Abstract: Based on the investigation data from 107 sampling plots in a small watershed of Fenshuilinggou in the Liupan Mountains of Northwest China, and by using multivariate statistical analysis, this paper analyzed the relationships of landform and vegetation characters with soil hydrophysical properties in the watershed. Soil water-holding capacity, total porosity, capillary water-holding capacity, bulk density, volumetric fragment content, and non-capillary porosity were considered as the important soil hydrophysical parameters for classifying soil hydrophysical properties, and soil capillary water-holding capacity was a sensitive parameter. The sampling plots were classified into 3 groups, with great differences in soil hydrophysical properties and vegetation types. Group III had the best soil hydrophysical properties, which was covered by the secondary broad-leaved forests mainly composed of birch (Betula spp.) and poplar (Populus davidiana) and mostly located on the middle section of shady slopes. Group II had relatively good soil hydrophysical properties, which was covered by Larix principis-rupprechtii plantation. Group I had the worst soil hydrophysical properties, which was covered by the natural forests mainly composed of Pinus armandii or shrubs and mostly located on steep slopes. The soil porosity was controlled by landform and vegetation characters. The most important parameters of landform affecting the soil porosity were relative elevation, slope position, and aspect, and the most important vegetation parameters affecting the soil porosity were DBH, tree height, and shrub layer coverage.

Key words: soil water infiltration, impermeable layer, red clay, tamping, experiential equation.