Reducing bushfire extent, a key benefit of prescribed burning

An Opinion Piece: John O’Donnell

Across south eastern Australia, prescribed burning rates remain at historically low levels, despite overwhelming evidence that this single mitigation tool is the most effective, scalable and proven method for reducing the extent of bushfires.

While public debate often focuses on fire intensity or severity, the extent of a bushfire, including how far it runs and how much country it consumes are important in relation to social, economic and environmental damage.

This article synthesises the empirical evidence, not modelling, demonstrating that prescribed burning reduces bushfire extent across Australian forests and outlines why SE Australia must urgently expand its fuel reduction programs.

Inadequate prescribed burning and large bushfire extent

Datasets show that prescribed burning across most of SE Australia is far below levels required to influence landscape scale fire behaviour. The review includes data showing that prescribed burning rates in most Australian states have remained extremely low for decades, while bushfire area has repeatedly and massively eclipsed prescribed burning over multiple decades. SW WA is an exception, as outlined in the review.

Victoria is a clear example of the consequences. As the review notes, insufficient prescribed burning in Victoria, typically <2% of public land per year, allowed fuels to accumulate to dangerous levels, contributing to three megafires that burned 3 million hectares and culminated in the Black Saturday tragedy. Despite Royal Commission recommendations for >5% annual treatment, the state has averaged only ~1.4% in recent years, culminating in the 1.6 million hectare 2019–20 fires.

The relationship is simple: when prescribed burning declines, wildfire extent increases exponentially. Western Australian data shows that when annual forest prescribed burning treatment falls below ~8%, the area burned by bushfire escalates rapidly. This suggested threshold of around 8% of forests prescribed burnt per year, or 40% of the landscape in fuels <5 years old.

South West Western Australia long term empirical evidence

South West Western Australia provides strong long term empirical evidence that prescribed burning reduces bushfire extent. For more than half a century, WA has treated around 6–10% of its south west forests annually. As Burrows and Sneeuwjagt summarise, this program has kept wildfire impacts remarkably low.

Boer et al. (2009) found that prescribed burning explained up to 71% of the variation in annual wildfire extent, and that keeping fuels younger than six years dramatically reduced the incidence of large fires.

The suggested path forward

The evidence is unequivocal: prescribed burning reduces bushfire extent. Long‑term WA datasets, Victorian analyses and case studies and international comparisons all point to the same conclusion. Yet SE Australia continues to rely heavily on suppression, with limited mitigation, to reduce bushfire risks.

A national shift is required from reactive suppression to proactive, landscape‑scale fuel management with effective suppression. This includes treating 8–10% of forested landscapes annually and embedding prescribed burning into risk‑management frameworks.

Australia has the evidence, the case studies and the operational experience. What is missing is the political and institutional commitment to act at the scale required

Read the full report

Source & image credit: John O’Donnell