Document ID: chunk:federal_register_of_legislation:F2024L00270:body:0:p14
Version: federal_register_of_legislation:F2024L00270
Segment Type: other
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Character Range: 38006–41105

hollow-bearing trees (Lindenmayer et al. 2015b), the TSSC described an ongoing decline in the extent and quality of suitable habitat based on the collapse of large hollow-bearing trees, fire and timber harvesting, with such decline causing a projected decrease of 83% (confidence range of 78–88%) in population size of Leadbeater's possum, over the period between 2006 and 2024 (i.e. three possum generations) (TSSC 2019; See Section 3.4.3 Decline in habitat extent, suitability and connectivity: montane ash forest).

3.2.5             Future range
Regardless of habitat loss due to fire or other disturbance, bioclimatic modelling incorporating projected climate change predicts considerable ongoing diminution of the range of the Leadbeater's possum and of its principal habitat, montane ash forest (Lindenmayer et al. 1991d; Burns et al. 2015), and the likely increase in fire severity and frequency (Keenan and Nitschke 2016). Recent climate modelling by researchers at Deakin University in collaboration with Zoos Victoria predict a significant contraction in the suitable climate space in the Central Highlands by 2090 due to climate change (Archibald et al. 2023). Other climate change effects may include reduced productivity and recruitment of mountain ash. Forest stand density is predicted to be reduced by approximately 15% by 2080 and the area of the Central Highlands suitable for natural regeneration may be reduced by up to 80% over this timeframe (Baker et al. 2017).

3.2.6             Survey techniques and effort
Conservation planning and management will be most effective when there is a high degree of confidence in known and prospective distribution, and the determinants of that distribution. There has been substantial investigation of, and refinement in, targeted survey techniques allowing for rapid and comprehensive sampling, although all sampling procedures have some interpretational and other constraints.
The longest-used monitoring method is 'stag-watching', which involves a set of observers positioned under large hollow-bearing trees on dusk to observe possums emerging from tree hollows (Seebeck et al. 1983; Smith et al. 1989). It is a generally reliable, but resource-intensive method (Lindenmayer 2009). It is important in the context of the long-standing research and monitoring program run by Professor David Lindenmayer of the Australian National University (ANU). Importantly, it specifically evaluates hollow-bearing tree occupation.
More recently, some surveys have successfully used call playback or imitation to lure the possums towards observers, with detection in dense vegetation further improved by the use of thermal cameras (Lumsden et al. 2013; Harley 2015b). There may be some caveats with interpretations of results from this method including uncertainty about the distance that responding possums may move to the playback (Harley 2015b) and variability in response rates relating to wind or rain, and to habituation (Lindenmayer et al. 2014a), or seasonal or site-specific variation.
Fixed remote (motion-sensing) cameras, directed at bait