Individual-level leaf trait variation and correlation across biological and spatial scales

Even with increasing interest in the ecological importance of intraspecific trait variation (ITV) for better understanding ecological processes, few studies have quantified ITV in seedlings and assessed constraints imposed by trade-offs and correlations among individual-level leaf traits. Estimating the amount and role of ITV in seedlings is important to understand tree recruitment and long-term forest dynamics. We measured ten different size, economic, and whole leaf traits (lamina and petiole) for more than 2800 seedlings (height ≥ 10 cm and diameter at breast height < 1 cm) in 283 seedling plots, and then quantified the amount of ITV and trait correlations across two biological (intraspecific and interspecific) and spatial (within and among plots) scales. Finally, we explored the effects of trait variance and sample size on the strength of trait correlations. We found about 40% (6~63%) variation in leaf-level traits was explained by ITV across all traits. Lamina and petiole traits...