资源环境科技发展态势分析平台

The degree of stoichiometric homeostasis can be indicated by the homeostatic coefficient (H), which reflects the ability of plants to maintain a stable nutrient composition regardless of changes in environmental nutrients. In previous studies, H had been determined primarily in herbs and varied significantly among organs and growth stages. However, whether H varies according to organ-type and age in tree species is unknown. In this study, nitrogen (N) and phosphorus (P) fertilization experiments were conducted in young and mature Metasequoia glyptostroboides plantation stands. The H of N (H-N) and H of N:P (H-N:P) was found in young trees, H of P (H-P) and H-N:P existed in mature trees. Also, leaf H-N:P of mature trees was greater than that of young trees (P < 0.05), and H showed significant difference among organs in mature trees (P < 0.05), but not in young trees (P > 0.05). Thus, stoichiometric homeostasis varied with tree age and among organs, and leaf N:P was more tightly constrained in mature trees than in young trees. These findings imply that stoichiometric homeostasis is coupled to tree growth and development, which suggest N limitation for young trees and P limitation for mature trees, at least in M. glyptostroboides.