196 Monitoring Threatened Species and Ecological Communities
(Smit h et al. 1985). It subsequently evolved into an investigation of the habitat
requirements of other species, as well as the attributes of den trees occupied by
arboreal marsupials (including Leadbeater’s possum). It then became clear that
understanding the habitat requirements of Leadbeater’s possum and other species
of arboreal marsupials required understanding the disturbance dynamics of
montane ash forests (Lindenmayer and McCarthy 2002), particularly logging
(Lindenmayer 1994), and then fire (following the 2009 wildfires) (Lindenmayer et
al. 2013b) as well as fire followed by logging (i.e. salvage logging) (Lindenmayer
and Ough 2006; Blair et al. 2016). Indeed, the long-term monitoring program for
Leadbeater’s possum has provided a pivotal framework from which a suite of more
than 30 other linked studies have been established. More recently, the monitoring
program has helped identify the key factors threatening not only Leadbeater’s
possum but also the montane ash ecosystems per se. This has led to a formal
assessment under the IUCN Red List of Ecosystem Categories and Criteria (Burns
et al. 2015). Key threats to both Leadbeater’s possum and montane ash forests
include widespread industrial clearfelling, the rapid decline and impaired
recruitment of large old hollow-bearing trees, the declining occurrence of areas of
suitable nesting habitat such as large old trees within growth forest, and recurrent
wildfire. Importantly, some of these threatening processes interact; for example,
young logged and regenerated forests are significantly more likely to burn at high
severity than old growth forests (Taylor et al. 2014).
Threatened species as a surrogate or indicator for the broader community of
arboreal marsupials
Leadbeater’s possum has been the target species for monitoring and management
for more than 30 years. However, it is important to determine whether
conservation efforts and management actions for this species also would benefit
other arboreal marsupials. That is: is Leadbeater’s possum a useful biodiversity
surrogate and/or management indicator species? The intuitive answer to this
question would be ‘yes’ because of shared dependence on large old hollow-bearing
trees. However, research to date suggests that differences in the kinds of trees
occupied, coupled with differences in habitat requirements among species, makes
Leadbeater’s possum, at best, a weak indicator for other species of arboreal
marsupials in montane ash forests (Lindenmayer and Cunningham 1997). This is
also ref lected in recent work suggesting that the optimal reserve system for
Leadbeater’s possum would need to be supplemented with significant additional
areas of protected forest to provide effective conservation for other species such as
the greater glider and yellow-bellied glider (Taylor et al. 2017).
Testing of field survey methods
The long-term monitoring program for Leadbeater’s possum has been based on
counting animals on a repeated basis across a suite of permanent field sites located