Productivity Primary producers Gross primary productivity- total amount of energy produced Net primary productivity- available to next trophic level Secondary productivity- Secondary production represents the formation of living mass of a heterotrophic Primary production is the rate of accumulation of biomass. Gross primary production (GPP) is the total amount of energy produced by vegetation; some of that energy is used for cellular respiration i.e. for the growth and development of the plant. What is left over is called net primary production (NPP) and that represents the total available energy in an ecosystem the form of dry plant biomass. The amount of organic matter or biomass produced by an individual organism, population, community or ecosystem during a given period of time is called productivity. ---------------Primary production refers to all or any part of the energy fixed by plants possessing chlorophyll. The total amount of solar energy converted (fixed) into chemical energy by green plants (by the process of photosynthesis) is called Gross Primary Production'(GPP). Net Primary Production (NPP) which appears as new plant biomass.