岷江上游三种典型植被下土壤优势流现象的染色法研究

优势流是土壤中存在的一种普遍现象,对水分运动有重要的影响。为了进一步了解森林涵养水源的机理,用亮蓝野外染色示踪试验研究了岷江上游垂直梯度上的三种典型植被下土壤中的优势流。从染色结果来看,在三种植被下的土壤中均存在优势流现象,而这种优势流的产生由于植被、海拔高度、成土过程、根系及土壤动物活动的不同,复杂程度不一。染色面积的百分数反映了入渗水分在剖面的分布,即使在整体水分仅仅停留在表层10cm以上时,部分水分可通过优势流进入到土壤底层。三种植被下优势流染色的分形维数在1.59到1.85之间,分维数反映出优势流通道的复杂性,低海拔的原始暗针叶林土和高海拔的亚高山草甸土具有复杂的优势流通道。优势流的存在对坡面水文过程产生重要的影响,是今后进一步认识森林水文效应的基础。

A study on soil preferential flow under three vegetations in the upper reach of Minjiang River by brilliant blue dye tracer

Preferential flow is common phenomena in soil,and has significant influence to soil water movement.The soil preferential flow under three typical vegetations was researched by using brilliant blue dye tracer method in field,in order to research the forest conserving water resources deeply.The results showed that the preferential flow exist in all soils under three typical vegetation in upper reach of Minjiang River,and the complex degrees of preferential flow is different for each soil due the deference of vegetations,elevations,soil formation processes,action of roots and soil animals.The dye area ratios reflected the distribution of infiltrated water in soil profiles,although most infiltrated water rested within 10 cm nearly soil surface,some water reached the bottom of profiles through the preferential flow channels.The fractals of preferential flow dye profiles were 1.59 to 1.85,and it reflected the complexity of preferential flow channels,the soils under the virgin coniferous fir forest and sub-alpine meadow had high fractals with complex preferential flow channels.The preferential flow brings key influences for knowing hydraulic processes in slope,and is a basis for understanding the hydraulic effects of forest.