Global distribution of soil organic carbon – Part 1: Masses and frequency distributions of SOC stocks for the tropics, permafrost regions, wetlands, and the world
The global soil organic carbon (SOC) mass is relevant for the carbon cycle budget and thus atmospheric carbon concentrations. We review current estimates of SOC stocks and mass (stock × area) in wetlands, permafrost and tropical regions and the world in the upper 1 m of soil. The Harmonized World So...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-04-01
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| Series: | SOIL |
| Online Access: | http://www.soil-journal.net/1/351/2015/soil-1-351-2015.pdf |
| Summary: | The global soil organic carbon (SOC) mass is relevant for the carbon cycle
budget and thus atmospheric carbon concentrations. We review current
estimates of SOC stocks and mass (stock × area) in wetlands,
permafrost and tropical regions and the world in the upper 1 m of soil. The
Harmonized World Soil Database (HWSD) v.1.2 provides one of the most recent
and coherent global data sets of SOC, giving a total mass of 2476 Pg when
using the original values for bulk density. Adjusting the HWSD's bulk
density (BD) of soil high in organic carbon results in a mass of 1230 Pg,
and additionally setting the BD of Histosols to 0.1 g cm<sup>−3</sup> (typical of
peat soils), results in a mass of 1062 Pg. The uncertainty in BD of Histosols
alone introduces a range of −56 to +180 Pg C into the estimate of global
SOC mass in the top 1 m, larger than estimates of global soil
respiration. We report the spatial distribution of SOC stocks per 0.5 arcminutes; the areal masses of SOC; and the quantiles of SOC stocks by
continents, wetland types, and permafrost types. Depending on the definition
of "wetland", wetland soils contain between 82 and 158 Pg SOC. With
more detailed estimates for permafrost from the Northern Circumpolar Soil
Carbon Database (496 Pg SOC) and tropical peatland carbon incorporated, global soils
contain 1325 Pg SOC in the upper 1 m, including 421 Pg in tropical soils,
whereof 40 Pg occurs in tropical wetlands. Global SOC amounts to just under
3000 Pg when estimates for deeper soil layers are included. Variability in
estimates is due to variation in definitions of soil units, differences in
soil property databases, scarcity of information about soil carbon at depths
> 1 m in peatlands, and variation in definitions of "peatland". |
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| ISSN: | 2199-3971 2199-398X |