绿洲化过程中阿拉尔垦区土壤粒径分形变化特征

Variation of Fractal Dimension of Soil Particle Size Distribution in the Aral Reclamation Area in Oasis Development

通过对绿洲化过程中阿拉尔垦区的7种典型土地利用类型样地的取样,以不同土地利用方式下,不同土层深度的土壤粒径分布PSD(soil particle size distribution)数据为基础,利用单重分形方法,分析土壤粒级与分维值D(fractal dimension valus)的关系以及绿洲化过程中土壤粒级分维值D的变化特征及机理。结果表明:研究区土壤属于砂质壤土。不同深度的分维值D介于1.88～2.41。D与<0.05 mm和0.05～1 mm范围的颗粒体积百分含量分别存在明显的正相关和负相关。0.05 mm粒径是决定绿洲化过程中土壤粒级与分维值D关系的临界粒径。绿洲腹地的土壤粒级主要集中于0.01～0.05 mm的细粉砂粒级,沙漠边缘土壤粒级主要集中于0.05～0.25 mm的细砂粒级。绿洲化过程中土壤细粒物质增多,粗粒物质减少,分形维数呈现逐渐增大趋势。

The study area,Aral Reclamation Area,is located in the northern marginal zone of the Tarim Bain,Xinjiang,China.In this paper,the variation of fractal dimension of soil particle size distribution（PSD） was researched,and the relationships between the fractal dimension of soil particles and the volume percentage of PSD and its affecting factors were analyzed using the single-fractal calculation method and the PSD data obtained with laser diffraction technique at different soil depths under different land use types.The study results will help us to characterize the change of soil physical environment in the transform of different land use types in oasis development,and even provide the suggestions for the rational utilization of different soils.The study results revealed that the soil in the Aral Reclamation Area was dominated by sandy loam,and the soil fractal dimension value varied in a range of 1.883-2.405.There was a significant negative correlation between the soil fractal dimension value and the volume percentage of soil particles within 0.05-0.25 mm and 0.25-1 mm,but a significant positive one between the soil fractal dimension value and the volume percentage of soil particles 0.05 mm.The grain size of 0.05 mm was the critical value for deciding the relationship between the soil particle fractal dimension and the volume percentage of soil PSD.The grain size of soil particles was mainly in a range of 0.01-0.05 mm in hinterland of the oasis,but a range of 0.05-0.25 mm in the marginal zone of the desert.The volume percentage of fine soil particles was increased,that of coarse ones was decreased,and the fractal dimension of soil particles was in a gradual increase trend.