巴丹吉林沙漠南部高大沙丘包气带水分空间分布特征研究

Spatial Distribution of Soil Moisture at Unsaturated Zone in Megadunes,Southeast of Badian Jaran Desert

水是影响沙漠生态系统的主要因子,决定着多年生植物的种类和数量。受恶劣的自然条件和研究手段限制,目前对沙漠地区包气带水分时空动态变化的研究相对薄弱。以巴丹吉林沙漠南部湖泊密集区为研究对象,通过随机采样和同一坡向剖面采样,综合运用DCCA和地统计学分析方法,揭示0～10m较深层包气带沙丘水分的空间变化规律和局部控制因子对包气带水分的影响。结果表明,0～10m沙丘包气带水分变化曲线呈指数、对数和对数正态分布3种类型,分别受地下水或下伏黏土层的毛管作用、湖心距和综合地形因子控制;影响沙漠包气带水分空间变化的主要局部控制因子与小流域的研究结果差异显著。地形、植被等局部控制因子影响对数分布型包气带水分的深度为表层1m,而影响对数正态分布型的深度为3～4m;沙丘水分随相对湖面高程空间变化差异显著,而空间相关距离则不显著。

Water is the main factor influencing desert ecosystem and limits the number and size of perennial plant species in arid areas.At present,very little is known about the spatio-temporal variation of soil moisture under the desert systems limited by natural conditions and study tools.The study examined the spatial pattern of soil water content and its relationship with local control factors in southeastern lakes area of Badain Jaran Desert.Results from geostatistics analysis and Detrended Canonical Correspondence Analysis（DCCA） revealed that soil moisture displayed three types： exponent,logarithm and log-normal vertical distributions,which were regulated by capillary fringe,distance to lake and comprehensive terrain attributes,respectively;soil moisture in unsaturated zone was influenced by local control at 0.75—1 m in logarithm while 3—4 m in log-normal distribution sites;soil moisture varied significantly with relative elevation and was highly sensitive to local control factors,whereas length correlation was insensitive.