Colonisation Disrupted Indigenous Fire Management, Fueling Australia's Bushfire Crisis
A millennial-scale sediment study reveals European colonisation abruptly ended Indigenous fire practices in south-east Australia, transforming open woodlands into dense, fire-prone eucalypt forests long before climate change amplified risks.
Colonisation caused a shift from open woodland to dense forest in south-eastern Australia, increasing fire intensity over a century before recent climate changes amplified bushfire risks. New research analysing 1,000 years of sediment from Purghagoolah Lake in Gippsland, Victoria, provides stark evidence of this transformation.
Researchers extracted a metre-long core from the lake bed in Croajingolong National Park, an area with a 10,000-square-kilometre catchment. Examining pollen and charcoal at half-centimetre intervals, they found a sudden change in sediment deposition 200 years ago. This shift coincided with European arrival and the end of millennia of landscape care by the Gunaikurnai people.
How Colonisation Disrupted Fire Management
The removal of Gunaikurnai people from Country ended cultural burning practices. For 800 years prior, pollen records showed a stable, open woodland with about 10 per cent tree cover. Michael-Shawn Fletcher, the study's lead author from the University of Melbourne, stated that prior to colonisation, "this was a cared for and managed landscape."
Between 1830 and 1860, settlers forcibly removed the Indigenous population. Cultural burning ceased. Shrub species swiftly invaded. Charcoal evidence shows bushfires became hotter, which triggered thicker regeneration of eucalypts. Tree cover ballooned to around 40 per cent. Fletcher said, "It’s actually land use change, more than a century before climate changes, that has allowed shrubs to increase, fires to get hotter." The system became trapped in a catastrophic loop: hot fires promote eucalypt recruitment, which drives further fire.
What This Means for Today’s Fires
The resulting dense eucalypt forests create dangerous fuel conditions. Canopy connectivity allows flames to spread more easily, while shrub growth acts as a ladder, carrying fire into the tree crowns. This combination dramatically enhanced bushfire risk, contributing to the catastrophic 2019-20 Black Summer fires, which burned 24 million hectares.
Fletcher argues the catastrophic fires now faced are the product of colonisation and land-use change, not solely climate change. He notes that these much denser forests do not store carbon securely because they are so prone to igniting. Analysis of other sites across south-eastern Australia reveals a similar story, with up to six times as many eucalypts today compared to the pre-colonial period.
The Path Forward: Restoring Indigenous Fire Knowledge
The research provides scientific evidence for integrating cultural burning into modern fire management. Cultural burning refers to First Nations people using low-temperature, carefully timed fire to maintain a safe and productive landscape. Fire scientist David Bowman from the University of Tasmania, who was not involved in the study, described the long-term records as critically important for understanding historical fire regimes.
Bowman said the research contributes to a growing realisation about the legacy of landscape change from the loss of Indigenous fire management, exacerbated by introduced species. He described it as a needed conversation opener as the fire crisis worsens. The study reinforces that a return to widespread cultural burning would help reduce future fire intensity and impact.
Broader Implications Across South-Eastern Australia
The pattern observed at Purghogoolah Lake is not isolated. Similar transformations are documented at other sites, confirming a regional legacy of disrupted fire management. This historical thickening of bushland has created a landscape primed for high-intensity blazes.
The research will energise debates around sustainable fire management and the key role for including Aboriginal fire groups in restoring overgrown bushland.
