In July 2022 the federal Department of Climate Change, Energy, the Environment and Water updated its conservation advice for the Southern and Central Greater Gliders. This factsheet compares our current approach to Greater Glider conservation with these latest recommendations.
What the conservation advice says about timber harvesting
Excerpts from the great glider conservation advice
Greater Gliders are sensitive to timber harvesting if insufficient hollow bearing trees are retained.
The sensitivity of greater gliders (southern and central) to timber harvesting has been well documented. Although some habitat across the species’ range is found in conservation reserves (Smith & Smith 2018, Wagner et al. 2020), where timber harvesting is excluded and the removal of HBTs is subject to constraints, prime habitat coincides largely with areas suitable for timber harvesting (Braithwaite 1984). There is a progressive decline in numbers of HBTs in some production forests, as harvesting rotations become shorter and dead stags collapse, and HBTs are not being replaced due to lack of recruitment (Ross 1999; Ball et al. 1999; Lindenmayer et al. 2011, 2012).
The degree impact depends on the forest type and the intensity of the harvesting. Declines in population appear to be related to hollow bearing tree loss through clearfelling.
The degree of impact depends on forest type and timber harvesting intensity, with larger declines in more heavily logged sites (Tyndale-Biscoe & Smith 1969b; Lunney 1987; Kavanagh et al. 1995; Kavanagh & Webb 1998; Kavanagh 2000; McLean et al. 2018). In the Central Highlands of Vic, where clearfelling is undertaken, Lindenmayer et al. (2017b) found that the rate of loss of HBTs greatly exceeded the rate of recruitment. The area of clearfelled forest adjacent to wildlife corridors was also found to increase the chance of collapse of HBTs, possibly due to the greater exposure of stems to elevated wind speeds at corridor edges. However, models investigating the impacts of forest disturbance on the greater glider (southern and central) in the same area found that timber harvesting in the surrounding landscape was not a significant covariate influencing the probability of occurrence of the species (Lindenmayer et al. 2020).
Recovery of subpopulations following timber harvesting is slow. Subpopulations in south-east NSW had not recovered 8 years after timber harvesting in sites retaining 62%, 52% and 21% of the original tree basal area (Kavanagh & Webb 1998). In the regrowth Mountain Ash forests (Central Highlands) of Vic, greater gliders (southern and central) were absent post-timber harvesting until the forests were >38 years old (Macfarlane 1988).
Greater Gliders can persist following harvesting, for example, if 40% of trees are retained and vegetation next to the harvest area is preserved – this includes in areas of very young re-growth.
Greater Gliders can persist, albeit likely in lower numbers, following harvesting. Kavanagh (2000) found that, in production forests in south-east NSW, subpopulations could persist post-timber harvesting if 40% of the original tree basal area was retained, provided (adjoining) riparian vegetation was also protected. An analysis overlaying all detections (from the Victorian Biodiversity Atlas and VicForests Species Observations layer) made post-harvest in timber harvesting areas in Vic since 1980, found that the species can persist in timber harvesting regrowth areas of very young age (VicForests 2021).
The impacts can be further reduced by landscape management to retain habitat corridors and hollow bearing trees.
The impacts of timber harvesting on greater gliders can be mitigated by landscape-level management strategies that retain habitat corridors and HBTs (Eyre 2006; Woinarski et al. 2014). In 2019, VicForests began moving away from clearfelling towards variable retention systems, which aim to retain more habitat trees and reduce the use of controlled burns for regeneration post-harvest. Protections for the species in East Gippsland and the Midlands (where Special Management Zones were required) were also revised to retain 40% of the basal area of eucalypts across each coupe where ≥5 greater gliders per km2 are identified. Under the new Victorian Forestry Plan, harvest rates will reduce from 2024, leading up to a cessation of all native forest timber harvesting by 2030 (VicForests 2021). However, cumulative impacts of the 2019-20 bushfires, ongoing prescribed burning, timber harvesting and climate change will continue to put pressure on remaining greater glider habitat. Fire-logging interactions likely increase risks to greater glider populations.
The Department of Climate Change, Energy, the Environment and Water (2022) 'Conservation Advice for Petauroides volans (greater glider (southern and central))', page 13.
How VicForests' current approach compares to the recommendations
Recommended conservation and recovery actions/priorities related to timber harvesting
How this compares to VicForests’ current approach
In the aftermath of bushfires, protect any unburnt habitat (within or adjacent to recently burnt landscapes) in order to support population recovery. This includes, but is not limited to:
Areas identified to be important post-fire refuges.
Protecting hollow-bearing trees from post-fire salvage timber harvesting and clean-up operations.
Protecting hollow-bearing trees from post-fire salvage timber harve
VicForests immediately halted all harvesting in the areas impacted by the 2019/20 fires until greater understanding of the extent and impact of the fires was established.
