Ecological Engineering Contributions to Slope Stability Through Root Reinforcement in Diverse Soils

Slope instability in mountainous regions poses serious challenges to infrastructure resilience, particularly under anthropogenic pressures and climatic variability. This study evaluates the mechanical reinforcement provided by Vetiver (Chrysopogon zizanioides) to stabilize slopes in seven representative soils of the Quillollaco Formation, southern Ecuador. Direct shear tests on soil–root composites were used to quantify root-induced improvements in cohesion (c′) and internal friction angle (ϕ′), and slope stability was analyzed with the Spencer limit equilibrium method for heights of 5, 10, and 15 m under dry conditions. Results demonstrated significant reinforcement effects, with Vetiver increasing shear strength parameters at all depths and maintaining safety factors above 1.10 in every scenario. The highest gains, up to 16%, were observed in high-plasticity soils (CH and MH). Sensitivity and inferential statistical analyses confirmed the robustness of these improvements, with over 95% of paired t-tests yielding p < 0.05. These findings highlight Vetiver as a reliable nature-based solution for slope stabilization in tropical mountain environments, offering a sustainable and transferable alternative to conventional geotechnical methods.