黄土区退耕封育草地微生境土壤水分变化规律

干旱、半干旱地区土壤水分亏缺是影响植被恢复与重建的限制性因子,探讨不同微生境0—60 cm土层土壤含水量的变化规律对指导植被恢复具有重要现实意义。按照机械布点原则,采用烘干法测定了土壤含水量。分析结果表明,（1）0—60 cm土层土壤含水量平均值表现为：半阴坡〉半阳坡〉阳坡;（2）同坡向不同微生境类型（峁坡坡面、峁坡坡面浅沟、峁坡坡面小切沟、大切沟沟底、大切沟阳坡或半阳坡、大切沟阴坡或半阴坡、沟坡坡面）之间0—60 cm土层土壤含水量差异极显著,其含水量的大小主要取决于局部地形和植被生长状况,局部小地形主要影响降水和日照的再分配,植被主要影响降水截留和蒸腾;（3）根据含水量的大小,将3个坡向21个微生境类型划分为3个类群,其含水量依次为11.68%,8.68%和5.77%。

Soil Water Content Variations in Various Micro-habitats on Closed Grasslands Returned from Farmlands in Loess Area

The shortage of soil water is a limited factor affecting restoration and the growth of vegetation in arid and semi-arid areas. Investigations of soil water content variations within depth of 0-60 cm in various microhabitats is therefore of great practical significance for guiding vegetation restoration. Soil samples were collected on sampling grids and soil water content were then measured via oven drying method. The results show that average soil water contents at depth of 0-60 cm was in order from high to low as semi-shade,semi-sunny,and sunny slopes. The average soil water content in 0-60 cm layer varied significantly among hilly slope,shallow gully,small gully,large gully bottom,large gully sunny or semi-sunny slope,large gully shade or semi-shade slope and valley slope on the same aspect of different types. The distribution of soil water content depended mainly on topography and vegetation growth status: the topography affected redistri-bution of precipitation and sunshine,and the vegetation determined rainfall interception and transpiration.Based on soil water content variations,the 21 microhabitat of three aspects were divided into 3 groups,with average soil water contents of 11.68%,8.68% and 5.77%,respectively.