滇中磨盘山典型林分土壤优先流特征及其归因分析

Characteristics and attribution analysis of soil preferential flow in typical stand of Mopan Mountain in central Yunnan

【目的】探究土壤优先流的形成机理,揭示林地土壤水分运移规律,加深对森林调节水文、涵养水源机理的认识,为滇中林区水源涵养、植被生态建设提供理论依据。【方法】以滇中磨盘山云南松林、华山松林、滇油杉林、高山栎林4种林分类型为研究对象,利用染色示踪法和Photoshop CS 5、Image Pro Plus 6.0图像处理软件获取优先流染色区域总面积和染色面积比,分析不同林分类型的土壤优先流特征及优先流染色面积比随土层深度的变化;同时测定各林分类型土壤的理化性质,采用相关分析、主成分分析和通径分析方法,研究影响4种林分土壤优先流特征的土壤因子。【结果】4种林分表层土壤水分运动以基质流为主,染色面积比随土层深度的增加逐渐减小,优先流现象明显,优先流发育程度表现为华山松林>云南松林>滇油杉林>高山栎林。4种林分不同土层深度的土壤理化性质存在显著差异(P<0.05),华山松林地的土壤疏松程度、持水特性、土壤肥力特性均表现最优。4种林分土壤容重均与染色面积比呈极显著负相关(P<0.01),pH、全钾含量与染色面积比呈负相关;除土壤容重、pH、全钾含量外,饱和持水量、毛管持水量、毛管孔隙度、有机质含量等土壤因子均与染色面积比呈正相关关系。主成分分析和通径分析结果表明,优先流的形成是不同土壤因子直接作用和间接作用的结果,其中土壤容重是引起染色面积比变化的决定性因子,全氮含量对优先流的形成具有限制性作用。【结论】土壤疏松程度、持水特性、土壤肥力特性等共同作用影响优先流的形成与发生,土壤理化性质是土壤优先流形成的重要驱动因素。

【Objective】This study explored the formation mechanism of soil preferential flow,revealed the law of soil water movement in forest land and deepened the understanding of forest regulating hydrology and water conservation mechanism to provide theoretical basis for water conservation and vegetation ecological construction in forest regions of Central Yunnan.【Method】Pinus yunnanensis forest,Pinus armandii forest,Quercus semecarpifolia forest,and Keteleeria evelyniana forest in Mopan Mountain in central Yunnan were selected and the total of dyeing area and dyeing area ratio of preferential flow were obtained by dyeing tracer method,Photoshop CS 5 and Image Pro Plus 6.0 image processing software.The characteristics of soil preferential flow and the changes of preferential flow staining area ratio with soil depth were analyzed.At the same time,the physical and chemical properties of soil in each stand type were measured,and the factors affecting the characteristics of soil preferential flow in four stands were studied by correlation analysis,principal component analysis and path analysis.【Result】The main surface soil water movement of the four stands was mainly matrix flow,and the dyeing area ratio gradually decreased with the increase of soil depth.The phenomenon of preferential flow was obvious with development degree in the decreasing order of P.armandii forest>P.yunnanensis fores>Q.semecarpifolia forest>K.evelyniana forest.There were significant differences in soil physical and chemical properties at different soil depths among the four stands(P<0.05).P.armandii forest had the best degree of soil porosity,water holding characteristics and soil fertility characteristics.Soil bulk density of the four stands showed a very significant negative correlation with the dyeing area ratio(P<0.01),while pH,total potassium content and the dyeing area ratio showed negative correlations.Except for soil bulk density,pH and total potassium content,soil factors such as saturation moisture capacity,capillary moisture capacity,capillary porosity and organic matter content correlated positively with dyeing area ratio.The results of principal component analysis and path analysis showed that the formation of preferential flow was the result of direct and indirect effects of different soil factors.Among them,soil bulk density was the decisive factor causing the change of dyeing area ratio and total nitrogen content had a restrictive effect on formation of preferential flow.【Conclusion】Soil porosity,water holding capacity and soil fertility affected the formation and occurrence of preferential flow.Soil physical and chemical properties were important driving factors for the formation of preferential flow.