采用经典统计和地统计学的方法，分析了2013年半干旱区科尔沁沙地(1.5 hm²)不同植被类型下0 ~ 160 cm剖面土壤水分的时空变异特征。结果表明：土壤含水量在剖面上的变异系数在18% ~ 177% 之间，属于中等或强变异水平；土壤水分状况影响其变异性，湿季的变异性低于干季。草本植被和灌木通过截留降雨和根系吸水，加剧了土壤水分在空间上的变异。在同一时期，土壤水分的空间自相关性随着深度的增加而不断减小；相同深度的空间自相关性为湿季大于干季。在湿季各层土壤含水量具有较好的空间连续性，而干季各层土壤水分变化均较为剧烈，土壤水分的破碎化程度较高。降雨有促使土壤水分分布趋于均匀及增强空间相关性的效果。

The spatio-temporal variation is a ubiquitous feature of natural ecosystems, especially in semi-arid regions of Horqin. The purpose of this study is to characterize variations in moisture content in the 0–160 cm soil layers in situ by means of intensive sampling in both space and time. The results indicated that soil moisture content in the 0–160 cm soil layers exhibited a high degree of spatial and temporal variability. The degree of variability was dependent on the water content. The CV of mean water content in the 0–160 cm soil layers spanned from 18% to 177%, indicating a level of middle or high variability. The result also suggested that CV was dependent more on soil moisture level than on soil depth. A large increase in CV for the soil layers was observed in dry condition. The spatial and temporal variations of the water content were related to vegetation types and soil moisture. At a fairly definite range, the heterogeneity of water content caused by spatial autocorrelation was evidently higher in wet season (July-August) than in dry season (September-October). The distance of spatial autocorrelation was different in different seasons and depths. It was more consecutive for spatial trend in wet season than in dry season. Clearly, the consumption of water by shrubs increases the spatio-temporal variability of soil water.

S152.7

973项目“植物固沙的生态–水文过程、机理及调控”(2013CB429902)资助