渝东南岩溶山区耕地利用变化下土壤颗粒体积分形特征研究

Study on volume fractal features of soil particle under different land use types in southeast karst mountain of Chongqing

通过对重庆东南部喀斯特山区的野外调查采样和室内粒度分析,利用土壤颗粒体积分维模型,分析了该区域耕地土壤与撂荒地土壤颗粒体积分形维数特征,探讨了颗粒体积分形特征与颗粒体积含量的关系。研究结果表明:土壤颗粒体积分形维数与土壤中粘粒(<0.002mm)含量呈明显的线性相关,表现为粘粒含量越高的土壤,其分形维数也越高。土壤粘粒含量与土壤颗粒体积分形维数在不同土地利用方式的土壤剖面上表现出相同的变化规律。土壤分形维数不仅受粘粒含量的支配,还与土壤质地的均一程度有关,分形维数与土壤质地均匀指数表现出一定的相关性,但相关性较弱。耕地土壤分形维数值(平均值为2.506 5)大于撂荒地分形维数值(平均值为2.483 5),说明岩溶区人类农耕活动对土壤质地尤其是粘粒含量影响明显。土壤体积分形维数可以作为区域耕地土壤质量评价指标之一。

Through field survey, sampling and laboratory analysis on soil grain size in southeast karst moun- tain of Chongqing, by means of soil particle volume fraction dimensional model the soil particle volume frac- tal dimension characteristics of the arable land soil and abandoned land soil are analyzed. Then the relation- ship of the soil particle volume fractal dimension characteristics and particle volume content are discussed. The results show that the soil particle volume fractal dimension and the content of soil clay particle （〈20. 002mm） is significant linear correlation, which proves that the more clay soil comtain, the higher frac- tal dimension it is. And the relationship between the content of clay particle and the soil particle volume frac- tal dimension in the soil profile under different land use types show the same change rule. The fractal dimen- sion of soil is not only affected by clay particle content but also by the homogenity of soil texture. The fractal dimension of soil texture shows certain correlation with uniform index, but the association is relatively weak. The fractal dimension of arable land soil （mean 2. 506 5） is greater than that in the abandoned land （mean 2. 483 5）, indicating that the impact of human agricultural activities on soil texture, especially on clay con- tent, is obvious. Soil volume fractal dimension can serve as a regional indicator for arable land soil quality as- sessment.