We know that climate change is making fire seasons longer and more intense. This is happening globally. It has enormous implications for the landscapes that we love, how we prepare for and fight fires, and even how we live in fire prone areas.
These fires are transforming the landscapes we know and love. Anyone who has driven out of Jindabyne into the Snowy Mountains, or Mt Beauty towards the Bogong High Plains knows what I am talking about – endless walls of grey, dead trees. Only 0.47% of old growth Alpine Ash still exists in Victoria. This has huge implications for the aesthetics of our mountain areas, and significant ecological implications.
Increased fire frequency could see mountain forests like Alpine Ash replaced by wattle woodlands. As recently noted by Brett McNamara, the manager of Namadgi National Park:
Recovery happens but it is “tainted with a sense of what does the future hold for us if we are to experience fire again and again with such intensity. This is where the question is unanswered. What these mountains will look like well into the future?”
The huge volumes of dead trees from previous fires also creates a lot of fuel that is already dry and hence ready to burn in future fires. What are the implications of this for our fire fighting and land management efforts?
Research from the USA outlines some of the problems we face:
‘California’s drought of 2012-2016 killed millions of trees in the Sierra Nevada — mostly by way of a bark beetle epidemic — leaving a forest canopy full of dry needles. A study published from the University of California, Davis, and the U.S. Forest Service helps answer concerns about what effect dense, dead foliage could have on subsequent wildfires and their burn severity.
In the study, published in the journal Ecological Applications, scientists found that the presence of recently dead trees on the landscape was a driver of wildfire severity for two large fires that occurred toward the end of the drought: the 151,000-acre Rough Fire in 2015 and the 29,300-acre Cedar Fire in 2016.
The publication is the first field-based study to document the important role recently dead trees can play in exacerbating fire severity in California forests that are historically adapted to frequent, low-severity fire.
Sadly, the Australian mountains are also seeing die back of Snow Gums due to beetle infestations, which seem to be made worse by the impacts of climate change (more water stress and warmer winters). This is leading to dead trees being left standing in otherwise healthy forests.
And across the Australian mountains, vast areas that were burnt in previous fires are now dominated by dead trees, often with a thick, very flammable understory of saplings emerging. Many snow gums that were burnt in the early 2000s have now collapsed onto the ground, leading to an enormous buildup of fuel that can create hot burns that can easily climb into the remaining canopy if a fire passes through.
Physically removing these tangles of wood by burning them is impossible. There are too many hectares of affected forests, often on steep and remote terrain. Simply putting fuel reduction burns through them would run the risk of igniting massive, runaway fires that could not be contained, or creating hot spots of burning logs and stumps that could flare up later. The economic cost of ‘blacking out’ these areas (the physical work of making an area safe after it has been burnt, by extinguishing remaining flames and hot spots) after a fuel reduction would be enormous and well beyond the capacity of existing state based firefighters.
Additionally, if these logs were burnt, there is a risk that soil heating would cause a massive burst of seedling growth, which would then make the forest more flammable.
So what should we do?
We know that older forests are less fire prone. We know that Alpine Ash and Snow Gum forests are becoming younger over time due to repeated fire. So how do we ‘grow’ old forests?
There are already restoration efforts underway to reseed Alpine Ash forests that have been devastated by fire. The Victorian government has allowed an extensive ‘salvage’ logging program in these forests in the central Alps and north east of the state, and the ecological impacts of salvage logging are well documented. Salvage logging programs should be halted and the Victorian government needs to fast track its commitment to end native forest logging in the state.
One alternative is to leave the forests to regenerate. The best available science shows that excluding fire from regenerating snow gum forest will allow it to move towards the less fire prone old growth stage where a thinner understory reduces the ‘ladder’ effect of fire climbing into the canopy.
As researcher Phil Zylstra says: ‘long unburnt snow gums are their own best protection.’ Older forests act as a break on fire spread, and if they do burn, they tend to burn at lower severity.
One significant piece of research that should inform our understanding about fire on snow gum forests looked at the impacts of fires on Lake Mountain and the Buffalo Plateau. The report How snow gum forests and sub-alpine peatlands recover after fire was written by Fiona Coates, Philip Cullen, Heidi Zimmer, James Shannon. They used the long unburnt Baw Baw Plateau as an example of what these systems could be like in the absence of fire events.
They found that:
- Even areas that have been subjected to hot and very destructive wildfire, such as on the Lake Mountain plateau during the 2009 Black Saturday fires, can be expected to recover – provided we can keep fires out of these systems. However, this will take time. For instance they suggest it will take the forests at Lake Mountain at least 70 years to return to pre-fire structure. No specific management needs to be undertaken to aid this process beyond excluding fires
- The researchers repeatedly note that there are serious doubts about the value of fuel reduction burning in these forests. They note that low intensity fires negatively impact on tree resprouting ability.
This approach would mean doing everything possible to protect these forests from fires entering via neighbouring vegetation communities, such as the mixed species foothills forests that exist downhill from the mountain forests. Fuel reduction in these systems can greatly reduce fire intensity.
Fire fighting resources need to be available to be deployed in the mountain forests when they are threatened, for instance by spot fires coming out of valley and hillside vegetation communities. This will mean air resources, which tend to be used to protect human assets where only a few planes are available. A smart move would be to purchase a publicly owned air fleet to increase the number of planes available to states and territories in bad fire seasons. You can sign a letter to the PM urging him to establish such a fleet here. Background information on the need for extra capacity is available here.
It also means continued investment in state employed remote area firefighting teams, as Victoria has done recently, and the creation of a volunteer remote area team in Victoria, to assist and support career firefighters (the ACT, NSW and Tasmania already have volunteer remote area teams). Remote area teams are important in stopping lightning strike caused fires before they become blazes.
Humanity must act to radically reduce greenhouse pollution as soon as possible if we are to avoid ever worse fire seasons driven by climate change. We need to understand that we still have much to learn about how to interact with and manage forest environments and how and where fire can be introduced into the landscape to reduce risk and provide ecological benefit. Cultural burning, as practised by First Nations, has been long absent from the high country and we must be cautious about efforts by some to introduce broad acre burning across mountain environments. Fuel reduction burning is a tool that needs to be applied carefully at the right time in specific vegetation communities. It is not a ‘golden bullet’ to the threat of fire risk. Some areas, such as rainforest should have fire excluded. The mountain forests also need to be treated differently to other more fire adapted vegetation communities.
“We Europeans have only been here for a couple of hundred years. We need to understand that what we do today has implications well into the future on a time scale that is very difficult for us to appreciate.”
- quote from Brett McNamara, the manager of Namadgi National Park, ACT