紫色土坡耕地不同坡位不同高度地埂土壤颗粒组成及分形特征

对比分析西南紫色土区植物固结地埂和等高植物篱的结构差异，并运用分形理论研究了西南紫色土坡耕地不同坡位不同高度地埂土壤的分形特征。结果表明:有地埂存在的坡耕地地埂土壤的颗粒组成主要分布在0.002~0.02 mm粒径范围内，较无地埂的对照坡耕地该粒径范围的含量高2.41%。说明地埂的存在增强了其对坡面上方侵蚀泥沙的拦截作用。而不同坡位地埂土壤的分形维数变化如下:坡面上部 > 坡面中部 > 坡面下部，且同一坡位有地埂土壤的分形维数小于无地埂土壤的分形维数。不同地埂高度土壤的分形特征变化规律为:CK > LS-H10G > LS-H15G。地埂土壤颗粒分形维数D值与黏粒和砂粒体积百分含量相关性较好，地埂土壤的分形维数可作为西南紫色土坡耕地地埂土壤质量评价的定量指标之一。

Particle Distribution and Fractal Features of Hedge Soils With Different Hedge Heights Along the Slope Position of the Purple Sloping Cultivated Lands

We compared the structure of terracing hedgerow with contour hedgerow and used the fractal theory to deal with the fractal features of hedge soils with different hedge heights along the slope position of the sloping cultivated lands in the purple soils of southeastern China. The results showed that the main particle distribution belonged to 0.002~0.02 mm of the terracing hedgerow and was 2.41% higher than the contrast treatment (sloping cultivated lands without hedgerow), which meant that the hedges could enhance the interception of eroded soils. Meanwhile, the fractal dimension with the different slope positions changed as the order:the upper slope position > the middle slope position > the lower slope position. And the fractal dimensions of the sloping cultivated lands with different hedge heights were lower than those without hedge height. The higher the hedge height was, the lower value of fractal dimension was, and the highest values of fractal dimension was the contrast treatment without hedge, followed by the sloping cultivated lands with 10 cm hedge height and with 15 cm hedge height. And correlation analysis results showed that the fractal dimension had remarkable negative correlation with contents of clay and sand. The fractal theory was also considered as a new tool to evaluate the structure and features of hedge soil on the sloping cultivated lands in the southeastern China.