Spatial heterogeneity of soil moisture under different vegetation types in peak-cluster depression

In this paper, the authors tries to illustrate the spatial heterogeneity of the soil moisture in surface layer (0～10 cm) under four typical vegetation types and the ecological processes and mechanism in peak-cluster depression. The results show that the soil moisture in surface layer increases significantly with the reduced disturbance gradient, and vegetation takes a succession change from crops (Ⅰ) to man-made forest (Ⅱ), to secondary forest (Ⅲ), to primary forest (Ⅳ). The spatial heterogeneity of the soil moisture in surface layer under the four vegetation types is diverse. Exponential, Gaussian, exponential and spherical models fit best for the spatial patterns of soil moisture in surface layer inⅠand Ⅲ, Ⅱ, and Ⅳ, respectively. The values of (C0/ (C0+C)) ranged from 0.269 to 0.500, which indicates the soil moisture in the four types having medium spatial autocorrelation. The spatial patterns of the soil moisture in surface layer are similar in type Ⅰand Ⅳ, with relative large value of (C0/ (C0+C)) and fractal, which suggests less dependence on spatial existed in the two vegetation types. The reverse is true to type Ⅱ and Ⅳ. The range in typeⅠis up to 252.9 m, and the ranges of the other three vegetation types are relative small (from 141.2 to 163.2 m). The Kriging contour maps clearly show the spatial distribution of the soil moisture in type Ⅰ and Ⅳ is convex, while that in Ⅱ is unimodal and in Ⅲ concave. It is suggested that spatial pattern of the soil moisture in surface layer is affected by a large number of factors, among which disturbance plays a key role through regulating vegetation. Therefore, to reduce disturbance might be an important measure for the improvement of water resource and the restoration of eco-environment in karst peak-cluster depression.