Almost half of Australia’s koala population will be under “high bushfire threat” by 2070, with coups vulnerable to extreme fire thanks to climate change.
A new report published by Flinders University reports that 39.56% of Australia’s koala habitat is already susceptible to fire, “with modelling predicting this will rise to 44.61%” over the next 50 years.
It claims that the increased risk in coups coincides with a general increase in the susceptibility of all Australian vegetation to bushfires.
The report, led by Assistant Professor Farzin Shabani, emphasised the importance of “forest rejuvenation through burning at appropriate intervals, spatial extents, and intensities” and claimed that “failure to use such strategies could have catastrophic consequences for koalas.”
The massive Black Summer fires of 2019/20 had an existential impact on Koala populations, with WWF Australia reporting that 61,000 koalas were killed or harmed during the fires, whilst an ANU report claimed that the fires severely burnt 25% of the total koala habitat in NSW.
A report published by the Australian National University claimed that the fires impacted 25% of NSW’s Koala habitat, whilst the NSW Department of Primary Industries revealed that koalas disappeared from high-severity fire areas before recolonising within a year.
A team of ecology experts have used species distribution modelling to study climate change impacts and identified the threat that wildfires pose to koalas now and under future climate change.
“It is crucial to strike a balance between ensuring that koala habitats and populations are not destroyed by fire whilst also allowing for forest rejuvenation and regeneration through periodic burns,” Associate Professor Shabani said.
Historically, State Forests have fared better than National Parks during significant fire events due to hazard reduction and prescribed burning.
However, Wood Central can reveal that the NSW Forestry Corporation reduced low-intensity burning in the decade leading up to the Black Summer bushfires, leading to higher-intensity burning in NSW State Forests.
The reduction, due to cost-cutting, led to increased fire damage in NSW Native State Forests.
Wood Central spoke to several fire experts connected to Koala habitat forests who emphasised the importance of “controlled and cultural burning” to protect the forests against more intense “mega-fires.”
Dr John Lleyelyn, the co-author of the Global Ecology Lab at Flinders University study, said the increased severity of bushfires, “which has been attributed to climate change, makes a recovery from events more difficult.”
He claims that “mega-fires” will reduce the quality of koala habitats, increase habitat fragmentation, make it harder for koalas to recolonise areas, and directly kill more koalas.
The research team generated fire susceptibility maps using the dynamic Decision Tree machine learning algorithm.
These show the proportion of Australia experiencing “high” or “very high” fire susceptibility increasing from 14.9% to 15.66% by 2070 — while fire susceptibility of areas suitable for the plants that koalas depend on will jump from 39.56% to 44.61%.
On a state-by-state basis, they project “that 89.1% of the total koala habitat in South Australia and 65.2% of Queensland habitat will have high or very high fire susceptibility.”
The report claims that “mega-fires” – will reduce the quality of koala habitats, increase habitat fragmentation, make it harder for koalas to recolonise areas, and directly kill more koalas.
“Koalas may still 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 neighbouring habitat,” Dr Llewelyn said.
“But this task is becoming more difficult due to habitat fragmentation and the increasingly large areas being burnt.”
By studying the tree species koalas depend on, earlier research by Professor Shabani, and colleagues found that suitable habitat for koalas may contract by as much as 62% of its current range by the year 2070 — and that was without considering the impact of fire on koala populations.
Together, these results highlight the challenges to koala conservation in the coming decades.
“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.
