Ancient mud reveals 130,000 years of Australia’s fire history and future solutions to the current fire crisis

The Conversation by Michela Mariani, Anna Florin, Heidi Cudd, Matthew Adley and Simon Connor
Flowchart describing the approach used in this study to quantify historical changes in fuels within the shrub layer (ladder fuels). Credit: Science (2024). DOI: 10.1126/science.adn8668
Intensified land management by Aboriginal people in southeastern Australia about 6,000 years ago cut forest shrub cover in half, according to a new study of fossilized pollen trapped in ancient mud published in the journal Science. .
Shrubs bind fires from the ground to the forest canopy, allowing them to spread quickly and intensify. Reductions in shrub cover, associated with increased population size and evidence of more extensive landscape use by Aboriginal people, would have dramatically reduced the likelihood of high-intensity wildfires.
They also found that the shrub layer in modern forests is even thicker than it was 130,000 to 115,000 years ago, when the climate was similar to today but there were no humans around.
Our in-depth research shows how important Indigenous cultural practices have been to reducing dangerous high-intensity fires. It also suggests ways to solve Australia’s current fire crisis, which is being exacerbated by climate change.
shrub problems
Australia has been trying to manage fires by suppressing them for decades. While this strategy may work in the short term, it has disastrous long-term consequences.
Over the past 20 years, forests and woodlands in south-eastern Australia have been hotspots for large-scale fires.
The suppression of the fires has allowed vegetation, especially the shrub layer, to grow without restrictions. Shrubby, medium-height plants act as ladders, allowing fire to spread from the ground to the canopy. The result is a more intense and uncontrollable fire.
Evidence for denser plants comes from tiny fossilized pollen grains deposited in layers of ancient sediment on wetland and lake beds. By extracting fossil pollen from mud, scientists can reveal what vegetation looked like in the past.
Our new research used archaeological data and information preserved in ancient mud. We investigated how the vegetation of southeastern Australia has changed in response to climate and human management over the past 130,000 years.
We wanted to find out how things changed during key periods: before humans arrived in Australia, during the period of indigenous occupation, and after British colonization.
We used sophisticated models to estimate vegetation cover and how it relates to human land use at different times.
care about the country
Indigenous Australians have been the guardians of this continent for thousands of years. Their journey to Australia began at least 65,000 years ago.
Direct evidence of cultural burning dates back at least 11,000 years in the Top End, but it may have begun much earlier.
The burning practices of Australia’s indigenous cultures are complex and diverse. However, many parts of the continent also included regularly managed burns. These helped manage vegetation growth and reduce the risk of severe fires.
Since British colonization, Australia’s landscape has changed significantly, with more open grasslands and denser forests. The introduction of European land management practices, including fire suppression, disrupted the fire protection regimes that Indigenous Australians had maintained for thousands of years.
This suppression-focused approach resulted in the accumulation of plant material, creating a tinderbox susceptible to ignition.
A call for change: integrating indigenous knowledge
Changes in fire management strategies are essential to address this crisis. One promising approach is to integrate Indigenous fire management practices into modern fire management plans and work with traditional owners to best care for the country.
This must be done in a way that supports indigenous livelihoods and fosters connections with country, and not by governing bodies that simply appropriate indigenous know-how.
Australia’s indigenous peoples have hundreds of generations of experience in managing the country’s fire-prone landscapes. Indigenous-led fire management is already gaining momentum in northern Australia.
Our research shows that the forests and woodlands of the Southeast have been effectively managed in the past and continue to benefit from indigenous practices of country care today.
Reducing dangerous fuels in the shrub layer means fewer high-intensity fires that threaten the forest-urban interface, such as the 2019-2020 Black Summer fires.
High temperatures and prolonged drought create ideal conditions for wildfires to spread. Colonization is exacerbating the problems arising from anthropogenic climate change.
But without fuel, there is no fire. Increasing biomass and climate warming are combining to generate fires of unprecedented scale and intensity, posing serious threats to human life, property, and ecosystems.
Australia’s fire crisis is a complex problem that requires multifaceted solutions. Australia can develop more effective and sustainable fire protection strategies by learning from and collaborating with Indigenous practitioners. This collaborative approach provides a path forward to quell the flames and protect this country’s unique and diverse landscape.
Further information: Michela Mariani et al., Shrub cover declines as indigenous populations expand into southeastern Australia, Science (2024). DOI: 10.1126/science.adn8668
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Source: Ancient mud reveals Australia’s fire history over the past 130,000 years, and future direction in the current fire crisis (3 November 2024) https://phys.org/news Retrieved November 3, 2024 from /2024-11-ancient-mud – Uncovering Australia’s History.html
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