[Leaf nitrogen and phosphorus stoichiometry across 654 terrestrial plant species in NSTEC]

Stoichiometry of leaf N and P is a characteristic of plant to adapt to environment, and can provide data for process-based modeling at large scale. Leaf nitrogen and phosphorus stoichiometry of NSTEC terrestrial plants were studied based on a NSTEC data set including leaf nitrogen and phosphorus observations for 654 plant species at 168 sites. The results showed that leaf nitrogen and phosphorus stoichiometry in NSTEC exhibited large variations, primarily ranging 2.17-52.61 mg x g(-1) for N, 0.10-10.27 mg x g(-1) for P, 1.7-74.6 for N/P ratio. Geometric means for all plant species were 17.55 mg x g(-1), 1.28 mg x g(-1) and 13.5, respectively. Leaf P of NSTEC (ever across China) was lower than global level, therefore plant growth was more limited by P in China region comparing to global environment. For all functional groups, the difference of leaf N was largest, but that of N/P ratio was smallest, since leaf N and P closely related in most of functioning groups; for leaf N and P of the different phylogenic functional groups, the difference was largest for farthest relative (seed vs fern), least for closest relative (monocotyledon vs. dicotyledon) . There were obvious correlation between leaf N (or P) and latitude (or mean annual temperature, MAT). Leaf N and P significantly increased with latitude increasing (or MAT decreasing), but the relationship between N/P ratio and latitude (or MAT) wasn't significant (p = 0.386 and p = 0.342), and the reason maybe include, leaf N and P had the same tendencies and large variations, and region in this research was smaller than global research.