Components of an Ecosystem

An ecosystem typically has two major components -

A)Abiotic or Non-living Components

    Abiotic component of the ecosystem comprises three type of components  - i)Climate conditions and physical factors of the given region such as air,soil,temperature,light,etc. ii)Inorganic substances such as water,carbon(C),nitrogen(N),sulphur(S),phosphorus(P), etc.These substances are involved in cycling of materials in the ecosystem through biogeochemical cycles .The amount of these inorganic substances present at any given time in an ecosystem is designated as standing state or standing quality . iii)Organic substances such as Carbohydrates,Proteins,Lipids and other complex molecules .

B)Biotic or Living Components 

   The biotic components of an ecosystem can be classified according to their mode of energy acquisition . In this type of classification , there are two types of components which are discussed as follows -

1)Autotrophic Component -Autotrophic component of ecosystem includes the producers or energy transducers which convert solar energy into chemical energy (that becomes locked in complex organic substances such as carbohydrate,protein,lipid, etc.)with the help of simple inorganic substances such as water and carbon dioxide and organic substances such as enzymes . Autotrophs fall into following two groups - i)Phatoautotrophs which contain green phatosynthetic pigment chlorophyll to transduct the solar energy of sun , e.g.,all green plants,algae,phatosynthetic bacteria . ii)Chemoautotrophs which use energy generated in oxidation-reduction process , but their significance in the ecosystem as producers is minimal,e.g.,microorganisms such as sulphur bacteria .

2)Heterotrophic Component - Heterotrophic components predominate the activities of utilization , rearrangement and decomposition of complex organic materials . Heterotrophic organisms are also called consumers , as they consume the matter built up by the producers (autotrophs) . The consumers are further categorised as -

  i) Macroconsumers - There are three groups of macroconsumers - a)Herbivores or Phagotrophs or primary Macroconsumers - Animals that feed on plants are called Herbivores ,e.g.,insects,cow,goar,etc. b)Carnivores or Secondary Macroconsumers - Animals that feed on herbivores are called Carnivores,e.g.,lion,tiger,owl,etc. c)Omnivores - Human beings are called omnivores as they feed on both plants and animals .

ii)Microconsumers - These are popularly known as decomposers . They are saprotrophs and include chiefly bacteria,actinomycetes and fungi . They breakdown complex compounds of dead or living protoplasm , absorb some of the decomposition or breakdown products and release inorganic nutrients in environment , making them available again to autotrophs . No ecosystem could function long without decomposers . Decomposers are not important to the ecosystem from the energy point of view but from the nutrient point of view they are important because energy can not be recycled , but matter(nutrients) can be .

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 .