Mammalian responses to fire on Newnes Plateau: A yardstick for future recovery

Abstract

A major fire swept through Newnes Plateau near Lithgow in 2013, burning 50,000 hectares of bushland. Long-term monitoring programs were already established, with half the sites impacted by the fire. It was then possible to record changes in fauna populations in response to the fire. Detailed surveys for a range of mammalian fauna were undertaken twice a year from 2011 to 2019. The results from the comprehensive surveys showed that even with high intensity fire over a large portion of the landscape, habitat recovery is relatively quick. Significant Before-After Control-Impact differences were observed for five microhabitat metrics. Ground cover components (forb and fern) returned to pre-fire levels quickly (within 0.5 years). Mid storey components returned to pre-fire levels within 6.0 years of the fire. Small mammal responses are species specific, but again, most return to pre-fire (or at least Control site) levels within 6.0 years. Antechinus mimetes mimetes is one exception, disappearing from Impact sites within 2.0 years of the 2013 fire. Recovery of both Rattus species was faster than Antechinus, and coincided with return of low shrub cover to unburnt site levels. Recovery to control site levels was often faster than to pre-fire levels. The arboreal mammal Petauroides volans increased (non-significantly) post-fire in Control sites, contrasting with declines seen in the species at lower elevations. Total native, non-volant mammal abundance at each site declined with fire (more so at burnt sites), yet species richness remained the same. Simpson’s Diversity Index increased post-fire in burnt sites. These three factors combine to suggest that all species in the community assemblage remain present after fire, albeit at lower levels than prior to the fire. Broad-scale, long term fauna monitoring has allowed us to analyse mammal and habitat responses to fire, though there are limitations placed on interpretations. Habitat Complexity Score is too coarse a metric to tease out differences in overall or lower habitat categories. Presence/absence data also limit our ability to fully describe site occupation for larger/introduced mammal species. The design of our analyses, however, provide a robust framework for analysing fauna responses to fire, and can be used to predict expected recovery trajectories for mammal populations after the larger, more recent Gospers Mountain fire in 2019.