Abstract: To investigate the effects of different slope aspects (half-shady slope, sunny slope, half-sunny slope) and enclosure management on the composition of medicinal plant resources, medicinal parts and efficacies, importance value, diversity, and biomass in the alpine meadows of Sichuan Jiajin Mountain, and to provide a scientific basis for the conservation and sustainable use of medicinal plant resources in this region. A total of 24 sites (half enclosed and half grazed) were established on half-shady, sunny, and half-sunny slopes in Jiajin Mountain, with 288 herbaceous quadrats surveyed. Species composition was recorded, and species importance value, Shannon-Wiener index (H), Simpson index (H'), Pielou evenness index (J), and species richness index (D) were calculated. Aboveground and belowground biomass were measured. Redundancy analysis was used to analyze the effects of slope aspect and enclosure management on diversity and biomass. The results showed that a total of 54 medicinal plant species belonging to 51 genera and 22 families were recorded, with whole plants being the most common medicinal part (51.11%–67.57%). The predominant medicinal efficacies were heat-clearing and detoxifying, as well as reducing swelling. Slope aspect and enclosure had a significant interactive effect on diversity indices. On the half-shady slope, diversity indices were significantly higher in the enclosed areas than in the grazed areas (P < 0.05). On the half-sunny slope, diversity in enclosed areas did not increase significantly and was even lower than in grazed areas. Aboveground and belowground biomass were significantly higher in enclosed areas across all slope aspects compared to grazed areas, and belowground biomass exceeded aboveground biomass in all sites. Redundancy analysis indicated that slope aspect and enclosure conditions together explained 28.0% of the total variation in plant communities. In conclusion, the promoting effect of enclosure on medicinal plant diversity is slope-dependent. It is most pronounced in favorable habitats with rich diversity and high biomass, such as the half-shady slope, whereas in more fragile vegetation with lower diversity and biomass, such as the half-sunny slope, moderate grazing disturbance may be more conducive to maintaining species coexistence. Therefore, differentiated management strategies are recommended for the region: enclosure for well-vegetated areas, and a combination of moderate disturbance and active restoration for more fragile vegetation, to achieve sustainable use of medicinal plant resources.

Key words: slope aspect, enclosure, medicinal plants, plant diversity, biomass