ABSTRACT
Terrestrial ecosystems sequester up to one half of annual fossil fuel CO2 emissions. That an ecosystem sequesters carbon implies that the gain of carbon by net primary productivity (NPP) exceeds the losses to the atmosphere by heterotrophic respiration and episodic disturbances such as fires, pest outbreaks, and harvests. Multiple residence times are associated with the cascade of terrestrial soil carbon pools, ranging from less than a year for the rapidly decomposing detritus up to thousands of years for the refractory soil carbon compounds. The different components of NPP all have different carbon sink potentials and are connected to carbon pools with significantly different turnover times. Several global models of terrestrial ecosystems have been developed to analyse and predict the response of terrestrial carbon pools and fluxes to changing land use and management practices, climate, and atmospheric composition.
