Abstract: Functional trait difference among species is one of the central issues in species coexistence. However, the effects of intraspecific variation in functional traits on species coexistence and distribution remain unclear. Based on a forest canopy tower crane platform, we explored the variations in leaf morphology, physiological, and biochemical functional traits of ten dominant tree species along the canopy vertical gradient from a broad-leaved Korean pine forest in Changbai Mountain. Leaf thickness, leaf mass per area, flavonoid, effective photochemical quantum yield, and leaf C/N tended to increase with increasing canopy height. Leaf functional traits varied significantly among tree species. Interspecific variations significantly affected morphological and chemical traits. Intraspecific variations contributed more to the variations of physiological traits, which was higher in the upper canopy than in the lower canopy. The interspecific variation was not significant along the vertical gradient. The significant variations of leaf functional traits among vertical canopy gradients demonstrated the importance of the interspecific variations for species coexistence in the broad-leaved Korean pine forest, but the intraspecific variations cannot be ignored.

Key words: canopy vertical gradient, functional trait, intraspecific variation, species coexistence