Short-term impact of a mega-fire on small mammal communities during prolonged drought

Abstract

Increased size, severity and frequency of wildfire is predicted as a consequence of prolonged droughts associated with climate change. In south-eastern Australia severe landscape-scale wildfires (mega-fires) have elicited a strong anthropocentric response due to the significant life and property impacts. However, the impact of mega-fires on fauna, habitat and subsequent management actions are poorly understood. Small mammals were surveyed to examine mega-fire impact using the post-2006 wildfire landscape of the Grampians National Park, Victoria, Australia. Long-term research sites were established with 9620 trap nights completed in autumn 2008 across thirty-six sampling units. Vegetation structure, floristics, fire severity, patch size and overall fuel hazard were measured to investigate correlations with changes in small mammal abundance.Two years post-wildfire, rapid resurgence of house mouse (Mus musculus) was detected, conversely the abundance of native small mammal species was severely impacted. No sampling category within the burnt perimeter provided superior refuge presenting potential conservation implications. A habitat vacancy model is introduced where small mammal recolonisation post-wildfire depends on a lack of isolation and connectivity of populations. Floristic and structural contributions of vegetation to higher overall fuel hazard areas are essential in maintaining diverse fauna assemblages. As such, prescribed burning or fire suppression tactics such as ‘patching out’ or ‘burning out’ require consideration when contributing to further reduction of complex habitat patches following fires.