Impact of canopy vertical height on leaf functional traits in a Cunninghamia lanceolata common garden experiment in Dagangshan

Plant functional traits represent resource acquisition strategies and, consequently, reflect ecosystem functions. As a critical focus on functional trait research, the study of intraspecific variation and vertical gradients in canopies can better reveal plant adaptation mechanisms to environmental conditions. In this study, we examined five provenances of Cunninghamia lanceolata in the common garden of Dagangshan, Jiangxi. We measured and analyzed nine functional trait indicators: the leaf dry matter content, relative chlorophyll content, specific leaf area, leaf tissue density, water use efficiency, leaf carbon content, leaf nitrogen content, carbon-to-nitrogen ratio, and equivalent water thickness. The results revealed that canopy height has a minor effect on the variation in leaf functional traits, with most of the variation attributed to geographic provenances. Notably, 50% of the leaf functional traits presented significant correlations, which were mainly associated with photosynthetic capacity-related traits. The correlations of leaf functional traits between the average canopy values and the middle part of the canopy are similar. The influence of canopy height on leaf functional traits in subtropical Cunninghamia lanceolata artificial forests is limited, but the provenances had a certain impact on the leaf functional traits. The consistency of trait relationships between middle part and the entire canopy making it feasible to analyze forest ecosystem functions by collecting leaf samples from the middle canopy. This study provides scientific evidence for research on the functional dynamics of Cunninghamia lanceolata artificial forest ecosystems and the selection of superior provenances.