An ecological tragedy is unfolding in Australia’s Red Centre, where wildfires have destroyed more than 100,000 ha of heritage-nominated Tjoritja West MacDonnell National Park, closed the world-renowned Larapinta Trail wilderness walk, and, in a separate ignition, reportedly destroyed one home and threatened others near Alice Springs.
The fires have fuelled calls for an introduced grass species known as buffel, which has been blamed for past fires in the region, to be officially declared a weed in the Northern Territory.
The Northern Territory Government responded this morning by announcing it will convene a working group to discuss approaches to buffel grass management in Central Australia, and consider declaring it a weed under the Weeds Management Act 2001.
Buffel grass is rapidly changing the nature of fire in the Centre, how it spreads across the desert landscape, and is degrading unique arid zone ecosystems.
For the first time in a decade, water bombing was used in the West MacDonnell Ranges to extinguish more remote parts of the intense fire, using water drawn from popular summer swimming spot Ellery Creek Big Hole.
Previously, fires had ravaged the same region in 2011 and 2018/19, but little attention was paid nationally to such events as they are so remote.
This year, following high average temperatures in March and three years of high rainfall under La Niña, fuel loads in the National Park were primed.
For the past three decades, the situation has been exacerbated by the unchecked spread of buffel grass, which researchers and conservationists blame directly for past wildfires, and are convinced represents a pressing danger to the region under climate change.
What is buffel grass?
Buffel grass (mainly Cenchrus ciliaris and C. pennisetiformis) is a deeply-rooted perennial grass native to Africa, Arabia and Asia, brought to Australia with camels in the 1860s.
Some call it “God’s grass”, others the “botanical equivalent of the cane toad.”
It began sprouting in patches across the Centre after construction of the Overland Telegraph Line, and pastoralists soon noted the grass was drought-hardy and able to withstand heavy grazing.
After World War I, buffel was planted widely throughout central, tropical and sub-tropical Australia, including Western Australia’s northwest and Queensland’s North. A deliberate seeding program was undertaken in the Northern Territory in 1961, which saw the grass sown on cattle stations across the region as fodder, and for dust suppression and erosion control.
Now, much of Australia’s centre is covered in buffel, but exactly how much is anyone’s guess, as there is little detailed mapping available.
Buffel remains valued by pastoralists as a feed and lends support to the beef industry in the Centre and parts of the North, but conservationists and land resource managers point to research proving it is a threat to conservation values.
The problems include a high burning temperature, high biomass, ability to spread rapidly after rainfall, and increasing the frequency and intensity of fires, as well as changing habitats and impacting Aboriginal culture and connection to country.
Why hasn’t it been declared a weed?
In 2015, the Australian Government issued a Threat Abatement Advice for buffel grass, declaring it responsible for ecosystem degradation, habitat loss and species decline in arid and semi-arid Australia, the aim being to protect biodiversity assets as well as Indigenous cultural sites.
An earlier 2011 study published in the Journal of Environmental Management had concluded that while buffel grass is listed among the ‘‘prohibited, regulated and restricted noxious weeds’’ of Arizona, USA, there has been “little concerted action to deal with its negative effects in Australia.”
South Australia declared buffel a weed in 2015, but outside this there have been few attempts to regulate its sale, planting or spread.
As a result, policy research officer for Alice Springs Arid Lands Environment Centre, Alex Vaughan, says our knowledge of the distribution of buffel grass in Central Australia is poor.
“One of the big issues is not having a good understanding of where the fuel is in some of these areas.
“By not being declared [a weed], there hasn’t been any comprehensive mapping of [buffel’s] gross distribution that’s publicly available.
“There are high concentrations of buffel immediately to the west of Alice Springs. [But] if we’re developing management plans as required once a weed declaration starts, you need to understand what you’re trying to manage and where.”
What does the research say?
Charles Darwin University ecologist, Christine Schlesinger, has written on the 2018 fires in Tjoritja, concluding that increased frequency, intensity and extent of fire promoted by introduced grasses is one of the most serious contemporary threats to biodiversity in arid ecosystems.
In that year, wildfires burnt 660 square kilometres of the park in 15 days, destroying 27% of large and ecologically significant trees at six sites surveyed by the researchers prior to the blaze.
Schlesinger now awaits more detailed reports of the current fire to emerge before assessing a role for buffel.
“But I think it’s really important that we talk about it,” says Schlesinger.
“We wrote a paper … about the big fires in Tjoritja National Park in 2018, and their devastating impact on centuries old river red gums that line the buffel-choked river banks.
“We also described how buffel grass has changed the nature of fire in the Macdonell Ranges, in terms of how fire spreads across the landscape, when fire can occur, and how it can be managed.
As for many wildfires, there were multiple factors at play in 2018, she says.
“One was the extreme dry weather that we’d had … which meant there was incredibly low moisture content in the soil, and dry fuel.
“Then a series of record high temperatures, which created the perfect storm in terms of flammability, so a part of the native vegetation burned that wouldn’t normally burn.
“That was coupled with the fire spreading through the landscape in areas invaded by buffel grass that would have previously been much less likely to burn.
“We predicted that there would be more fires like this happen in the West MacDonnell Ranges due to buffel grass and extreme weather.”
Also in Cosmos: Extreme levels of fuel for grassfires
Now, after two recent big rainfall events, the Centre is in some way experiencing the opposite conditions to last time.
“After big high rainfalls like this we do expect fires. And we do get fires in native vegetation.
“The native grasses are doing really well as well, so there is a lot more fuel on the ground everywhere.
“The impacts of the current fire need to be considered within the broader context where we are looking at these large-scale fires occurring more and more frequently under all types of conditions.
“We need to be asking to what extent buffel grass is driving those longer-term changes and what we can do about it.
“Buffel grass has taken the seasonality out of central Australian fires; now we can have fires at any time.”
In a press released early today, NT Minister for the Environment, Lauren Moss, announced a new working group to address buffel grass and consider its declaration as a weed.
It is understood the group will include pastoralists, many of whom still favour the grass.
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