An ecosystem is a community, where all living organisms live and interact with one another and also with their non-living environment such as land, soil, air, water etc. Ecosystems range in size from the smallest units (e.g. bark of a tree) that can sustain life to the global ecosystem or ecosphere. (e.g. Cropland, Pond ecosystem, Forest ecosystem, Desert ecosystem etc.). Biosphere harbours all ecosystems on the earth and sustains life forms including mankind.

Components of ecosystem:

An ecosystem consists of three basic components, namely

(A) Abiotic components

(B) Biotic components and

(C) Energy component 

(A) Abiotic Components:

Abiotic components include the non-living, inorganic, physical and chemical factors in the environment,

e.g. Land, Air, Water, Calcium, Iron etc.

(B) Biotic Components:

Biotic components include plants, animals and micro organisms.

Biotic components can be classified into three categories:

• Producers are self nourishing components of the ecosystem. Hence they are called Autotrophs. They are found both on land and water,

e.g. Plants, Algae, Bacteria etc.

• Consumers are those that depend on producers, directly or indirectly. Hence they are called Heterotrophs.

(C) Energy Components: All organisms in the biosphere use energy to work and convert one form of energy into another. The Sun is the ultimate source of energy for the biosphere as a whole. The solar energy gets transformed into other forms of energy through the various components in the ecosystem. The producers, consumers and the decomposers contribute a lot to the energy flow in an ecosystem.