Abstract: Abstract Aims Pinus tabuliformis, a representative species of temperate coniferous forests in China, exhibits strong ecological adaptability. Investigating the stoichiometric characteristics of leaves, twigs and roots across different age groups and their interrelationships is essential for understanding intraspecific variation and resource allocation strategies. Methods In this study, we sampled natural P. tabuliformis forests from nine regions in China and measured the carbon (C), nitrogen (N) and phosphorus (P) content in six organ types from 81 trees: current-year leaves, perennial leaves, current-year twigs, perennial twigs, absorptive roots and transport roots. Important findings (1) N and P concentrations were higher in current-year organs than in perennial organs, whereas C:N, C:P and N:P ratios were higher in perennial organs. The stoichiometric traits of each organ exhibited varying degrees of intraspecific variation among age groups, with organ age being the primary factor driving this variation. (2) Standardized major axis regression analysis indicated that, compared to current-year leaves, P. tabuliformis allocated more P to perennial leaves; compared to perennial twigs and perennial roots, more C, N and P were allocated to current-year twigs and current-year roots. (3) The allocation of C, N and P to current-year roots was significantly higher than that to current-year leaves and twigs. (4) Mean annual temperature (MAT) and soil phosphorus content (SPC) were the primary environmental factors influencing current-year and perennial leaves, respectively. Mean annual precipitation (MAP) and SPC were the main factors affecting current-year and perennial branches, while soil moisture content (SMC) and soil nitrogen content (SNC) primarily influenced absorptive roots and transport roots. This study elucidates the nutrient allocation strategies and environmental adaptability of P. tabuliformis across different organ ages. We recommend considering organ age differences when studying the stoichiometric characteristics of evergreen species to better understand their C, N and P allocation mechanisms and environmental adaptation strategies across different age groups.

Key words: intraspecific variation, Pinus tabuliformis, organ, age, stoichiometric characteristic