A body of research is challenging long-held beliefs that lessening fuel load inherently lowers fire risk.
Studies published by researchers from the Australian National University and Curtin University since 2022 have claimed long-held research that underpinned the Western Australia Department of Biodiversity, Conservation and Attractions’ burning regime is incorrect.
Their study published in August of that year replicated the department’s underpinning research from 2009 and determined prescribed burns had negligible effects on bushfire area. Another study published in March of 2022 found that forests in southwest Australia are at their highest fire risk during the tens of years of regrowth after a fire, but continuously decrease in fire risk once reaching their mature period.
A new study, just published by the researcher Philip Zylstra, an Adjunct Associate Professor at Curtin University, and David Lindenmayer, a Distinguished Professor at the Australian National University, delved further into this dichotomy and examined whether a full phase-out of prescribed burning would decrease severe bushfires and help forests return to their original, pre-frequent disturbance states.
The researchers said their study shows long-unburnt forests limit fire without human intervention, even as the climate changes. They found that 77% of all areas burned in over 500,000 hectares (1,235,527 acres) of forested national parks in southwest AU were due to prescribed burns, with 20% burned from escaped prescribed burns and 23% from backburning.
“If large-scale prescribed burning and incentives to backburn ended, the area burned annually would immediately fall 87%, leaving only fires started by lightning, accident or arson,” the researchers wrote this month in an article for The Conservation. “Our modelling suggests less area would be burned in the hotter, drier climate of 2100 than it is today if both widespread burning policies were ended.”
“Humans have a deep-seated desire to intervene in nature. But our research shows long-unburnt forests act to limit fire without human intervention – even as the climate changes.”
The researchers instead called on authorities to invest in rapid fire detection and attack, better resourcing firefighters, training and employing more specialist remote area firefighters and exploring fire-fighting drones.
They stressed that these latest findings relate only to the forests of south-west Western Australia. However, they quote their own 2023 research to claim that other Australian forests, and Northern Hemisphere forests, may also become more flammable through burning.
A spokesperson from the Western Australia Department of Biodiversity, Conservation and Attractions said that any claims that forest flammability declines with age rest on inadequate data and following them would be unwise.
“[DBCA] research confirms that prescribed burning is effective in reducing the frequency, severity and size of bushfires in south west forests when at least 45 per cent of the landscape has a fuel age of less than six years since last burnt,” the Department statement sent to The Conversation said. “Removing fire from fire-prone ecosystems often leads to high-severity fires, as seen in a range of significant bushfires that have occurred in Australia and overseas.”
The same researchers faced similar pushback from the department after they published their March 2022 study. The researchers say that scientists from the department told them that their own records contained flawed data and suggested ignoring all records for old forests. The researchers said their findings only became stronger after they removed the reportedly flawed data.
Read the researcher’s full article in The Conversation.
