The structural component of an ecosystem may be classified under two main types :

(i) Biotic components

(ii) Abiotic components

Biotic components comprise the  living organisms present in an ecosystem. These include plants, animals and micro-organisms (bacteria and fungi). The biotic components of an ecosystem has been classified into three groups :(i) Producers (Green plants)
(ii) Macroconsumers (Usually animals
(iii) Microconsumers or decomposers (organisms like bacteria and fungi).

Abiotic components consist of the non living components like light, temperature, water, oxygen, carbon, nitrogen and minerals.  Various important abiotic factors have been classified as follows :

(i) Climatic factors. These include light, temperature, precipitation, atmospheric humidity and wind.

(ii) Topographic factors. These include altitude, surface slope and exposure, etc.

(iii) Edaphic factors. These include soil and substratum.

â–² Fig. 6.7 Carbon cycle in nature.

1. The natural reservoir of phosphorus is rock in the form of phosphates.

2. Minute quantities of phosphates get dissolved in the soil solution during weathering of rocks.

3. Phosphates enter the plants through their roots and then the food chain.

4. The organic wastes and dead organisms are decomposed by phosphate-solubilising bacteria, which release phosphorus back in the soil.

5. The atmospheric input of phosphorus through rainfall or gaseous exchange of phosphorus between organisms and environment, is negligible.

Phosphorus Cycle