绿洲-荒漠交错带不同沙丘土壤水分时空动态变化规律

绿洲-漠交错带是植被恢复的一个重要区域，而植被恢复的关键又是了解沙丘土壤水分的变化规律。从2003年10月到2004年10月，对甘肃省张掖绿洲-荒漠交错带沙丘土壤水分进行了连续观测，并研究了生态垫在沙漠治理中的应用。结果表明：土壤水分时空动态变化主要受降雨、植被以及地表覆盖等因素的影响，沙丘土壤水分月变化滞后于降水变化。沙丘剖面土壤水分变异系数随土层深度的增加而减小，铺设生态垫减小了沙丘土壤水分的空间变异（CV=4．43％），流动沙丘0～40cm的含水量（0．19％～1.27％）低于固定沙丘（1.61％～1．75％），而其它各层的含水量（1．52％～1．73％）都高于固定沙丘（1．11％～1．38％）；流动沙丘含水量（1．27％～1．73％）从上部到下部依次升高，而固定沙丘（1．75％～1．11％）则与此相反；利用标准差和变异系数对沙丘土壤水分垂直变化进行分层，得出了土壤水分剖面分别为速变层、活跃层和次活跃层，并运用相关分析方法分析了生态垫覆盖下沙丘各层间土壤含水量及其与沙丘剖面平均含水量的关系。研究初步认为，生态垫能有效地保持沙丘土壤水分，将为沙漠治理提供一种新型的治沙模式。

Tamporal and Spatial Variation of Soil Water in Sand Dunes at Eco-Tone Between Oasis and Desert

The eco-tone between oasis and desert is a important zone for vegetation restoration.The key for vegetation restoration is to know the soil water content of dune.The temporal and spatial variation of soil water content in sanddunes in Zhangye city was measured continuously from October in 2003 to October in 2004,and the application of eco-mat to combating desertification was studied.The records showed that the dynamic variation of soil water content was affected by precipitation,vegetation and surface coverage,and the monthly change of soil water content lagged behind the precipitation.The variation coefficients decreased with increasing soil depth,and decreased when covered with eco-mat(CV=4.43%).The soil water content was significantly different between shifting dune and fixed dune.Soil water content of shifting dune in upper layer(1.19%~1.27%)was lower than fixed dunes(1.61%~1.75%),while the other layers was reverse;the soil water content of shifting dune(1.27%~1.73%) increased from the foot of dune to the crest,while the fixed dune(1.75%~1.11%) was reverse.Additionally,by using standard deviation and variation coefficient,the vertical layers of soil water content were divided into three layers,i.e.,rapid change layer,active layer and sub-active layer,respectively.Correlation analysis was applied to analyze the relationship of soil water content among different layers and coefficients of soil water content and means of all layers under eco-mat condition.The study showed that the eco-mat could maintain soil water content of dunes effectively,and meanwhile,provided a new mode of desertification combating.