中亚热带优势灌木根系对土壤抗剪切力的影响

在浙江南部的山体滑坡、泥石流易发区,对中亚热带常绿阔叶林中3种优势灌木植物(檵木、麂角杜鹃和香港黄檀)根系进行野外和室内剪切测试,探讨了灌木植物根系增强土壤抗剪切强度的作用。结果表明:须根相对丰富的植物能明显提高表层土壤的抗剪强度;根系抗拉力和抗剪力均与根径呈幂函数正相关关系;檵木和麂角杜鹃根系抗拉强度与根径呈幂函数负相关关系,而香港黄檀根系抗拉强度与根径无明显相关性;细根或比粗根更有利于土壤加固和抗剪强度的提高。

Effects of the root systems of dominant shrub species in mid-subtropical forest on soil anti-shearing strength enhancement

The mechanical stabilization of soil slopes by means of plant roots depends largely on the strength properties of the roots and their growth pattern within the soil.In particular area,the selection of indigenous plant species on the basis of their root properties is an essential part of biotechnical slope protection.In order to examine the effects of shrub roots on slope stabilization in the geological hazards of landslide/debris flow,the mountainous region in Qinyuan county,south of Zhejiang,three species(Loropetalum chinense,Rhododendron latoucheae,Dalbergia millettii) were studied,which were dominant shrubs in mid-subtropical evergreen broad-leaved forest.The results showed that plant roots had positive effects on shear strength of topsoil(≤15mm),and have obvious different in both tensile stress and tensile strength.In the topsoil,the shrub L.chinense and R.latoucheae have more fibrous root than that of D.millettii,in quantity,so that D.millettii provided the minimum value of shear strength.The values of root tensile resistance increased with the increase in root diameter,following a power law equation,and the relationship between which was significant positively correlated.The power root tensile strength root diameter relationships depend on plant species.The root tensile strength of L.chinense and R.latoucheae decreased with increasing root diameter,following a power law equation and a negative correlation.However tensile strength root diameter relationships within D.millettii did not follow a power law equation.The fine root is better than the coarse root in contributing to stabilize sloping terrain and increasing the value of shear strength within topsoil.