IUCN listing of the Mountain Ash Ecosystem as Critically Endangered
Our response to the listing of Mountain Ash forest in the Central Highlands on the IUCN Red List of Ecosystems.
VicForests Paper Edition No: 2020-01
The VicForests Paper is intended to provide transparent and open information on a wide range of issues relevant to stakeholders. These may include scientific outcomes, research findings, topics of stakeholder concern or other subjects related to VicForests and our operations.
The Mountain Ash forest ecosystem in the Central Highlands of Victoria is listed on the International Union for the Conservation of Nature’s (IUCN) Red List of Ecosystems and is categorised as critically endangered and at risk of collapsing. This listing is based on an ecological assessment conducted in 2014.
The conservation of hollow-bearing trees across the landscape was a major focus of the study. The study had some limitations:
Old growth is not the only predictor of hollow-bearing trees; they exist throughout the landscape and are often associated with riparian zones.
The report indicates 20% of Mountain Ash forests are preserved from timber harvesting; whereas at least 70% of the forest is preserved from timber harvesting. Some 50% of the forest extent formally preserved and a further 20% is excluded from harvesting in accordance to the Code of Practice for Timber Production 2014 and other regulations.
The recruitment and development of hollow-bearing trees over time was not considered.
Significantly, over the past six years since that study was published, VicForests has introduced and implemented a range of changes to its forest management systems to improve the protection of high conservation values such as hollow-bearing trees. This includes the use of formalised hollow-bearing tree surveys as part of all pre-harvest assessments and the use of variable retention harvesting and regeneration systems to maintain or enhance these values.
VicForests is continuing to strengthen these management systems through ongoing research, monitoring, and adaptive management, incorporating increased scope for stakeholder input.
This position paper sets out VicForests’ response to stakeholder concerns about the listing of Mountain Ash forest in the Central Highlands of Victoria on the IUCN Red List of Ecosystems, with the category of “Critically Endangered”. This listing is attributable to an assessment study published by Burns et al in 2014 in Austral Ecology.
2. What is the IUCN?
The International Union for the Conservation of Nature (IUCN) is a membership union composed of government and non-government organisations. Its mandate is to provide information and tools to international organisations to facilitate human progress, economic development and nature conservation.
3. What does the listing mean?
The Red List of Ecosystems (RLE) is a global framework for monitoring and documenting the status of ecosystems (Keith et al 2014) and the IUCN aims to assess the ecological or conservation status of all the world’s ecosystems by 2025.
An RLE assessment is not legally binding and does not trigger any need to create legislation. The assessment is a tool for the IUCN to highlight for governments and managers where conservation management efforts could be focused.
The IUCN provides a standard framework for users to assess the risk of collapse of an ecosystem, which can be measured by either: a reduction in the distribution of the ecosystem; or, the degradation of key processes and components of the ecosystem. Anyone can assess an ecosystem provided they follow the protocol (Bland et al 2016). Assessments submitted to the IUCN are evaluated by one or more qualified experts, but they do not carry the onus of quality and representativeness of the data. That onus provided in the assessment is on the contributing authors of the assessment.
There are five key criteria that each assessment needs to address:
A. Decline in the distribution of the ecosystem
B. Restricted geographic distribution
C. Decline in abiotic processes
D. Decline in biotic processes and interactions
E. Quantitative assessment of the probability of ecosystem collapse within 100 years
4. On what grounds were the Mountain Ash (Eucalyptus regnans) forests in the Central Highlands listed and how valid are they?
The IUCN listing of Mountain Ash forests in the Central Highlands of Victoria on the RLE was based on an assessment conducted by a team of researchers at the Fenner School of the Australian National University (ANU) and published in Austral Ecology in 2014 (Burns et al 2014).
A summary of the assessment findings under each of the criteria is set out in Table 1.
In relation to the distribution of the ecosystem, the authors found there was a 2% loss in extent and distribution of Mountain Ash forests between the 1750s and 2014. They concluded from this perspective the ecosystem was of “Least Concern”. This assessment generally aligns with other assessments, such as the Comprehensive Regional Assessments (CRA) undertaken as part of the Regional Forest Agreement (RFA) process conducted during the late 1990s, which showed the ecosystem was still relatively intact (RFA 1997). The RFA for the Central Highlands was recently extended through to 2030; however, the updated agreement did not incorporate or present updated data on the extent and reservation status of specific forest ecosystems within the Central Highlands region.
