What is Ecosystem?

' Ecosystem ' is a dynamic system in an area where the biotic and abiotic component , are constantly acting and reacting upon each other bringing forth structural and functional changes . In the term ' Ecosystem ' , its 'Eco' part implies the environment and the 'System' part implies an interacting , inter-dependent complex . In a given area , all organisms i.e., communities interact with their non-living (physical and chemical) environment in a way that flow of energy leads to clearly defined trophic structure , biotic diversity and material cycle (i.e., exchange of materials between living and non-living components) within the system . This unit of living organisms interacting with their non-living environment in an orderly self-sufficient manner is known as an ecological system or ecosystem . Different scientists described ecosystem in different ways . They are as follows -

• ''An ecological system(ecosystem) is a sum total of living organisms , the environment and the processes of interaction between and within all parts of the system'' -  S. Mathavan , 1974 

• ''Biotic community and its abiotic environment ; the whole earth can be considered as one large ecosystem'' -   C.J. Krebs , 1985

• ''An ecosystem is a given abiotic physico-chemical environment and its particular biotic assemblage of plants , animals and microbes'' -  E.J. Kormondy , 1986

• ''Ecosystem includes all the organisms of an area and the environment in which they live''  -   P.H. Collin ,1988

• ''The community and the non-living environment function together as an ecological system or ecosystem'' -  E.P. Odum , 1996

The earth can be considered as a giant ecosystem where abiotic and biotic components are constantly acting and reacting upon each other bringing forth structural and functional changes in it . This vast ecosystem - the biosphere is however , difficult to handle and ,thus, for the sake of convenience , we generally study nature by making its artificial subdivisions into units of smaller ecosystems(such as Terrestrial - forest , desert , grassland ; Aquatic - freshwater , marine ; Man-engineered - cropland etc.). An ecosystem may, thus, be as small as a pond , a cropland or as large as an ocean .Though these unit ecosystems are separated from each other with time and space , but functionally they all are linked with each other , forming an integrated whole .