Structure and Functions of Ecosystem ; Biotic Components and Abiotic Components

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 chain
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.

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