Soil moisture in plantation area and its affecting factors in the Gurbantonggute Desert.

Soil moisture is one of the most important limitative factors for maintaining growth and development of mixed plantation in the Gurbantonggute Desert,and at the same time,the planting density and terrain factors have the obvious influence that can't be ignored on the variation and redistribution of soil moisture.Choosing three typical slopes in Haloxylon Ammodendron and Calligonum mixed plantation of two years'old in the southern part of the Gurbantonggute Desert as study objects from February to December,2004.15 soil moisture monitoring places were placed in condition of different planting density and different terrain parts that contain dune crest,middle and lower slope,middle and upper slope.The results are as follows:Spatial and temporal distribution of soil moisture is closely related with precipitation,planting density,slope direction,slope degree,and relative elevation.And soil moisture can be divided into 3 layers in terms of vertical direction:0 - 30 cm is active layer;30-60 cm is subactive layer;and 60 -120 cm is relative stable layer.The main factors analysis shows that the effect of terrain factors and planting density on soil moisture are as follows:slope degreeslope directionplanting densityrelative elevation in the layer of 0 - 30 cm depth;slope directionplanting densityzslope degreerelative elevation in the layer of 30 - 60 cm depth;planting densityrelative elevationslope degreeslope direction in the layer of 60-120 cm depth.