The representation of hollow-bearing trees became the primary focus of the authors. Following their assessment, the authors concluded the decline of these trees was the only element of this ecosystem for which there was “critical endangerment”. The study observed that under all the scenarios tested in the assessment, there was a greater than 92% chance of ecosystem collapse (i.e. less than 1 hollow-bearing tree per hectare) by 2067. This was based on the author’s applied threshold of collapse being less than one hollow-bearing tree per hectare. It was also based on collapse rates of hollow-bearing trees identified in the 156 ANU long term monitoring plots as the basis for extrapolation across the extent of Mountain Ash forests in the Central Highlands.
This assessment was further tested when the Mountain Ash ecosystem was nominated for protection under the Flora and Fauna Guarantee Act (1988) in November 2016. The assessment process involves an independent review completed by the Victorian Governments’ Scientific Advisory Committee (SAC). The SAC final recommendation concluded the nominated item (Mountain Ash ecosystems) was not eligible for listing in accordance with the Act due to none of the listing criteria having been satisfied (DELWP SAC 2019).
Table 1: Summary of IUCN assessment criteria applied to assess the status of Mountain Ash forests in the Central Highlands
IUCN assessment criteria
Specific focus for the authors in applying the criteria
Author’s assessment using the criteria
A. Decline in distribution
A) Extent and distribution of Mountain Ash forests between the 1750s and 2014
B. Restricted geographic distribution
B1) Extent of occurrence
B2) Area of occupancy
B3) Number of locations
C. Decline in abiotic processes
C1) Current decline: environmental degradation through changes in precipitation and temperature over past 50 years
C2) Future decline: an estimated assessment of environmental degradation through climate change over the next 50 years (i.e. to 2064) V
C3) Historical decline: an assessment of environmental degradation through changes in precipitation and temperature since 1750
D. Decline in biotic processes and interactions
D1) Current decline: environmental degradation resulting from the loss of hollow-bearing trees over the past 50 years; using old-growth as a surrogate
D2) Future declines: environmental degradation resulting from the projected loss of hollow-bearing trees over the next 50 years
D3) Historical decline: an assessment of environmental degradation and relative severity through a loss of hollow-bearing trees (using old-growth as a surrogate) since 1750 (i.e. pre-European settlement and benchmark for RFSs)
Critically Endangered based on greater than 90% decline in hollow-bearing trees
E. Quantitative assessment of the probability of ecosystem collapse within 100 years
E) Modelling using parameters outlined above
Critically Endangered based on less than one hollowbearing tree per ha
Source: Derived from Burns et al 2014
5. Analysis of the key criteria for listing
VicForests has carefully considered the Burns et al (2014) study and acknowledges the concerns it raised in relation to the management of Mountain Ash forests and specifically hollow-bearing trees.
Since that study, VicForests has introduced and implemented a range of measures to change and adapt its management systems to identify, protect and enhance high conservation values, including hollow-bearing trees across its working forest area. These changes are discussed further below (refer to section 6).
VicForests also has some concerns about the validity of the study data and the application of its overall findings to the proposals.
VicForests’ main concerns relate to the following limitations:
1. Biased data was used to assess risk of decline of hollow-bearing trees across the ecosystem.
2. The figures relating to the area of forest where harvesting occurs were incorrect.
3. The recruitment of hollow-bearing trees in the present or next 40 years was not considered.
These aspects are discussed in turn below
Issue 1. Biased data was used to assess risk of decline of hollow-bearing trees across the ecosystem
Hollow-bearing trees are not only old-growth
A key issue with the risk assessment of the decline of hollow-bearing trees in Burns et al (2014) is that ‘hollow-bearing trees’ were not used as the unit of measure, as the authors did not have an unbiased inventory of this resource. Instead, the authors used old-growth forest as a proxy for hollow-bearing tree occurrence. This assumption vastly underestimated both the actual distribution and abundance of hollow-bearing trees, as hollow-bearing trees also occur in areas that are not old-growth.
