Objective This study aimed to provide a theoretical basis for elucidating the coexistence mechanism of typical temperate deciduous broadleaved woody plants by revealing the variation characteristics, sources of variation, and interrelationships among functional traits of leaf morphology and biochemical traits of different life forms of plants.

Method We investigated 8 leaf functional traits for 23 woody plants, including 12 shrubs and 11 trees in a deciduous broadleaved forest in Baihuashan Nature Reserve in Beijing, analyzed the variation characteristics of the leaf functional traits and relationships between these traits, and further examined the driving forces of the variations and plant ecological adaptation strategies.

Result (1) There was no significant difference in leaf carbon, nitrogen and phosphorus content, leaf relative water content and leaf tissue density between tree and shrub species. However, the specific leaf area of tree species was significantly lower than that of shrub species, and leaf thickness and leaf dry matter content were significantly higher than that of shrub species. (2) For most leaf traits, species was the best factor to explain the variation in leaf functional traits. The variations in leaf thickness and specific leaf area mainly came from species itself and life form, and the variation in leaf dry matter content was explained by species, individuals and life form. (3) In addition, the results of trait information axis showed that most shrub species were located at the end of the fast investment income of the leaf economic spectrum, while tree species were located at the end of the slower investment income. These differences indicated that there were diverse trade-off strategies for plant traits to adapt to environmental heterogeneity, and according to our findings, the specific leaf area was the key variable to divide the ecological strategies of two life-form plants.

Conclusion Different life-form woody plants can acclimate to the resource variation along a vertical canopy gradient by optimizing a combination of leaf structural traits. The slight environmental differences between habitats will accelerate niche differentiation of coexisting plants in the community.