Spatial heterogeneity of soil physical factors in karst warmtemperate tussock type of grassland in Guizhou

Spatial heterogeneity of soil is one of the important properties of soil. The semivariance analysis and the fractal analysis were used to examine the spatial heterogeneity of soil physical factors in karst grassland in Guizhou. This study showed that soil moisture content, bulk density and porosity had a significant spatial heterogeneity. The spatial heterogeneity scale was 4 m to 15 m at 15~20 cm soil layer and was 12 m to 30 m at 15~20 cm layer. Degree of spatial heterogeneity changed with scale, and the spatial heterogeneity of the soil upper layer was bigger than that of the lower soil layer. The spatial heterogeneity of soil porosity at the upper layer was mainly consisted of spatial autocorrelation, accounting for 68.0%, while the soil water content and bulk density were part of a relatively large spatial heterogeneity. Soil physical properties of the underlying spatial heterogeneity were all caused by the spatial autocorrelation. Soil moisture content, bulk density and porosity of the fractal dimension were large (greater than or close to 1.8), indicating a smaller scale ecological process of each variable factor played a control role in the development of spatial pattern.