贵州喀斯特区域土壤水分时空分布特征

基于贵州喀斯特区域2011-2015年53个自动土壤水分观测站0~100 cm的逐日土壤水分、降水、气温资料，分析了不同农业气候区土壤水分时空分布特征、变异系数以及土层之间的相关关系。得出以下主要结论:（1）各区土壤水分的范围总体相差较小，据 0~100 cm层土壤水分相对小值区的分布形态，可分为持续性土壤干旱区、季节性土壤干旱区、土壤湿润区。（2）依据各区土壤水分的变异系数相对大值区的时空分布形态类似可分为变异一致区、季节变异区及持续变异区。（3）通过10~50 cm对其下层土壤水分的关系研究发现，温暖湿润区、温和湿润区、高寒区研究土层（10~50 cm）与其下层（20~90 cm）土壤水分相关系数均>0.60，其余各区土层只与其下20~40 cm土层相关系数较大，而对其下更深土层相关系数较小；从滑动日数来看，各区10~50 cm土层与其下10~20 cm、30~50 cm、60~100 cm层最大相关系数的滑动日数随深度的增加而增加，分别为3~10日、10~20日、20~30日。（4）通过对比各区土壤水分与其变异系数分布特征发现，土壤水分的低值区发生的层次及时间与变异系数大值区基本相对应，土壤水分的变化除与降水、气温直接关系外，还可能与土质及环境等其他要素有关。 

Spatial and temporal distribution of soil humidity in karst areas of Guizhou Province

The spatiotemporal distribution, the coefficient of variation of soil moisture and the relationship between soil layers(0-100 cm) in different agricultural climate zones are analyzed, using daily data of soil moisture precipitation and temperature extracted from 53 automatic observation stations in karst areas of Guizhou in the period of 2011 to 2015. The results show that，(1)the ranges of soil moisture in every region are slightly different. According to the 0-100cm deep soil layer’s difference in soil moisture, the soil can be divided into three types, i.e. persistent soil drought, seasonal soil drought and wet soil zones.(2)Similarly, based on the coefficients of variation, the distribution of the soil moisture at profile with the depth range of 0-100 cm in each region can also be divided into consistent variation, seasonal variation, and persistent variation zones. (3)The research on the relationship between 10-50 cm and the soil moisture in the lower layers in karst regions of Guizhou province suggests that upper soil moisture has an effect on the lower layer in warm humid, moderate wet and alpine regions, the upper soil layer has effect on the lower 20-40 cm soil layer but its lower 50-90 cm soil layer is relatively slight. From the sliding days, the days with the maximum correlation coefficients of 10-20, 30-50 and 60-100 cm layer increase with depth in each region, which are 3-10, 10-20, 20-30 days, respectively. (4)Comparing the distribution of soil moisture and its variation coefficient in each region shows that the low value region of soil moisture largely corresponds to the area of large variation coefficient. Besides the direct relationship with precipitation and temperature, the soil moisture may also be related to its soil water holding capacity and other factors.