重庆四面山4种人工林地土壤粒径分形特征

Fractal Characteristics of Particle-size in Four Plantation in Simian Mountain of Chongqing

运用分形模型,对重庆四面山4种人工林地土壤结构进行分析,结果表明:4种人工林地的土壤粒径分形维数在土层0-40cm深度平均在2.625～2.693,随土壤层深度的变化土壤粒径分形维数差异不显著,而随林地类型的不同差异显著;从总体上看,4种人工林地土壤粒径分形维数变化由高到低依次为木荷石栎混交林(2.693)>杉木马尾松木荷混交林(2.688)>杉木马尾松混交林(2.659)>杉木纯林(2.625),木荷石栎混交林的土壤结构最好,杉木纯林的最差;在四面山地区阔叶混交林不仅对土壤良好结构的形成具有促进作用,而且其土壤的抗蚀能力和渗透性能也存在着明显的优势,对于该地区水土保持林的营造具有重要的指导意义。土壤粒径分形维数与土壤中黏粒含量存在显著的线性相关关系,表现为黏粒含量越高的土壤,其分形维数也越高,当土壤中直径<0.001mm黏粒含量的质量百分数在11.38%左右时,其土壤结构状况良好。

Fractal model has been applied to study soil structure by using mass-based soil particle-size distribution（PSD） data in four plantations in Simian Mountain of Chongqing.Results showed that the average range of fractal dimension of soil PSD is between 2.625-2.693 at the depth of 0-40 cm,which is not significantly different by the varition of soil depth,but significant varition in different plantations.Above all,the soil PSD from high to low in four plantations are as Lithocarpus glaber × Schima superba mixed forest（2.693）〉 Cunninghamia lanceolata×Pinus massoniana×Schima superba（2.688）〉 Cunninghamia lanceolata×Pinus massoniana（2.659） Cunninghamia lanceolata（2.625）.The soil structure of Schima superba ×Lit hocarp usglabra mixed forest is the best,Cunninghamia lanceolata is the worst;the mixed broadleaf forest is better than mixed broadleaf-conifer forest or coniferous forest,which not only makes better soil structure but also has stronger anti-erodibility and permeability in Simian Mountain.There is a clear linear correlation between the fractal dimension and the clay contents,when the clay content is higher,the fractal dimension is higher too,when the content of clay less than 0.001 mm is 11.38%,the soil structure will be better.