The long-term absence of natural fires restructures the small-bodied mammal assemblages across a Protected Area of Brazilian Cerrado

Natural fires are an important ecological process that over millennia have shaped savannahs. Local mammalian assemblage structure is influenced by vegetation diversity and complexity, whereby changes in composition and structure of vegetation due to fire absence lead to the reorganization of small-bodied mammal assemblages. We aimed to evaluate how small-bodied mammal assemblages respond to prolonged (i.e., 17 years) fire absence, given that this issue is crucial to understanding the long-term reassembling of small-bodied mammal assemblages in the Cerrado. In our study at Serra das Araras Ecological Station (SAES), we compared small-mammal assemblages sampled in 2016–2017 — during a prolonged period without fire — with those from a study conducted in 1999–2000, when fires had been occurring naturally. We used descriptive statistics, rarefaction to assess species richness, and Non-Metric Multidimensional Scaling (NMDS) with SIMPROF for site-specific analysis of mammal composition between both periods. Our major result showed clearly that the absence of natural fires during 2001–2016 in the SAES reassembled the small-bodied mammal fauna compared to the period with constant fires (1995–2000). Our findings indicate that most species are common to both forest and savannah environments, reflecting the homogenization of habitats due to the absence of natural fires. Based on our study, we can conclude that the absence of fire has partially reassembled the small-bodied mammal assemblages across an important protected area of Brazilian Cerrado. Considering that fire is a crucial factor for the dynamics of the Cerrado — which has evolved historically under fire-driven processes — further technical discussions about fire management are needed given its crucial role in maintaining (or erasing) aspects of local diversity, especially with high stocks of dry biomass. In terms of conservation, the evidence so far showed that big-fires are conclusively disastrous, but the absence of natural fires in native areas of Cerrado apparently also harmed the Cerrado-prone biotas.