Document ID: chunk:federal_register_of_legislation:F2024L00270:body:0:p44
Version: federal_register_of_legislation:F2024L00270
Segment Type: other
Provision Reference: 
Character Range: 120459–123328

contributed to ongoing reduction in the quality and extent of habitat suitable for Leadbeater's possum. Zoos Victoria and Deakin University have recently modelled the impacts of increasing temperatures on the suitable climate space for Leadbeater's possum for four future emission scenarios: RCP 2.6-SSP1, RCP 4.5-SSP2, RCP 7.0-SSP3 and RCP 8.5-SSP5, with the results indicating significant reductions in the habitable area within the Central Highlands by 2090 with greater emissions (Archibald et al. 2023). Under these scenarios, a subset of forest patches could be abandoned by Leadbeater's possum due to increased mean annual temperatures. Some sites, most likely towards the periphery of the range, may cross a tipping point whereby they would be no longer cold enough for this species.
Ongoing increases in the incidence of drought and high temperatures are likely to lead to further marked increase in the frequency and intensity of bushfires (Williams et al. 2009; Dutta et al. 2016), and hence to more frequent acute episodes of high mortality of possums (including direct mortality during extreme heat events), and chronic marked reductions in the landscape-scale abundance of hollow-bearing trees.
Regardless of the associated increased risks of severe bushfire, a higher incidence of drought and of extremely hot days is also likely to lead to high rates of mortality of large trees. For example, elevated rates of tree mortality were reported for the period 2004 to 2011 (during which 23% of large living trees died on unburned sites), associated with drought conditions (Lindenmayer et al. 2012; Lindenmayer et al. 2013a). While such drought-killed trees may stand as stags in the landscape, they are more susceptible to collapse during and after severe bushfire than are large living trees (Lindenmayer et al. 2012), so an increased incidence of severe drought in the future will result in further reductions in the abundance of hollow-bearing trees. Ecological thinning of some forests should be investigated. Retention of suitable (dense) vegetation structure in aging forests is challenging, and thinning can contribute to loss of structure where midstorey recruitment is not occurring, such as at Arnold Gap (at Lake Mountain) and elsewhere (D. Harley, pers. comm.).
Because mountain ash and alpine ash have moderately narrow limits of climatic suitability climate change will lead to a reduction in the distributional extent of these two tree species (Wang et al. 2016). There is expected to be a severe impact on the regeneration of mountain ash, reducing the total area suitable for natural regeneration by more than 80% by 2080 (Baker et al. 2017). Mountain ash stand density and volume will also be reduced by about 15% (Baker et al. 2017). The impact of increased incidence of severe fire will be especially profound where future fires recur at