Changes in small mammal populations after fire in a patch of unburned cerrado in Central Brazil

We studied the populations of small mammals in a patch (1 ha) of closed woodland (cerradao physiognomy) that naturally escaped burning within an area of cerrado vegetation in Central Brazil. The animals were censured by live-trapping during 9 months prior to a prescribed fire (18 September 1996) and subsequently for 6 months after fire. The results in the unburned patch of cerradao within a burned cerrado area were compared with another area of unburned cerrado physiognomy. The frequently trapped species in the patch of cerradao, Calomys callosus, C. tener and Oryzomys subflavis declined after fire. Calomys callosus showed a small decline followed by a strong increase in density after fire. Demographic analysis indicated that the observed postfire decline and the posterior peaks in density were caused by the use of the patch by transient individuals from neighboring populations. The patterns of microhabitat use of C. tener changed in response to fire. Before fire, the marginal area of the grid was preferred by C. tener; after fire, the inner area was more important compared to pre-fire levels. The mean body weights of C. tener decreased subsequent to fire. The data suggest that many species could use this patch for shelter and/or as a source for food both before and after fire. From the ratio of the mean abundance (after fire) of transient individuals to the mean density of residents ones (before fire) we estimated that individuals from the surrounding eight hectares could use the patch.