Whoever wins power in Victoria’s election tomorrow will no doubt have a long to-do list. Here’s an urgent item: protect the mountain ash forests of the state’s Central Highlands.
We have discovered that this ecosystem is at very high risk of collapse within half a century, driven by the effects of clearfell logging and bushfires.
Our research suggests that under business-as-usual management, there is a 97% chance that large, hollow-bearing trees will decline to less than one per hectare by 2067, leaving marsupials such as the globally endangered Leadbeater’s possum with almost nowhere to live.
The legacy of past logging practices, as well as current clearfelling, is driving the system towards collapse. Our modelling suggests that even if logging ceased today, and there were no bushfires, there is still a 92% chance of ecosystem collapse as defined above.
We suggest that the government needs to deliver a Great Forest National Park, covering a far wider area of the Central Highlands than the existing parks. This will ensure that one of the key collapse drivers – industrial clearfell logging – is removed from a significant part of the forest estate.
Forests under threat
The Central Highlands region contains about 157,000 hectares of mountain ash forest, the mature trees of which are the world’s tallest flowering plants. Our research assessed the state of this ecosystem with reference to the newly adopted IUCN Ecosystem at Risk protocol, which involves identifying what species live in an ecosystem, and the factors they depend on (such as the presence of large trees as habitat).
Mountain Ash forests deliver other benefits too. This forest is the most carbon-dense in the world, and protecting it would double its carbon storage, potentially delivering about 8% of Australia’s overall emissions reduction target for 2020.
Forest catchments dominated by old-growth trees yield more water than logged regrowth forest catchments. Meanwhile there are many animals that depend on the forest – particularly arboreal marsupials of which there are eight species in this ecosystem, including Leadbeater’s Possum, which is Victoria’s state animal emblem and is listed by the federal government as endangered.
What business-as-usual would deliver
The forest delivers wood products, and jobs associated with this industry. These are important factors, and any revision in management needs to be mindful of the impacts on local people and the economy. It is estimated that there are 485 jobs associated with the total area of native forestry (491,000 ha) in eastern Victoria, a subset of which would be in the Central Highlands.
The mountain ash forest is being damaged by the practice of clearfell harvesting, in which 60% of the total biomass remains on the site as waste slash which is burnt, and 40% is used as wood products. From these wood products, 72% is used to make paper. This is despite the fact that wood chips to make paper can be sourced from existing plantations.
Making paper from plantation wood would be a win-win outcome for carbon storage. Carbon stocks in plantations would be maintained by ensuring they are not converted to grazing pastures. At the same time carbon stocks in native forests are increased by not logging them.
If we choose instead to carry on with business-as-usual, some of the ecosystem services discussed above would still apply, but at lower levels of carbon storage, water supply and biodiversity. However, our research indicates that the ecosystem as a habitat for many tree-dwelling animals will not be sustained over future decades.
A sustainable future
The evidence that things are not well in the mountain ash ecosystem is overwhelming and compelling. If Australians want to retain this ecosystem, and continue to benefit from the ecosystem services that it provides for the next 50-100 years (and beyond), it needs comprehensive protective measures.
Management needs to change to avoid ecological collapse. It won’t be viable to continue with industrial clearfelling, which increases the risk that future fires will be crown-scorching ones that kill old forest trees and, by extension, animals like Leadbeater’s possum.
That is why we consider an enlarged conservation park to be so important for the Central Highlands, and the major parties should consider adding it to their environmental policies.
Meanwhile, consumers of paper need to think carefully about their purchasing choices, lest they contribute to the collapse of the ecosystem and the extinction of iconic, emblematic species like Leadbeaters possum.
Emma Burns' position is funded through the Terrestrial Ecosystem Research Network (TERN). The Long Term Ecological Research Network (within TERN), of which she is the Executive Director, receives funding from the Australian Government.
David Lindenmayer receives funding from the Australian Research Council, the Terrestrial Ecosystem Research Network, and the Government of Victoria. He is a member of the Canberra Ornithologists Group and Birdlife Australia.
Heather Keith receives funding from Fujitsu Laboratories Ltd, Japan for environmental research.