Seared into country and memory, lessons for a fiery future

This year’s La Nina has allowed some respite and healing after the devastation of Black Summer, but scientists warn that recognising the risks of more fires, more often, will be crucial to species survival.

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Before the fires: The Newnes Plateau swamps. Credit: Ian Baird/Blue Mountains Conservation Society

The lush folds of the Newnes Plateau swamps, a critical but endangered habitat in the Blue Mountains of New South Wales, have long provided refuge for vanishing species of plants and animals.

Vulnerable shrub species grow there – the bristly Deane’s Boronia with its vibrant pink flowers, Veronica blakelyi sporting a crown of purple, and the geebung, a spiky plant hoisting turgid, green fruits. Endangered giant dragonflies dance above, and rare amphibians like the Blue Mountains water skink, the giant burrowing frog and the red-crowned toadlet navigate the waterways beneath.

But one year on from Australia’s worst bushfire season on record, a number of these swamps have run dry. Victims of a cocktail of human and climatic factors, including having lost a measure of their sustaining water table from nearby mining, a great portion of these swamplands were pushed over the edge by the monstrous Gospers Mountain Bushfire that rolled through the region last summer.  

“It’s a moonscape, nothing’s come back whatsoever,” says Dr Ooii, a plant and fire ecologist at the University of New South Wales. “They’re definitely not coming back.” 

Those dried-out swamplands joined a growing list of casualties from the unprecedented 2019-20 fire season. Coming on the back of a decade of increasingly frequent fires in much of South-Eastern Australia, Black Summer carved huge chunks from many of Australia’s most iconic ecosystems, from the niche refugia swamps to the great alpine ash forests of Victoria.

The NSW Bushfire Inquiry Report, handed down on 31 July last year, warned that more frequent and more intense fires were likely inevitable, and that changing climates and drought conditions were a critical factor in last summer’s mega-fires. As leading US fire historian Steven J. Pyne has warned, we seem to be living in a new era of runaway fires.

“It’s the era of the mega fire, so it’s changing the way that we look at how ecosystems – even ones that are adapted to fire – how they’re being pushed,” says Dr Ooi. 

Finding ways to head off spiralling losses as a result of these pressures is the mission of the New South Wales Bushfire Risk Management Research Hub (the Hub), of which Dr Ooi is a member. 

The problem – and the key theory – that underpins the Hub’s research is what the experts call fire interval squeeze, that is, the shrinking timeframe between firestorm events.

Acknowledging that fire has been an integral cog in Australia’s complex ecological machine for tens of thousands of years, Dr Ooi says the length of time in between fire events in many ecosystems is decreasing, meaning usually robust plants can’t back on their feet quickly enough before the next fires roll in.

“Even though fire’s a part of our natural environment, a typical return interval for forests and woodlands here is 20 years, maybe ten years for more shrubby areas,” he says, but these average intervals have been shortening dramatically over the past decade. And recent research in the field supports the common-sense notion that normally fire-tolerant trees struggle to re-sprout when the fires come too regularly.

Associate Professor Trent Penman, a specialist in bushfire behaviour at the University of Melbourne, agrees. 

“We’re seeing changing climates, so plants that might have persisted in these areas for a long time may be on their limits,” he says. 

Of particular concern, he says, is the plants’ capacity to cling on through the sensitive early stages of germination and growth in newly disturbed environs.

“We know our forests do recover, but there’s been a lot more fire activity in the last decade, and so those repeated fires across the landscape, how they’re going to interact, we don’t really know,” he says. “It’s an area that we should be concerned about.”

On top of concerns about plant life, scientists have warned fire interval squeeze could put dangerous pressure on animal populations, with vulnerable arboreal species that rely on highly specialised plants first in the firing line. 

An investigation by Victoria’s Department of Environment, Land, Water and Planning (DELWP) into the devastation of Black Summer found that the legacy of fire has wound its way up the trophic system – 244 species of animals lost at least 50% of their statewide habitat in this latest bushfire season alone.

It’s a story playing out around the country, with delicately balanced ecosystems struggling to cope with a new normal. In July 2020, it was reported that 3 billion animals had been killed or displaced in the fires. 

