Ecology

Ernst Haeckel in 1869

German biologist
Greek word “oikos” meaning “home”
“logy” meaning “the study of”

Ecology as “the study of one’s house or home”

Study of the interaction among organisms and between organism(biotic)and
their physical environment (abiotic) such as temperature, soil, water and
other forms of matter and energy.

Ecological Organization

The individual organisms make up a population which belong to the same

species living together in the same area ex. Human population. In turn,
community is an interaction among species of plants and animals.

Community and its environment make up an “ecosystem”.

Arthur Tansley in 1935 “ecosystem an integration between biological(biotic)
communities and its physical (abiotic) environment as a fundamental unit of
ecology”

While communities are organized into biosphere: atmosphere(air),

hydrosphere(water), geosphere(soil, rocks) and Biosphere(living things) are
the four major earth’s life support system.
Ecosystem Functions

Regulatory function: it regulates the essential ecological processes, it

supports life systems and renders stability, it is responsible for the cycling of
nutrients between biotic and abiotic components by providing us clean air
and water.

Habitat function: ecosystems provide habitat to wild plants and animals and
thus conserve biological and genetic diversity. It supports different food
chains and food chains.

Production function: production of wide range of goods ranging from food to

raw materials (i.e. minerals, medicine).

Informational function: ecosystems provide an essential 'reference function'

and contribute to the maintenance of human health by providing
opportunities for spiritual enrichment, cognitive development, recreation and
aesthetic experience.

Components of an Ecosystem

Biotic Components

Ecologist assign each organism in an ecosystem to a feeding level or trophic

level based on the source of nutrients. Organisms are classified as autotrophs
(producer) where they can make their food or heterotrophs ( consumer) that
depend on other organisms as their source of food. A self sustaining
ecosystem, received a constant source of energy this living system known as
producers (green plants ) are capable of incorporating energy to form organic
molecules (carbohydrates) this process is called photosynthesis.

Other organism is an ecosystems are consumers and decomposers.

Consumers include herbivores (eats plants), carnivores (eats meat), and
omnivores (both) and can be categorize as primary consumer, secondary
consumer and tertiary consumer. Decomposers are consumers that get their
nutrients by breaking down waste or remains of plant and animals.

Scanvengers (eat dead animals)

Abiotic Components

In an ecosystem, every factors can be directly or indirectly be affected. Abiotic

components such as water, light, soil, temperature, ph can be a limiting factor
for certain organisms. These factors can determine the type of organism that
exist in the environment. A change in temperature can affect the growth of
certain plant and animals. Increase in temperature can eliminate organism
that can’t adapt.

Pathway of Energy Flow

Ecosystem are based on photosynthesis and mainly green plants,

photosynthesis as the basis of all growth in an ecosystem it is described as
primary productivity- is the production of new organic matter, or biomass, by
autotrophs in an ecosystem during some period of time , while consumers
are termed as secondary productivity, refers to the production of biomass by
heterotrophic consumer organisms feeding on plants, animals, microbes,
fungi, or detritus in some period of time (Molles, 2013).

Food Chain and Food Web

Energy flows through ecosystem is linear, or “one way” thru the pathway of
Food chain and Food web. During the process of energy flow plants being the
producers absorbed sunlight with the help of chloroplast and convert raw
materials (CO2 and H2O) into chemical energy (C6H12O6 and O2) in the
process of photosynthesis. A food chain is a series of organism with each
serving as a source of nutrients or energy for the next level while food web is
a complex network of interconnected food chains. As energy is transferred
from one organism to another it involves a lost of energy in the form of heat,
as required by the second law of thermodynamics.

Feeding status in an ecosystem can be express as trophic level ,organism can

be identified in each feeding level based on the food they eat. Herbivores
feeds on plant, carnivores flesh eater and omnivores eat both plant and
animals. Scavengers clean up dead carcasses ex. Jackals. Detritivores consume
litter debris ex. Ants and decomposer complete the final breakdown ex.
Bacteria and fungi.
Food Chain

Ecological Pyramid
The concept of energy flow in ecosystem is one of the cornerstones of
Ecology.

Developed by R.L. Linderman and it is based of the following assumptions

that the Laws of Thermodynamics hold for plant and animals. The first Law of
Thermodynamics state that “energy is neither created nor destroyed but is
transformed from one state to another and that the sum total can be
accounted for”. The second Law of Thermodynamics states that “during each
energy transfer from one state to another, some of it is transformed into an
unusable form, heat”. Therefore, plants and animal can be arrange into
feeding groups with at least three trophic levelsplant herbivores and
carnivores and the system is said to be in equilibrium.

