Relation Between Hedysarum Mongdicum Spatial Distribution And Soil Properties In Hunshandake Sandland

This article is based on the research of soil physical and chemical properties under three Hedysarum mongdicum plots with different densities in the desertification vegetation recovery and reconstruction process. It investigated the impact of the density of Hedysarum mongdicum shrub on soil physical and chemical properties in the sand vegetation restoration and reconstruction process. The conclusion is as follows:With density of Hedysarum mongdicum increased, the content of soil coarse sand (>0.5mm) was gradually reduced in three plantations. The content of Sticky powder (<0.05mm) and organic carbon, the hydrolysable nitrogen and available P, and the fractal dimension D of soil particles increased with the rise of Hedysarum mongdicum density. Soil bulk density was reduced with improvement of the Hedysarum mongdicum density. In the0-5cm soil layer, soil total nitrogen increased in the order of low-density<medium density<high density In the0-20cm soil, the percentages of soil total P rose in the order of low density<medium density <high-density plots. Differences were significant between the plotsThe variation of soil particle fractal dimension, soil bulk density, total P and the hydro lysable nitrogen of the coefficient followed the order as:low-density> medium-density> hig-h-density. The degree of variation of pH value and the content of organic carbon in the0-40cm soil layer is substantially the same. The variation of total nitrogen and available P o f coefficient in the0-5cm soil layer was low-density> medium-density> high-density. In the0-20cm soil layer, the degree of variation of the soil available potassium are low-density> density> High-density plots.The spatial heterogeneity of the soil carbon in every layer was basically decreased with th e increasing of the density of Hedysarum mongdicum. The spatial heterogeneity of the soil tot al nitrogen content in every layer increased at first and then decreased with the increasing of t he density of Hedysarum laeve. Soil organic carbon content in low density plots had spatial au tocorrelation. The maximum range of space-related changes was relatively small; the change d egree of soil nitrogen content was relatively big. Autocorrelation had big contribution to soil or ganic carbon content and spatial heterogeneity of the total nitrogen content. In medium and hig h density plots, the autocorrelation in soil organic carbon content was large but the Total nitrog en variable-range was small. The random factors had a big contribution to soil organic carbon c ontent and spatial heterogeneity of the total nitrogen content. The heterogeneity process of the spatial distribution of Hedysarum mongdicum cover is as same as the heterogeneity pr-ocess of the spatial distribution of soil organic carbon and nitrogen, the distributed heter ogeneous process of Hedysarum mongdicum results to the the heterogeneous of soil orga- nic carbon and total nitrogenIn desertification vegetation restoration and reconstruction process, the higher the d-ensity of the distribution of Hedysarum mongdicum, the deeper the impact of soil phy-sical and chemical properties. Higher density of Hedysarum mongdicum distribution can significantly improve the physical condition of the soil texture and soil nutrient conte-nt and effectiveness. With the Hedysarum mongdicum cover distribution getting uniform, the degree of heterogeneity of soil physical and chemical properties became weak to-wards uniformity.