Effects of Near Soil Surface Characteristics on Soil Detachment by Overland Flow in a Natural Succession Grassland. Issue 2 (21st March 2014) - Wang, Bing
Abstract : Vegetation restoration probably has great effects on the process of soil detachment. This study was conducted to investigate the effects of near soil surface characteristics on soil detachment by overland flow in a 7‐yr restored natural grassland. Four treatments were designed to characterize the effects of dead roots, live roots, biological soil crusts (BSCs), and plant litter‐stems in succession. For comparison, an undisturbed bare Loess soil was used as a baseline. The testing area (1.0 m in length and 0.1 m in width) of each treatment was subjected to flow scouring under five different shear stresses ranging from 6 to 13 Pa. The results showed that near soil surface properties of plant litter‐stem, BSCs, and plant roots enhanced the resistance of soil to water detachment significantly. With these factors subsequently superimposed, soil detachment capacity decreased progressively. Taken together, the 7‐yr restored natural grassland would decrease soil detachment capacity by 98.9% compared with the bare Loess soil, in which plant litter‐stem, BSCs, and total roots contributed to 30.3, 14.9, and 53.7%, respectively. Furthermore, for the total root effects, chemical bonding of root exudates accounted for 14.7% while physical binding of root systems accounted for 39.0%. Results also indicated that BSCs were unable to protect the soil from detachment when the shear stress was greater than 11 Pa, and tended to accelerate soil erosion. This paper developed an equation for adjusting WEPP's rill erodibility for use in natural succession grassland in the Loess Plateau of China, and the result seemed satisfactory with the Nash‐Sutcliffe efficiency (NSE) coefficients ranging from 0.28 to 0.77. Further studies are needed to detect the dynamics of near soil surface characteristics with succession age of grassland in the Loess Plateau.