重庆缙云山典型林地土壤分形特征对水分入渗影响

Impacts of fractal features on moisture infiltration of soil of typical forest stands of Jinyun Mountain in Chongqing,southwestern China

该文以土壤颗粒组成分维和孔隙组成分维来表征土壤结构特征，研究土壤结构分形特征对重庆缙云山典型林型林地土壤入渗率和入渗过程的影响．研究表明，缙云山土壤分形特征表现为：机械组成分维明显大于微团聚体分维和孔隙分维，各层之间孔隙分维变异最大，从表层到底层，孔隙分维呈下降趋势；根据土壤入渗过程曲线将入渗过程划分为3个阶段：①初渗阶段（0-5min）；②过渡阶段（5-30min）；③稳渗阶段（30-180min）．在初渗阶段，入渗率主要受A1层土壤结构影响；在过渡阶段，入渗率主要受AB层孔隙组成和B层土壤结构影响；稳渗阶段，C层土壤结构是入渗率的主要影响因子．土壤入渗过程受土壤机械组成、微团聚体和孔隙组成的综合影响．在入渗整个过程中灌木林地的入渗率远大于其他林地和农耕地．在初渗阶段，农耕地大于其他林地；到稳渗阶段，林地大于农耕地．

The soil structure is expressed with fractal dimensions of particle size distribution （PSD）, aggregate size distribution （ASD） and soil pore size distribution （SPD）. The effect of soil fractal features on soil infiltration velocity and its process was studied. The result of the fractal feature shows that fractal dimensions of PSD is obviously greater than that of ASD and SPD, and in different soil genetic horizons, the fractal dimension of ASD has the greatest variability, and takes on down trend from top to bottom genetic horizon. According to the soil infiltration process curve, the infiltration process is divided into 3 phases, 1 ） the initial phase （0-5 min）,2） the transition phase （5-30 min） and 3）the stable phase （30-180 min）. In the initial phase of infiltration, the soil structure of A1 soil genetic horizon was the major influencing factor; in transition phase of infiltration, the pore distribution of AB horizon and soil structure of B horizon were the major influencing factors; in the stable phase of infiltration, the soil structure of C horizon is the major factor affecting the infiltration velocity. Soil infiltration process is influenced comprehensively by soil PSD, ASD and SPD. In the whole soil water infiltration, the infiltration of shrub forest land was much faster than other forest lands; in the initial infiltration phase, arable land soil infiltration was far faster than forest land; in the stable infiltration phase, the infiltration velocity of forest land was faster than arable land.