Fire impacts recruitment more than survival of small-mammals in a tropical savanna

Abstract

The frequency and spatial patterning of fire for optimal biodiversity conservation is often poorly understood by managers, in part due to a lack of understanding of the mechanisms responsible for altering population dynamics of individual species. We investigated changes in the vital rates (survival and recruitment) of four small mammal species (three marsupials and one rodent) in a tropical savanna under four different experimental fire treatments applied at a landscape scale. Apparent survival declined in all fire treatments for only one of four small mammal species (northern brown bandicoot Isoodon macrourus). Recruitment was reduced in three of four species in multiple fire treatments. The suppression of recruitment in the northern brown bandicoot and the brushtail possum Trichosurus vulpecula populations was greatest immediately after the initial fire treatment was applied, compared to remaining treatment applications in successive years, possibly due to an elevated fire intensity as a result of higher initial fuel loads. The results suggest that higher intensity fire impacted recruitment more than survival for small mammals at this site. To assist fire managers to conserve small mammal populations in tropical savannas, we recommend fire regimes that optimise habitat resources for recruitment. This may be achieved by a reduction in fire frequency and managing fuel loads to prevent an increase in fire intensity.