Ecosystem

Ecology

Ecology

• All living organism, whether

plant or animal or human being is • The term ecology was coined by
surrounded by the environment, Earnst Haeckel in 1869.
on which it derive its needs for its
survival.

• Each living component interacts • Derived from Greek word ‘Oikos

with non –living components for = home’ + ‘logos = study’
their basic requirements form Study of home
different
ecosystem.
 Ecology

Definition

• Ecology is the study of interactions among organism or group of

organisms with their environment.
• The environment consists of both biotic components (living
organisms) and abiotic components (non – living).
or
• Ecology is the study of ecosystems.
 Ecosystem

Ecosystem is the basic functional unit of ecology. The term ecosystem is

coined form a Greek word meaning study of home.

Definition
A group of organisms interacting among themselves and with environment
is known as ecosystem. Thus an ecosystem is a community of different
species interacting with one another and with their non living environment
and one another and with their non- living environment exchanging energy
and matter.

Example
Animals cannot synthesis their food directly but depend on the plants either
directly or indirectly.
 TYPES OF ECOSYSTEM- Natural ecosystem

Natural ecosystems operate themselves under 2. Aquatic ecosystem

natural conditions. Based on habitat types, it This ecosystem is related to water. It is
can be further classified into three types. further sub classified into
two types based on salt content.
•Fresh water ecosystem
(i)Running water ecosystems.
Examples
Rivers, Streams
1. Terrestrial ecosystem (b) Standing water ecosystems
This ecosystem is related to land. Examples
Example Pond, lake
Grassland ecosystem, forest ecosystem, (ii) Marine ecosystem
desert ecosystem, etc., Example :
Seas and sea shore
TYPES OF ECOSYSTEM- Manmade Ecosystem

Man – made (or) Artificial ecosystems

Artificial ecosystem is operated (or) maintained by

man himself.

Example
Croplands, gardens
 Structure (or) Component of an Ecosystem

• The term structure refers to the various components.

So the structure of an ecosystem explains the relationship
between the abiotic (non –living) and the biotic (living)
components.

• An ecosystem has two major components:

•Biotic (living) components
•Abiotic (non living) components
 Biotic components

The living organisms (or) living members in an ecosystem

collectively form its community called biotic components
(or) biotic community.

Examples

•Plants (producers),
•Animals (consumers),
•Microorganisms (decomposers).
 Biotic components Classification

Members of components of an ecosystem (or) Classification

biotic components

The members of biotic components of an ecosystem are

grouped in to three based on how they get food.

•Producer (plants)
•Consumer (Animals)
•Decomposers (Micro-organisms)
 Producer

1.Procedures (Autotrophs)
Procedures synthesize their food themselves through
photosynthesis

Example :
All green plants, trees.

Photosynthesis
The green pigments called chlorophyll, present in the
leaves of plants, converts CO2 and H2O in the presence
ofsunlight into carbohydrates.
6CO2 + 12H2O ----> C6H12O6 + 6O2+6H2O
This process is called photosynthesis
 Consumers

Examples
Plant eating species
Insects, rabbit, goat, deer, cow, etc.,

Classification of consumers
Consumers are further classified as

(i) Primary consumers (Herbivores) (Plant eaters)

Primary consumers are also called herbivores, they directly
depend on the plants for their food. So they are called plant
eaters.
Examples :
Insects, rat, goat, deer, cow, horse, etc.,
 Consumers

(ii) Secondary consumers (primary carnivores) (meat eater)

Secondary consumers are primary carnivores, they feed
on primary consumers. They directly depend on the
herbivores for their food.
Example
Frog, cat, snakes, foxes, etc.,

(iii) Tertiary consumers (Secondary carnivores) (Meat-eaters)

Tertiary consumers are secondary carnivores, they feed
on secondary consumers. They depend on the primary
carnivores for their food.
Examples
Tigers, lions, etc.,
 Decomposers

3. Decomposers

Examples
Microorganisms like bacteria and fungi. Decomposers attack the dead
bodies of producers and consumers and decompose them into simpler
compounds. During the decomposition inorganic nutrients are released.