Following the 2019-20 bushfires threats to Greater Glider were assessed as part of the Threatened Species and Communities Risk Assessment required under the RFA. DELWP identified modelled high-quality Greater Glider habitat predominantly outside the reserve system and with limited impact from the 2019-20 fires. Within 50 forest compartments in East Gippsland RFA which were identified, harvesting must be excluded from 85% of the high-quality habitat.
VicForests updated its post-fire salvage prescriptions before commencing any salvage operations. The importance of hollow bearing trees was recognised in these prescriptions. Which stated:
Following disturbance, the importance and functionality of old forests and hollow-bearing trees in the medium-term increases, so the retention of these features is still considered a priority. Large hollow bearing trees, both alive and fire-killed, should be prioritised for retention where possible. Situate habitat tree exclusion areas to maximise retention of high priority habitat trees.
Habitat trees have the following order of priority: (a) large live hollow trees; (b) large live trees without hollows; (c) large dead trees; (d) small live trees; then (e) small dead trees.
VicForests initially started salvage harvesting in fire-killed Ash forests. In these areas all live trees were retained unless they had to be removed for safety reasons.
For every coupe in the fire footprint 500 hectares of habitat within 3,500 metres was identified and protected. This focussed on unburnt or lightly burnt fire refuges, modelled Old Growth, areas with threatened species detections and mature forest elements.
Ensure that eucalypt forests and the impacts of disturbance (including fire) are managed to prevent them transitioning to less nutritious, hotter, and/or more fire-prone plant communities, and to ensure that food tree species preferred by the greater glider (southern and central) continue to be the dominant canopy trees.
The Code of Practice for Timber Production requires all coupes to be regenerated and that the canopy species composition present before harvest remains. VicForests does not change the eucalypt species composition.
Harvested areas of native forest are successfully regenerated.
The natural floristic composition and representative gene pools are maintained when regenerating native forests by using appropriate seed sources and mixes of dominant overstorey species.
188.8.131.52 Following timber harvesting operations, State forest must be regenerated with overstorey species native to the area, wherever possible using the same provenances, or if not available, from an ecologically similar locality.
184.108.40.206 Regeneration must aim to achieve the approximate canopy floristics that were common to the coupe prior to harvesting, if known.
The 2019-20 bushfires burnt large areas of Ash forests, with 17,800 hectares of this being reproductively immature ash forest that burned at high severity. Ash species are not sexually mature until about 15-20 years, and large areas of these forests, having been variously impacted by fires in 2003, 2006-07, 2009 and 2013, were vulnerable leading into the 2019-20 fire event. Without timely intervention with immediate re-seeding, many of these areas were likely to convert to non-forest environments. VicForests was a partner agency in the largest single native forest re-seeding program ever undertaken in Victoria. 11,586 hectares of ash forest was re-sown with 4682 kilograms of seed. A significant quantity of ash seed was held in store by VicForests prior to the fires. VicForests currently manage most of the seed collection, extraction and storage in Victoria. A current agreement exists between DELWP and VicForests to facilitate the collection of seed for future fire recovery purposes. VicForests in turn engage highly skilled seed collection crews who obtain most of the seed by climbing selected trees and delimbing capsule laden branches for ground crew to prepare for extraction and storage.
Protect and maintain sufficient areas of suitable habitat, including denning and foraging resources and habitat connectivity, to sustain viable subpopulations throughout the species’ range.
Victoria has five regional forest agreements (RFAs) between the federal and state governments. One of the main objectives of the Victorian RFAs is:
to identify a comprehensive, adequate and representative (CAR) reserve system and provide for the conservation of those areas.
There are three CAR reserve components (on public land) outlined in the JANIS criteria:
Formal (Dedicated) Reserve – includes Crown land formally reserved for environmental protection and where timber harvesting is prohibited (such as national parks, state parks, forest parks, nature conservation reserves and other conservation reserves)
Informal Reserve – includes public land protected to achieve conservation values while excluding timber harvesting, or protected under an approved management plan; this is mostly defined by areas of SPZ within State forest
Values Protected by Prescription – in Victoria, these prescriptions are defined under the Timber Code and include prescriptions related to areas of steep slopes, or very rare values, values with fragmented distributions, or values naturally occurring in linear form such as riparian vegetation.
Following the 2019-20 bushfires threats to Greater Glider were assessed as part of the Threatened Species and Communities Risk Assessment required under the RFA. DELWP identified modelled high-quality Greater Glider habitat predominantly outside the reserve system and with limited impact from the 2019-20 fires. Within 50 forest compartments in East Gippsland RFA which were identified, harvesting must be excluded from 85% of the high-quality habitat. The proposed permanent protection is to change these areas to SPZ.
