Productivity is an ecological term referring to the fixation of solar energy by plants and algae, and the subsequent utilisation of that fixed energy (or biomass) by plant-eating herbivores, animal-eating carnivores, and detritivores that feed upon dead biomass. This complex of energy fixation and utilisation in an ecosystem is called a food web.

Ecologists refer to the productivity of green plants (and algae) as primary productivity, meaning it comprises the base of food webs. Gross primary productivity is the total amount of energy fixed by plants. Net primary productivity is smaller because it is adjusted for energy losses associated with plant respiration. If the net primary productivity of green plants in an ecosystem is positive, then the biomass of vegetation is increasing over time.

The productivity of herbivorous animals (which feed on plant biomass) is known as secondary productivity (both gross and net). That of carnivores (which feed...