Unraveling tree species connections and their relationships with environment in a vegetation mosaic in Brazil

Biotic interchange plays a key role in the assembly of regional biotas in the Neotropics. The transition between different phytogeographic regions promotes a floristic mixture that offers a useful model to investigate the role of deterministic processes in the structuring of Neotropical communities at regional scales. We aimed to examine a possible separation of the phytogeographic domains and vegetation types of the Amazon-Cerrado-Pantanal mosaic into distinct floristic groups, and to elucidate the drivers that explain its tree species composition. Based on 30,930 occurrence records of 2,258 tree species, besides environmental variables, we used clustering (UPGMA), ordination (PCoA and RDA) and variation partitioning analyses. The seven floristic groups that emerged in the Amazon-Cerrado-Pantanal mosaic generally reflected the floristic identity at the phytophysiognomic level. Grassy cover, followed by seasonal potential evapotranspiration, temperature seasonality, silt, water bodies coverage and topographic wetness index (TWI) were the most important predictors of floristic variation. We discuss how our study allows advance in the phytogeographic knowledge of such comprehensive South American mosaic.