人工小叶锦鸡儿(Caragana microphylla)灌丛土壤水分动态研究

采用由植被空间序列断时间系列的方法。分析了1984，1987，1995和1999年建立的人工小叶锦鸡儿固沙植被土壤水分的时空变化特征，结果表明，受沙地土壤机械组成的影响，沙地土壤组成以物理性沙粒为主，＞0.01mm沙粒占97％以上，凋萎湿度为1．55％，田间持水量5．5%,大有效水为3．95％，随着固沙植被优势度的增加，小叶锦鸡儿灌丛下土壤含水量持续下降，1984年建立的植被区土壤含水量明显低于1999年建立的植被区；在年内土壤水分季节变化中，4个阶段植被区土壤水分状况在4－6月不断降低，到6月达到最低值，7－10月逐渐回升；对于建立较早的植被区（1984和1987年），土壤水分垂直变化表现出随着土层深度的增加，土壤含水量逐递减的趋势，特别是70cm下土层中，土壤含水下降明显，含水量低于凋萎湿度，由于对根际区域土壤水分的利用，加剧了固沙植被区深层土壤（70cm下）水分的亏缺，进而影响植被物种的组成，随着小叶锦鸡儿灌丛年龄的增加，浅根性植物所占比重增加。

Soil moisture dynamics under artificial Caragana microphylla shrub

Applying the methods of deducing time series from vegetation space alignment,we analyzed the spatial and temporal variation features of soil moisture under artificial Caragana microphylla shrubs built in 1984,1987,1995,1999. The results showed that affected by mechanical composition of mobile sandy dunes,the soil of sandy land was mainly composed of sandy particle,and the particles of >0.01 mm were accounted for 97%. The withered moisture was 1.55%. The field waterhold capacity was 5.5%,and the available moisture storage was 3.95%. With the increase of the dominance of fix sand vegetation,the moisture content of soil under artificial Caragana microphylla shrubs was decreased. The soil moisture of vegetation built in 1984 was lower than that built in 1999. The soil moisture conditions of four stages vegetation were continued depressing from April to June in a year,the lowest point presenced in June ,and then gradually increased from July to October. The vertical change of soil moisture showed the tendency of increasing with soil depth. The soil moisture decreased by the degrees of early built vegetation (1984,1987). Especially in 70 cm soil depth,the moisture content of soil decreased obviously. Caragana microphylla shrubs absorbed water and aggravated the shortage of soil moisture content near the root system,which affected the component of vegetation in Caragana microphylla shrubs .The species of herbaceous plants and annual plants increased during the growth of Caragana microphylla shrub.