Using functional diversity and taxonomic diversity to assess effects of afforestation of grassland on bird communities

Birds are important bioindicators of environmental change and perform essential processes for ecosystem functioning. Afforestation of grasslands may lead to the reduction or loss of specific functions performed by bird species. We investigated the effects of afforestation of grasslands in southeastern South America on taxonomic and functional diversity of birds using multidimensional functional diversity indices. We collected data from bird communities in mosaics of native habitat and in eucalyptus plantations. We recorded taxonomic impoverishment in plantations, but no reduction in functional diversity was found in planted areas. The results demonstrate greater functional redundancy in riparian forest, which may confer greater stability for these communities, while higher values of functional diversity in plantations may indicate quite dynamic and less stable communities from a functional point of view. None of the diet categories were strongly associated with the sampled habitats. Nonetheless, omnivorous and insectivorous bird species were among the first to colonize plantations after cutting. Since the response of species to habitat changes are mediated by their traits, we can infer that, for a group of species, forest plantations are not totally unsuitable. However, to conserve different dimensions of diversity, it is essential to conserve mosaics of native vegetation to maintain bird diversity.