Similar alpha yet varied beta functional diversities between invasive and native plant species along an elevational gradient

Illuminating the invasive strategies of alien species in mountainous regions is critical to preventing the increasing frequency of invasion events and enhancing our understanding of the vulnerability of these ecosystems. Here, we investigated differences in diversity between invasive and native species across an elevational gradient through field experiments conducted along a 1200 m range, combined with measurements of plant functional traits and environmental factors. Our results revealed significant distinctions in diversity patterns between invasive and native species when considering multiple aspects of taxonomic and functional diversity at both α and β levels. Native species showed clear species replacement along elevation, while invasive species at higher elevations tended to be a subset of those found at lower elevations. Although invasive and native species shared relatively similar functional α diversity, they exhibited more significantly different functional β diversity. Elevation-related environmental factors played a major role in shaping functional dissimilarity and species similarity across plots. In contrast, functional redundancy at both α and β levels was more influenced by species status. Our findings highlight that invasive species exhibit a dissimilar strategy compared to native species along the elevational gradient and emphasize the importance of decreasing the introduction of alien species to better manage and prevent plant invasions in mountainous regions.