Final answer:
Net primary productivity (NPP) represents the useful chemical energy produced by plants, available for consumption by herbivores, after accounting for plant respiration. The NPP in boreal forests is lower than in temperate and tropical wet forests, due in part to slower decomposition of organic material and simple forest structure impacting carbon sequestration.
Step-by-step explanation:
The net primary productivity (NPP) is a measure of the rate at which all the plants in an ecosystem produce net useful chemical energy; in other words, it is the balance of energy left after subtracting the energy plants need for respiration from the Gross Primary Productivity (GPP). Specifically, NPP represents the amount of energy (biomass) that is available to primary consumers (herbivores). The GPP of a forest in North America, like a boreal forest, for instance, might be affected by various factors such as temperature, moisture availability, soil fertility, and the forest's plant species composition and structure.
Boreal forests generally have lower NPP than temperate and tropical wet forests. This is due to several factors including slow decomposition rates, leading to fewer nutrients being returned to the soil, and the structure of the forest typically containing only a tree layer and a ground layer. These conditions contribute to a lower rate at which carbon is sequestered in the form of plant biomass, which ties into the concept of carbon sequestration, the process through which CO2 is absorbed from the atmosphere and held in solid or liquid form.