2002 ARCSS All-Hands Workshop

Predicting Carbon Storage in Tundra Soils of Arctic Alaska

James G. Bockheim¹, Frederick E. Nelson², Kenneth M. Hinkel^3
1Soil Science, University of Wisconsin, 1525 Observatory Drive, Madison, WI, 53706-1299, USA, Phone 608-263-5903, Fax 608-265-2595, bockheim@facstaff.wisc.edu
²Geography, University of Delaware, Newark, DE, 19716, USA, fnelson@udel.edu
³Department of Geography, University of Cincinnati, Cincinnati, OH, 45221, USA, ken_hinkel@compuserve.com

The distribution of soil organic carbon (SOC) was determined in 60 pedons from northern Alaska by horizon, within the seasonal thaw layer, and to a depth of 1 m. Concentration of SOC, bulk density, and SOC density were remarkably uniform for a given genetic horizon and had low standard errors. With increasing degree of decomposition, the bulk density increases, the % SOC decreases, and the soil horizon C density increased in organic horizons. For mineral horizons, gleying is accompanied by an increase in C density, which is due to the effect of saturated on reduced decomposition of organic matter. Cryoturbation of organic or mineral minerals into the subsoil results in an increase in C density primarily from an increase in bulk density due to compaction from the overlying layers and more closely packed soil particles from frost stirring. Estimated SOC densities for individual horizons and for the seasonal thaw layer were highly correlated (p <0.01) with measured values from an independent data set for the same region published by other investigators. Variable quantities of segregated ice in the upper permafrost made it more difficult to estimate quantities of SOC to 1 m (p = 0.05). The equations generated by this study will be useful for preparing a detailed soil C map of the arctic regions.

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