Soil Water Infiltration Characteristics Analysis under Different Vegetation on the Hilly Ground of Yangtze River Delta

Soil under three vegetation types- pure forest of Quercus acutissima, mixed forest of Pinus massoniana and Quercus acutissima, and shrub- of typical yellow brown areas in Nanjing Purple Mountain were collected by stratified sampling(0 ~ 20 cm, 20 ~ 40 cm, 40 ~ 60 cm, 60 ~ 80 cm, and 80 ~ 100 cm). Soil physical properties were determined by traditional methods, spatial variability of some soil physical properties and their relationships with the infiltration law. The results showed that, soil infiltration rates decreased by degrees from the surface to the bottom in the vertical direction under all these types of vegetation. Soil initial infiltration rates and soil silt contents, soil capillary porosities, and soil total porosities were significantly correlated; besides that, soil steady infiltration rates were significantly correlated with soil non-capillary porosities. Meanwhile, the infiltration rates of soil under pure forest of Quercus acutissima were the maximum among all these three vegetation types, combined with the comprehensive analysis of soil water holding capacity under these three vegetation types; therefore, the Quercus acutissima pure forests were inferred to provide the most ideal soil hydrological effects in the study area, and could provide a scientific basis for vegetation structure collocations of the plantation in those surrounding areas.