The Mu Us Sandland(107°20′~111°30′E,37°30′~39°20′N,1 300~1 600 m a.s.l.)is a very vulnerable ecotone.Climate change has been occurring dramatically in this area.For example,the mean annual air temperature increased by 0.5~1.8℃.Based on the prediction of GCM,if atmospheric CO\-2 concentration were doubled,the future mean annual air temperature would increase by 3.5~5.0℃ in the Mu Us Sandland.As a dominant xeric tree species,\%Salix matsudana\% will be intensively affected by the future climate change such as...