干旱沙区植被恢复过程中土壤颗粒分形特征

统计分析了干旱沙漠地区植被恢复过程中土壤颗粒分形特征及其与土壤沙粒(>0.05mm)、粉粒(0.05~0.002mm)和粘粒(<0.002mm)含量和土壤养分状况间的关系。结果表明:土壤颗粒分形维数随恢复时间延长有增大的趋势,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。0.05mm粒径成为土壤各粒径的分界值——即土壤分形维数的临界粒径,大于这一粒径颗粒含量越高,土壤分形维数越小;而小于这一粒径的颗粒含量越高,分形维数越大。土壤各养分状况均与土壤颗粒分形维数有极显著的线性正相关关系(p<0.0001),表明了土壤颗粒分形维数能客观地反映土壤肥力特征。在干旱沙漠地区,伴随着植被恢复和流沙固定,土壤颗粒分形维数可作为一个评价土壤演变程度的综合定量指标。

Fractal dimension of soil particle size distribution during the process of vegetation restoration in arid sand dune area

This paper analyses the relationships etween the fractal dimension of soil particle size distribution,sand content,silt content,clay content and soil properties during the process of vegetation restoration in arid sand dune area.The result showed that fractal dimension of soil particle increased during the process of vegetation restoration with soil texture getting thinner and fertile.The longer the time of vegetation restored,the greater the fractal dimension of soil particle,the higher the <0.05mm content.The fractal dimensions tend to decrease with the texture coarser at the soil profile.Fractal dimension and soil texture have significant difference within different soil layers.There is a significant positive linear correlation between fractal dimension and the content of <0.05mm soil matter(p<0.0001), and a negative linear correlation between fractal dimension and >0.05mm content.So,<0.05mm content of soil particle size can be regarded as a critical diameter for determining fractal dimension which reflects the content of distribution of particle size fraction,the more the <0.05mm content,the higher the fractal dimension;adversely,the more the >0.05mm content,the lower the fractal dimension.With soil particle size getting thinner,the soil fertility changed remarkably associated with the process of sand dune stabilization.There are significant positive linear correlations between fractal dimension with all soil nutrient status(p<0.0001).Fractal dimension acts as a synthetical index.There a remarkable positive linear correlation with soil properties(p<0.0001).Therefore,the fractal dimension could be used to describe the texture and fertility states,evaluate degree of vegetation restoration in the arid sand dune area,and could be used as an integrated quantitative index to evaluate the degree of soil succession with the re-vegetation practice.