Outback extremes

Published 11 Dec 2018 

A more sophisticated understanding of how climate change will impact Cravens Peak and Ethabuka reserves is focusing our conservation efforts when and where they will do the greatest good.

A desert storm moves across Cravens Peak Reserve, Qld, at the end of a major boom event in 2011. Photo Dr Aaron Greenville.
A desert storm moves across Cravens Peak Reserve, Qld, at the end of a major boom event in 2011. Photo Dr Aaron Greenville.
Deserts are driven by extremes. Temperatures soar in summer, plunge on winter nights and when the rains finally come, the landscape blooms. Vivid greenery replaces the drab grey of drought, and myriad forms of life spring from the land – quick to capitalise on food aplenty.

“The transformation can be so rapid and pronounced, it's like you've just stepped into a different environment altogether,” says ecologist Dr Aaron Greenville.

Aaron has witnessed this phenomenon, called a major ‘boom’ event, through his work with the University of Sydney’s Desert Ecology Research Group (DERG), with which Bush Heritage has a long-standing partnership. The group has been conducting fieldwork at Cravens Peak and Ethabuka reservesWangkamadla country, on the eastern fringes of the Simpson Desert – for almost three decades, giving them one of Australia’s longestrunning ecological datasets.

After studying 100 years’ worth of data collected from weather stations across the Simpson Desert, Aaron and his fellow researchers noticed something peculiar about these major boom events: not only are they starting to happen more often, they’re also (on average) getting bigger.

A Desert Mouse, usually sighted only after heavy rains, on Ethabuka Reserve. Photo Dr Aaron Greenville.
A Desert Mouse, usually sighted only after heavy rains, on Ethabuka Reserve. Photo Dr Aaron Greenville.
Given the fact that desert species typically experience dramatic spikes in their populations following rain, it would be easy to assume that more rain in these landscapes is good news. But ecosystems are made up of a multitude of species all interacting with each other in a delicate balancing act. Even small changes in those interactions can cascade through the food chain, eventually having far reaching impacts.

Scale those small changes up – to something as all-pervasive as climatic change – and things start to get a lot more complicated.

“If we want to continue to effectively protect the species living in these landscapes in the future, then we need to be paying attention to these changes,” says Bush Heritage ecologist Dr Alex Kutt. “If we know what to expect, we can plan accordingly – that’s why the University of Sydney’s research is an important component of our management.”

In 2010-2011, when the last big rains fell in the Simpson Desert, the subsequent flush of growth across arid Australia was so expansive that it sucked up about 60% of the world’s carbon stocks for the year. The plants grew, bloomed, produced new seeds and then quickly dried out, leaving behind a mass of fuel. Not long after, wildfires swept through.

Cravens Peak Reserve Manager Jane Blackwood. Photo by Lachie Millard/The Courier Mail.
Cravens Peak Reserve Manager Jane Blackwood. Photo by Lachie Millard/The Courier Mail.
This pattern of wildfire occurring after heavy rain in the desert is a well-documented phenomenon, and it’s one of the main reasons why more frequent and more intense boom events across the Simpson Desert aren’t necessarily good news for Cravens Peak and Ethabuka reserves.

Wildfires remove vegetation, making small mammals such as hopping mice, mulgaras, and dunnarts “more vulnerable to predators,” says Aaron. They can also reduce the abundance of bush foods, which is a concern for Wangkamadla elders.

With boom events happening more often, it follows that the occurrence of wildfires will increase, too. And that will mean that small mammals are exposed to predation more frequently. Research has found that feral cats will travel long distances – over 12km – to get to a burn area to hunt and take advantage of exposed prey.

Depending on how large the burn area is, they can stay around for weeks at a time and their presence can have a catastrophic effect on native animal populations.

For Alex and the rest of the team looking after Ethabuka and Cravens Peak, these findings have led them to rethink their management strategy. Over the past two years, they’ve begun to prioritise the protection of old growth spinifex so that native animals have a place to hide from predators after wildfires have come through.

“The longer and older the spinifex is out there, the better and more diverse the small mammal and reptile communities are… because that spinifex is what’s going to allow those small mammals to outlast predation peaks,” says Alex. “Then, when you have the next period of better resources, they can breed up again.”

A strategic fire break on Cravens Peak Reserve. Photo by Lachie Millard/The Courier Mail.
A strategic fire break on Cravens Peak Reserve. Photo by Lachie Millard/The Courier Mail.
To protect the old-growth spinifex, the team is creating strategic fire breaks 200 to 500 metres wide by continuously burning the same stretches of land.

Combined with Bush Heritage’s ongoing feral predator control program, the aim is for the old-growth spinifex to confer the native species on Cravens Peak and Ethabuka enough of an advantage that they will be able to maintain their presence in the landscape.

“Think of it as habitat protection burning, and not the traditional mind-set of fuel reduction burning,” says Alex.

Wangkamadla people were actively living on country and using fire stick burning to manage overgrowth up until the 1970s. Traditional Owner Avelina Tarrago says there are similarities between the two different fire management strategies, and she can see a pathway to the integration of both knowledge bases in the future.

“Recognising that traditional practices and modern science can work cohesively to achieve the same outcomes will benefit everyone involved, and increase our capacity to deal with future climate change events,” she says.

One thing is certain: this part of Australia is not the same as it was 200 years ago, and more change is coming.

“We have lots of different people managing this region now – different neighbours with different world views and with largely agricultural land uses, and the climate has changed,” says Alex. “We have to accept that global climate change is beyond our control; but we can manage our patch within those constraints.”

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