Prescribed burns can reduce our bushfire risk, but how do they impact our wildlife?

Australia’s threatened species are experiencing widespread habitat declines thanks to more frequent fires and a reduction in unburnt areas according to Aussie researchers who say their findings paint a sobering picture for threatened species in fire-prone landscapes.

The study looked at fire patterns across southern Australia from 1980 – 2021, spanning 415 reserves (21.5m hectares) which house 129 threatened species of birds, mammals, reptiles, and frogs.

They found fire frequency had increased by 32% and the area of unburnt vegetation dropped from 61% to 36%.

Unburnt vegetation, particularly long-unburnt vegetation or old growth, is recognised as a crucial habitat for animal species in fire-prone landscapes.

These areas often contain tree hollows, fallen timber, and other complex structures for animals to hide, breed, move around, and feed in.

Associate Professor Diana Fisher from the University of Queensland, who was not involved in the study, told the Australian Science Media Centre “many animals in Australia and around the world need old growth vegetation or mountain habitat that is sensitive to fire”.

The results of the study indicate the most severe impacts of these widespread changes are being seen at areas at high elevation, high environmental productivity, and strong rainfall decline.

Fisher added the animals that live in these areas “will decline faster because of increasing droughts and subsequent fires under climate change”.

“Mountain species are already under threat by other mechanisms of climate change – many cannot physically tolerate heat, and their envelope of suitable cool, wet habitat is rising so their distribution becomes rapidly smaller until it disappears.”

While the study renews conversations about the best fire management practices, it does not offer specific solutions – this is a question for future research.

But according to Associate Professor Brett Murphy at Charles Darwin University, “these alarming findings present a management conundrum” for fire managers in Australia.

“One of the most foremost tools used by fire managers (including in reserves) is deliberate burning under mild fire weather conditions (known as prescribed burning or hazard reduction burning),” he says.

While broad-scale prescribed burning is useful for reducing the intensity of bushfires, it tends to increase the area that is burnt each year, which decreases the amount of long-unburnt areas so crucial for these at-risk species.

“We will need new fire management approaches, moving beyond broad-scale prescribed burning, that specifically target the conservation of long-unburnt habitat,” he added.

Conservation experts such as Professor Euan Ritchie from Deakin University seem to agree the findings highlight the need to consider changing prescribed burning practices and fire management policies.

One common practice in particular should be called into question, he says: “’Clean-up’ burns – where managers will often target and burn any unburnt patches following wildfires or prescribed burns, as a means of attempting to reduce the risk of future fires – must be increasingly scrutinised and reduced.”

Forest Ecology expert Associate Professor Grant Wardell-Johnson from Curtin University echoed these sentiments, adding that protection burning philosophies are “scientifically outdated” and “must be redressed as a matter of urgency”.

He suggested focusing on the development of overstory shelters – the top leafy layer in a forest – in eucalypt forests to provide protection from fire.

The development of an overstory shelter “reduces the severity and potential for forests to burn,” Wardell-Johnson says, adding that areas with an understanding of this theory now experience less severe burns with long-unburnt vegetation than vegetation burnt within the three previous years.

Patch mosaic burning could also be a more viable alternative, University of the Sunshine Coast’s Dr Sanjeev Kumar Srivastava added, which would allow managers to maintain patches of burned and unburned regions, rather than trying to control large unburnt areas that could lead to high-intensity and largescale fires.

Overall, the study findings highlight the balance fire managers must maintain to ensure the safety of residents and a healthy environment – something that is becoming increasingly difficult with climate change.

UNSW Canberra Bushfire Scientist, Professor Jason Sharples, says the findings are consistent with similar studies in other fire-prone parts of the world, and highlight the impact climate change is having on our wildfire regimes.

“Anthropogenic climate change has long been expected to shift wildfire regimes towards more frequent and extreme fire events across many parts of the globe, including southern Australia and this study provides further confirmation that these shifts are already underway.”

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