What is the relationship between GPP, Net Primary Productivity (NPP), and respiration?

Gross Primary Productivity (GPP), Net Primary Productivity (NPP), and respiration are foundational concepts in understanding energy flow in ecosystems.

GPP refers to the total amount of energy that photosynthetic organisms—primarily plants—capture through photosynthesis in a given area over a specific time period. It represents the overall productivity of an ecosystem and indicates how much energy is available for all trophic levels, including herbivores and decomposers.

Respiration is the process through which plants and other organisms consume oxygen and release carbon dioxide, breaking down the organic matter produced during photosynthesis to obtain energy for vital functions. During this process, some of the energy captured during GPP is lost as heat.

NPP is derived from GPP by accounting for the energy that is lost to respiration. It represents the actual amount of energy that is available for consumption by primary consumers (herbivores) in the ecosystem. The relationship can be summarized as: NPP = GPP - Respiration. This means that to find NPP, one must subtract the energy lost through respiration from the total energy captured through GPP.

In terms of the choices presented, the correct relation is that NPP is equal to GPP minus respiration, making the distinction clear regarding