Abstract
Soil organic carbon dynamics as related to land use history in the northwestern Great Plains
South Dakota Center for Biocomplexity Studies, Brookings, South Dakota, USA
SAIC, Sioux Falls, South Dakota, USA
South Dakota Center for Biocomplexity Studies, Brookings, South Dakota, USA
U.S. Geological Survey, Sioux Falls, South Dakota, USA
U.S. Geological Survey, Sioux Falls, South Dakota, USA
Research Associateship Program at the USGS National Center for EROS, National Research Council, Sioux Falls, South Dakota, USA
U.S. Geological Survey, Sioux Falls, South Dakota, USA
Strategies for mitigating the global greenhouse effect must account for soil organic carbon (SOC) dynamics at both spatial and temporal scales, which is usually challenging owing to limitations in data and approach. This study was conducted to characterize the SOC dynamics associated with land use change history in the northwestern Great Plains ecoregion. A sampling framework (40 sample blocks of 10 × 10 km2 randomly located in the ecoregion) and the General Ensemble Biogeochemical Modeling System (GEMS) were used to quantify the spatial and temporal variability in the SOC stock from 1972 to 2001. Results indicate that C source and sink areas coexisted within the ecoregion, and the SOC stock in the upper 20-cm depth increased by 3.93 Mg ha−1 over the 29 years. About 17.5% of the area was evaluated as a C source at 122 kg C ha−1 yr−1. The spatial variability of SOC stock was attributed to the dynamics of both slow and passive fractions, while the temporal variation depended on the slow fraction only. The SOC change at the block scale was positively related to either grassland proportion or negatively related to cropland proportion. We concluded that the slow C pool determined whether soils behaved as sources or sinks of atmospheric CO2, but the strength depended on antecedent SOC contents, land cover type, and land use change history in the ecoregion.
Received 14 April 2005; accepted 15 June 2005; published 17 August 2005.
Citation: (2005), Soil organic carbon dynamics as related to land use history in the northwestern Great Plains, Global Biogeochem. Cycles, 19, GB3011, doi:10.1029/2005GB002536.
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