The inorganic nutrients together with other organic substances are then
utilized by the procedures for the synthesis of their own food.
 Abiotic Components
Abiotic (non-living) components
The non-living components (physical and chemical) of ecosystem collectively form a
community called abiotic components (or) abiotic community.
Examples
Climate, soil, water, air, energy, nutrients, etc.,
1. Physical components
They include the energy, climate, raw materials and living space that the biological
community needs. They are useful for the growth and maintenance of its member.
Examples
Air, water, soil, sunlight, etc.,
 Abiotic Components

2. Chemical Components

They are the sources of essential nutrients

Examples

•Organic substances : Protein, lipids, carbohydrates, etc.,

•Inorganic substances: All micro (Al, Co, Zi, Cu) and macro
elements (C,H, O, P, N, K) and few other elements.
 Function of an Ecosystem

To understand clearly the nature of ecosystem its functioning should be

thoroughly understood.

The function of an ecosystem is to allow flow of

energy and cycling of nutrients.
Types of Functions
Functions of an ecosystem are of three types.

1. Primary function
The primary function of all ecosystem is manufacture of starch
(photosynthesis).

2. Secondary function
The secondary function of all ecosystem is distribution energy in the
form of food to all consumers.
Tertiary Function

All living systems diet at a particular stage. These dead

systems are decomposed to initiate third function of
ecosystems namely “cycling”.

The functioning of an ecosystems may be understood studying

the following terms.

•Energy and material flow.

•Food chains
•Food webs
•Food pyramids
 Energy flow in the Ecosystem

Energy is the most essential requirement for all living organism. Solar
energy is the only source to our planet earth. Solar energy is transformed
to chemical energy in photosynthesis by the plants (called as primary
producers). Though a lot of sunlight falls on the green plants, only 1% of
it is utilized for photosynthesis. This is the most essential step to provide
energy for all other living organisms in the ecosystem.

Some amount of chemical energy is used by the plants for their growth
and the remaining is transferred to consumers by the process of eating.

Thus the energy enters the ecosystems through photosynthesis and passes
through the different tropic levels feeding levels.
Nutrient Cycles
The cyclic flow of nutrients between the biotic and abiotic components is
known as nutrient cycle (or) biogeochemical cycles.

The nutrients enter into procedures and move through the food chain
and ultimately reach the consumer. The bound nutrients of the
consumers, after death, are decomposed and converted into inorganic
substances, which are readily used up by the plants (procedures) and
again the cycle starts.

The major nutrients like C, H, O and N are cycled again and

again between biotic and biotic component of the ecosystem.
 Energy flow in the Ecosystem

Energy is the most essential requirement for all living organism. Solar
energy is the only source to our planet earth. Solar energy is transformed
to chemical energy in photosynthesis by the plants (called as primary
producers). Though a lot of sunlight falls on the green plants, only 1% of
it is utilized for photosynthesis. This is the most essential step to provide
energy for all other living organisms in the ecosystem.

Some amount of chemical energy is used by the plants for their growth
and the remaining is transferred to consumers by the process of eating.

Thus the energy enters the ecosystems through photosynthesis and passes
through the different tropic levels feeding levels.
 Energy flow in the Ecosystem

Hydrological Cycle
Movement of water
in a cyclic manner is
known as
hydrological cycle.
Carbon Cycle
Carbon cycle
Carbon is the basic component in all the organic components. The carbon is present
in all biotic components in different forms as food.

Examples:
Carbohydrates, proteins, fats and amino acids. Carbon is present in the atomosphere
as CO2. The CO2 taken up by the green palnts as a raw material for photosynthesis of
different food. This food moves through food chain, finally the carbon present in the
dead matter is returned to the atmosphere as CO2 by microorganisms.

Sources of CO2 in atmosphere

•During respiration, plants and animals liberates CO2 in the atmosphere.
•Combustion of fuels also release CO2.
•Volcanic eruptions also release
Nitrogen Cycle
Nitrogen cycle
Nitrogen is present in the atmosphere as N2 in large amounts (78%). The nitrogen is present
in all biotic components in different forms as food.

