# Rare Primate Rhinopithecus bieti Can Sustain the Resilience of Montane Forests

## TL;DR

The endangered black-and-white snub-nosed monkey helps maintain healthy and diverse montane forests in China by creating tree gaps that boost plant biodiversity.

## Contribution

This study shows that rare primates can have long-lasting positive effects on forest resilience and biodiversity.

## Key findings

- Current monkey habitats have 38% tree gaps, compared to 29-33% in abandoned sites.
- Plant species richness in current habitats is more than double that in 40-year abandoned areas.
- Even 20 years after monkeys disappear, their past activity maintains higher plant diversity.

## Abstract

Understanding how rare animals contribute to ecosystem health is crucial for conservation. This study explored how the endangered black-and-white snub-nosed monkey helps maintain forests in southwestern China. These monkeys break branches and create gaps in tree canopies, which scientists think might strengthen forests by altering light and temperature patterns. Comparisons between currently used monkey habitats and those abandoned decades ago revealed that active habitats exhibited higher tree gap prevalence (38%) compared to abandoned sites (29~33%), which supported greater plant biodiversity. For example, plant species richness in current habitats is more than double that in areas abandoned for 40 years without monkey presence. Even 20 years after monkeys disappear, their past disturbances leave lasting benefits like higher plant diversity. This shows the monkeys play a vital role in keeping forests healthy and diverse over time. Protecting such rare species is therefore key to sustaining ecosystems, as their long-term effects help forests adapt to challenges like climate change. These findings stress the importance of safeguarding not just individual animals but also their unique ecological impacts for healthier environments.

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.