Spatial Variation of Moisture Content in Shallow Aeolian Sandy Soil in the Southern Marginal Zone of the Gurbantonggut Desert

Abstract

In May 2008,the vegetation,terrain and landforms were investigated at a plot of 200 m x 50 m in a typical region of longitudinal sand dunes in the southern marginal zone of the Gurbantonggut Desert.At the plot 180 quadrats were selected for the observation,measurement and soil sampling.These soil samples were sampled from the surface layer(0～10 cm)and shallow layer(10～30 cm),and their moisture content values were measured. Under the support of geostatistical software,such as GS~+ and geostatistical model in ArcGis,this paper analyzes the spatial varying pattern of soil moisture content at the different positions of two longitudinal sand dunes in the study area.The results show that the semi-variance functional values of soil moisture content in the two layers can be well fitted as an exponential model.The variation ranges of surface layer and shallow layer of aeolian sandy soil are 37.8 m and 21.3 m,and the ratios of partial sill and sill[C/(C_0+C)]are 75.1%and 75.6%,respectively.These reveal that there is a high spatial autocorrelation in soil moisture between the surface layer and the shallow layer of aeolian sandy soil,and the spatial variation of the soil moisture content comes mainly from a structural difference. The results can objectively reflect the spatial structure pattern of soil moisture in the plot.The figure of Kriging interpolation shows that soil moisture content is correspondently increased with the height increase of terrain.The analyzed results show that the values of soil moisture content are in an order of crestwindward slopeleeward slopeinter-dune land in the surface layer(0～10 cm)of aeolian sandy soil,and an order of windward slopecrestleeward slopeinter-dune land in the shallow layer(1030 cm).