岷江上游干旱河谷土壤粒径分布分形维数特征

具有分形特征是土壤的客观属性之一,为了探讨分形维数与土壤性质之间的关系与影响因素。运用土壤体积粒径分布分维模型计算了岷江上游干旱河谷不同土地利用方式下土壤表层(0～20cm)161个样品的分形维数,分析了分形维数的空间变化特点及其与粒度组成、有机质和土壤养分之间的相关性。土壤粒径分布分形维数可以作为表征土壤结构和性质的重要指标。结果表明:不同土地利用方式下土壤的粒径分布具有不同的分形特征,分形维数在2.5011～2.7825之间,粉壤土>壤土>砂壤土,耕地大于灌林地。土壤颗粒体积分形维数与黏粒(<0.002mm)和粉粒(0.002～0.05mm)的体积百分含量以及土壤全钾含量呈极显著正相关关系,与砂粒(>0.05mm)的体积百分含量呈极显著负相关关系,而与土壤有机质,全氮,全磷,速效磷和速效钾含量的相关性未达到显著水平。研究结果可以为研究区植被恢复和土地利用开发提供一定的依据。

Fractal dimension of soil particle-size distribution characteristics in dry valley of upper Minjiang river

Fractal is one of the impersonality characteristics of soils. In order to study correlation of fractal dimension with soil properties and related affecting factors, the fractal dimensions of particle-size (Ds) for 161 surface (0-20 cm) soil samples under different land use patterns collected from the dry valley of upper Minjiang River were calculated by the equation of volume fractal dimension. The spatial distribution of the Ds values as well as the correlations between Ds and volumetric contents of particle size, organic matter and soil nutrients were analyzed. Ds can be used as an important parameter for characterizing the soil structures and properties. The research showed that: soil particle size distribution had different fractal characteristics under different land use patterns, its fractal dimensions were between 2.5421 to 2.6691, where silty loam > loam> sandy loam, and Ds values of farmland were bigger than the woodland. Ds had a highly significant positive correlation with the volume percentage of soil clay (<0.002 mm) and silt (0.002-0.05 mm), as well as the total potassium contents, whereas a highly significant negative correlation with the volume percentage of soil sand (>0.05 mm) contents. But the correlations of Ds with the contents of soil organic matter, soil total nitrogen, total phosphorus, available phosphorus and potassium were not significant. The result can provide a theoretical guidance for vegetation restoration and land use development.