Spatial variability of soil moisture after rainfall in different type sands of Horqin Sand were studied by
geostatistics
approach.The results showed that soil moisture in light disturbed sandy grassland,undisturbed semi-mobile dune and heavy disturbed inter-dune bottomland,had distinctive variability and larger spatial change range of variability,after rainfall.The variability degree of soil moisture in three sands is in the order: sandy grassland > semi-mobile dune > inter-dune bottomland.The spatial correlation coefficient and range of soil moisture of sandy grassland,were 0.62 and 181.80 m at 0～20 cm and 0.98,4.55 m at 20～40 cm,respectively.The difference of
spatial variability between these two layers was striking.The degree of spatial variability between topsoil and sub-topsoil moisture in semi-mobile sand was less than that between the topsoil and subsoil of sandy grassland,and had a strong spatial dependence. Moreover,the spatial variability of topsoil and sub-topsoil moisture caused by stochastic factors accounted for 50% and 48% in the total spatial variability,respectively,mainly in the scale of one meter.However soil moisture after rainfall in inter-dune bottomland had obvious spatial structure and small difference in variability between the topsoil and sub-topsoil.Contour maps expressed the descended distribution trend from the center to the periphery,and this occurred only in certain scale distances.The variances of sandy ecosystems in Horqin Sand were mainly due to natural changes and human activities and the change of soil moisture was driven by rainfall.Landform,vegetation and the intensity of human disturbance,even in small scale,played profound role in soil moisture.