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Macropores in the soil of vegetated slopes greatly affect the rainfall infiltration process. In this paper, a realistic 3D macropore network model of a soil column sample is established by CT scanning. Then, the transmission process of the macropore flow is simulated based on MODFLOW. The results show that (1) the shapes of macropores in the soil contain not only the dominant proportion of the circular tube but also a small proportion of the flake. (2) The velocity of macropore flow has a maximum of up to 0.2~0.3 m/s, which is much higher than that of matrix flow. In every single macropore, the flow velocity is the greatest at the central axis perpendicular to the extension and at the throat along the extension. (3) Due to the development of the macropore network system, rainwater can quickly pass through the soil profile in the form of preferential flow or pipe flow, which shortens the lag time of the peak discharge response to rainfall. This process can free up space for the next recharge, but reduce the overall quality of the soil, laying the foundation for the slope failure. Our work helps to unravel the mechanism of rainfall-induced landslides and promote harmony and sustainable development between humans and nature. [ABSTRACT FROM AUTHOR]

The moisture and thermal characteristics of expansive soil slopes have a significant impact on the strength and overall stability of the soil. In this study, the medium-strength expansive soil vegetated slope in Baise, Guangxi, was taken as the research object. Through the combination of numerical simulation and measured meteorological data, the impact of moisture and heat characteristics on slope stability was then analyzed, and optimal geometric parameters conducive to the stability of vegetated slopes were proposed based on these findings. The research results indicate that under long-term climatic conditions, solar net radiation has the most sensitive effect on the evaporation of slope soil. During the evaporation process, vegetation transpiration dominates in the vegetation-covered layer, while below the depth of the vegetation cover layer, soil evaporation itself plays a dominant role. Under the conditions of evaporation-rainfall-evaporation, slopes with a smaller permeability coefficient in the vegetation cover layer have significantly higher safety factors than slopes with a larger permeability coefficient and bare slopes. A steep vegetated slope with a slope gradient of 50° can maintain slope stability with proper handling of its height. The research findings have reference value for the design and construction of vegetated slopes with expansive soil. [ABSTRACT FROM AUTHOR]

The soil–water characteristic curve is an important tool to evaluate the water-holding capacity of unsaturated soil. Plant roots can affect the matric suction of soil and the water-holding capacity and permeability of the soil. Therefore, the morphological characteristics of plant roots will lead to the difference in soil–water characteristics between soil slope and plant-covered slope. This study aims to investigate the effect of Vetiver root morphology on soil–water characteristic curves of plant-covered slope soil. The hydrological effect of the root distribution on the root–soil system was also discussed. The results showed that: (1) The root surface area index (RAI) and root volume ratio (Rv) of each soil section of the vetiver root system varied with depth in accordance with the Gaussian function distribution; (2) In the process of natural drying, the matric suction generated within the root system is significantly higher than that generated by evaporation of bare soil in the same soil layer. The ability of vegetation soil to enhance soil matrix suction increases with the increase of soil root surface area index; and (3) The α and n values of the SWCC model decreased with the increase of Rv (root volume ratio of soil), while the air entry value increased. Under the same water content, the matric suction corresponding to vegetation soil is significantly greater than bare soil. In addition, the soil–water characteristic curve can be effectively predicted by combining the Rv of vegetated soils. [ABSTRACT FROM AUTHOR]

The presence of vegetation in urban soil is both visually appealing and environmentally beneficial. Vegetation contributes to changes in soil water content (SWC) and soil suction (SS) through transpiration. These changes ultimately affect slope stability, soil erosion, runoff generation, and water infiltration. This study closely examines the impact of tree canopy covers on SWC and SS dynamics in an urban slope site with a diverse mix of vegetation (trees and grass) in a tropical region. Field monitoring revealed that slope areas with higher tree canopy cover consistently exhibited lower SWC and higher SS at shallower depths, highlighting the stabilizing effects of vegetation. During wet periods, the difference in SWC between high and low canopy cover areas increased by 36% compared to dry periods, emphasizing the role of canopy cover in regulating soil moisture under varying climatic conditions. Furthermore, stations with lower canopy cover demonstrated a stronger correlation between SWC and relative humidity (R values of 0.64 in dry and 0.71 in wet periods) than those with higher canopy cover (R values of 0.57 in dry and 0.63 in wet periods), indicating distinct soil moisture retention patterns based on canopy density. These findings underscore the critical role of tree canopy cover in controlling SWC and SS dynamics, particularly for urban slope stability and sustainable landscape management., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Planting vegetation is an environmentally friendly method for reducing landslides. Current vegetated slope analysis fails to consider the influence of different root architectures, and the accuracy and effectiveness of the numerical simulations need to be improved. In this study, an explicit smoothed particle finite element method (eSPFEM) was used to evaluate slope stability under the influence of vegetation roots. The Mohr–Coulomb constitutive model was extended by incorporating apparent root cohesion into the shear strength of the soil. The slope factors of safety (FOS) of four root architectures (uniform, triangular, parabolic, and exponential) for various planting distances, root depths, slope angles, and planting locations were calculated using the shear strength reduction technique with a kinetic energy-based criterion. The results indicated that the higher the planting density, the stronger the reinforcement effect of the roots on the slope. With increasing root depth, the FOS value first decreased and then increased. The FOS value decreased with an increase in slope angle. Planting on the entire ground surface had the best improvement effect on the slope stability, followed by planting vegetation with a uniform root architecture in the upper slope region or planting vegetation with triangular or exponential root architecture on the slope's toe. Our findings are expected to deepen our understanding of the contributions of different root architectures to vegetated slope protection and guide the selection of vegetation species and planting locations. [ABSTRACT FROM AUTHOR]

