三峡地区阔叶林地植物根系分布特征与优先路径关系分析

The Relationship between the Plant Root Distribution and Priority Flow Paths of the Broad-Leaved Forest in Three-Gorges Area

优先路径研究是研究地下水分运动的重要环节。本文通过亮蓝染色示踪试验法直接观测并区分林地土壤基质和土壤优先路径,分别对染色区和未染色区观测到的土壤优先路径、植物根系根长密度和根重密度进行分析,研究发生土壤优先流过程中植物根系的作用及由植物根系形成的优先路径的联通情况。研究发现,降雨强度越大,优先路径染色区的表层呈现越加明显的宽区域聚集分布。雨强为25mm/d时,样地土壤染色区域表层大区域优先路径聚集分布厚度平均为50cm。根径>5mm的根系根长密度的大小对土壤孔隙的大小影响显著,根径<5mm的根系根长密度的大小对于土壤孔隙的联通有明显作用。此外,土壤中植物根重密度的大小与优先路径数量和联通程度正相关,根重密度越大越有利于构成优先路径,有利于形成优先流。不同样地两区域植物根重密度在土壤10—20cm和30—40cm深度范围内具有极显著差异(P<0.05),而优先路径在30cm深骤然减少。此方法在一定程度上可为优先路径的研究提供新的借鉴和参考。

The study on priority flow paths is an important topic on the underground water movement re- search. In this paper, the bright blue dyeing tracer test method was used to directly observe and distinguish woodland soil substrate and soil priority path, respectively, and analyze the soil priority flow paths, the root length density and root weight density of the plant in the roots, the formation of the priority flow paths and the referential flow in soil process. The results showed that the more rainfall intensity was, the surface of the priority flow paths dyeing presented the bigger obvious wide area gathered distribution. When the rainfall was 25 mm/d, the average gathered distribution thickness of large area in sample soil dyeing area was 50 cm. It also showed that the root long density of roots 〉 5 mm affected the soil pore size significantly, and the root long density of roots 〈 5 mm affected the soil pore linkage obviously. In addition, the value of root weight density of plant in soil was closely related to the quantity and the linkage degree of priority flow paths. The more value of root weight density is, the more preferred priority flow paths formatted, and more preferred priority flow formatted. The root weight density of plant presented very significant difference in 10--20 cm and 30--40 cm soil depth in the different two regions （P〈0.05）, the priority flow paths suddenly decreased in the depth of 30 cm. It is a new method for study of the priority flow paths.