Net Primary Production (A-level Biology)
Net Primary Production
Net Primary Production
Understanding NPP
Not all of the chemical energy from GPP is ‘useful’ because some of it can be used in respiration. The ‘useful’ GPP left over is called net primary production (NPP). Like GPP, the units are mass / area / time – mass of carbon per unit area per year (g C m−2 yr−1) is the most common unit.
NPP is therefore the difference between GPP and the amount of chemical energy used in respiration.
GPP = Gross Primary Production
R = Respiratory Losses to the Environment
The NPP energy can be used by the plant for growth and reproduction, and therefore adds to biomass. Therefore this energy can be passed on the food chain to other trophic levels, such as herbivores and decomposers.
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