The impacts of Robinia pseudoacacia litter cover and roots on soil erosion in the Loess Plateau, China

The impacts of vegetation on soil erosion are closely associated with the combined effects of above-and below-ground components. In this study, we explore the effects and contributions of Robinia pseudoacacia litter cover and roots on soil erosion. Experiment sites under natural conditions with vegetation cover, plant roots and bare ground plots were investigated for overland flow discharges of 0.5, 1.0 and 2.0 L s(-1) and slope gradients of 8.7%, 17.6%, 26.8%, 36.4% and 46.6%. Results indicate that litter cover and roots have a significant impact on sediment reduction; soil loss was reduced by about 57% and plant roots had a greater impact on the reduction of soil erosion than litter cover. The combination of litter cover and plant roots had a significant effect on decreasing K-r, increasing tau(c) and consequently strengthening soil resistance capacity to erosion. When plants and roots existed on the slopes, K-r decreased by 81% and 66%, and tau(c) increased by 319% and 246%, respectively, in comparison with bare slopes. These results illustrate the importance of high-forest in controlling soil erosion by quantifying the specific contributions of litter cover and plant roots in erosion reduction in the Loess Plateau.