沙柳沙障对沙丘土壤颗粒粒径及分形维数的影响

统计分析了库布齐沙漠流动沙丘、设置沙柳活沙障和死沙障沙丘的土壤颗粒粒径分布、分形维数及其与土壤砂粒(>0.05 mm)、粉粒(0.05~0.002 mm)和黏粒(<0.002 mm)含量的关系。结果表明:与流动沙丘相比,设置沙障沙丘的粉粒和黏粒含量增加,且随着土层的加深而表现为下降趋势,不同部位则均呈沙丘下部>上部>中部的趋势。土壤颗粒分形维数因设置沙障而呈增大趋势,且表现为活沙障沙丘>死沙障沙丘>流动沙丘;垂直分布上,设置沙障沙丘的土壤分形维数随土层加深而逐渐减小,而流动沙丘表现为表层与下层大而中层小的特征,沙丘不同部位的分形维数则均表现为沙丘下部>上部>中部。土壤颗粒分形维数大小与土壤质地的细粒化有一致的变化趋势,且与砂粒含量呈极显著负相关关系,而与黏粒含量、粉粒含量呈极显著正相关关系。<0.05 mm粒径物质含量的增加和>0.05 mm粒径物质含量的降低共同导致了土壤颗粒分形维数在设置沙障后的增大。

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 diameter>0.05 mm caused the increase of fractal dimension of soil particle size after setting up sand barriers.