High hydraulic safety, water use efficiency and a conservative resource-use strategy in woody species of high-altitude environments: A global study.

Understanding the impact of altitude on leaf hydraulic, gas exchange, and economic traits is crucial for comprehending vegetation properties and ecosystem functioning. This knowledge also helps to elucidate species' functional strategies regarding their vulnerability or resilience to global change effects in alpine environments. Here, we conducted a global study of dataset encompassing leaf hydraulic, gas exchange, and economic traits for 3391 woody species. The results showed that high-altitude species possessed greater hydraulic safety (K_leaf P₅₀), higher water use efficiency (WUE_i) and conservative resource use strategy such as higher leaf mass per area, longer leaf lifespan, lower area-based leaf nitrogen and phosphorus contents, and lower rates of photosynthesis and dark respiration. Conversely, species at lower altitudes exhibited lower hydraulic safety (K_leaf P₅₀), lower water use efficiency (WUE_i) and an acquisitive resource use strategy. These global patterns of leaf traits in relation to altitude reveal the strategies that alpine plants employ for hydraulic safety, water use efficiency, and resource, which have important implications for predicting forest productivity and acclimation to rapid climate change.