河西走廊斑块植被区表层土壤粒径及其分形维数的空间变异特征

Spatial Variability of Soil Particle Size and Its Fractal Dimension of Patchy Vegetation in Hexi Corridor

结合描述性统计和地统计学的方法,对河西走廊典型斑块植被区表层土壤粒径及其分形维数的空间变异特征进行分析。结果表明：①该样地表层土壤粒径（d）主要以细砂（0.25 mm≥d〉0.075 mm）和中砂（0.5 mm≥d〉0.25 mm）为主,两者占土壤颗粒组成的88.33%,分形维数为1.09-2.12;②分形维数与粗砂（d〉0.5 mm）、中砂、细砂的质量含量分别成负相关关系,且相关系数都较小,而与粉砂（d≤0.075 mm）含量呈极显著的正相关关系（R=0.94,P〈0.01）;③粗砂含量和细砂含量变异函数的最佳理论拟合模型均为指数模型,且空间自相关性较强,空间自相关分别为29.4 m和37.5 m;分形维数、中砂含量和粉砂含量变异函数的最佳理论拟合模型均为线状模型,空间自相关性较弱,且自相关为167.24 m,由随机因素引起的变异占总变异的比例较大;④土壤颗粒组成的普通Kriging插值结果表明,粗砂含量和中砂含量在样地东北方位分布的比重较大,与细砂含量和粉砂含量的分布成相反的分布状态。

In this paper,the methods of descriptive statistics and geostatistics were applied to analyze the spatial variability of surface soil particle size and its fractal dimension of patchy vegetation in Hexi Corridor,which located in the middle reaches of Heihe River. The analysis results revealed that ：（ 1） surface soil particle size（ d） mainly distributed in the fine sand（ 0. 25 mm ≥d 〉0. 075 mm） and medium sand（ 0. 5 mm≥d〉 0. 25 mm） in the area,because their sum in the proportion of 88. 33% of soil particle composition,and fractal dimension mainly changed in the range of： 1. 09-2. 12;（ 2） the relationship between the fractal dimension and coarse sand（ d〉 0. 5 mm） content,medium sand content,fine sand content all showed a negative correlation,and the correlation coefficients were low,but highly significant positive correlation with silt content（ d ≤ 0. 075 mm）,the correlation coefficient R = 0. 94;（ 3） the spatial variability has significant difference of fractal dimension and content of different soil particle size distribution,for example,the coarse sand content and fine sand content,the variogram model were exponential model,with the strong spatial autocorrelation,and their spatial variability scale were relatively small,respectively were 29. 4 m and 37. 5 m; fractal dimension,medium sand and silt content the variogram model were linear models,the spatial autocorrelation were very weak,and spatial autocorrelation range was 167. 24 m,so a large proportion of the variation caused by the random factors;（ 4） Ordinary Kriging interpolation results of soil particle composition showed that coarse sand content,medium sand content in the study area have a larger proportion of spatial distribution in Northeast,which were opposite to fine sand content and silt content distribution.