Exploring the variation in leaf functional traits and their relationships among dominant woody plants during their growth and development across the vertical structure of a typical mountainous plant community revealed the adaptive strategies of dominant species in response to their growth trajectories and environmental changes. This research provided a crucial data foundation for vegetation protection and sustainable forest management in this region. This study investigated dominant woody plants in a typical community in Beijing's northeastern mountainous region. The canopy layer included Cotinus coggygria and Prunus davidiana, while the shrub layer comprised Vitex negundo var. heterophylla and Rhamnus parvifolia. Periodic field surveys and measurements of six leaf functional traits were conducted from July to September. We analyzed the monthly variations and interrelationships of leaf functional traits among these species, and investigated the similarities and differences in resource trade-off strategies over time, as well as the variations in resource allocation strategies between canopy and shrub layer species. The results showed that: (1) In terms of monthly variation, the specific leaf area (SLA) and maximum net photosynthetic rate (A_max) of V. negundo var. heterophylla and R. parvifolia showed a decreasing trend over time, with values in July significantly higher than those in September (P<0.05), indicating that plants allocated more resources to leaf photosynthetic capacity during the vigorous growth period to support rapid growth. Furthermore, a significant negative correlation was observed between leaf tissue density (LTD) and SLA among the four dominant woody plants across different months, reflecting a resource allocation trade-off between physical defense structure and photosynthetic capacity. (2) Regarding the vertical structure of the community, the leaf thickness (LT) of C. coggygria and P. davidiana was significantly greater than that of V. negundo var. heterophylla and R. parvifolia from July to September (P<0.05). This suggested that plants in the upper vertical structure of the community increased LT to reduce water loss and protect leaves from physical damage caused by strong light. This study demonstrated that the four dominant woody plants shifted over time from a "rapid investment-return" strategy to a "slow investment-return" strategy, reflecting adaptive adjustments in resource trade-off strategies in response to growth and developmental stages. In terms of the vertical structure of the community, the upper-layer trees in the community (i.e., C. coggygria and P. davidiana) tended to adopt a "slow investment-return" strategy throughout the study period. In contrast, the lower-layer shrubs (i.e., V. negundo var. heterophylla and R. parvifolia) showed a "rapid investment-return" strategy to better adapt to the variations in resource availability across the vertical structure of the community. These findings confirmed that woody plants optimized their resource trade-off strategies by regulating leaf functional traits and their synergistic or trade-off relationships in response to growth, development and environmental changes.