In an ecosystem, rate of production of organic matter during photosynsis is termed as

Gross primary productivity is the rate at which photosynthesis or chemosynthesis occurs. Net primary production is the rate at which all the plants in an ecosystem produce net useful chemical energy; it is equal to the difference between the rate at which the plants in an ecosystem produce useful chemical energy (GPP) and the rate at which they use some of that energy during respiration. Gross primary production (GPP) is the amount of chemical energy as biomass that primary producers create in a given length of time.