Many hollow-bearing trees were excluded from the analysis
By ignoring that hollow-bearing trees exist outside of stands classified as ‘old-growth forest’, which is defined as forest units with a minimum stand size of one hectare, the assessment greatly underestimates the numbers of hollow-bearing trees already in the landscape - for example in mixed aged Eucalyptus regnans forest (e.g. McCarthy and Lindenmayer 1998). These contains a multitude of trees with old-growth characteristics, such as large old trees with hollows, but do not form part of a consolidated stand classified as old-growth forest.
Issue 2. The figures relating to the area of forest where harvesting occurs were incorrect
Most of the ‘Wet Forest’ is in conservation reserves
Burns et al’s (2014) projections of future loss of old-growth and hollow-bearing trees was given as evidence of critical endangerment. However, their projections may not have properly considered the absence of logging over most of the forest where Mountain Ash occurs.
Specifically, they claim that 80% of Mountain Ash is in areas broadly designated for pulp and timber production, which appears to have influenced the authors’ findings.
“The Central Highlands region supports approximately 157 000 ha of mountain ash forest. Approximately 20% is in closed water catchments, parts of which are also managed as the Yarra Ranges National Park (Viggers et al 2013). The remaining 80% is in areas broadly designated for paper pulp and timber production (Flint & Fagg 2007; Lindenmayer 2009a).”
The Central Highlands Forest Management Plan (1997) shows the total area of the Wet Forest Ecological Vegetation Class (‘EVC 30’), where Mountain Ash occurs, was around 113,815 ha. Of this total area of Wet Forest, 31% has been set aside in conservation reserves and 19% persevered in Special Protection Zones (exclusion zones to protect values such as habitats of threatened species). This means that currently around 50% of Wet Forest is in formal reserves and this area will continue to increase over time with the introduction of new reserves and Special Protection Zones, such as the ones associated with Leadbeater’s possum detections.
The remaining area comprises Special Management Zones (areas managed to conserve specific features such as flora, fauna, aesthetic or historical features) (4%), General Management Zones that are available (but not necessarily suitable) for timber production (39%), and General Management Zones for other purposes (4%). As outlined in Poynter and Ryan (2018), the Burns et al (2014) source documents do not support the figures cited in the assessment. The 80% figure is a substantial overstatement of the area available for timber production and this appears to influence the findings of their paper. It makes a considerable difference if only 20% is reserved and 80% is described as available; compared with the current situation in which approximately 50% is reserved and a further 20% is set aside for Code of Practice exclusions and other exclusions. Therefore, only around 30% is available and suitable for timber harvesting.
Issue 3. The recruitment of hollow-bearing trees in the present or next 40 years was not considered
New hollow-bearing trees were not counted
Burns et al (2014) did not model the recruitment of new hollow-bearing trees up to 2060. This was based on their assumptions that hollow-bearing tree recruitment occurs at 120 years and the 1939 fires were of equal intensity across the entire forest ecosystem. These assumptions lead to an over-simplified position of the future decline of hollow-bearing trees in the Mountain Ash forests of the Central Highlands.
While the probability of hollows occurring in trees increases with age, they do occur in trees much younger than 120 years old (Fox et al 2013). This can be through natural stochastic processes such as storm events, fires, and insects, or even silvicultural interventions (Ryan 2013).
6. What is VicForests doing to ensure the sustainability of this ecosystem?
Current and future hollow-bearing trees are protected
Most hollow-bearing trees are in areas excluded from harvesting, such as streamside reserves, or are actively marked out for exclusion. VicForests’ timber harvesting operations regularly exclude areas with high densities of hollow-bearing trees either because meet the definition of Zone 1A or Zone 1B habitat for Leadbeater’s Possum or they are identified as areas of high habitat quality.
Since the Central Highlands Forest Management Plan was published in 1997, old-growth forest and areas with greater than 10 large live hollow-bearing trees in every three hectares have been excluded from harvesting as Zone 1A Leadbeater’s Possum habitat. In addition, areas with more than 12 hollow-bearing trees (live or dead) over 10 ha or more with a dense wattle understorey are also excluded for Zone 1B Leadbeater’s possum habitat. This means substantial areas of new reservations are excluded from timber harvesting in the General Management Zone and it has extended the protection measures for high density areas of hollow-bearing trees. Since 2014 VicForests has reserved (either formally or informally) over 500 ha of additional Leadbeater’s Possum Zone 1A habitat within the General Management Zone, regardless of actual colony detections. More broadly, since 2014 Leadbeater’s Possum detections within State forests have resulted in new reservations totalling approximately 6900 ha (up to April 2020); and much of this area is likely to contain hollow bearing trees.
