Elevational variation and driving factors of leaf functional traits in alpine shrubs of Sanjiangyuan Nature Reserve, China

Leaf functional traits (LFTs) are key indicators of plant responses to environmental conditions and nutrient acquisition strategies. However, the macroscopic variations in LFTs and their drivers in different habitats remain unclear, particularly for alpine shrub. Our study measured LFTs (including morphological traits, economic traits and anatomical traits) within an elevation range of 3500-4500 m in the Tongtianhe Sub-area of the Sanjiangyuan Nature Reserve. Correlation analysis and variance decomposition were used to reveal the sources of variation, adaptive strategies and influence mechanisms of functional traits in alpine shrubs. Our results indicate that LFTs varied significantly along the elevational gradient, especially morphological and anatomical traits (P < 0.05). Interspecific variation is greater than intraspecific variation for most functional traits. Phylogenetic analysis demonstrated that morphological and economic traits exhibited significant phylogenetic signals. The trade-offs between LFTs reflect the community's balance in resource use strategies, environmental adaptability, and community stability. Morphological and anatomical traits were significantly affected mainly by elevation, while economic traits were significantly affected by soil nutrient content. Topography, climate, soil properties, plant functional types (PFTs) and phylogeny together explained 67 % of LFTs variation, with environmental factors (31 %) having a stronger influence than PFTs (24 %) and phylogeny (12 %). Our findings highlight that environment variable across altitudinal gradients is the key driver of LFTs variation in alpine shrubs. This study is significant in revealing the adaptation strategies of alpine shrub plants in different environments.