Examples
Proteins, vitamins, amino acids, etc.,

• The N2 from the atmosphere is taken up by the green plants as a raw material for
biosynthesis of different foods (amino acids, proteins, vitamins) and used in metabolism.
• These food move through the food chain.
• After death of the plants and animals, the organic nitrogen in dead tissues in decomposed
by several micro organisms ammonifying and nitrifying bacteria) into ammonia, nitrites
and nitrates, which are again used by the plants.
• Some bacteria convert nitrates into molecular nitrogen (N2) which is again released back
into atmosphere and the cycle goes on.
Nitrification
• The conversion of ammonia into nitrates is termed as nitrification.
• This is brought about by nitrifying bacteria.

Examples
Nitrobacter, Nitrosomonas.

Denitrification
• The conversion of nitrates into nitrogen (N2) is termed dentrification.
• This process is brought about by centrifying bacteria.

Examples
Pseudomonas, flurescence.
Phosphorus Cycle
Phosphorus cycle
Phosphorus is mainly present in the rocks and fossils. The phosphorus is present in all
biotic components in different forms.

Examples
Bones, teeths, guano deposits.
• Phosphate rocks is excavated by man for using it as a fertilizers. Farmers use excess of
fertilizers for the crops.
• The excess phosphate fertilizers move with the surface run-off reaches the oceans and
are lost into the deep sediments.
• Sea birds eat sea – fishes, which are phosphorus rich, and the excreta of the birds
return the phosphorus to the land.
• Thus the sea birds, are playing an important role in phosphorus cycling animals and
plants use these dissolved phosphates during the biosynthesis.
 Ecological Succession
In an area one community may be replaced by another community or by a series of communities.
Thus the progressive replacement of one community by another till the development of stable community in a
particular area is called ecological succession.

Stages of ecological succession

1. Pioneer community
The first group of organism, which establish their community in the area is called ‘Pioneer’ Community.

2. Seres (or) Seral community

The various developmental stages of a community is called ‘seres’. Eg. grass stage, herb sage, shrub stage, etc

Community
It is the age group of plants or animals living in an area
Types of ecological succession
Ecologists recognize two types of ecological succession, used on the conditions present at the beginning of the
process.
• 1. Primary succession
It involves the gradual establishment of biotic communities on a lifeless ground. Primary Succession starts in
a newly formed area where environmental conditions are elementary, such as a bare area formed by lava flow,
a new pond created by a landslide, sand dunes formation or bare rock surface formed by the retreating
glaciers.
• The primary area contains no biological legacy, i.e., no vegetation, seed bank or organic matter.
• The area is not initially occupied by any community and the seeds or propagules for the first organism should
arrive by immigration.
a. Hydrarch (or) Hydrosere
Establishment starts in a watery area like pond and lake.
b. Xerarch or Xerosere
Establishment starts in a dry area like, desert and rock
2. Secondary Succession
It involves the establishment of biotic communities in the area, where some type of biotic
community is already present.

• Secondary succession starts in an area previously occupied by a community, but now

• devegetated by some natural or human activities like fire, storms, tree cutting, disease
outbreak, cultivation, biotic interventions, etc.
• After several years, some new community again occupies that area. It is called secondary
succession. The area is not having living matter above ground, but its substratum is built
up with the nutrients, organic matters deposites previously occupied community.
• Thus, the process of secondary succession is comparatively rapid than primary
succession.
Process of Ecological Succession
The process of ecological succession can be explained in the following steps.

1. Nudation: It is the development of a bare area without any life form

2. Invasion: It is the establishment of one or more species on a bare area through migration followed by
establishment.
a. Migration -Migration of seeds is brought about by wind, water or birds.
b. Establishment: The seeds then germinate and grow on the land and establishes their pioneer
communities.

3. Competition: As the number of individual species grows, there is a competition with the same species
and between different species for space, water and nutrients.

4. Reaction: The living organisms take water, nutrients and grow and modify the environment is known as
reaction. This modification becomes unsuitable for the existing species and favour some new species,
which replace the existing species this leads to seral communities.

