Rare Primate Rhinopithecus bieti Can Sustain the Resilience of Montane Forests

This study addresses a critical challenge in global conservation: understanding how rare species contribute to ecosystem structure and resilience. The ecological role of the endangered black-and-white snub-nosed monkey in China's temperate mountain forests was examined, with the hypothesis that its tree-shaking behavior alters forest structure and microclimates to enhance ecosystem health. To assess long-term impacts, current monkey-inhabited forests were compared with historical sites abandoned over decades, by analyzing tree gaps, forest structure, and environmental conditions. Monkeys' canopy-disturbing actions were also directly observed. Findings revealed monkey activity created more canopy gaps (38.3% in current habitats vs. 29.9~33.5% in abandoned sites) and altered microclimate conditions, which boosted plant diversity and optimized the community's vertical and age structures. Current forests supported nearly twice as many tree species, 2.5 times as many shrub species, and threefold more herb species than areas abandoned for 40 years. Even 20 years after monkeys disappeared, abandoned sites retained higher diversity and gaps, showing lasting ecological benefits. These results confirm the monkey's vital role as a resilience promoter, demonstrating how rare species can shape healthier ecosystems. This highlights the need to prioritize protecting such species, as their survival not only preserves biodiversity but also sustains ecosystem functions crucial for human well-being.