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对川南坡地的农耕地以及退耕成慈竹林、杂交竹林、桤木+慈竹混交林和弃耕地5年后土壤颗粒分形维数、微生物和酶活性变化进行了研究,探讨了分形维数与土壤肥力之间的关系。结果表明,退耕后土壤有机质、粘粒(<0.001 mm)含量、颗粒分形维数、颗粒组成中物理性粘粒(<0.01 mm)与物理性砂粒(>0.01 mm)含量的比值、细菌、真菌、放线菌和总微生物数量以及蔗糖酶、脲酶和磷酸酶活性增加,呈现出慈竹林>杂交竹林>桤木+慈竹混交林>弃耕地>农耕地的规律。土壤颗粒分形维数、物理性粘粒与物理性砂粒含量的比值、有机质含量与微生物数量、酶活性之间相关性较好,颗粒分形维数及物理性粘粒与物理性砂粒含量的比值也具有较好的相关性。说明农耕地退耕对提高土壤粘粒含量、肥力水平及改善颗粒组成比例具有较好的作用;土壤颗粒分形维数可以作为坡地退耕后土壤肥力变化的评价指标;土壤颗粒组成中物理性粘粒与物理性砂粒含量的比值能反映土壤肥力特征,也可评价坡地退耕后土壤肥力的变化状况。
The changes of fractal dimension, microorganism and enzyme activities in the cultivated land of slope farmland in south Sichuan and the conversion of cultivated land to the plots of bamboo forest, hybrid bamboo forest, alder and bamboo mixed forest and abandoned farmland for five years were studied. The effects of fractal dimension and soil The relationship between fertility. The results showed that the contents of soil organic matter, clay (<0.001 mm), fractal dimension, ratio of physical clay (<0.01 mm) to physical sand (> 0.01 mm) , Actinomycetes and total microorganisms, as well as sucrase, urease and phosphatase activity increased, showing the law of Cixin forest> hybrid bamboo> Alnus japonicus + Cunninghamia lanceolata mixed forest> abandoned farmland> agricultural land. The fractal dimension of soil particles, the ratio of physical clay to physical sand content, the correlation between organic matter content and microbial population, and enzyme activity were good, the fractal dimension of particles and the ratio of physical clay to physical sand content Have a good correlation. It is concluded that returning cultivated land to farmland can improve soil clay content, fertility level and improve the proportion of grain composition. The fractal dimension of soil grain can be used as the evaluation index of soil fertility change after slope farmland conversion. Physical clay and The ratio of physical sand content can reflect the characteristics of soil fertility, but also evaluate the change of soil fertility after slope farmland conversion.