Intentional burning is increasingly being recognized as an important force in shaping ecosystems over time. In Australia, the impact of anthropogenic fire has been particularly significant, with indigenous burning hypothesized to have radically altered the continent's biogeography.
By Daniel Strain
In Australia, Martu hunter-gatherers light fires to expose the hiding places of their prey: monitor lizards called goanna that can grow up to six feet long. These generations-old hunting practices, part of the Martu day-to-day routine, have reshaped Australia's Western Desert habitats, according to Stanford University anthropologists Douglasand Rebecca Bird.
"Martu" refers to a group of about 800 indigenous Australians from eight dialect-groups that inhabit the Western Desert. For 10 years, the Birds have been investigating Martu hunting strategies and their lasting environmental impacts. With support from the Woods Institute for the Environment, the researchers have begun to explore what makes aboriginal hunting grounds molded by fire more biologically diverse than lands untouched by humans.
"The results of our work will be used to assist conservation efforts and joint indigenous land management policy in the Western Desert," said Douglas Bird, an assistant professor (research) of anthropology and principal investigator on the Woods Institute Environmental Venture Projects (EVP)grant.
In many cases, humans aren't the wrench in nature's gears but an important piece of the clockwork, he added. And because so much of Australia's Western Desert, from lizards to shrubs, revolves around Martu practices, conservation efforts will only succeed if they incorporate traditional goanna-hunting practices, he said.
"We're trying to demonstrate what would happen if you did pull people off the landscape," he said. "What happens when you break all of these co-evolutionary links between people who've lived on the landscape for thousands of years and the diversity of the faunal and floral community?"
Martu life revolves around hunting and fire, Douglas Bird explained. Martu inherit ritual duties that correspond to certain tracts of desert called "estates." An important part of this inheritance is the knowledge of when and where to light smoldering brush fires. Martu never start blazes without knowing every nook and cranny of a territory and often forgo campfires when traveling through foreign estates, he said.
"You never burn unless you're with someone who has all of that knowledge about that estate," he added. "If your fire were to threaten one of those totemic spots where they keep all their religious paraphernalia associated with these rituals, it's technically punishable by death."
The middle-aged and elderly women who typically hunt for goanna can spot the animal's burrows and tracks better in burn scars than in thick spinifex grass, Rebecca Bird explained. Goanna hunters burn desert in about 55-acre chunks, making their hunting grounds a patchwork quilt of recently burnt earth and recovering vegetation. These scars are much smaller than those left by lightning wildfires, which char an average of 2,000 acres.
Burning back grasses and other fire-prone plants encourages the growth of a diverse range of annual vegetation, she said. The variable turf of Martu hunting grounds allows small mammals to find plenty of places to hide from predators, she added, while areas free of human burning lack this patchwork quality and are home to fewer plants and animals.
"The thing that anthropogenic fire does is rearrange the landscape variation into smaller and smaller bits," said project collaborator James Holland Jones, an assistant professor of anthropology and a Woods Institute center fellow. "It happens to be the scale that animals, plants and people work at."
While Martu families believe strongly in preserving their lands and know all the animals and plants that benefit from burning, their fires are, first and foremost, tools for nabbing goanna meat.
"Martu don't think of it as, 'We apply fire in order to promote the future long-term biodiversity,'" Douglas Bird said. "They can talk about all those effects, but that's not what maintains the system."
To determine the impact of Martu hunting practices over times, the research team is searching the geologic record for evidence of burning thousands of years into the past. The researchers will also recreate the diversity of historic plant communities using molecular clues hidden in animal remains.
Despite growing awareness of the role that fire plays in wild space, many Australians have been slow to accept Martu burning practices, Rebecca Bird said. "They see it as a destructive force. It's in line with the thinking of most ecologists who view humans as a disturbance of the natural equilibrium," she said. "The Martu perspective is much more that humans are part of it all."
Most Australian conservationists have only paid lip service to Martu hunters, Douglas Bird noted. But desert conservation programs won't work unless they include an understanding of Aboriginal fire, he said. And because hunting is so central their culture, Martu men and women will only accept land-management practices that are compatible with their day-to-day subsistence.
"When you're drafting a fire-management program for a national park, if it's not done with respect to the actual practice of folks and the trade-offs people face on a daily basis, then those prescriptions are disregarded," he said.
To bring Aboriginal representatives into a true dialogue on land management, a delegation from the Western Desert will meet with researchers on the Stanford campus in 2011 or 2012. The Birds and Martu leaders also will host an international conference for anthropologists and ecologists in Australia in 2011 on the role of fire in hunter-gatherer communities and ecosystems. A goal of the conference is to communicate that "indigenous knowledge is not different from scientific knowledge," Rebecca Bird said.
"Through generations of hunting for goanna, Martu appreciate fire for what it can be: A tool for shaping human communities, as well as the natural world," she said. "They see the burned areas beautiful. They say, 'It's safe. There are no snakes, no nasty things living here now that we've cleaned it up.'"
Daniel Strain is a science-writing intern at the Woods Institute for the Environment at Stanford University.
Page Chamberlin Professor of Geological Sciences
Tadashi Fukami Associate Professor of Biology
James Holland Jones Associate Professor of Earth System Science and Senior Fellow at the Woods Institute for the Environment
Katherine Maher Associate Professor of Earth System Science and Senior Fellow at the Woods Institute for the Environment