Fire affects the occurrence of small mammals at distinct spatial scales in a neotropical savanna

Abstract

Fire is a major disturbance event that affects biomes worldwide, altering vegetation structure and flora and fauna assemblages. Here, we investigated the effects of an extensive wildfire (~ 6240 ha) on small mammal assemblages in savanna woodland (cerradão) at two spatial scales (meso- and macrohabitat) in a neotropical savanna (Brazilian Cerrado). At each spatial scale, we assessed relationships between habitat structure and small mammal species composition and abundance before and after the fire in four natural patches (one burned, three unburned) using partial redundancy analysis. From July 2009 to October 2013, we captured 1319 individuals belonging to 14 species. Our results showed that the fire had consequences for small mammal assemblage at both scales. After the fire, the burned patch differed from the other patches in vegetation attributes and species composition. At a fine scale, fire increased the herbaceous layer and decreased the litter layer and understory obstruction. On a larger scale, the main consequences of fire on vegetation structure were increased variation in litter depth, tree diameter, and distance to the nearest tree. We observed a relationship between mesohabitat structure and the abundance of species with different habitat requirements during the post-fire succession. Fire favored the invasion of generalist species from open Cerrado habitats (rodents Calomys tener, Calomys expulsus, Cerradomys scotti, and Necromys lasiurus) at the expense of more specialized forest species. Our results reinforce the relevance of incorporating multi-scale habitat heterogeneity in future studies assessing the effects of fire on wildlife.