Soil erosion and significance for carbon fluxes in a mountainous Mediterranean-climate watershed Article uri icon

abstract

  • In topographically complex terrains, downslope movement of soil organic carbon (OC) can influence local carbon balance. The primary purpose of the present analysis is to compare the magnitude of OC displacement by erosion with ecosystem metabolism in such a complex terrain. Does erosion matter in this ecosystem carbon balance? We have used the Revised Universal Soil Loss Equation (RUSLE) erosion model to estimate lateral fluxes of OC in a watershed in northwestern Mexico. The watershed (4900 km2) has an average slope of 10° ± 9° (mean ± SD); 45%25 is > 10°, and 3%25 is > 30°. Land cover is primarily shrublands (69%25) and agricultural lands (22%25). Estimated bulk soil erosion averages 1350 Mg·km -2·yr-1. We estimate that there is insignificant erosion on slopes < 2° and that 20%25 of the area can be considered depositional. Estimated OC erosion rates are 10 Mg·km -2·yr-1 for areas steeper than 2°. Over the entire area, erosion is ∼50%25 higher on shrublands than on agricultural lands, but within slope classes, erosion rates are more rapid on agricultural areas. For the whole system, estimated OC erosion is ∼2%25 of net primary production (NPP), increasing in high-slope areas to ∼3%25 of NPP. Deposition of eroded OC in low-slope areas is ∼10%25 of low-slope NPP. Soil OC movement from erosional slopes to alluvial fans alters the mosaic of OC metabolism and storage across the landscape. © 2007 by the Ecological Society of America.

publication date

  • 2007-01-01