中文摘要：

以毛乌素沙地南缘沙柳人工固沙灌丛为研究对象,对不同栽植密度（0.2、0.6和0.8株·m-2）沙柳灌丛生长季土壤水分动态和蒸散量变化进行研究.结果表明：不同栽植密度沙柳灌丛区土壤水分动态和蒸散量存在明显差异,土壤含水量随着栽植密度增加呈单峰型曲线;生长季内沙柳灌丛土壤含水量变化呈＂S＂形曲线,并与降雨存在密切的关系.蒸散量以栽植密度0.8株·m-2的沙柳灌丛最高（114.5mm）,占同期降雨量的90.8%;以0.6株·m-2的沙柳灌丛最低（109.7mm）.根据生长季土壤水分动态和水分平衡特征,毛乌素沙地南缘沙柳灌丛适种密度为0.6株·m-2.

英文摘要：

Taking the artificial sand-fixing Salix psammophila shrubs with different plant density （0.2, 0.6, and 0.8 plants·m-2） in Mu Us Sandy Land as test objects, this paper studied the soil moisture dynamics and evapotranspiration during growth season. There existed obvious differences in the soil moisture dynamics and evapotranspiration among the shrubs. The soil moisture content changed in single-hump-shape with the increase of plant density, and in ＂S＂ shape during growth season, being closely correlated with precipitation. The evapotranspiration was the highest （114.5 mm） in the shrubs with a density 0.8 plants·m-2, accounting for 90.8% of the total precipitation during growth season, and the lowest （109.7 mm） in the shrubs with a density 0.6 plants·m-2. Based on the soil moisture dynamics and water balance characteristics, the appropriate planting density of S. psammophila shrubs in Mu Us Sandy Land could be 0.6 plants·m-2.