渝北水源区水源涵养林构建模式对土壤渗透性的影响

Effects of structures of plantation forests on soil infiltration characteristics in source water protect areas in northern Chongqing City

土壤渗透性是评价土壤水源涵养作用重要指标之一,其受制于许多外在和内在因素的影响,与植被类型、土壤结构、土壤种类和降雨强度等关系密切。为探讨不同构建模式水源涵养林对土壤渗透性能的影响,以裸地为对照,以土壤初渗速率,稳渗速率,平均渗透速率和渗透总量表征土壤渗透性,对重庆北部水源区8种不同构建模式的水源涵养林地的土壤渗透性及其与理化性质的关系进行研究。结果表明:不同模式水源林地和同一模式林地不同层次土壤渗透性能存在较大差异,各林地土壤渗透性随土壤深度的增加而降低,母质层土壤渗透性受林分类型和林分结构等外界条件的干扰较小,差异不显著;8种林地土壤渗透性均好于裸地,各林地土壤渗透性能大小依次为:广东山胡椒×杉木混交林>马尾松×柳杉混交林(火烧迹地)>四川大头茶×四川山矾混交林>毛竹×四川山矾×马尾松混交林>马尾松×广东山胡椒混交林>马尾松×四川大头茶混交林>广东山胡椒×四川杨桐混交林>毛竹纯林>裸地,根据土壤渗透能力可将8种模式林分类型分为4类:第1类,广东山胡椒×杉木混交林和马尾松×柳杉混交林,土壤渗透性最好;第2类,四川大头茶×四川山矾混交林,土壤渗透能力较好;第3类,毛竹×四川山矾×马尾松混交林、马尾松×广东山胡椒混交林、广东山胡椒×四川杨桐混交林、马尾松×四川大头茶混交林,土壤渗透性好;第4类,毛竹林和裸露地,土壤渗透性最差。以广东山胡椒和杉木混交的林分模式的土壤渗透性最好,毛竹纯林地最差,毛竹纯林对提高土壤渗透性作用较差,营林时适当增加毛竹林中其他树种的混交比例可增强林地土壤渗透性能。通用经验方程对各林分土壤入渗过程的拟合效果最好,比较适用于描述本研究区域水源涵养林地土壤入渗特征的模型,Kostiakov方程拟合效果次之,Horton方程最差;结合相关分析,筛选出9个极显著或显著影响土壤渗透性能的土壤理化性质因子,通过主成分分析法,得到土壤渗透性能综合参数α及与其极显著相关因子的综合参数β,并构建土壤渗透性各指标及其综合参数α与β的线性回归模型,为重庆北部的水源涵养林建设和防治水土流失提供理论依据。

Soil infiltration rate is an important index in evaluating functions of soil and water conservation,which depends on many internal and external factors,and is closely correlated with forest types,soil structure,soil types,and intensity of rainfall and so on.It is also the a key factor in modeling soil water movement and erosion process where,The goal of this study was to determine the effects of reforestation methods that employ different water conservation forests on soil infiltration capability in northern water source area of Chongqing City.We used bare land as a control.We measured soil initial infiltration,stable infiltration,average infiltration and accumulative water quantity as soil infiltration capability,and determined the relationship between soil infiltration capability and soil physical and chemical properties under eight models of water conservation forest practices.The results showed that the soil infiltration capability values were significantly different in different forest models and different soil layers in the same forest.The soil infiltration capability declined with the increase of soil depth.Vegetation covers had no effect on the haplite soil layers.We found that the infiltration capability of all forest plots was higher than that of bare land.The order of soil infiltration capability from high to low was：Lindera kwangtungensis Cunninghamia lanceolata forest 〉Pinus massoniana Cryptomeria fortunei Hooibrenk forest Gordonia acuminate Symplocos setchuanensis forest 〉Phyllostachys pubescens Symplocos setchuanensis Pinus massoniana forest 〉Pinus massoniana Lindera kwangtungensis forest 〉Pinus massoniana Gordonia acuminate forest 〉Lindera kwangtungensis Adinandra bockiana fores Phyllostachys pubescens forest bare land,and the test eight models of water conservation forest could be classified into four groups,based on soil infiltration capability.The first group,L.kwangtungensis C.lanceolata forest and P.massoniana C.f.Hooibrenk forest,had the strongest soil infiltration capability,and the second group with a stronger soil infiltration capability was G.acuminate S.setchuanensis forest.P.pubescens S.setchuanensis P.massoniana forest,P.massoniana L.kwangtungensis forest,L.kwangtungensis A.bockiana forest and P.massoniana G.acuminate forest were classified into the third group with a relatively strong soil infiltration capability,while P.pubescens forest and bare land belonged to the fourth group.In the eight reforestation models,L.kwangtungensis C.lanceolata forest,was best in improving soil infiltration capability.The role of P.pubescens forest,however,was the least.Because bamboo pure forest cover was largest in the study region,and the bamboo forests played a poor role in improving soil structure and infiltration capability,bamboo forests should be managed by increasing the proportion of other species of mixed forest soil to enhance soil infiltration capability.A common empirical infiltration model could give the best performance on the infiltrating processes in the eight forest models,followed by the Kostiakov and the Horton model.Correlation analysis showed that soil infiltration capability was greatly affected by soil physical and chemical properties.Based on the correlation analyses,nine factors,which have extremely significant or significant effect on soil infiltration capability,were selected.The comprehensive parameters of soil infiltration（α） and soil physical and chemical properties（β） were obtained by the Principal Component Analysis,and the linear regression models of five indices of soil infiltration capability and the comprehensive parameters（α and β） was built.These research results may be useful for local reforestation campaigns in term of tree species and forest community selections.