Environment, phylogeny, and photosynthetic pathway as determinants of leaf traits in savanna and forest graminoid species in central Brazil

Abstract

Leaf traits are closely linked to plant responses to the environment and can provide important information on adaptation and evolution. These traits may also result from common ancestry, so phylogenetic relationships also play an important role in adaptive evolution. We evaluated the effects of the closed forest environment (gallery forest) and the open savanna environment (cerrado) on the selection of leaf traits of graminoid species. The two plant communities differ in light, nutrients, and water availability, which are important drivers in the selection and differentiation of these traits. We also investigated the functional structure and the role of phylogeny in the functional organization of species, considering leaf traits. Patterns of leaf trait variation differed between forest and savanna species suggesting habitat specialization. Wider and longer leaves, with higher values of specific leaf area, chlorophyll, and nitrogen, seem to be an advantage for graminoid species growing in forest environments, while thicker leaves, with higher values of leaf dry-matter content and carbon, benefit species growing in savanna environments. We found few phylogenetic signals related to leaf traits in each environment. Therefore, the functional similarity that the gallery forest and cerrado graminoid species share within their group is independent of their phylogenetic proximity. Environmental filters affect the functional structure of communities differently, generating communities with trait values that are more distant than expected by chance in cerrado (functional dispersion), and closer than expected by chance in the gallery forest (functional convergence).

Keywords: Cerrado; Functional diversity; Grasses; Open habitats; Shaded habitats.