羊柴(Hedysarumleave)林沙地水分状况及其动态变化的研究

A Study on the Water Regime and Its Heterogeneity of Sandy Land Cultivated with Hedysarum leave Shrub

对毛乌素沙地中生长的人工羊柴林的沙地水分状况及其动态变化进行了研究．结果表明：受沙地机械组成粗的影响，羊柴林沙地的田间持水量为３．９７５％，凋萎湿度为０．７８１％；水分状况是４～７月初日趋变差，０．１％和２．０％含水量等值线持续下移；有效含水量在７月初达到最低值．７月份以后随降雨补给，其水分状况明显好转，有效水贮量在８月份达到最大值．受羊柴根系吸水的影响，沙地水分存在着空间异质性，在羊柴植丛基部、距羊柴植丛５０ｃｍ处和距羊柴植丛２００ｃｍ处的三个位点上，沙地平均有效水贮量依次增大．控制羊柴林的植丛密度，维持沙地水分的空间异质性，对实现羊柴林的持续生存有着极其重要的意义．适宜的植丛密度下，羊柴林不会恶化其沙地水分状况而限制其持续生存．

A study was carried on the water regime and its heterogeneity of sandy land cultivated with Hedysarum leave artificial shrub in Maowusu Sands.The results were showed as below.Based on the coarse mechanical composition,the sandy land had only a little water retention ability with field capacity 3.975% and wilting percentage 0.781%.Its available moisture got less steadily with the lapse of growing time from April 1st to the beginning of July.The isoplethes with 1.0% and 2.0% moisture continuously went downward.The water regime took a favourable turn with raining after July,and the available moisture storage got maximum value in August.The moisture in sandy land had spatial heterogeneity created by H.leave roots′ absorbing water.In order of the basal site and the 50 cm site and the 200 cm site from thicket of H.leave, the medial storage of the available moisture in the sandy land increased successively.In order to maintain the sustainable survival of H.leave Shrub,the thicket density of H.leave Shrub must be limited to keep the spatial heterogeneity of moisture.Within a proper thicket density, H.leave Shrub will not deteriorate water regime of the sandy land.