5. Stabilizations: It leads to stable community, which is in equilibrium with the environment .

Succession is a series of complex processes. There are three main causes of succession:

a) Initiating causes: these are climatic as well as biotic factors. The former includes landslide,
volcanic activity, wind, soil erosion, etc. and the latter includes various activities of organisms. The
 Food Chain
Definition
“There sequence of eating and being eaten in an ecosystem is known as food chain”
(or)
“Transfer of food energy from the plants through a series of organisms is known as food
chain”
When the organisms die, they are all decomposed by microorganism (bacteria and fungi)
into nutrients that can again be used by the plants. At each and every transfer, nearly 80-
90% of the potential energy gets lost as heat. A food chain always starts with plant life and
ends with animal.
Herbivores: Animal that eat only plants are called herbivores.
Carnivores: Animals that eat other animals are called carnivores
 Type of Food Chain
Food chains are classified into two main types
1. Grazing food chain
2. Detritus food chain

1.Grazing food chain

Found in Grassland ecosystems and pond ecosystems. Grazing food chain starts with
green plants (primary procedures) and goes to decomposer food chain or detritus food
chain through herbivores and carnivores.

2.Detritus food chain

Found in Grassland ecosystems and forest ecosystems. Detritus food chain starts with
dead organic matter (plants and animals) and goes to decomposer food chain through
herbivores and carnivores.
Types of food chain
Food chains are classified into two main types

1.Grazing food chain 2.Detritus food chain

Found in Grassland ecosystems and pond Found in Grassland ecosystems and forest
ecosystems. Grazing food chain starts with ecosystems. Detritus food chain starts with
green plants (primary procedures) and goes to dead organic matter (plants and animals) and
decomposer food chain or detritus food chain goes to decomposer food chain through
through herbivores and carnivores. herbivores and carnivores.
 Trophic Level
Tropic Levels (T1,T2, T3, T4, T5) (or) Feeding levels:
The various steps through which food energy passes in an ecosystem is
called as tropic levels.
The tropic levels are arranged in the following way as Where ,

• The green plants or producers represent first tropic level T1,

• The herbivores or primary consumers represent second tropic level T2.
• The carnivores or secondary consumers represent third tropic level T3.
• The tertiary consumers are fourth tropic level T4.
• Finally decomposers represent last tropic level T5
 Food Web
Definition
The interlocking pattern of various food chains in an ecosystem is
known as food web. In a food web many food chains are interconnected,
where different types of organisms are connected at different tropic
levels, so that there is a number of opportunities of eating and being
eaten at each tropic level.
Example
Grass may be eaten by insects, rats, deer's, etc., these may be eaten by
carnivores (snake, tiger).
Thus there is a interlocking of various food chains called food webs
 Difference between food chains and food web
• In a linear food chains if one species gets affected (or) becomes extinct, then the
species in the subsequent tropic levels are also affected. But, in a food web, if one
species gets affected, it does not affect other tropic levels so seriously. There are
number of options available at each tropic level.

Significance of food chains and food webs

• Food chains and food webs play a very important role in the ecosystem. Energy
flow and nutrient
• cycling takes place through them.
• They maintain and regulate the population size of different tropic levels, and thus
help in maintaining ecological balance.
• They have the property of bio-magnification. The non – biodegradable materials
keep on passing from one tropic level to another. At each successive tropic level,
the concentration keep on increasing. This process is known as bio-magnification.
 ECOLOGICAL PYRAMIDS
Definition
“Graphical representation of structure and function of tropic levels of an ecosystem,
starting with producers at the bottom and each successive tropic levels forming the
apex is known as an ecological pyramids.”

In food chain starting from the producers to the consumers, there is a regular decrease
in the properties (ie.,, biomass and number of the organisms). Since some energy is
lost as heat in each tropic levels, it becomes progressively smaller near the top.
Types of Ecological pyramids
1. Pyramid of numbers.
2. Pyramid of energy.
3. Pyramid of biomass.
Pyramid of Energy
Thank you