollution of water, air, and
land has increased, resulting in a rapid increase in the number of humans suffering from serious,
pollution-related diseases

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 image from Center for Immigration Studies
U 8.4.7 If human populations do not live sustainable, they will exceed carrying capacity and risk
collapse.
One of the consequences of this explosive growth in human numbers is that human demands have
outrun the carrying capacity of the economy’s natural support systems — its forests, fisheries, grasslands,
aquifers, and soils. Once demand exceeds the sustainable yield of these natural systems, additional
demand can only be satisfied by consuming the resource base itself. We call this overcutting, overfishing,
overgrazing, overpumping, and overplowing. It is these overages that are undermining our global
civilization.

A 8.4.1 Evaluate the application of carrying capacity to local and global human populations
Applying the concept of carrying capacity to local human populations can be very difficult.

 Wide range of resource used

 Lifestyle effect resource requirement
 Technological development changes resources required and available for consumption
 Resources can be imported or recycled

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By examining carefully the requirements of a given species and the resources available, it might be
possible to estimate the carrying capacity of that environment for the species. This is problematic in the
case of human populations for a number of reasons. The range of resources used by humans is usually
much greater than for any other species. Furthermore, when one resource becomes limiting, humans
show great ingenuity in substituting one resource for another. Resource requirements vary according to
lifestyles, which differ from time to time and from population to population. Technological developments
give rise to continual changes in the resources required and available for consumption.
Human populations also regularly import resources from outside their immediate environment, which
enables them to grow beyond the boundaries set by their local resources and increases their carrying
capacity. While importing resources in this way increases the carrying capacity for the local population, it
has no influence on global carrying capacity. All these variables make it practically impossible to make
reliable estimates of carrying capacities for human populations.
A 8.4.2 Compare and contrast the differences in the EF of two countries
Data for food consumption are often given in grain equivalents, so that a population with a meat-rich diet
would tend to consume a higher grain equivalent than a population that feeds directly on grain. Be aware
that in MEDCs, about twice as much energy in the diet is provided by animal products than in LEDCs.
Grain production will be higher with intensive farming strategies.

Populations more dependent on fossil fuels will have higher CO2 emissions. Fixation of CO2 is clearly
dependent on climatic region and vegetation type. These and other factors will often explain the
differences in the ecological footprints of populations in LEDCs and MEDCs.

LEDCs have small ecological footprints as MEDCs have much greater rates of resource consumption.
This is partly because MEDCs have higher incomes and the demands for energy resources is high.
MEDCs consume a lot of resources as they are wasteful, they also have more waste and pollution.
LEDCs are the opposite with lower consumption as people do not have too much to spend. The economy
of the country forces them to recycle many resources, however they are developing and they’re
ecological footprint is increasing.

Canada (5.4 ha/person) – low productivity from trees as located in high latitudes, large distances to cover
by car, wealthy population, heating needed in cold winters and electricity in winter for dark evenings.

Peru (0.9ha/person) – fast growing trees (high NPP), largely vegetarian diet, low car ownership, warm all
year round, poor population.

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A 8.4.3 Evaluate how environmental value systems impact the ecological footprint of individuals
or populations
Individuals in MEDCs generally have a technocentric worldview, which encourages continued high
consumption of resources, in the expectation that technology will provide solutions to minimize the
environmental impact

Individuals in LEDCs have not only had a historically low consumption of non-renewable resources, but
have also adapted environmental value systems that have encouraged working in balance with nature.

Key Terms
resources environmental biotic potential carrying capacity recycle
reuse resistance lifestyle consumption economic
affluence per capita standard of over population footprint
rate of global life-support living LEDC global capacity
energy optimum population MEDC under
population

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