A standing crop is the total biomass of the living organisms present in a given environment.
Net Primary Productivity or NPP can be defined as the rate of accumulation of biomass or energy. The energy utilised during metabolic processes such as respiration is excluded from gross productivity (GPP).
Secondary productivity is the rate at which the consumers convert the chemical energy of their food into their own biomass.
Gross primary productivity is the amount of carbon fixed during photosynthesis by all producers in the ecosystem.