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Plant roots improve the stability of collapsing walls and prevent their collapse; they are thus important for controlling the degree of Benggang erosion in southern China. The vegetation species on the collapsing walls are diverse, and the interaction of the root systems with soil affects the stability of the collapsing walls. Most recent studies have only examined the effects of single plants. In order to investigate the effects of the roots of different vegetation types on the shear strength of soil in collapsing walls and their interaction mechanisms of action, this study was conducted using the roots of the herb Dicranopteris dichotoma and the shrub Melastoma candidum. A direct shear test of indoor remodeled soil was carried out by varying water content (15%, 25%) and herb to shrub root ratio (100:0, 75:25, 50:50, 25:75, and 0:100). The results showed that the shear strength (96.09 kPa) and cohesion (49.26 kPa) of root-containing soil were significantly higher than plain soil (91.77 kPa, 42.17 kPa), and the highest values were obtained when herb to shrub root ratio was 100:0 (113.27 kPa, 62.85 kPa). Here, tensile tests and scanning electron microscopy revealed that the tensile force and tensile strength of the roots of Dicranopteris dichotoma were weaker but effective for maintaining soil stability because of their abundance roots, which could achieve a stronger bond to soil. Simultaneously, herbaceous roots have a small diameter, the Root Area Ratio (RAR) of the roots is larger under the same mass condition, which can better contact with soil and the mechanical properties of roots are fully utilized. Therefore, the soil shear strength is higher and can better resist external damage when herbaceous roots accounts for a larger proportion. The results of this research have implications for the selection and allocation of ecological measures for prevention and control of Benggang.

来源平台：JOURNAL OF MOUNTAIN SCIENCE