• It generally refers to the rate of biomass production
  • It is of two types – primary productivity and secondary productivity.
  • Primary productivity: During photosynthesis, plants produce the amount of biomass per unit area over a time period.
  • In terms of weight or energy it expressed. It is of two types – GPP and NPP.
  • Gross primary production or GPP–  Generally It is the estimation. In it the producers in an ecosystem absorb chemical energy as Biomass in the given time. In addition GPP depends on the chlorophyll content.
  • Net primary productivity NPP – Green plants stores the amount of biomass. It provides the energy that drives all biotic processes. For example the trophic webs that sustain animal populations and the activity of decomposer organism. Further It recycle the nutrients required to support primary production.

Net primary productivity = gross primary productivity– desperation losses. (GPP-R= NPP)


Secondary productivity is consumers synthesize the amount of biomass per unit area per unit time.

It comes through the transfer of organic material between trophic levels. Further it represents the quantity of new tissue created for the use of assimilated food.

The annual net primary of the whole biosphere is approximately 170 billion tons of organic matter.

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