Ancient mud reveals Australia’s burning history of the past 130,000 years – and a way forward in the current fire crisis

Increased land management by Aboriginal people in southeastern Australia about 6,000 years ago cut forest cover by half, according to our data. new study published in Science of fossil pollen trapped in ancient mud.

Shrubs connect fires from ground covers to the forest canopyallowing fires to spread and intensify quickly. The reduction in shrub cover, coupled with evidence for an increase population size and wider use of the landscape by Aboriginal people would have dramatically reduced the risk of high-intensity bushfires.

We also found that the shrub cover in modern forests is even greater than it was 130,000 to 115,000 years ago, when the climate was similar to today’s but no humans were around.

Our in-depth research shows how important indigenous cultural practices were in reducing dangerous, high-intensity fires. It also suggests a way forward in Australia’s current fire crisis climate change is getting worse.

The problem with shrubs

Australia has been trying to control fires by suppressing them for decades. This strategy may be effective in the short term, but has led to serious long-term consequences.

Over the past two decades, the forests and forests of southeastern Australia have become hotspots for major fires.

Fire suppression has allowed vegetation, especially in the shrub layer, to grow unhindered. Shrubby, mid-height vegetation acts as a ladder, allowing fires to spread from the ground to the canopy. This results in more intense and uncontrollable fires.

Evidence for denser vegetation comes from small, fossilized pollen grains deposited in layers of ancient sediment in wetlands and lake beds. By extracting fossil pollen from mud, scientists can develop a photo of the vegetation in the past.

Our new study used archaeological data and… information preserved in old mud. We looked at how the vegetation of southeastern Australia has changed over the past 130,000 years in response to climate and human management.

We wanted to see how things changed during key periods: before human arrival in Australia, during periods of indigenous occupation and after British colonization.

We used advanced models to estimate vegetation cover and how it compared to human land use at different times.

Take care of the country

Indigenous Australians have been stewards of this continent for millennia. Their journey in Australia began at least 65,000 years ago.

Direct evidence of cultural burning goes back at least 11,000 years in the Top End, although it may have started much earlier.

Indigenous Australian cultural burning practices are complex and varied. However, in many parts of the continent this involved regular, controlled burns. These helped control vegetation growth and reduce the risk of high-intensity fires.

Since British colonization, Australia’s landscape has undergone significant changes, with both more open meadows and denser forests. The introduction of European land management practices, incl firefightingdisrupted the fire regimes that indigenous Australians had maintained for thousands of years.

This oppression-oriented approach has led to a build-up of plant material, creating a tinderbox ready to ignite.

A call for change: integrating indigenous knowledge

To tackle this crisis, a change in firefighting strategies is essential. One promising approach is integrating indigenous fire management practices into contemporary fire management plans, working with traditional owners to best care for the land.

This must be done in a way that supports indigenous livelihoods and promotes connection to the land, and not by management organizations that simply appropriate indigenous knowledge.

Indigenous Australians have hundreds of generations of experience managing the country’s fire-prone landscapes. Indigenous-led fire management is already being revived in northern Australia.

Our research shows that southeastern woodlands and forests were effectively managed in the past and could also benefit from indigenous care-of-land practices today.

Reducing hazardous fuels in the bush layer means fewer high-intensity fires that threaten the bush-urban interface. such as the Black Summer fires of 2019-2020.

Higher temperatures and prolonged droughts have created ideal conditions for the spread of forest fires. Colonization has exacerbated the problems arising from human-induced climate change.

But there is no fire without fuel. It is the combination of increased biomass and a warming climate that is now fueling fires of unprecedented size and intensity, posing significant threats to lives, property and ecosystems.

Australia’s fire crisis is a complex problem that requires a multi-faceted solution. By learning from and working with indigenous practitioners, Australia can develop more effectively and sustainably firework management strategies. This collaborative approach offers a path forward to tame the flames and protect the country’s unique and diverse landscapes.

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