| Domain | Terrestrial | Description | Carbon in soils occurs in organic and inorganic forms. The inorganic carbon is derived from weathered bedrock, is relatively inert and constitutes little to the carbon cycle. Soil organic carbon is derived from plant and other decaying matter and is a significant part of the carbon cycle. About 10% of the atmospheric carbon cycles through soils each year. Soil organic carbon represents the largest terrestrial carbon pool, amounting to about two to three times the net size of the biomass pools. Carbon sinks may be explained by changes in above-ground biomass on seasonal to decadal time scales, but soil organic carbon stocks become significant on longer time scales, and can be a significant source at all time scales after disturbances. Globally, the largest soil organic carbon stocks are located in wetlands and peat lands, most of which are located in boreal and tropical regions. [GCOS-195 6.3.14] |