The impact of forest canopy cover on small mammal community diversity in the giant panda National park, sichuan, China

Small mammals play crucial roles as seed dispersers and ecosystem engineers in forest ecosystems. This study explores the impact of canopy cover on small mammal communities in the Xiaozhaizigou National Nature Reserve, part of the Giant Panda National Park, Northern Sichuan. Field surveys were conducted across 16 sampling plots (50 × 50 m²) in four canopy cover classes (0-24%, 25-49%, 50-74% and 75-100%) during 2023 and 2024. Forests with lowest canopy cover (Class I) exhibited the highest alpha-diversity due to greater habitat heterogeneity, while highest canopy cover forests (Class IV) supported habitat-specialist species, including endemic species Sciurotamias davidianus and Niviventer excelsior. Rodentia showed significantly higher abundance than Eulipotyphla across all canopy classes. Beta-diversity analysis revealed that species turnover (β_SIM) was the main driver of community differentiation, with non-endemic species exhibiting higher beta-diversity than endemic species. Redundancy analysis demonstrated that endemic species showed positive associations with herb layer complexity, while non-endemic species preferred simpler habitat structures. Phylogenetic and functional diversity analyses revealed predominantly random community assembly processes. Current forest restoration strategies prioritizing canopy closure for flagship species like giant pandas may overlook small mammal habitat requirements. The findings underscore the necessity of balanced forest management strategies maintaining both high- and low-canopy environments in a mosaic approach, maximizing biodiversity conservation and ecosystem resilience.