Woody encroachment affects multiple dimensions of ant diversity in a Neotropical savanna

Woody encroachment resulting from fire suppression has become a global phenomenon and a major threat to the conservation of grassy biomes (savannas and grasslands). Yet, little is known about how animal communities respond to woody encroachment. In the manuscript, we used a combination of field surveys, a species-level phylogeny, and functional metrics drawn from a morphological dataset, to evaluate how the progressive increase in tree cover in a fire-suppressed savanna landscape affects the taxonomic, functional, and phylogenetic diversity of neotropical ant communities. We sampled ants along an extensive tree cover gradient, ranging from open savannas to forests established in former savanna areas due to fire suppression. We found that ant responses to variation in tree cover were largely non-linear as differences in alpha diversity and in the dissimilarities of the sampled communities were often much more marked at the savanna/forest transition than at any other part of the gradient.