重庆缙云山典型林分土壤结构分形特征

 为了解长江三峡库区森林土壤的物理性质,运用分形原理,研究重庆缙云山4种典型林分林地土壤分形特征,建立土壤结构分维与土壤性质预测模型,运用弹性分析与边际分析,探讨土壤结构分形变化与土壤性质变化的关系。研究表明:土壤机械组成分维、微团聚体组成分维和孔隙组成分维可作为评价土壤结构的指标。不同林分林地土壤颗粒机械组成分维值为2.7～2.9,土壤微团聚体组成分维为2.5～2.8,土壤孔隙组成分维为2.3～2.8。从质地、微团聚体组成和孔隙组成来看,常绿阔叶灌丛土壤结构要明显优于其他林地土壤,而楠竹林最差。不同林分及农地土壤的微团聚体组成、机械颗粒组成和孔隙组成分维与土壤性质存在较明显相关关系,相关系数都在0.5以上。由弹性系数和边际量可以看出,机械分维的影响要大于微团聚体分维和孔隙组分维。这对进一步探讨分形学在土壤结构与土壤性质的应用方面有重要的意义。

Soil fractal features of typical forest stands in Jinyun mountain of Chongqing city

For exploring the forest soil physical property in Three Gorges Reservoir areas, based on the fractal theory, the soil fractal features of the 4 typical forests (mixed Pinus massoniana-broadleaf forests, evergreen broadleaf forests, Phyllostachys pubescens forests and evergreen broadleaf shrub forests) in Jinyun mountain, Chongqing City were studied as well compared to arable land. It has been proposed that the model can be used for the analysis of the relationship between the fractal dimensions and the properties of forest soil. The impacts of fractal dimensions change on soil properties change were analyzed with the elasticity analysis and marginal yield analysis. The results showed that the fractal dimension of partical size distribution (PSD), the micro-aggregate size distribution (ASD) and the soil pore size distribution (SPD) can be used as the indexes of soil structure evaluation. In the typical forests of Jinyun mountain, the soil PSD is 2.7-2.9, the ASD is 2.5-2.8, and the SPD is 2.3-2.8. The soil structure of evergreen broadleaf shrub forests are all the best in PSD, ASD and SPD, and the soil of Phyllostachys pubescens forests is the worst. There also were the certain relationships between the PSD, ASD, SPD and some soil properties in the different forests and farmland. The related coefficients is over 0.5. Based on the elasticity analysis and marginal yield analysis, the effect of PSD was more than those of ASD and SPD. Obviously, the further research on the fractal theory application in soil structure and soil properties has important significance.