Objective This study evaluated the contents and ecological stoichiometric characteristics of carbon (C), nitrogen (N) and phosphorus (P) in Betula platyphylla forest leaves across a chronosequence of stand ages in the cold temperate zone. The research aimed to elucidate the variation patterns of leaf nutrient contents and nutrient limitation status in B. platyphylla with increasing stand age, thereby providing a scientific basis for the management of cold temperate forest ecosystems and nutrient cycling research.

Method This study selected three B. platyphylla forests of distinct stand ages (32, 47, and 68 years) as research objects, measured the leaf C, N, and P contents alongside their ecological stoichiometric ratios from May to September using homeostasis index and RDA analysis to examine the correlations between leaf nutrient contents and environmental factors.

Result (1) From May to September, the leaf C content in B. platyphylla forests varied from 440.20 to 497.81 mg/g, N content from 8.75 to 25.31 mg/g, and P content from 2.56 to 6.45 mg/g across different stand ages. During seasonal progression, leaf C content exhibited a gradual increase, whereas N displayed a progressive decline. The P content decreased from May to August, followed by a slight increase in September. Leaf C and N contents showed an increasing trend with increasing stand age, while P content first decreased and then increased. (2) From May to September, the leaf C∶N and C∶P showed a consistent increasing trend across all stand age, while the N∶P exhibited fluctuations. With increasing stand age, leaf C∶P and N∶P showed an increasing trend, while C∶N showed a decreasing trend. (3) Soil water content exhibited positive correlations with leaf P content, but negative correlations with leaf C∶P and N∶P of B. platyphylla of different stand ages. Soil temperature showed positive associations with both leaf C and N∶P. Soil pH was positively correlated with leaf C∶N of B. platyphylla forests.

Conclusion B. platyphylla forests exhibite persistent N limitation throughout their growth process. It is recommended that timely tending and management is implemented according to the age of B. platyphylla forests to accelerate litter decomposition, enhance nitrogen inputs, and thereby ensuring adequate nutrient availability for the growth of B. platyphylla forests.