The picture emerging is not one that threatens only niche or marginal habitats. Also at risk are landscapes like the iconic mountain forests of Victoria, where towering alpine ash (Eucalyptus delegatensis) can grow up to 90 metres tall, their habitat tracing the spine of the central highlands into New South Wales. In these wet, cold inclines, trees that reach a suitable age and size provide habitat for rare and embattled species, including Victoria’s faunal emblem, the Leadbeater’s possum. 

Professor Penman says this latest bushfire season, coming close on the back of others, has done significant damage to these forests. 

“They’re supposed to be left unburnt for around 20 years so they can start to reach maturity and seed and therefore you get the next generation before fire comes through,” he says.

Escalating fire frequency in Victoria is damaging the giant trees’ capacity to germinate in these forests that saw 87% of their area burnt in the wildfires of 2003, 2007 and 2009 cumulatively.

In Black Summer alone, around 13,000 hectares of alpine ash trees younger than 20 years old were affected, according to Sarah McColl-Gausden, a researcher in bushfire behaviour at the University of Melbourne whose work focuses on these trees.

It’s a cruel irony for eucalypts that depend on fire to propagate, and Ms McColl-Gausden says saving these trees, which are among “some of the most beautiful forests I’ve experienced”, will probably depend on aerial re-seeding by forest managers – something the Victorian Government has already invested $7.7 million into.

Professor Penman warns that if alpine ash decreases in significant numbers, the forests may become more flammable as species like acacia fill the gaps.

Even Australia’s wet, temperate rainforests, which are usually safe havens during bushfires, have been damaged by last year’s fires – like the Gondwanan rainforest at Barrington Tops in New South Wales.  

“Because these fires were so big and so hot, they burned into areas that were not traditionally part of a burning regime,” says Dr Ooi. “These mega fire events are part of this new cycle where we’re getting these big drought periods beforehand, so there’s a risk these fire-sensitive areas will be burnt too frequently”

Despite these grim forecasts, Professor Penman is hopeful that the experience of Black Summer presents Australia with an opportunity to rethink the way land is used and managed. 

“From an environmental viewpoint, we need to see this as an opportunity to learn rather than a case for misery,” he says. “I really feel like we’ve had an environmental system reset and we now need to have a management reset.”

Professor Penman says the forest management infrastructure in Australia needs to be prepared to adapt to the times and incorporate better methods, including enlisting practices like Indigenous cultural burning across landscapes, which keeps fuel low.

Adding voice to a growing movement to include Indigenous people and knowledge in land management, the NSW Bushfire Inquiry Report also makes the case for cultural burning to manage increasing fire risk. It reflects an overdue institutional recognition that Indigenous knowledge, having co-evolved with the landscape, may hold more sustainable management answers. 

This year’s cooler, wetter conditions – driven by the La Nina weather event – are offering damaged ecosystems a much-needed reprieve according to Dr Ooi.

And Professor Penman says the viciousness of last summer’s fires will most likely buffer us from Black Summer-sized mega-fires for the next few seasons, because the supply of fuel on forest floors is low. This, he says, means there’s time to gather data on what’s been lost and plan for a better approach – one that acknowledges that the fire regimes of the future will be very different beasts from what has been dealt with in the past.

“We’ve almost got a clean slate to start with, and we probably do have a few years to work that out, but we do have to accept that we will see losses in the future.”

The efforts to map out the extent of the damage from this latest bushfire season are really only just beginning, and Dr Ooi says it could take years to get a full picture of the damage.

The process of investigating – and supporting – ecosystem recovery after Black Summer has been bolstered by an ambitious new citizen-science project. Known as the Environment Recovery Project: Australian Bushfires, the initiative is enlisting members of the public who are out in the bush to record and report their observations of various species in sites affected by last year’s fires. Thus far, nearly 12,000 observations have been logged, amounting to 2,106 species of plants and animals.

“Obviously there’s recovery, and a good chance that a lot of our vegetation are going to recover well, but we have to be careful that we don’t miss something,” Dr Ooi says. “It’s a watch-this-space.”