希拉穆仁荒漠草原不同覆盖土壤粒度特征研究

Grassland degradation characteristics has been transformed by changes in vegetation primarily for soil degradation stage, to a certain extent, its vegetation change can reflect the status and process of degradation.The wind erosion situation of different degradation stage in Xilamuren desert grassland was studied in this paper, which is of great significance for protecting and utilizing grassland resources in this area properly. In this research, the topsoil(0~1cm) of 7 different vegetation covers （0%、5%、20%、40%、60%、80% and 100%）were selected .To analyze the soil particle size characteristics in desert steppe, by use of laser diffraction technique to identify the soil particle size distributions and calculated the particle size parameters such as the average particle size, standard deviation, skewness, kurtosis and fractal dimension..The results indicated that 1）With the decrease of the vegeration coverage, Leymus chinensis and Stipa krylovii vegetation types gradually turned into Artemisia frigida . vegetation types, species, height, plant density, the ground biomass reduced in turn. 2) Most topsoil particle size in desert steppe was mainly sand and silt , where the clay content is low. 3)With the decrease of the coverage,， the average particle size grew bigger , the sorting characteristics got better and the requency curve changed by nearly symmetrical to positive skewness and partial negative skewness eventualkly, the kurtosis sharp change flat, fractal dimension increases after the first reduce the trend. 4)The particle size distribution was bimodal distribution, the smaller basic coverage is, the more obvious of the second wave lags behind, and the lower level of uniform distribution, the more coarse of particle size of the particles concentration.