Final answer:
Net Primary Productivity (NPP) is the amount of chemical energy that remains after autotrophs consume part of the energy they create through photosynthesis for respiration and growth.
Step-by-step explanation:
Net Primary Productivity (NPP) is defined as the rate at which all the autotrophs in an ecosystem produce net useful chemical energy; in other words, it is the balance of energy that remains after subtracting the energy autotrophs expend for respiration from the total energy they produce through photosynthesis.
It can be expressed in units such as grams of carbon per day (gC/d). This contrasts with Gross Primary Productivity (GPP), which is the total amount of energy or biomass produced by autotrophs in an ecosystem.
One key difference between NPP and GPP is that NPP accounts for the energy used by primary producers for their life processes such as growth and reproduction, whereas GPP does not subtract the energy lost to respiration and other metabolic functions.
Thus, NPP represents the actual rate of production of new biomass that is available for consumption by heterotrophs, or non-producing organisms, at the next trophic level.
Scientists often analyze NPP because it more accurately reflects the amount of energy that is available to the rest of the ecosystem beyond the primary producers.
By considering the respiration and heat loss of producers, NPP provides insight into the production at present and next trophic levels of the ecosystem.