毛竹杉木混交林土壤团粒结构的分形特征研究

运用分形理论对杉木纯林（19年生）、毛竹纯林（19年生）、6种杉木毛竹混交林（杉木19年生）的土壤团粒结构进行研究,建立了土壤团粒结构的分形维数与土壤团聚体含量、土壤结构体破坏率之间的回归模型,在此基础上,运用弹性分析与边际分析法进一步探讨了土壤团粒结构的分形维数对土壤性质变化所产生的影响效应。结果表明:土壤>0.25mm水稳定性团聚体含量越大,团粒结构的分形维数越小,土壤的结构与稳定性就越好;土壤团粒结构分形维数与水稳定性团聚体（>0.25 mm及>5.0mm）含量及结构体破坏率之间均存在极显著的回归关系;土壤团粒结构分形维数对土壤性质的变化产生较大的影响效应。本研究为毛竹杉木混交林的栽培管理,土壤肥力的科学评价提供依据。

Fractal Features of Soil Aggregate Structure under Mixed Plantations of Phyllostachys edulis and Cunninghamia lanceolata

Fractal characteristics of soil aggregate structure under Cunninghamia lanceolata and Phyllostachys edulis mixed plantations in Fujian were studied by using fractal theory. Six plots with different Cunninghamia lanceolata and Phyllostachys edulis densities in mixed plantations, and two plots of pure stands of the two species were chosen. All the plants in plots were 19-year-old. Regression models for fractal dimension (D) of aggregated structure and water stable aggregate (>0.25 mm) content, and for D and destroyed structure percentage, were established. The effect of fractal dimension of aggregates on soil properties were evaluated by elasticity and limit analyses. The results showed that the higher the content of water stable aggregates (>0.25 mm or >5.0 mm) in soil, the smaller the fractal dimension of aggregates, and thus the better structure and stability the soil. The regression relationships of all the modelswere remarkable. Fractal dimension variation of aggregate structure had a great effect on soil properties, which will provide a scientific basis for the culture of such mixed forest.