岷江上游典型植被下土壤分形特征及对水分入渗的影响

Fractal Characteristics of Soils and Their Effects on Water Infiltration Under Typical Vegetations in Upper Reaches of Minjiang River

以岷江上游5种典型植被类型下(高山栎林、岷江冷杉林、灌竹林、阔叶乔木林、高山草甸)土壤颗粒组成数据为基础,运用分形模型计算出这5种类型土壤颗粒的分形维数,研究了土壤颗粒分形维数与土壤性状的关系。结果表明,15个样地表层土壤颗粒的分形维数D为1.117～1.315。通过逐步多元回归分析,土壤颗粒分形维数仅与<0.002 mm的颗粒含量相关系数达到极显著。根据土壤入渗过程曲线将入渗过程划分为3个阶段:(1)入渗瞬变阶段(0～8 min);(2)入渗渐变阶段(8～30 min);(3)入渗稳定阶段(30～120 min),表明土壤入渗过程主要受土壤机械组成、团聚体和孔隙组成的综合影响。在整个入渗过程中,高山栎林、灌竹林和阔叶林的渗透速率要高于冷杉林和草甸。

The relationship between soil fractal dimension and soil properties under five vegetation types（Quercus aquifolioides,Abies taxoniana,Sinarundinaria fangiana,board leaved forest and subalpine meadow） in upper reaches of Minjiang River was studied based on data of the soil particle composition and fractal theory.The fractal dimension of surface soil particle size distributions of the fifteen plots ranged from 1.117 to 1.315.This fractal dimension only had a significant correlation with the content of 0.002 mm soil particles by stepwise multivariate regression.The infiltration process was divided into three phases according to the soil infiltration process curve：（1） the initial phase（0～8 min）;（2） the transition phase（8～30 min）;（3） the stable phase（30～120 min）.Soil infiltration process was influenced comprehensively by soil partical size distribution（PSD）,aggregate size distribution（ASD） and soil pore size distribution（SPD）.During the process of soil water infiltration,the infiltration rate of Quercus aquifolioides,Sinarundinaria fangiana and board leaved forest was faster than that of Abies taxoniana and subalpine meadow.