Contribution of soil matric suction on slope stability under different vegetation types

Purpose Elucidating the effects of vegetation on soil mechanical and hydrological behavior is crucial to understand shallow landslide stability. However, in geohazard-prone regions, quantifying the soil hydrological behavior is challenging because of large variations in soil water. The positive effects of vegetation hydrological effects have not been clearly delineated. The objective of this study was to analyze the contribution of vegetation types to slope stability under different soil matric suction conditions. Methods The hydrological and mechanical properties of soil were measured and the extended Mohr–Coulomb failure criterion were used to estimate the differences in hydrological reinforcement on slopes under three vegetation types (grasslands, trees, and shrubs). The slope stability was compared using a two-dimensional finite element model. Results The results showed that the increase in soil hydrological reinforcement of grasslands (16%) was higher than that of shrubs (13%) and trees (9%). The displacement vector and plastic strain cloud map indicated that slope failure was initiated from the foot of the slope; additionally, the plastic strain area of the grasslands was considerably larger than that of the shrubs and trees. Furthermore, with increase in matric suction, the factor of safety (FoS) of slope for trees, shrubs, and grasslands increased from 1.87 to 2.87, 1.50 to 3.53, and 1.47 to 3.32, respectively, with minimum variations in the FoS of slope for trees. Conclusions This study provides valuable insights for quantifying the contribution of soil matric suction to the hydrological reinforcement of shallow slopes under different vegetation types. To maintain slope stability, understanding the soil hydrological properties is important to select suitable plants that can strengthen slope stabilities, allocate plant communities scientifically and rationally, and guide the implementation of appropriate land management practices.