喀斯特峰丛洼地坡面土壤水分空间变异研究

Spatial variability of soil moisture on hillslope in clusterpeak depression areas in Karst region

以线形取样方式测定了喀斯特峰丛洼地坡面表层（0～5、5～10、10～15cm）的土壤水分，采用经典统计结合地统计学方法分析了其空间分布特征及变异结构。结果表明：在坡面特定土地利用结构下（上坡到下坡分布有自然坡地、退耕地和耕地），表层土壤水分沿上坡向下具有不断减小的变化趋势，坡面纵向和横向土壤水分均呈中等变异，横向上由于特殊的土壤分布和地形地貌特征使得变异程度较纵向强烈，土地利用和坡度因子是造成坡面土壤水分分布和变异的重要因素；半方差分析显示，坡面表层土壤水分具有明显的块金效应和较大的基台值，呈中等或较强的空间相关性，土壤水分总体上具有较好的变异结构和空间连续性，因此可以应用地统计学方法在该地区开展土壤水分空间变异研究。

Spatial pattern and variability of surface（0～5, 5～10, 10～15 cm） soil moisture on hillslope were analyzed combining with classical statistics and geo-statistics with data measured by linear sampling method in Karst cluster-peak depression areas. Results show that under the condition of special land use structure on the slope （natural vegetation, abandoned cropland and cultivated land distributed along the slope）, the surface soil moisture content decreases from upslope to downslope, and they are medium variability along the longitudinal and horizontal directions on the hillslope. The variability of soil moisture along horizontal direction is greater than that along longitudinal direction for special soil distribution, topography and physiognomy conditions. Land use type and degree of slope are key factors that affected the distribution and variability of surface soil moisture on the slope. The results from Semi-variogram analysis indicate that the surface soil moisture has significant nugget effect, very great sill, and middle or strong spatial correlation on the slope. Despite of the complicated land use structure, topography and thin rocky soil on the hillslope, the surface soil moisture has good variable structure and spatial continuity as a whole. It is viable to apply Geo-statistics method to study the spatial variability of soil moisture in Karst area.