Abstract: Based on grid (80 mx80 m) sampling and by using the methods of classical statistics and geostatistics, an investigation was conducted on the spatial heterogeneity of trace elements (Pb, Cr, Ni, Cu, Zn, and B) in 163 surface soil (0-20 cm) samples in a small catchment in a typical Karst cluster-peak depression area of South China. There was a great difference in the concentrations of the soil trace elements. Their average concentrations were in the order of Zn>Cr>Ni>Pb>B>Cu, and the average variation coefficients were in the sequence of Ni>Cu>Zn>Pb>B>Cr. Except that the Cr had a medium spatial autocorrelation with longer range and a better spatial continuum, the other five trace elements had a stronger spatial autocorrelation with shorter range and a stronger spatial dependence. The similar Kriging contour maps indicated that the distribution patterns of the six trace elements were almost similar, i.e., higher in the east and lower in the north and south, and higher in depression and lower on slope. It was suggested that human disturbances and natural conditions (vegetation, bare rock rate, slope, and aspect) were the primary factors affecting the spatial patterns of the soil trace elements in small catchments in Karst peak-cluster depression regions.

Key words: niche, niche differentiation, interspecific association, fish.