Patterns of diaspore functional diversity in Araucaria Forest successional stages in extreme southern Brazil

Resumen

Dispersal is an essential process for community assembly, since it defines the species that have the potential to colonize a particular site. It is possible to infer the dispersal agent from the traits that constitute the plant dispersal syndrome, such as diaspore color and size. The vegetation of southern Brazil consists of forest-grassland mosaics, in which forest expansion is occurring where land management does not preclude the process. Here, we assessed: (1) if there is variation in the functional diversity of zoochorous diaspore traits of young trees along a canopy openness gradient in Araucaria and Podocarpus forest patches, and (2) what diaspore traits of tree species are associated with the canopy openness gradient. Additionally, we present a list of tree species occurring at the study site. Zoochory is the main dispersal syndrome in these forests, in both early and advanced stages of vegetation succession. Diaspore functional diversity decreased from large forest to small patches, likely due to habitat-use patterns of vertebrate seed dispersers. Our results suggest that the disperser fauna is essential to the forest-grassland dynamics throughout the process of forest expansion over the grassland.