The CAR reserve system makes up a substantial proportion of public land. Timber harvesting operations are excluded from these areas and the protect and maintain large areas of suitable habitat and also support large populations of Greater Glider.
Greater Glider has a specific prescription within the Code for East Gippsland requiring a 100 hectare protection area (SPZ) where more than 10 Greater Gliders are located in a spotlight kilometre. These areas are converted to SPZ to protect these populations.
The DELWP Greater Glider action statement included the immediate protection of more than 96,000 hectares of State forest in the Strathbogie Ranges, in the Central Highlands, in East Gippsland and near Mirboo North. A 2018 Arthur Rylah Institute assessment report estimated a total population of 69,000 Greater Gliders across the Strathbogie Ranges.
In addition to the CAR reserve system and values protected by prescription are the addition protections put in place by VicForests. Since July 2019 VicForests has shifted to Variable Retention harvesting which sees suitable hollow-bearing and feed trees retained across coupes. This is described further below.
Establish, maintain and enforce effective prescriptions in production forests to support populations of the greater glider (southern and central). This includes, but is not limited to:
appropriate levels of habitat retention, timber harvesting exclusion and timber harvesting rotation cycles
maintenance of wildlife corridors between harvested patches
maintenance of vegetation buffers around habitat patches excluded from harvesting
protection of existing hollow-bearing trees with appropriate buffers
adequate recruitment of hollow-bearing trees
maintaining preferred food tree species as dominant canopy trees
minimal use and adequate containment of regeneration burns.
Clearfelling should be avoided, as well as timber harvesting in climate or post-fire refuges.
Since November 2019, in accordance with the Greater Glider Action Statement – developed by Government on the basis of expert scientific advice, VicForests retain at least 40% of trees across each timber harvesting coupe, prioritising live, hollow bearing trees, wherever a density of Greater Gliders equal to or greater than five individuals per spotlight kilometre. Following the 2019-20 bushfires the density of Greater Gliders used to trigger this management action has been dropped to 3 per spotlight kilometre.
Native forest harvesting in Victoria will cease in 2030. So, there will be no second rotation.
Since July 2019, VicForests have been moving away from clearfall silviculture to greater use of variable retention silviculture that can see up to 80% of a forest stand retained within a coupe after timber harvesting. Variable retention silviculture features a shift towards:
increased level of habitat tree retention within and around coupe areas, to enhance habitat resources and facilitate multi-cohort forest management
reduced use of high-intensity controlled burns for regeneration post-harvest.
The 2021 DELWP Forest Audit Program noted: Explicit planning for habitat retention is now commonplace. More recently planned coupes typically provide for the retention of undisturbed patches of overstorey and understorey vegetation throughout the coupe, as well as along waterways and/or in areas where slopes are too steep for harvesting (Figure 5.5). In some of the audited coupes (e.g. 21 Galicia, 30 Shazam), habitat patches were also planned around large or giant trees (>2.5/4.0 m diameter at breast height, respectively) to provide additional protection from harvesting and regeneration activities.
A range of exclusion and retention areas are mapped and form an extensive network of additional corridors and large habitat areas, in addition to those in formal reserves and SPZ.
Monitor the incidence and impacts of fire and timber harvesting in the species’ range, particularly in areas adjacent to those burnt in the 2019–20 bushfires. Petauroides volans (greater glider (southern and central)).
VicForests will continue to undertake post-harvest monitoring of a range of coupes.
Current monitoring program is finding Greater Gliders are persisting within and around coupes harvested using VicForests Variable Retention harvest systems due to the retention of important habitat features including hollow-bearing trees and feed trees.
Monitor the abundance, age and size structure of hollow-bearing trees and their responses to management measures. This includes before and after prescribed burns, and before and after timber harvesting.
Since July 2019 VicForests has been undertaking habitat tree surveys on coupes pre-harvest. Habitat Tree and Resource Inventory Surveys have been designed to ensure that planning data estimates are robust, and that pre-harvest reference data is comprehensive enough to ensure high-quality evaluation of management practises. This survey design allows an estimate of habitat tree density, category composition, and distribution across a coupe.
Monitoring of post-harvest retention has been occurring through the use of drone and plane capture aerial imagery. VicForests is also investigating ways to better monitor hollow-bearing tree retention post-harvest. This includes targeted monitoring programs and including tree retention assessment during regeneration surveys.
Continue to undertake surveys on high priority timber harvesting coupes as part of DELWP’s Forest Protection Survey Program (begun in 2018), and other pre-harvest surveys, to inform adaptive management in timber harvesting areas.
VicForests will continue to undertake pre-harvest surveys.
FPSP has received further funding and will continue to undertake pre-harvest surveys.