Paradise revisited: how to fire manage our most pristine places?

In the late 1970s, few travellers of New South Wales’ south coast might have taken the Mt Agony Road turnoff from the Princess Highway into Murramarang National Park, 4 hours south of Sydney.

For a high school surfing mate and I, the route offered a chance for isolation and uncrowded waves.

So it was always with heightened expectations that we turned onto an occasionally steep dirt track winding 8km through thick spotted gum forest to a pristine stretch of rocky southern NSW coastline.

At the end of the track was Depot Beach, where my mate’s parents had a shack.

In March this year I took the turn off again with my wife Fiona. My friends’ shack was still there, recently upgraded, also the old NPWS campground, rebuilt in 2021, where we’d booked to stay.

Kangaroos still dotted the beachfront, although—astonishingly—perhaps even more of them. Waves still broke quietly on Depot’s sandy beach, others dashed against adjacent rock platforms.

Fiona and I were interested in a 3 day South Coast Walk tracing 35km of rock platforms and beaches from Pretty Beach further north, to Maloney’s Beach 25km south near Bateman’s Bay.

The forests of Murramarang—spotted gum, burrowang and sub-tropical rainforest—are an increasingly rare treat for holiday makers. On the drive in, however, we were surprised to see tracts of blackened tree trunks remaining so long after the Black Summer Fires of 2019/20.

The fires had scorched 80% of Murramarang National Park’s 1970ha as NSW’s recorded its worst ever fire season, which across the state claimed 26 lives, 2,448 homes and 5.5 million hectares of land.

Paradise reburned

Fire weather has become more common under climate change.

In research published in 2021 CSIRO scientists concluded climate change was behind the Black Summer fire season, part of an 800% rise in the area of Australian forests burned each year over three decades.

The following year, a review of global research on climate change blamed Australia’s 2019/20 fires on “fire weather conditions that were considerably more likely due to climate change.”

Soon after the Black Summer fires, Australian researchers set to work counting their cost.

Three scientific research papers, published in late 2023 and early this year, are now helping shed light on the impacts of the 2019/20 fires on eastern Australian ecologies.

Two papers focus on Murramarang region, separately on fauna and soils; a third uses citizen science observations from NSW and the ACT before and after the fires to discuss biodiversity.

All three sketch a mammoth task ahead for scientists and environmental managers as Australia tries desperately to manage its fires in a warming climate.

240309 in 2019 20 fires burned from the princess hwy thru to the coast
In 2019-20, fires burned from the Princess Hwy thru to the coast (Image: Morrison)

Foxes on the fireground

Researchers from the Universities of Sydney and Charles Sturt examined how the fauna of Murramarang National Park fared in the Black Summer fires and published their findings in the British Ecological Society’s Journal of Applied Ecology in November

Led by Dr Vivianna Miritis, 40 monitoring sites were set up 1.5km apart in a grid pattern across the Park.

With a sense of urgency, it seems, work began just 3 months after the fires, the authors noting in their paper that: “despite extensive research in fire ecology, studies exploring vertebrate responses to megafires, and to nuanced fire characteristics, remain limited.”

Grid sites burnt and unburnt were classified for varying fire severity. Motion sensitive cameras were mounted on trees at each grid point, and PVC pipe bait canisters pegged nearby to attract animals. In all, 830,725 images and 24 surveys were recorded over two years.

Read more: data and fire management

Key fire-related variables included time since the fire, whether an area was burnt or unburnt, fire severity, proportion burnt, proportion of high or low severity fire, and vegetation type.

Results showed that vegetation type strongly influenced the response to fire, and that some species benefitted while others were disadvantaged.

For example, there was little evidence feral cats were more active after fires, while foxes returned more swiftly to severely burnt areas; small to medium-sized mammals followed more gradually, while wet forest birds preferred unburnt areas.

The megafires impacted many forest invertebrates, but effects varied between species, suggesting “several mechanisms drive faunal responses to fire.” Two key recommendations emerged: to protect unburnt refuges, and—crucial for fire sensitive species—to maintain large, intact areas of forest and restore habitat where needed.

Hazard reduction or cool burning?

The second paper compared hazard reduction burns, which fire-fighting authorities across Australia have used for decades, with so-called cool or Indigenous cultural burns.

A joint investigation published in Fire by members of the Ulladulla Local Aboriginal Land Council (ULALC) and academics from the University of Wollongong, the study’s importance cannot be understated: In the Western scientific literature, relatively little is known about the effects of cultural burns.

From July to August 2022 field work was undertaken on 12 hectares of Narawallee Creek on Murramarang Country north of Depot, where evidence of Aboriginal use spans 20,000 years.

Three sites were examined: A control or “no burn” site, a prescribed burn by the NSW Rural Fire Service in September 2020, and an Indigenous-led burn by ULALC in May 2021.

Indigenous custodians used patch burning to “promote ecological health, encourage plant regeneration, and maintain cultural connections to the land.”  Government-led burns aimed to reduce fuel load and mitigate against severe wildfires.

The researchers measured how different fire management techniques affected soil properties, an impact dependent on fire severity and soil characteristics.

Both fire treatments saw rises in soil moisture, greatest for the agency-led burn.  Both saw a lowering of soil bulk density—important for nutrient availability, microbial activity and soil health—and a rise in organic matter. Both were considered positive for soil health, a plus for above-ground ecosystems, though the greater effect was from the Indigenous-led burn, judged best at reducing soil bulk density and increasing carbon and nitrogen stores.

The authors’ conclusions remained that both treatments had “positive, quantifiable effects on soil and ecosystem health.”

A warning on biodiversity

Publishing in Global Change Biology in October, researchers from University of NSW analysed differences in species diversity after the Black Summer fires using data from across eastern NSW.

Tens of thousands of wildlife observations of invertebrates, plants and vertebrates were collected by citizen scientists before and after the 2019–2020 megafires, from regions both burnt and unburnt.

Collecting was done under the Environment Recovery Project using the iNaturalist platform, which shares citizen observations—such as simple smart phone snaps of plants—with scientific data repositories like the Global Biodiversity Information Facility.

Leading the study was PhD candidate Simon Gorta, from the UNSW Centre for Ecosystem Science.

“Our findings illustrate the extent and severity that fires can reach under … conditions typical of climate change projections,” he says.

“As we grapple with the effects of these events on lives and property, we should also be concerned about how our wildlife and ecosystems respond, and how this can be better managed.”

Rebound in species diversity (or richness) in burnt areas was greater than for unburnt areas, suggesting biodiversity recovers well if fires are not too severe. But a warning remains: Fires of high severity would have the opposite effect.

The future

From all three studies, results are complex and nuanced, though perhaps a glimpse of science to come.

It would seem Indigenous fire practises can help. For their part, Parks NSW say they recognise the importance of working with Aboriginal communities to manage park reserves, and point to their cultural fire management policy.

Also helpful, as Gorta says, are amateur scientists, “to help grow the dataset … to monitor and manage the environmental impacts of wildfires in a rapidly warming and fire-conducive climate.”

The Greenlight Project is a year-long look at how regional Australia is preparing for and adapting to climate change.

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