Effects of Sand Barriers of Salix Psammophila on Soil Particle Size and Fractal Dimension

The soil particle size distribution,the fractal dimension and the relationships were analyzed between the fractal dimension of soil particle size,sand content( 0.05 mm),silt content(0.05-0.0002 mm) and clay content( 0.0002 mm) for shifting sand dune,setting up living and dead sand barriers of Salix Psammophila dune in Kubuqi desert.The result showed that: Silt and clay content of setting sand barrier dune was improved compared with that of the shifting sand dune,silt and clay content all declined with the increasing soil depth,and in the order of content of silt and clay at different locations of dune were the lower part the upper part the middle part.Fractal dimension of soil particle size had the trend of increasing for setting up sand barriers,and its sequence was: with living sand barrier with dead sand barrier on shifting sand dunes.In vertical distribution,the fractal dimension of soil particle size decreased gradually for sand dunes with sand barriers,while for shifting sand dunes,it showed characteristics of being high at the surface layer and bottom layer and low at the middle layer.The fractal dimension of soil particle size at different part of sand dunes showed as: the lower part the upper part the middle part.Fractal dimension of soil particle size had the same trend with the soil texture getting finer.The soil fractal dimension was a significant negative correlation with sand content,and significant positive correlation with proportion content of silt and clay.Both the increase of particle content with diameter 0.05 mm and decrease of particle content with diameter0.05 mm caused the increase of fractal dimension of soil particle size after setting up sand barriers.