As Australia and the world face the challenges of global warming and rising bushfire threats, ecologists at the University of South Australia are focusing on how prescribed burns affect native wildlife.
In a recent study published in the International Journal of Wildland Fire, researchers examined the peak temperatures lizards may encounter during prescribed (controlled) burns in South Australia’s Mount Lofty Ranges, comparing these with the reptiles’ maximum tolerable heat levels.
Studying Skink Survival in the Fire-Prone Mount Lofty Ranges
The Mount Lofty Ranges—both a biodiversity hotspot and a fire-prone area—undergo extensive prescribed burning each spring and autumn. To assess the impact, scientists recorded surface and shelter temperatures during four separate burns and compared them with laboratory-determined “critical thermal limits” for three skink species.
Results showed that average temperatures beneath common shelters, such as logs and rocks, reached 108°C and 53°C, far exceeding the skinks’ survivable heat range of 37.5°C to 43.0°C.
Although the study focused on reptiles, lead researcher and UniSA Ph.D. candidate Shawn Scott emphasized that such extreme heat levels likely pose risks to many other native animals, suggesting the findings have wider ecological implications.
“These conditions far surpass the 60°C limit tolerated by most terrestrial vertebrates,” says Scott. “In our study, logs and rocks provided the best protection against extreme heat during prescribed burns.”
“Still, if prescribed burns occur under conditions that intensify fire severity, the extreme temperatures and their duration could be deadly for small vertebrates,” the researchers warn.
Higher Ambient Temperatures Intensify Fire Impact on Skink Shelters
They also found that higher ambient temperatures on burn days led to increased peak temperatures beneath shelters and prolonged periods of dangerously high heat.
“Our analysis revealed that fire temperatures rose by as much as 700°C when ambient temperatures increased from 17°C to 22°C,” Scott explains.
“The hotter the fire, the more intense the heat becomes inside or beneath the shelters used by small animals, significantly reducing their chances of survival—especially with prolonged exposure.”
Co-researcher and UniSA wildlife ecologist Associate Professor Sophie (Topa) Petit adds, “In terms of thermal protection, rocks and logs retained the lowest temperatures, highlighting their vital role as shelters for small wildlife.”
“Still, many of those areas recorded temperatures well beyond what reptiles can tolerate. Not all logs and rocks offer sufficient protection,” the researchers note.
Climate Change Likely to Increase Prescribed Burns in Fire-Prone Regions
With climate change driving up bushfire risks, the frequency of prescribed burns is likely to rise—particularly in fire-prone Mediterranean climates such as the Mount Lofty Ranges, other regions of Australia, as well as Greece, Italy, Spain, and California.
Scott emphasizes that protecting wildlife and preserving biodiversity should be central to prescribed burning practices, and he believes his team’s findings can guide strategies both in Australia and internationally.
“To achieve lower-intensity burns, these fires should be carried out on cooler days when ambient temperatures are below 17°C,” he explains.
“In Australia, prescribed burns are often conducted on so-called mild days—ranging from 17°C to 22°C—but our study shows that even under these conditions, peak temperatures and their duration can still pose serious risks to small animals seeking refuge under logs or rocks.”
He adds that conducting pre-burn surveys to assess the availability and quality of shelter sites is crucial to improving animal survival during fire events.
The researchers also recommend future studies focus on larger and subsurface shelters—such as soil, tree hollows, and burrows—as well as monitoring wildlife movement and mortality during and after burns.
Read the original article on: Phys.Org
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