There have been substantial changes to harvesting and regeneration systems
Since 2014 (and publication of the Burns et al assessment in Austral Ecology), VicForests has made substantial changes to silvicultural practices in Mountain Ash forests, notably implementing regrowth retention harvesting (a form of variable retention harvesting) in 50% of all mountain ash forest in the Central Highlands. Regrowth retention harvesting aims to protect current hollow-bearing trees and other important habitat features within a coupe and retain trees that will provide future hollows in the next 50–100 years. It ensures 50% of the harvested area is within one tree height (approximately 80 m) of the retained forest.
VicForests’ retention systems now systematically identify hollow-bearing trees as a high conservation value resource, which are targeted for retention by exclusion as individuals, in clumps or islands.
This approach to improving biodiversity conservation has been promoted by the Fenner School at the Australian National University, as reflected in a study of the variable harvest retention system and its implications for biodiversity in the Mountain Ash forests of the Central Highlands in 2007:
“Although a relatively small percentage of the overall Mountain Ash forest estate is subjected to timber harvesting each year, the community perception is that these activities may be incompatible with biodiversity conservation. However, improvements in silviculture and an adaptive management approach have the potential to deliver positive outcomes for both timber production and biodiversity conservation.
If such improvements in timber harvesting activities are embraced in the Mountain Ash forests of the Central Highlands of Victoria, they offer the potential to become one of very few examples of demonstrated ecologically sustainable forest management in Australia and indeed around the world.” (Lindenmayer 2007)
The Fenner School continues to conduct research on variable retention harvesting in the Mountain Ash forests of Victoria, and its more recent publications have continued to highlight the systems’ merits; notably, the environmental benefits for some key groups such as small mammals and birds and likely also vascular plants (Lindenmayer et al 2019). They also observe that some important operational issues remain; specifically, the authors have concerns around the impacts of high-severity regeneration burns on the integrity and condition of retained patches within ‘cutblocks’ (harvested areas).
Increased habitat retention
Since 2019 VicForests has expanded its application of variable retention harvesting and is now retaining a significant number of trees in each coupe for current and future habitat for native species. This is achieved by assessing all coupes for the presence of threatened species (both flora and fauna) and habitat values, especially hollow-bearing trees. VicForests then plans for retention and enhancement of habitat values, by:
protecting hollow-bearing trees, which provide habitat for many species
recruiting future hollow-bearing trees, through the retention of trees likely to form hollows in the medium term (50–100 years)
connecting habitat patches, allowing animals to move between areas in the forest
regenerating forests with lower intensity regeneration burning operations and increased use of mechanical disturbance.
VicForests’ current approach to selecting harvesting and regeneration systems is reflected in Figure 1.
Figure 1: Schematic of VicForests’ harvesting and regeneration reforms and systems in place to manage habitat values.
Source: VicForests Harvesting & Regeneration Systems, August 2019
Through this process, VicForests has shifted its focus from clear-felling and seed tree systems to significantly higher levels of retention across many coupes.
This changes the longer-term habitat values and the visual impacts of these coupes. VicForests is also actively focusing on the shift from using high intensity regeneration burns to create a receptive seedbed, to using ‘cool burns’ or otherwise reduced intensity regeneration burns, and mechanical disturbance wherever appropriate in place of burning operations to facilitate regeneration.
VicForests is also investing in ongoing research with the University of Melbourne to investigate the formation of tree hollows in these forests and collect a definitive inventory of their distribution and abundance. This will allow unbiased and representative predictions of their future existence. The research will enable VicForests to continue to build on scientific research and evidence that underpins management decisions affecting the Mountain Ash forest resource and long-term sustainability of this ecosystem.
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Victorian Government Department of Environment, Land Water and Planning Scientific Advisory Committee (2019) Flora and Fauna Guarantee – Scientific Advisory Committee Final Recommendation on a nomination for listing – Mountain Ash Forest Community. Available at: https://www.environment.vic.gov.au/__data/assets/pdf_ file/0021/435324/Mountain-Ash-Forest-Community.pdf