毛乌素沙地西南缘不同植被下的土壤水分时空变化研究

Study on the Temporal and Spacial Different Plant Coverage on Change of Soil Water Content under the Southwestern Edge of Maowusu Sandy Land

在一个生长季内通过对毛乌素沙地不同植被下的土壤水分的连续观测,研究毛乌素沙地不同植被下的土壤水分时空动态变化规律。结果表明：各样地土壤含水量生长期末低于生长期初,按时间变化可划分为三个时期,土壤水分积累期（4～6月）、土壤水分消耗期（7～9月）、土壤水分稳定期（10月至次年3月）。在空间上,各样地土壤含水量均随深度的增加而有所增加,整个土壤剖面自上而下按水分变化规律可划分为四层：土壤水分速变层、活跃层、过渡层和稳定层。土壤水分活跃层的深度与根系分布层密切相关,深根系的植物其水分活跃层分布较深。固定沙丘不同部位的土壤含水量及其变化规律不同,土壤含水量从大到小依次为：坡脚〉坡腰〉坡顶。

Spatial and temporal variations of soil water content was studied in different part of the sand dune-fixing and soil covered by different plant community in the Maowusu sandy land. The study shows that, water content in the soil is higher at the beginning of the growing season than that of at the end of the growing season. Temporal variations of soil water content in every plots can be portioned into three periods, they are the period of accumulation （April-June）, consumption （July-September） and stabilization （October-next March）, while the soil can be divided into four lays according to the spatial variations of water content： vertiginous layer, active layer, transitional layer and relative stable layer from the top to the bottom. The changing of the vertiginous lay was closely related to the distributing of the roots growing in the soil, deeper distributing of the roots leading to deeper vertiginous lay. Soil water content was variable in different part of the sand dune-fixing, The biggest water content was shown at the bottom of the slope, the next was,shown at the middle and the smallest water content was shown at the top.