Aims Leaf is the organ of plant photosynthesis, and it is important to understand the drivers for the variations of leaf nitrogen (N) and phosphorus (P) stoichiometry along geographical and climatic gradients. Here we aimed to explore: 1) the changes in leaf nitrogen (N) and phosphorus (P) stoichiometry of woody plants along an altitudinal gradient in Changbai Mountain, and 2) the relative contribution of climate, plant characteristics, and phylogeny to the changes in leaf N, P concentration and N:P.
Methods We measured leaf N and P concentration, and N:P of 48 woody species in 14 plots along an altitudinal gradient in Changbai Mountain. General linear models (GLMs) and variation partitioning analyses were used to explain leaf N and P stoichiometry with parameters related to plant functional groups, climate and phylogenetic groups.
Important findings Leaf N concentration and N:P decreased with altitude, and were positively correlated with mean annual temperature (MAT) but negatively correlated with mean annual precipitation (MAP). Leaf P concentration had no significant relationship with altitude. Leaf N, P concentration and N:P were significantly different among different plant functional groups. Leaf N concentration of shrubs was higher than that of trees, but leaf P concentration and N:P did not differ significantly between shrubs and trees. Leaf N, P concentration and N:P of broad-leaved plants were significantly higher than those of coniferous plants. Similarly, leaf N, P concentration and N:P of deciduous plants were significantly higher than those of evergreen plants. The effects of climate on leaf N, P concentration and N:P were significant but very weak, with MAT and MAP together explaining 1.50%-2.98% of the variations. Phylogenetic groups explained 30.36%-54.38% of the variations, suggesting the critical effect of phylogeny. Our study also showed that the synergistic effect of climate and species composition (phylogeny) on leaf N and P stoichiometry was neglectable, at least along the altitude gradient of Changbai Mountain. More comparative studies between altitudinal and latitudinal gradients are needed to better understand the drivers of the changes in leaf stoichiometry along an environmental gradient.