Spatial variation in soil resistance to flowing water erosion along a regional transect in the Loess Plateau

摘要

The factors influencing soil erosion may vary with scale. It remains unclear whether the spatial variation in soil erosion resistance is controlled by regional variables (e.g. precipitation, temperature, and vegetation zone) or by local specific variables (e.g. soil properties, root traits, land use, and farming operations) when the study area enlarges from a hillslope or catchment to the regional scale. This study was performed to quantify the spatial variations in soil erosion resistance to flowing water under three typical land uses along a regional transect on the Loess Plateau and to identify whether regional or local specific variables are responsible for these changes. The results indicated that the measured soil detachment capacities (D-c) of cropland exhibited an irregular trend along the regional transect. The D-c of grassland increased with mean annual precipitation, except for two sites (Yijun and Erdos). The measured D-c of woodland displayed an inverted `U' shape. The changes in rill erodibility (K-r) of three land uses were similar to D-c, whereas no distinguishable trend was found for critical shear stress (tau(c)). No significant correlation was detected between D-c, K-r and tau(c), and the regional variables. The spatial variation in soil erosion resistance could be explained reasonably by changes in soil properties, root traits, land use, and farming operations, rather than regional variables. The adjustment coefficient of K-r for grassland and woodland could be well simulated by soil cohesion and root mass density (R-2 = 0.70, P<0.01), and the adjustment coefficient of critical shear stress could be estimated with aggregate stability (R-2 = 0.57, P<0.01). The results are helpful for quantifying the spatial variation in soil detachment processes by overland flow and to develop process-based erosion model at a regional scale. Copyright (c) 2015 John Wiley & Sons, Ltd.