中文摘要：

干旱区的土壤水分分布特征受气候、区域地形、植被、土壤质地等因素的影响，其本身也是整个区域环境的重要影响因子。文中通过对位于毛乌素沙地西北缘鄂托克旗境内的裸露流动沙丘、灌木覆盖沙丘、乔木覆盖沙丘3种类型沙丘不同地貌部位O～4m深度范围内的土壤含水量研究，采用钻孔取样、烘干称重和粒度测试等方法，分析不同植被、地形和土壤质地等N素对研究区土壤含水量分布特征的影响。结果表明：对于垂直方向0～4m深度范围内的裸露流动沙丘、灌木和乔木覆盖沙丘平均含水量变化均表现为迎风坡高于背风坡，且在灌木覆盖沙丘和乔木覆盖沙丘的丘间洼地的土壤含水量多高于迎风坡和背风坡，不同类型沙丘在各地貌样点不同层段含水量变化差异明显，变化趋势不统一。相同的沙丘微地貌，不同类型植被覆盖对于沙丘土壤含水量在垂向上的变化有较大影响，且灌木植被的影响大于乔木植被。除了植被以外，浅层基岩的隔水作用对土壤含水量同样有重要影响。土壤水分分布特征与土壤中不同粒级的颗粒含量有关，而植被通过拦截空气中的粉尘，提高了土壤中粘土与粉砂等持水能力强的颗粒组分，进而提高了土壤平均含水量。

英文摘要：

The distribution characteristics of soil topography, vegetation, soil texture, etc. , and soil moisture in arid areas are affected by climate, regional moisture is also an important factor of regional environ- ment change. In the study area, the sand dunes are divided into bare migratory dunes, shrubs-covered dunes and trees-covered dunes according to the vegetation forms and vegetation coverage on the surface of sand dunes, and the samples of drilling holes in the depth of 4 m at different topography sites of the dunes were taken for analyzing the change of soil moisture content and soil granularity characteristic of the sand dunes. The results are as follows：The average soil moisture varies in different types of dunes, with the following sequences ordered from highest to lowest ： in three types of dunes the sequence is from windward slope to leeward slope, and in the shrub-covered dunes and the tree-covered dunes the se- quence is from inter-dunes lowland to windward slope and leeward slope in most situations, the variation of soil moisture content at different depth of each type dune was different. Vegetation form and surface coverage affect the range of soil moisture of different types of dunes in the same topographic position. The coefficient of variation of the soil moisture of shrub-covered dunes is higher than that of other types of dune. Furthermore, the shallow bedrock aquifuge affects sharply the variation of soil moisture content near the bedrock of different topographic position. The average moisture of vegetation-covered dunes ex- isted in obvious correlation with clay and silt constituent of sandy soil, which can be explained in terms of the greater ability of vegetation special shrubs to trap fine-grained atmospheric dust and hold mois- ture.