Ecosystem
refers to the interactions of organisms with one another and with their
environment in which they occur. The structure and functions of an ecosystem include two basic
components:
Biotic components and Abiotic components
Biotic components : on the basis of production and consumption of food energy, the green
plants are called producer components. Other living organisms like animals are
considered as consumer components and living microorganisms are considered as
decomposer components. All these together constitute biotic components.
The biotic components of an ecosystem have been classified by Odum
(1971) into three groups: producers, consumers and decomposers.
1. Producers: make their own food example: Algae and water plants
2. Consumers:
a) Primary consumers: Feed on Producers Example: Protozoan's
and Crustaceans
b) Secondary consumers: Frog, Insects, small fishes
c) Tertiary consumers: Fishes, Snakes
3. Decomposers: feed on dead organic matter-convert it into simple soluble inorganic
molecules that can be taken up by the plants. Example of decomposers: Bacteria, fungi and microbes
Abiotic components: It includes mainly materials and energy. The materials are water,
minerals, gases, salts etc. And energy is like light, stored energy in chemical
compounds, heat etc.
1. Inorganic
components Example
: CO2, H2O, N, S, Ca, P
2. Organic
components Example
: Protein, carbohydrate, Lipid
3. Climatic
factors: Example :
Temperature, light, wind, soil, rainfall
Functions of an Ecosystem
Plants in the ecosystem form a link between biotic and abiotic
components. They absorb water an d minerals from the soil and combine them with
carbon dioxide in the presence of sunlight to make carbohydrate, fats,
proteins, vitamins etc. This process is known as photosynthesis. Small
herbivores and organism consume this vegetable matter and covert it into animal
material. These may, in turn, by large carnivores. The sequence of eating and
being eaten, with the resultant transfer of energy, is known as food
chain. Each step in the food chain is known as trophic level. The producers
forms the first trophic level, herbivores the second, and carnivores
constitutes the third level.
Food chains are not isolated from one another. They are directly or
indirectly interconnected. This inter connecting network of species in the
ecosystem is termed as food web.