Land use changes and its impacts on bird diversity and community homogenization in fragmented Atlantic Forest landscapes of Minas Gerais

Abstract

Land-use changes and the resulting modification of natural environments represent one of the major threats to Neotropical biodiversity, especially in highly fragmented biomes such as the Atlantic Forest. In this thesis, composed of three scientific articles, I investigate how different anthropogenic land uses - including pastures and coffee and eucalyptus monocultures - affect the taxonomic and functional diversity of bird communities in agricultural landscapes within the Atlantic Forest domain of southern Minas Gerais. The work integrates bibliographic synthesis, methodological assessment, and empirical field analysis. The first article presents a systematic review of studies published between 2001 and 2024 that examine the impacts of land use on Neotropical forest birds. The review reveals consistent patterns of decline among forest specialists, frugivores, and insectivores in areas converted to agriculture and pasturelands, as well as evidence that species richness often masks profound shifts in community composition and functional structure. The second article compares the efficiency of in person point counts and low-cost autonomous recording units for sampling birds across the studied land use types, demonstrating that the two methods are complementary and that their integration increases detection capacity, reduces sampling biases, and enhances avifaunal monitoring in heterogeneous and highly fragmented landscapes. The third and main article evaluates whether anthropogenic land uses promote biotic homogenization and functional simplification of regional bird assemblages, using native forest communities as a reference. The results reveal high beta diversity driven primarily by species turnover, strong environmental filtering in coffee plantations and eucalyptus stands - with coffee showing the greatest homogenization potential - and the maintenance of higher functional integrity in forest remnants. Taken together, the findings demonstrate that land use change selectively reorganizes bird communities, reducing functional diversity and redundancy while favoring a small set of generalist species. These shifts undermine the functional resilience of these systems and reinforce the importance of forest remnants and landscape heterogeneity for the conservation of avifauna and the ecological processes it sustains. The results presented in this thesis provides essential guidance for avian conservation planning and for the development of more sustainable agricultural practices in the highly fragmented landscapes of the Atlantic Forest.