Alexandre Ramlo Torre Palma

Post-fire succession of small mammals in the Cerrado of central Brazil

In the Cerrado savannas from Brazil fire events are common and strongly influence the vegetation structure and, consequently, the associated small mammals. In this paper, we investigate changes in the structure of small mammal communities related to sites of different post-fire ages. Mammals were captured in similar Cerrado sites that differed in time since the last burn (1 to 26 yr). We sampled six sites in the wet season of 1997 (phase 1) and, three years later, six sites in the wet and dry seasons (phase 2). Six rodent species and four marsupials were captured. Community composition changed drastically as a function of time since fire. The diversity and abundance of small mammals reached maximum values in the early successional stages. The rodent Calomys tener was present only in early seral stages. The rodent Bolomys lasiurus was more frequent in mid-successional stages and decreased in later seral stages, and the rodent Oryzomys subflavus occupied all successional stages. The marsupial Gracilinanus agilis was dominant in the area that did not burn for at least 23 yr. Changes in composition of the community of small mammals were more accelerated in early successional stages, when there are more drastic vegetational changes. The ability of small mammals to cope with Cerrado fires and the great dissimilarity among post-burning seral stages suggest that a mosaic of areas representing different post-fire seral stages could increase the regional diversity of this group.

Variação morfológica de pegadas de roedores arborícolas e cursoriais do Cerrado

Considering that species of rodents have different means of locomotion, this study presents and discusses variations on the anterior and posterior footprints shape of seven species [Akodon cursor (Winge, 1887), Necromys lasiurus (Lund, 1840), Oecomys bicolor (Tomes, 1860), Oecomys concolor (Wagner, 1845), Oligoryzomys nigripes (Olfers, 1818), Hylaeamys megacephalus (Fischer, 1814) and Rhipidomys macrurus (Gervais, 1855)], using geometric morphometrics and discriminant analyses. Shape variables were related to phylogenetic topology and means of locomotion of the species to verify the influence of historical or ecological factors on footprints morphology. Footprints shape of the arboreal rodents (short and wide) was clearly distinct of cursorial ones (narrow and elongated). The anterior (Kappa = 0,72) and posterior (Kappa = 0,88) footprint reclassification was considered substantial and almost perfect, respectively. The posterior footprints presented better results of species discrimination and set the levels of arboreal and cursorial activity of rodents. Allometric effects were observed in anterior (13%) and posterior (3%) footprint analysis. The means of locomotion explained 90.3% of footprint rodents shape variation (p = 0.02), indicating convergence on footprint morphological patterns of arboreal and cursorial rodents.