Objective The ecological environment in low-latitude alpine regions is fragile, with prominent issues of slope stability and soil erosion. Studying the root morphology and mechanical properties of slope protection plants in these regions and conducting quantitative analysis and evaluation of their soil stabilization and slope protection effectiveness are of great importance for optimizing the regional ecological protection system.

Methods Six typical slope protection plant species were selected as research subjects. Based on interspecific competition effects, sowing ratios were designed using an orthogonal experimental method. After one year of growth in PVC pipes, root morphology scanning, single-root tensile tests, and single-root pull-out tests were conducted. Principal component analysis was then applied to quantitatively evaluate the soil stabilization and slope protection effectiveness of different slope protection plants and sowing methods.

Results 1) under mixed sowing, Lolium perenne, Caragana sinica, and Piptanthus concolor generally have superior root morphology. Under single sowing, root morphology of herbaceous plants and shrub plants exhibits significant differences. L. perenne and C. sinica have the greatest competitive advantage under mixed sowing. 2) Medicago sativa shows the highest average single-root tensile force and pull-out force, reaching 5.62 and 5.42 N, respectively, while Poa annua demonstrates the highest single-root tensile strength and pull-out strength, reaching 139.10 and 220.13 MPa, respectively. 3) Among the six slope protection plant species, P. concolor and L. perenne achieve better soil stabilization and slope protection effectiveness, while Hippophae rhamnoides shows the weakest effectiveness. Based on the analysis of root soil stabilization effectiveness, the optimal sowing ratio is determined as: L. perenne (15 g/m²), M. sativa (10 g/m²), P. annua (5 g/m²), C. sinica (15 g/m2), P. concolor (22.50 g/m²), and H. rhamnoides (7.50 g/m²). The research findings can provide theoretical references and technical support for the optimized configuration of slope protection plants and for slope vegetation restoration projects in low-latitude alpine regions.

Conclusions Plant species and sowing method significantly influenced root morphological characteristics. Root diameter was overall positively correlated with single-root tensile force and pull-out force, but negatively correlated with tensile strength and pull-out strength.