Document ID: chunk:federal_register_of_legislation:F2024L00270:body:0:p17
Version: federal_register_of_legislation:F2024L00270
Segment Type: other
Provision Reference: 
Character Range: 46282–49230

to the 2009 bushfires, and repeated after those fires. For the Lake Mountain area, an estimated subpopulation of 200–300 individuals, based on survey results prior to the fire, was reduced to just six individuals following the bushfire, indicating that the fire resulted in greater than 95% mortality at that locality (Harley 2016). The monitoring data collected between 2010 and 2021 indicate that the subpopulation has yet to show any significant signs of recovery, with the plateau estimated to support fewer than 10 individuals throughout most of this period (Zoos Victoria, unpublished data).
Leadbeater's possums have recently been detected at three lowland areas within the Central Highlands, all severely burnt in the 2009 bushfires, the Buxton Silver Gum Nature Conservation Reserve, Murrindindi Scenic Reserve and Marysville Sate Forest. These areas are notable as they support lowland swamp forest with Mountain Swamp Gum (Eucalyptus camphora) and share habitat affinities with that occupied by Leadbeater's possums at Yellingbo. The recent detections were in habitat with dense, post-fire regeneration (D. Harley, pers. comm).
The most substantial monitoring program reporting on changes in the abundance or incidence of Leadbeater's possum was established in 1983 (and subsequently expanded) for the montane ash forests. The most recent analysis reported a 50% decline in the number of sites occupied since 1987, from approximately 20% of sites occupied to less than 10% in 2017 (Lindenmayer and Sato 2018).
Importantly, while monitoring of possums directly is valuable, it is the availability of hollow bearing trees, as the most limiting resource for Leadbeater's possum, that is the key variable in all attempts to assess or model the population trend of the possum into the future (Lumsden et al. 2013; LPAG 2014b; Todd et al. 2016; TSSC 2019). The dynamics of the trees are quite well understood and it is widely accepted that their availability will continue to decline until approximately 2065 (Lindenmayer and Sato 2018). It also generally accepted that subsequent fires will exacerbate the decline of both hollow-bearing trees and possums. There is also a developing understanding of the interplay between the dynamics of hollow-bearing trees and of the growth and senescence of midstorey trees essential for foraging and movement (Baker et al. 2022). Recent advances in forest dynamics modelling could be incorporated into future PVA to improve these aspects of the model (Baker et al. 2017; Trouvé et al. 2019; Nitschke et al. 2020), albeit they are unlikely to alter the overall trends that reflect forest condition.

Implications for conservation management
    * Population and habitat monitoring has provided a vital contribution to understanding this complex system, and existing monitoring programs should be retained and expanded to including all relevant habitat types, forest ages and throughout all of the species'