. . . "gross primary productivity of carbon" . " Gross primary productivity is the rate of synthesis of biomass per unit area from inorganic precursors by autotrophs, especially by photosynthesising plants using sunlight for energy. The producers also respire some of this biomass and the difference is net_primary_producivity. \"Productivity of carbon\" refers to the production of biomass expressed as the mass of carbon which it contains. \"Productivity\" means production per unit area." . "Climate and Forecast (CF)" .