Spatial Variability in Physical Soil Properties in a Pinus koraiensis-Dominated Broadleaved Mixed Forest Gap in Xiao Xing’an Mountains of Northeast China

Locations of sampling points in Pinus koraiensis-dominated broadleaved mixed forest gap in Xiao Xing’an Mountains of Northeast China were determined by grid method. Spatial variability in physical soil properties (PSPs) at those locations in 2 depths of 0–20 cm and 20–40 cm was analyzed by descriptive statistics and geostatistics. The results indicated that soil water content (SWC), saturated moisture capacity, capillary water-holding capacity and porosity were higher in 0–20 cm than in 20–40 cm except for bulk density. PSPs in 0–20 cm had relatively higher ranges and coefficients of variation. The total and autocorrelative spatial heterogeneity in PSPs were larger in 0–20 cm than in 20–40 cm. SWC had a strong anisotropic structure in an easterly and northerly direction, but porosity exhibited isotropy structure in the same directions. With increasing spatial distance, the three other PSPs presented anisotropic structures. Within spatial autocorrelative range, the interactive effect between semivariograms of PSPs in 0–20 cm was not significant. For spatial distribution of PSPs in 2 different depths, the patches with the middle and lower ranks dominated in the forest gap. Patches with higher rank were only distributed in 0–20 cm and were located north of the forest gap.