What does gross primary productivity measure?

Gross primary productivity (GPP) measures the total amount of chemical energy produced by primary producers, such as plants and phytoplankton, in a specific area over a certain time period. This encompasses the energy captured through photosynthesis before any of it is used by the producers for their own metabolic processes, such as respiration.

By understanding GPP, ecologists can assess the energy input into an ecosystem and estimate how much energy is available to support herbivores and, subsequently, higher trophic levels. This metric is crucial for evaluating ecosystem health and productivity, giving insights into the efficiency of energy conversion in biological systems. It serves as a foundational concept in ecology, linking the flow of energy from the sun through producers to consumers.