Soil and climate effects on leaf nitrogen and phosphorus stoichiometry along elevational gradients

Leaf nitrogen (N) and phosphorus (P) concentrations are critical to plant metabolic processes and growth. Understanding the contribution of climate and soil nutrients on leaf nitrogen and phosphorus concentrations across plant life-forms (trees, shrubs, and herbs) remains incomplete, especially along elevational gradients. To investigate these effects, we combined data from the Plant Trait (TRY) database, containing 528 species distributions, with elevation, climate and soil information for each study site. Results show that leaf N and P content were significantly correlated with elevation (P < 0.05). The explanatory ability of altitude for changes in N (R-2 = 0.40) and P (R-2 = 0.21) content in herb leaves is greater than that in trees (R2 < 0.1). The explanatory ability of elevation for changes in P content (R-2 = 0.26) in shrub leaves is higher than that of N content (R-2 = 0.12). Furthermore, leaf P was more strongly associated with mean annual precipitation and mean annual temperature. Soil C:N and soil pH were significantly correlated with leaf N and P content, but their ability to explain elevational patterns in leaf N and P was limited. Overall, in leaves, P is more susceptible to environmental influences than N. These findings reveal differences in nutrient cycling and physiological regulation of N and P among different plant forms. (C) 2020 The Author(s). Published by Elsevier B.V.