Shrinking koala habitats face an escalating threat of bushfires

Australian koalas, already battling diminishing numbers due to widespread bushfires in recent years, face an escalating threat. According to a new study led by Flinders University, nearly half of the vital koala habitats in Australia will be at a high risk of bushfires by 2070.

Further studies by the team show that, by 2070, suitable habitats for koalas might shrink by a staggering 62 percent without even accounting for the impact of fires. These findings collectively highlight the challenges ahead for koala conservation efforts.

Multiple threats

The increasing threat of bushfires only adds to the pressures of climate change and human activities, which are already placing enormous strain on koala populations. 

“In addition to being highly sensitive to changes in climate, habitat reduction and fragmentation arising from land clearing for development has placed more koalas in close proximity to humans. This has escalated mortality rates of koalas due to domestic animal predation and road-kill,” wrote the researchers. 

Focus of the study

The experts noted that koalas are dependent on eucalyptus for both shelter and food. This means that their survival depends on a minimum level of Eucalyptus forest cover.

The researchers evaluated the effects of climate change on fire risk across the forests that provide crucial habitats for koalas. The findings reveal a distressing surge in the vulnerability of these habitats to wildfires.

Highly susceptible habitats

Currently, 39.56 percent of the koala habitat in Australia is deemed highly susceptible to bushfires. This is projected to climb to 44.61 percent by 2070. The prediction represents a broader rise in the vulnerability of all Australian vegetation to these fires.

“Wildfires will increasingly impact koala populations in the future. If this iconic and vulnerable marsupial is to be protected, conservation strategies need to be adapted to deal with this threat,” said lead author Professor Farzin Shabani, who now works in the Department of Biological and Environmental Sciences at Qatar University.

“It is crucial to strike a balance between ensuring that koala habitats and populations are not completely destroyed by fire while also allowing for forest rejuvenation and regeneration through periodic burns.”

Fire susceptibility maps 

The researchers used the dynamic Decision Tree machine learning algorithm to develop fire susceptibility maps. 

These maps vividly depict an increase in Australia’s regions with “high” or “very high” fire susceptibility, rising from the current 14.9 percent to an anticipated 15.66 percent by 2070. For areas conducive to koala-sustaining plants, the vulnerability is set to leap from the 39.56 to 44.61 percent.

What the researchers learned 

The models revealed that koala habitats in South Australia and Queensland will face a more pronounced threat compared to other states. 

By 2070, a staggering 89.11 percent of koala habitats in South Australia and 65.24 percent in Queensland will be exposed to high or extremely high fire susceptibility.

“Koalas may still be able to survive in areas highly susceptible to bushfires if their food sources can also withstand the fire-prone conditions, and if koalas can re-populate previously burnt-out areas from neighboring habitat – but this task is becoming more difficult due to habitat fragmentation and the increasingly large areas being burnt,” explained study co-author Dr. John Llewelyn, an expert in the Global Ecology Lab at Flinders University.

Conservation challenges 

Dr. Llewelyn emphasized the urgency of devising strategies to safeguard koalas and other fire-sensitive species, while also facilitating forest rejuvenation through controlled burns. 

“While many of the affected tree species have an inherent resilience to fire, the massive biogeographic and demographic impact of widespread wildfires may leave ecosystems declining across landscapes, increasing susceptibility to regeneration failure,” says Dr Llewelyn.

“Fires of greater severity – megafires – will likely reduce the quality of koala habitats, increase habitat fragmentation, make it harder for koalas to recolonize areas, and directly kill more koalas, leading to increasingly isolated and smaller populations that are vulnerable to local extinction.”

The research is published in the journal Environmental Technology & Innovation. 

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