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Lake Qinghai area locating at the northeast Qinghai-Tibetan Plateau is a typical wind erosion area,characterized by high elevation,low vegetation,high temperature difference and high frequency of strong-wind.It is significant to explore the influence of wind erosion on soil degradation under the different land-use pattern.In this paper,38 soil profiles of 5 typical plant communities (Stipa breviflora Griseb,Gramineae,Achnatherum splendens,Kobresia humilis and Elymus nutans Griseb) around Lake Qinghai are systematically studied with the soil grain size fraction and soil nutrient.The grain size frequency distribution curve of the surface soil sediment shows anobvious spacious heterogeneity: surface soil sediment collected from the severest desertification area in the Qinghai Lake area presents a unimodal pattern,an asymmetrical bimodal pattern presented in an enclosed grassland and multimodal pattern presented in the north where have experienced a long-term cultivation presents.The average particle size,kurtosis values,standard deviation and skewness of the surface soil are calculated and analyzed.Compared to enclosed grassland,the long-term cultivation of the northern of Lake Qinghai silt loam resulted in an extensive depletion of organic matter associated with particles > 20 μm (30% of the initial C lost).Fine clay (<1 μm) associated organic matter was rapidly depleted from high coverage vegetation to low coverage vegetation,and the 5 typical plant communities show a similar characteristic of grain size.Losses of fine silt (8 to 2 μm) and coarse clay (2 to 1 μm) associated organic materials were substantially less,and the proportion of total soil organic matter in these forms increased under the cultivation.Based on the based on the soil grain size and nutrient content analysis,the irrational land use will aggravate the land desertification in Lake Qinghai area.