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.