Intraspecific variation in leaf traits facilitates the occurrence of trees at the Amazonia-Cerrado transition

The ability of plant species to adjust key functional traits through intraspecific variation may determine their success in persisting on our planet in the future, especially in unstable habitats, such as the Amazonia-Cerrado transition zone. We assessed intraspecific variation in 12 leaf morphological and anatomical traits for four tree species along a savanna-forest gradient, including rocky cerrado, typical cerrado and woodland savanna. Generally, all evaluated species showed great intraspecific variation. Our findings demonstrate that trees occurring in the woodland savanna are potentially more vulnerable to climate change, while in the cerrado the individuals presented higher tolerance to water deficit and high temperatures. Trees occurring in open-canopy habitats showed smaller stomata, higher stomata and trichome densities, compared to the same species growing in the woodland savanna. In contrast, the individuals in the woodland savanna shift leaf traits to increase resource acquisition (e.g. light), showing higher specific leaf area and larger stomata, compared to cerrado individuals. We have shown that vegetation-induced shifts in leaf morphological and anatomical traits are a major effect in within-species variability, with consequences for persistence and tolerance of species under future climatic conditions.