祁连山退化高寒草甸土壤水分空间变异特征分析

利用传统统计学方法和地统计学方法，对祁连山地区受到过度放牧影响而退化为以狼毒为优势种的高寒草甸的土壤水分垂直变异特征、水平空间异质性以及分布特征进行了系统分析. 结果表明：在垂直方向上，0~100 cm土壤水分含量随深度的增加而逐渐减少，土壤水分含量的变化速度随深度的增加也趋于减少；土壤水分分布的变异系数在浅层和深层土壤较大，在中层土壤较小. 在水平方向上，0~40 cm土壤水分具有中等空间变异性，其中10~20 cm土壤水分变异性主要受根系的影响，随机部分引起的变异性最大；而在其他土壤层，随着深度的增加土壤水分含量由随机部分引起的空间异质性程度减弱，由空间自相关部分引起的异质性程度增强. 整体上，土壤水分含量与微地形关系密切，与距离溪流的远近程度正相关，与高程分布负相关.

Analysis of the spatial variability of soil moisture in degrading alpine meadow in the Qilian Mountains

Traditional statistics and geostatistics methods are used to study the soil moisture variation characteristics in vertical direction, spatial heterogeneity in horizontal direction and spatial distribution in the overgrazed and the nocuous grass invading alpine meadow in the Qilian Mountains. The results show that in vertical direction, soil moisture decreases with depth, and so does the variation rate. Coefficient of variation of the soil moisture distribution in superficial layer and deep layers are larger than that in middle layers. In horizontal direction, the soil moisture in 0~40 cm depth range possesses a feature of moderate variability. The 10~20 cm depth range is mainly affected by root system, with the maximum variability in the random section. For the rest layers, soil moisture due to variability of random section decreases with depth, while that due to the autocorrelation section increases. In macroscopic view, content of soil moisture is closely related to micro-topography, with positive correlation with the distance to rivers and negative correlation with the height above sea level.