北京地区表层土壤分形特征研究

Fractal Dimension Characteristic of Soil Particle-size Distribution in Beijing Region

土壤是一种具有分形特征的复杂系统。分形维数可以反映很多土壤特性。本研究考虑了7种土壤类型、4种土地利用类型,在北京地区选取了30个典型样点,对复杂地理环境表层土壤的分形特征进行了分析,探讨了分形维数与土壤质地、土壤理化性质等方面的关系。研究结果表明,在复杂地理环境条件下,土壤颗粒分形维数总体变异性较弱;分形维数与黏粒含量呈显著正相关,与(砂粒含量+粉粒含量)和黏粒含量的比值呈显著负相关。分形维数可以反映土壤质地,但仅可指示部分重要土壤的理化性质。

Soil has the fractal characteristic. Soil fractal dimension （SFD） can be used as an important index of soil. In this study, 30 soil samples from 7 soil types and 4 landuses were collected. Soil particle-size distribution, soil bulk density, saturated water content, saturated hydraulic conductivity, and soil organic matter were measured. The SFD was then calculated according to soil particle-size distribution. Results showed that the fractal dimension in Beijing region had a low variation coefficient. Significantly positive correlative relationships between the SFD and clay content and between the SFD and saturated hydraulic conductivity were found. The fractal dimension was negatively correlated with the ratio of （sand content ＋ silt content）/clay content. The SFD can be a potential parameter to reflect soil texture, but is not a rational indicator to reflect soil physical properties under complex geographical environment.