北疆退化荒漠草地土壤颗粒的分形特征

Fractal characteristics of soil particles of degraded desert grassland in Northern Xinjiang

研究了新疆北部退化荒漠草地土壤颗粒的分形特征，探讨了土壤颗粒分形维数与土壤理化性质的关系。结果表明，该退化草地土壤颗粒的分形维数在2．316～2．753，随着草地退化程度加剧，土壤黏粒含量增高，分形维数逐渐增大。表层土壤的分形维数与粉粒含量呈极显著负相关，与黏粒含量显著正相关。土壤颗粒的分形维数与土壤物理性质没有相关性。由于土壤表层（0～10cm）受放牧影响较大，致使其化学性质与土壤颗粒的分形维数没有相关性。土壤颗粒的分形维数与土壤下层（10-30cm）的全磷、pH值、全钾和速效钾含量显著正相关。土壤颗粒的分形维数的变化在一定程度上能够很好地表征退化草地土壤的理化性质的变化趋势，可以作为评价退化草地土壤性状的一个综合指标。

Fractal characteristics of degraded desert grassland in Northern Xinjiang were studied based on the soil particle size distribution. The results showed that the soil clay particle content increased,and the fractal dimension of soil particles in surface layer augmented along with desert grassland degraded. In topsoil, there was a very significant negative correlation between fractal dimension and the soil silt particle content; fractal dimension had a significant correlation with content of clay particles;no significant correlations were observed between the fractal dimension and the soil physical properties. As a result of influence of grazing,there is no correlation between chemical properties and fractal characteristics in topsoil. In lower soil,there was a significant correlation between fractal dimension and soil chemical properties including the contents of total phosphorus,pH,total kalium and available kalium. Obviously, fractal dimension could commendably reflected the transformation trend of the soil physicochemical properties,so it can be used as a comprehensively quantitative index to evaluate the soil properties of degraded desert grassland.