为了探讨草本植物根系固土的主要机制。以适宜的护坡植物白三叶、小冠花、黑麦草、早熟禾为研究对象，对它们的根系分布特征和抗拉特性进行研究。结果表明：随着土层深度的增加，禾本科植物的根长密度以指数函数形式逐渐减少，豆科植物的根长密度以多项式形式先增后减；随着距主茎距离的增加，禾本科植物根长密度逐渐减少，豆科植物根长密度先增后减；在根径0.1~3 mm范围内，豆科植物平均抗拉力大于禾本科植物，豆科植物的抗拉力与根径呈幂函数关系，早熟禾和黑麦草的抗拉力与根径分别呈指数函数和对数函数关系；四种植物根系抗拉强度均表现为随根径的增加而减小；四种植物根系应力与应变关系表现为对数函数关系，表现为非线性弹性特征；根径相同时，不同植物的应力表现为：白三叶>小冠花>黑麦草>早熟禾。运用主成分分析法综合分析其护坡特性，表现为豆科植物优于禾本科植物，其中白三叶的护坡效益最好。

In order to reveal the mechanism of soil reinforcement by herb roots, we selected 4 typical hillslope protection plants, Trifolium repens L, Coronilla varia L, Lolium perenne L and Poa annua L to study the spatial distribution of root length density and tensile properties. The result showed: With the increase of the soil depth, the root length density (RLD) of gramineous plants gradually reduced in the form of exponential function, while the RLD of legumes first increased and then decreased, with a polynomial fitting curve. With the increase of the distance to the stem, RLD of gramineous plants decreased gradually, while RLD of legumes plants increased first and then decreased. In the roots diameter range of 0.1 mm~3 mm, the average tensile resistance of leguminous plants was greater than that of the gramineae plants. Legume’s root tensile resistance and root diameter showed a power function relationship, and the relationship between tensile resistance and diameter of Kentucky bluegrass and ryegrass was exponential function and logarithmic function relationship, respectively. The tensile strength of four species decreased with the increases of root diameter and their stress and strain showed a logarithmic function relationship, which illustrated that their roots were inelastic. At the same diameter, different plants showed variance with stress as ranked: White Clover > Crown vetch > Ryegrass > Kentucky bluegrass. Using the principal component analysis (PCA) to comprehensively analyze the characteristics of the plant to protect the slope, we could conclude that leguminous plants were better than gramineous plants and White Clover was the optimal in the four plants.

“十二五”国家科技支撑计划课题（2011BAD31B01）