Vertical Distribution of Butterfly Community (Lepidoptera) and Its Drivers on Mount Gongga, Western China

Butterfly elevational distribution patterns are modulated by temperature stratification, vegetation composition, butterfly functional traits, and anthropogenic disturbances. To explore the elevational patterns of butterfly α- and β-diversity and their driving mechanisms on Mount Gongga, we established 18 standardized 1000 m transects at 200 m intervals across an elevational range of 1000-4500 m. Butterfly species richness and abundance were systematically surveyed using the line-transect method. The results indicated that both butterfly species richness and abundance significantly decreased with increasing elevation. Notably, butterfly β-diversity exhibited a distinctive nonlinear trimodal pattern along the elevational gradient, with three peak values occurring at 1900-2300 m, 3500-3900 m, and 4300-4500 m. This pattern differs substantially from the monotonically decreasing or unimodal β-diversity trends widely reported for most mountain insect communities. Vegetation ecotone effects, habitat heterogeneity differentiation, elevational species turnover, and topographic microclimate heterogeneity collectively drive this unique distribution pattern. Based on these findings, we propose targeted conservation recommendations: (1) prioritize the protection of key vegetation transition zones; (2) sustain vegetation integrity to guarantee sufficient food and habitat resources for butterflies; (3) address climate change threats to conserve high-elevation endemic butterfly species; (4) develop long-term monitoring programs to improve regional biodiversity conservation systems.