To be able to determine the energy flow in each feeding level ecological

pyramid were constructed, pyramid of energy, pyramid of numbers, pyramid
of biomass. Each succeeding trophic level has less energy flow that the
preceding level indicating that only a fraction of the energy is passed along in
the food chain which follows the 10% rule.

Nutrient Cycling in Ecosystem

Nutrient cycling is one of the essential aspect of ecosystem function. In a self
sustaining ecosystem, elements or materials must be cycled among living
organism and abiotic environment, this complex cycle is referred to as
Biogeochemical cycle. Elements are required for development, maintenance
and reproduction of all organism in an ecosystem.
Hydrologic cycle is a path of water through our ecosystem. Most of the water
are stored in the ocean. The heat coming from the sun is the driving force for
this cycle. The energy from the sun evaporates water. Water condense and
precipitate in the form of rain, snow or fog. Plants also emit water in the form
of transpiration.

Nitrogen Cycle
Nitrogen molecule make up 78% of the atmosphere. It is essential component
of proteins, enzyme, DNA and organic compounds.

1. Nitrogen Fixation: Gaseous nitrogen is converted to ammonia by nitrogen

fixing bacteria
N2 (Gaseous nitrogen)-> NH3 (ammonia)

2. Nitrification: a process of converting ammonia to nitrates accomplished by

Nitrosomonas and Nitrococcus bacteria NH3 (ammonia)-> NO2(Nitrites)→
NO3(nitrates)

3. Assimilation
Plants roots absorb ammonia and Nitrites->Plant

4. Ammonification- involve the conversion of biological nitrogen to ammonia

by ammonifying bacteria
Biological Nitrogen-> decomposition-> NH3 (ammonia)

5. Denitrification
NO3 ( nitrates)→ nitrogen Gas-> atmosphere
Human activity enriches ecosystem with nutrients especially with nitrogen.
Nitrogen enrichment came from a variety of sources: combustion of fossil
fuel, agricultural fertilizers, land clearing, forest burning, industry and animal
waste.

Carbon Cycle
Carbon molecule account 0.03% the atmosphere is gaseous form as carbon
dioxide( CO2), it is a structural component of organic molecules. The carbon
cycle begins with the intake of carbon dioxide by photosynthetic organism
plus oxygen and hydrogen in water. Carbon dioxide is also released during
respiration.

In the ocean carbon is in the form of carbonate and bicarbonate use to build
shells and skeleton of marine organisms. We accelerate the movement of
carbon when we use fossil fuel. Since the industrial revolution concentration
of CO2 increases significantly.

Phosphorus Cycle
Phosphorus is essential to the energetics, genetics and structure of living
organisms. It forms part of the ATP, RNA, DNA and phospholipid molecules.
Large quantities of phosphorus are found in marine deposit, marine
sediments and sedimentary rocks. However, sedimentary rocks are mined for
fertilizer for agricultural purposes. Phosphorus are released through
weathering of rocks. As phosphorus is released, it is absorbed by plants and
some are washed in oceans.

Types of Ecosystem

The earth’s surface is a series of connected ecosystems which is connected to

a larger area called biomes. Biomes is a general type of communities with
similar climate condition, growth patterns and vegetation types. Temperature
and precipitation are the most important determinants in biome distribution
on land. There are two types of biomes: Terrestrial and Aquatic Biomes.

Terrestrial Ecosystem

1. Forest
a. Tropical Rain Forest occur in areas where the temperature are high
throughout the yearand precipitation occurs almost daily. It is the most
diverse biome in the world. Many staplefood are found in the tropics such as
corn, banana and sugarcane, even prescription drugs like erythromycin is
derived from tropical fungi.

b. Boreal Forest or Taiga these forest are confined from Scandinavia, through
European Russia, across Siberia, to central Alaska and across central Canada.
They are dominated by evergreen conifers belonging to Picea (spruce and
abies(fir) Animals consists of caribou, wolves, black bears and moose.

c. Temperate Deciduous Forest is a forest found between tropical and boreal

forest. Sequoias of Western North America and Eucalyptus trees of southern
Australia and found in this biome. In Asia temperate forest are found in
Japan, China, Korea and eastern Siberia.
2. Grassland

a. Tropical Grassland or savanna mainly composed of wide stretches of grass

and trees like Acacia which are fire-adapted and have extensive underground
systems. It contains large numbers of hoofed animals such as giraffes, zebras
and lions.

b. Temperate Grassland is also known as steppes or prairies, they are highly

suited for agriculture, they are also known as the breadbaskets of the world
providing crops like corn and wheat.

