The Alpine Ash Forests: A Delicate Balance Under Threat
The tall alpine ash forests in Australia’s high country have maintained a complex and delicate relationship with fire for tens of thousands of years. However, the intensifying fire seasons in recent times are pushing this balance to its limits. As a result, the Federal Government has officially listed this forest type as an endangered ecosystem. This designation highlights the significant risk these forests face of collapse or even extinction.
It is alarming that alpine ash forests are now facing an existential threat. What does this mean for the future of these unique ecosystems, and what steps can be taken to protect them?
What is Alpine Ash?
Alpine ash (Eucalyptus delegatensis) is a tall species of eucalypt found on the Australian mainland, with a related species in Tasmania. It covers over 350,000 hectares of high country across the Great Dividing Range, stretching from Canberra to east of Melbourne. These trees can grow up to 90 metres tall, and when dusted with snow, they create a stunning landscape that provides shelter and habitat for a range of rare mammals, such as Leadbeater’s possums and greater gliders.
Additionally, alpine ash plays a vital role in First Nations cultural landscapes. In north-east Victoria, the Taungurung people harvested Bogong moths (or Deberra) when the moths migrated to mountain forests where alpine ash is a key part of the landscape.
Alpine ash is considered a “fire sensitive” eucalypt, but its relationship with fire is paradoxical. While mature trees die after intense fire, it also clears the way for a prolific flush of regeneration from fallen seeds. However, these regenerating alpine ash trees won’t produce their own seed for 20 years. Another severe fire during this time—known as the Achilles heel of the species—kills the regenerating forest, with no seed to save it. In such cases, the only option is to artificially sow seeds, usually by aircraft.
Why is Alpine Ash Now Endangered?
The federal government uses a range of factors to assess the status of an ecological community, which refers to naturally-occurring species that live together in the same habitat. Over the past 20 years, there has been a major decline in numbers of alpine ash trees due to extensive and severe bushfires. During these fires, a third of all alpine ash forest burned more than once during their vulnerable immature regrowing phase.
The frequent fires have severely affected these forests, leading to a loss of tree cover, the usual rich mix of species, and their ability to function effectively. Future predictions suggest that alpine ash forests may decline by half within the next 60 years because of more-frequent fires, which will lead to regeneration failure. Losing this much forest would be devastating for the landscape and the species that live there, as well as releasing the carbon these forests store.
Can We Save Alpine Ash Forests?
These predictions should prompt a substantial rethink of how we manage, protect, and care for these forests. Traditionally, mainstream forest protection focuses on stopping logging and creating national parks. However, in the case of alpine ash, these solutions have limited use.
Alpine ash forests are already well represented in conservation reserves, with over half in existing national parks. Additionally, climate change and more frequent fires will occur inside national parks as well as outside them. Logging is now banned in Victoria and the ACT, and does not occur in the majority of alpine ash forests.
For alpine ash forests to flourish, creative and active management is needed. This includes:
- ambitious, long-term seed collection programs so that after severe repeat bushfires we are able to rapidly sow alpine ash and stop regeneration failure. These programs can be costly, but are a long-term insurance policy
- planned burns around important alpine ash forests to reduce future fires burning these forests severely
- ecologically informed thinning, which involves the selective removal of trees from a patch of forest. When done in young alpine ash stands, it can speed up the growth of trees, and it has been shown that larger trees survive fire more often than smaller ones
However, we must be realistic about how many alpine ash forests can be saved. Even with our best management, extensive areas of alpine ash will be lost.
Accepting Loss
We need to work out which forests can be saved and those that cannot. One approach that may help is the ‘Resist-Accept-Direct’ framework developed by the US National Parks Service. This acknowledges that ecosystems will be severely stressed by climate change and change is unavoidable. It gives forest managers three options:
- resist change by maintaining the current forest type. This could mean suppressing fire or resowing alpine ash after repeat fires
- accept change and embrace new ecosystems that arise. This means not intervening after frequent disturbance, and monitoring what happens
- direct change to a new type of ecosystem. This approach—considered the most controversial—means in forests likely to be frequently burned, alpine ash is replaced with more fire-tolerant eucalypts
Working out which of these paths are suitable for alpine ash is a major task for land managers, researchers, and the community.
A Clear Warning
The listing of alpine ash as endangered is a clear warning to Australians. One of the most widespread types of forest in our high country is facing an existential threat. Doing nothing is not an option.
We need bold and innovative action to steward alpine ash forests through the next century, before it is too late.
