Variations in soil infiltration capacity after vegetation restoration in the hilly and gully regions of the Loess Plateau, China

PurposeTo control the severe soil and water losses on the Loess Plateau, China, a series of vegetation restoration projects were conducted. A better understanding of the effect of vegetation types on the soil infiltration capacity is important for the sustainable development of vegetation restoration. The aim of this study was to establish a soil infiltration capacity index (SIC) and to analyze the mechanism influencing variations in the soil infiltration capacity after vegetation restoration on the Loess Plateau.Materials and methodsEight vegetation types (community dominated by Artemisia scoparia, Stipa bungeana, Artemisia gmelinii + S. bungeana, A. gmelinii + Stipa grandis, A. gmelinii + Artemisia giraldii, Sophora viciifolia, Caragana korshinskii, and Robinia pseudoacacia) and bare land as the control were selected for this study. The SIC was established by a steady infiltration rate (SR, 50-60min) and stage I average infiltration rate (ARSI, 0-5min) according to principal component analysis (PCA). Path analysis was used to investigate how the soil properties and plant fine root affected the soil infiltration capacity.Results and discussionThe SIC values of the eight vegetation types were all higher than that of the bare land. The R. pseudoacacia community had the highest SIC value (0.43), followed by the A. scoparia community (0.30) while the bare land (-0.56) had the lowest value. Path analysis showed that the increase in the fractal dimension and non-capillary porosity of soil particles enhanced the SIC directly. Increases in the clay content increased the SIC by affecting the fractal dimension of soil particles, while increases in the fine root density reduced the SIC by affecting the non-capillary porosity. Plant functional groups (grasses and legumes) affected SIC indirectly via non-capillary porosity and plant root.ConclusionsA comprehensive index, the SIC, was established to describe the soil infiltration capacity by the PCA method. Based on a comparison with bare land, vegetation restoration enhanced the soil infiltration capacity. The R. pseudoacacia community was the most effective at improving the soil infiltration capacity. The improvement in infiltration was closely related to direct increases in the soil non-capillary porosity and soil particle fractal dimension.