A new methodology to incorporate the mechanical root anchorage effects in both short- and long-term slope stability analysis is proposed based on observed and assumed behaviour of rooted soil during shear failure. The main focus of the present work is the stress–strain range comparison for both soil and roots and development of a stability model that would incorporate relevant root and soil characteristics based on the fact that available soil–root composite shear resistance depends on the magnitude of the shear strain. This new approach, combining stress–strain analysis, continuum mechanics, and limit equilibrium stability assessment, allows for a more realistic simulation of the rooted soil composite whereby the stabilising effect of the rooted soil is incorporated in the slope stability calculations by means of the synchronisation of root and soil mechanical behaviour during failure. The stability of vegetated terraces in a study area in Spain is used as a case study to demonstrate the proposed methodology and to compare the results with the traditional use of the perpendicular root reinforcement model. The results of the study show that as the shear displacement (strain) increases, the stress is transferred from the soil that provides most of the resistance at low strains onto the roots that provide the most of the resistance to shear at high strains. Including this behaviour in the overall resistance to failure of the root–soil continuum resulted in a more conservative and realistic assessment of the stability of a vegetated slope immediately after a precipitation event when a progressive failure is most likely to be triggered. [ABSTRACT FROM AUTHOR]

Grasses and shrubs occupy large areas of fragile ecosystems following ecological restoration. Therefore, it is increasingly important to assess and monitor the environmental safety of pastures. However, previous studies on this topic lacked systematicity and directionality. In this study, we reviewed the literature on runoff and erosion to summarise the core issues for future research, resolve the current research bottleneck, and promote the balance of soil, water, and energy in fragile ecological areas. The results of the review indicate that coverage remained the main vegetation feature considered when characterising rangeland slope erosion and runoff. Erosion energy should be comprehensively considered based on the influence of vegetation on rainfall distribution and runoff erosivity. Rangeland slope erosion and runoff changes can only be explained by integrating the above- and below-ground characteristics of vegetation. Additionally, the impact of vegetation on runoff separation and the sediment transport processes at different erosion stages under rainfall conditions vary. Therefore, studying the comprehensive indicators of vegetation at different erosion stages in response to erosion and runoff will be vital in rangeland erosion research. From the perspective of disciplinary development, this study can promote the further development of soil erosion, ecology, soil science, hydrology, hydraulics, and other disciplines. • Research on soil erosion and overland flow on rangeland slopes lacks systematicity. • Effect of plants on runoff separation under rainfall varies between erosion stages. • Vegetation also affects sediment transport differently under rainfall. • Responses of comprehensive vegetation indicators to erosion and runoff are important. • Vegetation indicators will offer a breakthrough in rangeland research. [ABSTRACT FROM AUTHOR]

Although ecosystem degradation is often caused by existing slopes vegetated with commercial species, limited data are available for implementing practical approaches for nature restoration by transplanting native species to those vegetated slopes. Existing vegetated slopes are characterized by spatial heterogeneity in the habitat environment and competition with existing vegetation, which affect the behaviors of transplanted native species. In this study, we examined the factors affecting the survival, growth, verticillation, and flowering of Lilium pensylvanicum , a native coastal-meadow species transplanted to a vegetated road slope in Hokkaido, Japan. In the fourth year after transplantation, the number of surviving plantlets was 364 (57% of 640 transplanted plantlets) and the number of plantlets that shifted to verticillate leaves was 181 (50% of the survivors). The flowering plantlets accounted for 9% (n = 34) of the survivors. The generalized linear model showed that plantlet survival is strongly promoted by a larger bulb scale, that is, nutrient reserves. Furthermore, the survival ratio was greatly improved in the drought-prone, stressful habitats with low vegetation coverage, even for plantlets with relatively smaller bulb scales. However, in the moist habitat with high coverage, the survival ratio was greatly decreased regardless of the bulb scale size. Growth, verticillation, and flowering were facilitated by higher soil nutrient availability, such as a lower C/N ratio and thicker soil layer. Therefore, transplanting of native species to vegetated slopes requires the selection of stress-tolerant species with large nutrient reserves and identification of optimal habitats for transplanting, namely stressful environments with reduced vegetation coverage. • The transplantation of native species on slopes for nature restoration was examined. • Plantlet survival was most strongly affected by nutrient reserves. • Survival negatively correlated with vegetation cover and soil water content. • Plantlet growth and flowering were facilitated by higher nutrient availability. [ABSTRACT FROM AUTHOR]