Short-Term Effects of Wildfire on Bird Assemblages in a Core Area of the Pantanal Biosphere Reserve

Abstract Extreme drought and wildfires have affected the world’s largest continuous floodplain, the Pantanal. Understanding biodiversity responses to these disturbances is essential to inform management and conservation actions aimed at maintaining ecological processes and functions. We evaluated the effects of fire on bird assemblages and their short-term recovery in a protected area the Taiamã Ecological Station encompassing swamp and marsh habitats. We compared the taxonomic and functional diversity and species composition before and after fire across three degrees of exposure (directly, indirectly and not affected by fire) and at different times since fire, using a generalized linear mixed models and beta diversity indices. Species richness and abundance increased after fire, particularly in marsh habitats. Changes in composition were stronger for sites directly affected, with high turnover of species and functional traits. Although trait turnover decreased with time since fire, functional trait composition has not returned to pre-fire levels. In sites not affected, functional richness increased in marshes but declined in swamps during the post-fire cycle. Functional evenness declined after fire in both directly and indirectly affected sites across habitats. The post-fire increase in diversity likely reflects the high conservation status of the area, including fire-suppression actions that provided refuges, as well as the emergence of new habitats for colonization that may attracted opportunistic predators. However, reduced functional evenness suggests increased niche overlap and potential competition for resources, which may negatively affect species specialized in inland wetlands. We highlight the importance of integrated fire management and long-term monitoring to assess biodiversity recovery.