Does stoichiometric homeostasis differ among tree organs and with tree age

Abstract

Abstract 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 (HN) and H of N:P (HN:P) was found in young trees, H of P (HP) and HN:P existed in mature trees. Also, leaf HN:P of mature trees was greater than that of young trees (P\u202f \u202f0.05). 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.