北京山区土壤粒径分布分形维数特征

Fractal Dimension of Soil Particle-size Distribution Characteristic in the Beijing Mountains

分形是许多自然事物和现象的客观特征之一,土壤颗粒具有一定的分形特性。基于抽样调查的方法,应用土壤颗粒的体积分布计算了北京山区195个土壤样品的粒径分布分形维数。统计结果表明,研究区的土壤质地主要是粉砂土、粉砂壤土、砂壤土、壤砂土、砂土,土壤质地偏粗,分形维数介于2.23～2.69之间,总体偏低。结合已有研究成果分析表明,土壤粒径分布分形维数随质地的粗细程度发生明显变化。质地越粗分形维数越小,质地越细分形维数越大。土壤粒径分布分形维数与土壤砂粒含量呈显著负相关,与土壤粉粒含量呈显著正相关,与粘粒含量呈显著对数关系。土壤粒径分布分形维数与土壤容重呈显著负相关。研究结果表明土壤粒径分布分形维数可以作为判断土壤质地差异的重要指标。

Fractal is the impersonality characteristic ot many nature phenomena ana things, soil particle nave me fractal characteristic. The studying of particle-size distribution （PSD） fractal dimension has much value for the analysis of soil characteristics and with mountainous land are gradually used. However, some assumptions, such as uniform density, have been questioned in calculating soil mass fractal dimension. Additionally, traditional methods to obtain particle-size distribution （PSD） are laborious. For this reason, the concept of the volume fractal dimension of soil particles is developed. There have no correlation study about the PSD in the Beijing mountains at the present time, so the research get soils samples in the field of the Beijing mountainous with stratum sample. The study calculated 195 samples of soil fractal dimension with the soil particle volume distribution on the base of sample survey in the North Lithoid mountain of China. The statistic result indicate that the soil texture are sand,loamy sand,sandy loam,sih loam and silt sand in the Beijing mountains, the proportion is 2% , 33% , 20% , 44% and 1%. Soil texture is leaning coarse. The fractal dimension value is between 2.23 and 2.69. Most of fractal dimension value leaning low. The fractal dimension is variety significant among different soil texture. Integrating with previously result, the fractal dimension value is high when the soll texture is thin. The other way round, the fractal dimension is lower when the soil texture is coarse. For the soil of Beijing mountains, the PSD fractal dimension can be used as index for confirming soil texture. Statistic analysis indicated that the fractal dimension of soil PSD is significant correlated with the soil sand and soil silt content. The fractal dimension of soil PSD decreased with sand content increased with silt content. Both of them pass the significant test with the correlation coefficient - 0. 571 4 and 0. 549 5 respectively. The mathematical relationship between soil particles content is established. The fractal dimension of soil PSD is significant logarithm correlated with the soil s particles clay content. This result indicated that soil fractal dimension is mostly decided by clay content. Otherwise, the PSD variety with soil particles-size, when the clay content is invariableness the PSD increased whir particles-size. Some studies have shown that PSD have significant correlated with soil physics characteristic and nutrient characteristic. Soil bulk density is a major index, which can decide soil physics characteristic. So this study the relationship PSD and soil bulk density. Results indicated that the fractal dimension of soil particles-size distribution is significant correlated with soil bulk density. The fractal dimension of soil particles-size distribution can be used as a quantitative index of soil texture.