吕梁关帝山不同植被坡面土壤优先流特征及其影响因素

Preferential flow characteristics and its influencing factors on slope positions in different vegetation types in Guandi Mountain,Lüliang

土壤优先流对坡面产流和流域水循环具有重要影响,研究坡面优先流的特征及其影响因素对理解坡面优先流的产生机理有重要意义。本研究以关帝山针阔混交林、针叶林和灌丛3种植被为对象,采用野外亮蓝示踪实验和室内图像解析技术,揭示不同植被类型、不同坡位点处土壤优先流在垂直和水平方向的空间异质性,并分析土壤理化性质对其影响。结果表明:1)针阔混交林和灌丛覆盖下土壤优先流垂直发育程度坡上>坡下>坡中,而针叶林优先流垂直发育程度则随坡位上升而减小。2)针叶林和灌丛水平染色路径以>10mm为主,且针叶林总染色路径数量随坡位的上升先增大后减小,而灌丛则随坡位的上升而下降。3)电导率、有机质、坡度、黏粒含量是影响垂直剖面优先流特征的主要因素,而有机质、砂粒和粉砂含量、坡度则是影响水平剖面染色特征的主要因素。本研究揭示了坡位和植被类型是如何通过影响土壤理化性质,进而对坡面土壤优先流发生和发育产生重要影响,丰富了对坡面土壤优先流特征及机理的认识。

Soil preferential flow affects slope runoff and water cycle in watershed.Understanding the characteristics and influencing factors of preferential flow are helpful for uncovering the mechanism of preferential flow in different vegetations.In this study,we investigated the spatial heterogeneity of soil preferential flow in a mixed broadleaf-conifer forest,coniferous forest,and shrubland in Guandi Mountain by using bright blue tracer and image analysis,and analyzed the impacts of soil physical and chemical properties.The results showed that:(1)Soil preferential flow under the mixed broadleaf-conifer forest and shrubland was in an order of upper slope>lower slope>middle slope,while the preferential flow in the coniferous forest decreased with increasing slope position.(2)The horizontal dyeing pathway in the coniferous forest and shrubland was mainly>10 mm.The total number of dyeing pathway in the coniferous forest was firstly increased and then decreased with increasing slope position,while that in the shrubland decreased with increasing slope position.(3)Electrical conductivity,organic matter content,slope position,and clay content were the main factors affecting the vertical dyeing characteristics of preferential flow,while organic matter content,sand content,silt content,and slope position were the main factors affecting the horizontal dyeing characteristics of preferential flow.Our results indicated that slope position and vegetation types had important impacts on the occurrence and development of preferential flow,improving the understanding of the effects and underlying mechanism of slope position on the preferential flow.