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1) Primary productivity:
This is associated with the producers which are autotrophic (photosynthetic and to a much lesser extent chemosynthetic microorganisms). Primary productivity (PP) is defined as ‘the rate at which radiant energy is stored by the autotrophic activity of producers.’ PP is further distinguished as
-Gross primary productivity (GPP) : The rate of storage of organic matter in plant tissues in excess of the respiratory utilization by plants during the measurement period ( the rate of increase of biomass) i.e. is total photosynthesis
-Net Primary Production (NPP) is gross photosynthesis minus respiration i.e. NPP = GPP – R. NPP is the amount of energy available to next tropic level made up of primary consumers e.g. herbivores i.e. the balance between gross photosynthesis and respiration and other plant losses due to death
2) Secondary productivity: This is the rate of energy storage at consumer level. The consumers simply convert the food matter to different tissues; hence it is not divided into gross and net secondary productivity.
3) Net productivity (NP): this is the rate of storage of organic matter not utilized by heterotrophs i.e. the equivalent of net primary productivity minus consumption by the heterotrophs during a unit period. It is the rate of increase of biomass of the primary producers which has been left over by the primary consumers.
4) Stability of ecosystem: This refers to the balance between the production and consumption of each element in an ecosystem i.e. the balance between the input & output of energy, the normal functioning of different biogeochemical cycles and the stable conditions of equilibrium.
marto answered the question on March 20, 2019 at 07:17
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