Savannas are not old fields: functional trajectories of forest expansion in a fire-suppressed Brazilian savanna are driven by habitat generalists

Under fire suppression, many tropical savannas transform into forests. Forest expansion entails changes in environmental variables and plant community structure. We hypothesized that forest expansion into savanna results in a shift in community-weighted mean functional traits from stress tolerance to competitiveness, with generalist species having trait values intermediate between those of specialists of savanna and forest habitats.

We studied 30 plots distributed over three savanna-forest boundaries undergoing forest expansion in the Brazilian Cerrado, capturing a gradient from open savanna to recently formed forest. We measured functional traits of 116 woody species of savanna specialist, generalist, and forest specialist functional groups and quantified changes in species composition and mean traits across the basal area gradient.

We identified two main axes of species traits. The first separated forest and generalist species from savanna specialists, with the latter possessing...