Runoff maintenance and sediment reduction of different grasslands based on simulated rainfall experiments

Large-scale vegetation restoration generally reduces local water yield and influences river ecosystem health. Thus, scientific evaluation of vegetation restoration consequences is necessary for maintaining the stability of the surface water system and water cycle in semi-arid regions. In this study, we compared the efficiencies of different typical grasslands in regulating runoff and sediment yields and proposed feasible suggestions suiting for local environments. Four grasslands, including two Gramineae species (Elymus dahuricus and Bromus inermis) and two legume species (Medicago saliva and Trifolium repens), were tested during a two-year period with simulated rainfall experiments, and using bare land as control. Three replicates were done for each treatment, and fifteen plots with a slope of 20 degrees were constructed. Three indices were used to assess the runoff and sediment yields reduction capacity of the grasslands, including runoff reduction benefit (RRB), sediment reduction benefit (SRB), and soil infiltration rate (SIR). The results showed that RRB and SRB were significantly different (P < 0.05) among treatments across the two-year experiments. The values of SRB increased considerably in the second year. In particular, the values of SRB for E. dahuricus and B. inermis was 98.79% and 98.07%, respectively, while that of RRB was - 11.84% and 4.01%, respectively. The two Gramineae grasslands showed greater effectiveness in sediment reduction and runoff maintenance than the two legume species owing to the dense fibrous roots and higher biological soil crust coverage. Therefore, Gramineae grasslands can be considered as a suitable management practice to achieve the socio-ecological sustainability of the semi-arid areas during vegetation restoration.