Leaf nitrogen and phosphorus stoichiometry of Quercus species across China

Abstract

Leaf stoichiometry patterns and their controlling factors at different scales, such as the global flora or single species/genus, are still poorly understood. Here, we analyzed a national-level dataset of leaf nitrogen (N) and phosphorus (P) concentrations and their stoichiometry for 13 Quercus species from 41 study sites in China, aiming to document the patterns of leaf N and P concentrations and N:P ratio to investigate how these patterns vary with geographic and climatic variables. The averages of leaf N and P concentrations and N:P ratio were 17.27mgg−1, 1.54mgg−1 and 13.96, respectively, across all Quercus species studied. Significant differences in leaf N and P concentrations were detected, while no significant difference in leaf N:P ratio was found among species. Leaf N and P concentrations and N:P ratio showed single-peak curves or linear patterns along the geographic and climatic gradients. Principal component analysis (PCA) revealed that the first PCA axis, which reflected the temperature and evaporation variations along the altitude and longitude, had good relationships with leaf N and P concentrations and N:P ratio. The second PCA axis, which reflected temperature and moisture variations along the latitude, only showed a significantly correlation with leaf N concentration. Leaf N:P ratio was well constrained to a relatively stable range for Quercus species and was less influenced by environmental variables. Leaf N and P concentrations were mainly driven by heat and water distribution induced through geographic variations. Leaf stoichiometry-geography relationships are more complicated than stoichiometry-climate relationships.