Ellen Phiddian
Cosmos science journalist
Ancient pollen and charcoal remains uncovered from islands north of Tasmania (Lutruwita) suggest that human fire management practices were happening in the region 41,600 years ago.
This predates the oldest archaeological evidence of people in Tasmania by roughly 2,000 years.
The study, published in Science Advances, draws on 2 sediment records collected from islands in the Bass Strait.
These islands were once part of a land bridge connecting Tasmania to the Australian mainland, as part of the ancient continent of Sahul.
When the Palawa/Pakana communities arrived, current archaeological records suggest that they would have been the southernmost people in the world.
The researchers, guided by Palawa/Pakana rangers, collected 2 mud cores – one 3m deep and the other 4m deep – from sites on Three Hummock Island and Clarke Island.
“We’re very fortunate to be invited to work on these landscapes,” study co-author Professor Simon Haberle, a palaeoecologist at the Australian National University, tells Cosmos.
These sediment cores had built up layer by layer over tens of thousands of years, collecting pollen and charcoal from the surrounding environment over time.
“They both, surprisingly, went back quite a long way – longer than most other records in the region have been found to go,” says Haberle.
“That uncovered the opportunity to have this window of inquiry into how vegetation and fire changed over at least 50,000 years or more.”
The team analysed pollen and charcoal deposits in the cores, combined with radiocarbon dating, to judge vegetation and fire in the environment.
They found a striking increase in charcoal 41,600 years ago, followed by a change pollens – meaning there was also a change in vegetation.
“This suggests these early inhabitants were clearing forests by burning them, in order to create open spaces for subsistence and perhaps cultural activities,” says lead author Dr Matthew Adeleye, from the department of geography at the University of Cambridge, UK.
Haberle says that the results are similar to those from another study he recently co-authored, which used pollen records to find a clear change in vegetation across the southeastern Australian mainland after human arrival.
“The arrival of people, and the burning regimes that were then set up, had the impact of opening up environments – grasslands became more prominent.”
But the vegetation changes also have their own idiosyncrasies, as can be seen from the differences in vegetation in the cores on the western and drier eastern side of the Bass Strait.
“It’s not a simple widespread burning and a unidirectional change. It’s much more nuanced than that,” says Haberle.
“That’s perhaps a characteristic of Aboriginal burning regimes. They’re not just widespread and random, but much more adapted to specific vegetation types and caring for Country in these different regimes.”
Cultural burning practices, once done across the continent, have recently been reintroduced in large parts of Australia to help manage the severity of bushfires.
“The Western science information is really more of an affirmation that cultural burning and care for Country has been a feature of the landscape for many, many thousands of years,” says Haberle, adding that Palawa/Pakana people “certainly know a lot of this story already”.
The current research “clearly shows that different ecosystems, whether they’re relatively wet or dry, can be managed through cultural burning application”, says Haberle.
“Introducing cultural burning can be certainly beneficial and appropriate for these kind of ecosystems that we are studying.”
