中文摘要：

为探讨紫色土区草类根系特征及对土壤抗侵蚀性的影响,本试验选取坡地香根草和马唐为研究对象,分0~10cm、10~20cm和20~30cm土层采集根系和土壤样品,分别采用WinRHIZO（Pro.2004c）根系分析系统、ZJ型应变控制式直剪仪和改进的原状土冲刷水槽测定根系指标、根-土复合体抗剪和抗冲性能,研究了不同土层香根草和马唐的根系特征及与土壤抗侵蚀性之间的关系。结果表明,0~30cm土层范围内,香根草根系的总体指标和径级指标（根长密度、根表面积密度、根体积密度和根重密度）均优于马唐;较之马唐,香根草更有利于降低土壤容重,改善土壤微团聚体组成状况和提高土壤有机碳含量;上述2种草类根-土复合体的抗冲剪性能均表现为：0~10cm土层最优,10~20cm土层次之,20~30cm土层最差,且各土层均表现为香根草的优于马唐的;相关分析表明,

英文摘要：

The aim of this study was to investigate the characteristics of grass root distribution and its effects on soil anti-erodibility in purple soil areas.Two grass species,Vetiveria zizanioides and Digitaria sanguinalis,growing on slopelands were chosen as the experimental materials.Root and soil samples were taken from 0-10,10-20,and 20-30 cm soil depths.Root parameters,soil shear strength,and anti-scourability of the rootsoil system were measured to explore the relationship between root distribution and soil anti-erodibility.The values of overall root parameters and diameter parameters（root length density,root surface area density,root volume density,and root weight density）were higher for V.zizanioides roots than for D.sanguinalis roots in0-30 cm soils.Compared with D.sanguinalis roots,V.zizanioides roots were more conducive to reducing soil bulk density,improving soil microaggregate composition,and increasing the soil organic carbon content.Soil shear strength and anti-scourability of the root-soil systems were highest in 0-10 cm soils and lowest in20-30 cm soils.The values of both parameters were higher for V.zizanioides than for D.sanguinalis.A correlation analysis indicated that 1.0d（diameter）≤2.0 mm was the critical diameter class affecting cohesion and the anti-scourability index,followed by d≤1.0mm.The results of this study provide a theoretical basis for vegetation management strategies to conserve soil and water in purple soil areas.