Phenotypic variability within tree species responds to local tree species richness. However, we lack evidence on how different sources of trait variation shape tree-tree interactions. Along a diversity gradient from one to eight tree species, here we collect 4568 leaves from 381 trees to study changes in intraspecific and intraindividual leaf trait variability, and assess their contribution to community functional diversity. Intraspecific trait variability in functional traits decreases with tree species richness, while similar responses for intraindividual variability are revealed by spectral traits. Functional overlap between conspecific trees increases through intraindividual variation, but is reduced through intraspecific variability, meaning that intraspecific variability may reduce intraspecific competitive interactions while intraindividual variability could arise due to varying light within the canopy. Last, intraspecific and intraindividual variability explain high community functional richness and divergence, respectively, especially in mixtures. Our findings emphasize that fine-scale variability influences tree-tree interactions and drive local functional diversity.
Figure 1. Main axes of leaf trait variation and effect of tree species richness on intraspecific and intraindividual leaf trait variability.
Figure 2. Effect of tree species richness on intraspecific and intraindividual leaf functional trait variability, as reflected by two multivariate functional indices.
Figure 3. Spectral segmentation and effect of tree species richness on the variability of spectral components at the intraspecific and intraindividual level.
Figure 4. Piecewise structural equation model (SEM) studying the mechanisms driving the intraspecific overlap in leaf functional traits.
Figure 5. Differences between observed and random values of community functional diversity along a species richness gradient for four null models that randomized different sources of trait variation.
Literature:
Pablo Castro Sánchez-Bermejo*, Carlos P. Carmona, Meredith Christine Schuman, Raquel Benavides, Lena Sachsenmaier, Shan Li, Xiaojuan Liu, and Sylvia Haider. 2025. Intraspecific and intraindividual trait variability decrease with tree richness in a subtropical tree biodiversity experiment. Nature Communications. 16(1):11009. https://www.nature.com/articles/s41467-025-67265-8.