3. Tundra is also considered as “arctic desert”, it is known for its permafrost.

They have large number of organism that were able to adapt to survive the
cold. It composed of mosses, lichens, grasses and dwarf trees, while animal
community are made up of arctic fox, snowy owls and hawks. There are no
reptiles, amphibians and insect like mosquitoes.

4. Desert biomes are very dry area found in temperate and tropical areas.
Composed mainly of cacti, yuccas and Joshua trees. Animals tend to be small.

Aquatic Ecosystem

A. Marine ecosystem is make up majority of the ocean the Atlantic, Pacific,

Indian, Arctic and Antarctic which comprise approximately 70% of the earth’s
surface. The largest and deepest ocean basin is the Pacific. Oceans can be into
vertical and horizontal zones. Each zones support distinctive assemblage of
marine life.

B. Freshwater Ecosystem includes rivers, lakes and streams.

Freshwater wetlands, marshes and estuaries

Freshwater wetlands, marshes and estuaries occur at the transitions between
freshwater and marine and terrestrial environment.
Rivers and Streams
They characterized to have unidirectional currents, plants and animals have
adaptive mechanisms for attaching themselves in rocks to prevent them from
being swept away by the current.
Lakes
They are much like small seas. Most are found in regions, work over by
tectonics, volcanism and glacial activity, the geological forces that produce
lake basins.

Interactions Among Organism in an Ecosystem

Each individual in an ecosystem has a role in the structure and functions of an
ecosystem, this is referred to as ecological niche. The term niche was first
used by the English animal ecologist Charles Elton (1927) and the University
of California naturalist Joseph Grinnell (1917 and 1928). According to Grinnell,
the word niche “stands for the concept of the ultimate distributional unit,
within which each species is held by its structural and instinctive limitations…
no two species in the same general territory can occupy for long the same
ecological niche”. One of biological factor that can influence individuals role
and function in an ecosystem is symbiosis.

Symbiosis refers to any form of intimate relationship or association between

members of two or more different species. They are classified into the
following categories:

• Mutualism
Is a symbiotic relationship in which both partners benefit
Ex. Plant roots and mycorrhizae, the plant provide the fungus with food from
its photosynthetic activity while the mycorrhizae enable the plant to better
tolerate environmental stress.

• Parasitism
Is a form of symbiotic relationship where a partner benefits while the other is
adversely affected. It is a host and parasite interaction
Ex. Human as a host and tapeworm as the parasites, the parasite obtained
nutrients from the host while the host weaken and sometime leading to
death

• Commensalism
Is a type of relationship in which one organism benefit without causing harm
to the other partner Ex. Orchid and a tree, where epiphytes does not obtain
nutrients from the tree
• Amensalism
Is an association between organisms of two different species in which one is
inhibited or destroyed and the other is unaffected.

• Predation
Is a biological interaction where one organism, the predator, kills and eats
another organism, its prey.

• Competition
Involves the interaction between two or more organisms that uses a common
resource, which is in short supply. Competition can take form to intraspecific
competition and interspecific competition. Intraspecific competition,
competition with members of their own species. Interspecific competition,
competition between individuals of two species that reduces the fitness of
both. Competition may occur between native and invasive species.

Threats to Ecosystem
Human influences have a major role in altering the balance of our ecosystem.
Some of these threats are: Habitat destruction, human settlement, pollution,
introduction of exotic species, overharvesting, overgrazing, oil exploration
and extraction, hunting or poaching of wildlife animals.

Terrestrial ecosystem are not spared from human influences. Large cities like
Tokyo, Beijing, New York, Seattle and Berlin are built on lands that once
supported by temperate forest. Tundra has been the focus for oil exploration
and extraction. Agriculture practice lead to clearing of forest, plants and
animals are harvested.

In aquatic systems include overexploitation and waste dumping are potential

threats. Construction of reservoir had a major negative impact on river
ecosystem since it affects flow regulation. Freshwater environment are
particularly vulnerable to the introduction of exotic species ex. Janitor Fish in
Marikina River.