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GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 19, GB3011, doi:10.1029/2005GB002536, 2005

Soil organic carbon dynamics as related to land use history in the northwestern Great Plains

Zhengxi Tan

South Dakota Center for Biocomplexity Studies, Brookings, South Dakota, USA


Shuguang Liu

SAIC, Sioux Falls, South Dakota, USA


Carol A. Johnston

South Dakota Center for Biocomplexity Studies, Brookings, South Dakota, USA


Thomas R. Loveland

U.S. Geological Survey, Sioux Falls, South Dakota, USA


Larry L. Tieszen

U.S. Geological Survey, Sioux Falls, South Dakota, USA


Jinxun Liu

Research Associateship Program at the USGS National Center for EROS, National Research Council, Sioux Falls, South Dakota, USA


Rachel Kurtz

U.S. Geological Survey, Sioux Falls, South Dakota, USA


Abstract

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.

Keywords: General Ensemble Biogeochemical Modeling System (GEMS); land use history; soil organic carbon.

Index Terms: 0428 Biogeosciences: Carbon cycling (4806); 0414 Biogeosciences: Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912); 0402 Biogeosciences: Agricultural systems; 1632 Global Change: Land cover change.

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Citation: Tan, Z., S. Liu, C. A. Johnston, T. R. Loveland, L. L. Tieszen, J. Liu, and R. Kurtz (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.