In terms of energy flow, what does net secondary productivity measure?

Net secondary productivity measures the energy converted into biomass by consumers in an ecosystem. When consumers consume producers, such as plants, they utilize some of the energy stored in the producers' biomass for their own growth and reproduction. This energy, after accounting for the energy lost through respiration, represents the net energy available to consumers for the creation of new biomass.

In this context, net secondary productivity is crucial for understanding how much energy is effectively transferred through the food chain, contributing to the overall productivity of an ecosystem. By distinguishing between energy gained versus energy lost, it allows ecologists to assess the efficiency of energy transfer among trophic levels by focusing specifically on the energy that contributes to the growth of consumer populations. This makes it a vital concept in studying ecosystem dynamics and energy flows.