Document ID: chunk:federal_register_of_legislation:F2024L00270:body:0:p6
Version: federal_register_of_legislation:F2024L00270
Segment Type: other
Provision Reference: 
Character Range: 16235–19170

TSSC (2019) concluded that the population of the species (explicitly as informed by data on the abundance of old or hollow-bearing trees) had declined and would continue to decline by more than 80% over three generations (18 years) spanning the recent past and near future, despite a suite of existing conservation planning and management actions.
In conducting its assessment, the TSSC used hollow-bearing trees as an index of abundance for Leadbeater's possum on the basis that they are the most limiting resource, have the longest renewal time after depletion, a decline in hollow-bearing trees should cause decline in Leadbeater's possum and that a projected decline in hollow-bearing trees indicates a future decline in Leadbeater's possum.
A range of assessments has consistently described severe and ongoing reduction in the abundance of hollow-bearing trees, projected until at least 2065 (Lindenmayer et al. 1990b; Lindenmayer et al. 2015b, Lindenmayer and Sato 2018). This decline is largely due to the ongoing collapse of large hollow-bearing trees killed in the extensive 1939 bushfires, reduction in the extent of mature ash forest, or areas that will become mature in the future, through historical timber harvesting, and the impacts of the 2009 bushfire. Any future extensive bushfire will further exacerbate this severe decline in available old hollow-bearing trees and impact future hollow recruitment. These declines will become more severe when climate change is considered, through direct effects on the possum and also the regeneration potential of mountain ash. Beyond 2065 Leadbeater's possum habitat extent may increase as new hollow-bearing trees recruit, but this will be contingent on the incidence and extent of future bushfires and the effects of climate change.
The total size of the 'lowland' subpopulation at Yellingbo has shown a severe and ongoing deterioration over recent years (from more than 110 individuals in 2003 to 23 individuals in 2022
D. Harley pers. comm.), notwithstanding a program of substantial and intensive research and conservation management actions (Harley 2012; Harley 2016; DELWP 2016).
The entire Lake Mountain plateau was burnt at high severity in the 2009 bushfires (Harley 2016) and there is little evidence of population recovery as at July 2019 (D. Harley pers. comm.). It is clear that rates of habitat recovery and recolonization are far slower in sub-alpine woodland relative to montane ash forest.
However, surveys in 2017 at sites selected randomly across the main range of the species (using randomised stratified sampling) detected Leadbeater's possums at 37% of these sites (ARI unpublished data). Recolonisation of the 2009 bushfire footprint commenced within 8 years, with 25–50% of a large sample of the fire-affected sites surveyed by the Arthur Rylah Institute (ARI) in 2017 to 2019 recording Leadbeater's possums, including at some burnt sites a considerable