Response mechanisms of leaf nutrients of endangered plant (Acer catalpifolium) to environmental factors varied at different growth stages

The response patterns of N and P in plant leaves are one of the tools for investigating the ability of plants to cope with current environmental conditions and predicting their future viability. Endangered species are more sensitive to environmental changes, lack of nutrients such as NP will adversely affect the survival of species. 119 Acer catalpifolium are the only ones left in the world were studied and were divided into different growth stages (small, adult and old trees) to study the environmental response of leaves to NP. Results showed that: the NP stoichiometric characteristics of Acer catalpifolium leaves were lower in small stage, with the growth of plants, the NP content increased. There was a significant correlation between the soil nutrient and leaf NP stoichiometry in all growth stages, and with the increase of soil N:P, the leaf N:P changed from N limitation to N and P limitation, showing a poor adaptability to soil environmental changes. Under the influence of environmental conditions, the adaptation strategy of leaf NP at different growth stages were different. With the return of nutrients, the leaf N:P at adult and old stages increased with litter thickness. Small and old stages showed poor adaptation with environmental changes. These results indicate that leaf NP differed significantly among different life stages and that these differences can accounted for part of the causes of endangerment of Acer catalpifolium. Keywords: Endangered plant, Acer catalpifolium, Growth stages, NP stoichiometry