Increasing fire severity negatively affects greater glider density

Abstract

Context Fire severity and frequency is predicted to increase over the remainder of the 21st century in Australia’s temperate forests; therefore, the effects of fire severity on forest-dependant species is of major conservation concern. Aims Determining the short-term (<1 year) effect of fire severity on a forest-dependant species, the greater glider, Petauroides volans, in Monga National Park, south-eastern New South Wales. Methods Three fire-severity classes were investigated, namely, low (canopy unburnt), moderate (partial canopy burn) and high (complete canopy consumption). Fifteen randomly allocated sites were visited in total, with five sites in each fire-severity class being visited on three separate occasions. Spotlighting of two off-track transects per site was completed over a 4-week period by using multi-covariate distance sampling (MCDS) to estimate greater glider densities at each fire-severity class. Key results An overall mean greater glider density estimate of 0.456 ha−1 (95% confidence interval (CI) 0.256–0.654 ha−1) was calculated across all sites in Monga National Park. Density estimates varied among fire-severity classes; low 0.779 ha−1 (95% CI 0.358–1.692 ha−1), moderate 0.472 ha−1 (95% CI 0.262–0.848 ha−1), and high 0.077 ha−1 (95% CI 0.0142–0.414 ha−1). Conclusions Distance sampling estimates suggested that areas affected by high-severity fire have lower densities of greater gliders. Implications The importance of areas experiencing low fire severity as a source of greater glider refugia during wildfire events is evident. Under a changing climate, frequent major wildfire events may significantly affect population viability of greater gliders if insufficient time between fires allow for population recovery.