Abstract: Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions. Abiotic factors have strong effects on N-P stoichiometry, yet the impact of plant community structure, especially in forests, has not been fully elucidated. We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves. The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests, P concentration and N:P ratio of leaves were significantly related to those of soil. Except for larch forest type, N-P stoichiometry was also regulated by elevation, climatic factors, and community structure. With increasing age (from 25 to 236 years), soil N and N:P ratio significantly increased, especially in the topsoil. With increasing mean DBH, leaf N concentration and N:P ratio also increased, indicating a shift in nutrient limitations with stand growth. These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry, which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.

Key words: N-P stoichiometry, Larch forest, Community structure, Stand age, Leaf