Variation Features of Soil Physical Property of Different Forest Land Types in Southern Slope of Qilian Mountain

The research material in this article is the four forest lands in the southern slope of Qilian Mountain, they are the forest of Picea crassifolia, Sabina przewalskii and the Potentilla fruticosa shrubwood, Caragana jubata shrubwood, we discuss the influence of different forest land types to the soil physical property and the water conservation function. The research result shows that the soil water content and porosity of different types of forest lands present a decreasing trend along with the increase of soil depth. Different soil depth acts roughly as Picea crassifolia > Potentilla fruticosa > Sabina przewalskii, Caragana jubata changes between the three ones, on the whole, it would be Picea crassifolia > Potentilla fruticosa > Sabina przewalskii, the soil water content of Caragana jubata and Potentilla fruticosaare are almost the same.