Final answer:
Net primary productivity is the measure of the energy that remains in primary producers after cellular respiration, representing the actual rate of new biomass available to the next trophic levels.
Step-by-step explanation:
The term net primary productivity refers to the dry weight of organic matter produced by primary productivity. This measure accounts for the energy that remains in the primary producers after accounting for their cellular respiration and metabolic heat loss. In essence, it is the total amount of carbon fixed by photosynthesis in a given time period minus the carbon expended during cellular respiration. It effectively indicates the amount of new biomass that is available to the next trophic levels, such as primary consumers.
Net primary productivity is a crucial component of an ecosystem's energy budget and represents the actual rate of production of new organic matter that is available for consumption. This measurement is key to understanding the energy accumulation within an ecosystem, and is often used by ecologists to assess the productivity of different habitats, such as terrestrial biomes and aquatic ecosystems like those experiencing ocean upwelling.