- A devastating bushfire season in Australia has led to significant forest loss in tropical and subtropical regions of Australia’s east coast.
- One of the areas most affected is the border region straddling the states of New South Wales and Queensland, which includes significant sections of the Gondwana Rainforests of Australia World Heritage Area.
- Early findings from the Queensland State Government’s Department of Environment and Science indicate the habitat of 648 threatened species in Queensland has been damaged to some extent by the fires.
- As ecologists travel back into the regions to determine the extent of the damage, questions are being raised about the status of affected species, and the additional threats posed by feral animals, weed infestation and sediment pollution.
The landscape spanning the border region of the eastern Australian states of New South Wales (NSW) and Queensland is ecologically rich and diverse, and home to ancient rainforest. However, despite its fire-retardant nature, large swathes of this rainforest – which are bordered by drier forests dominated by eucalyptus – have been devastated by the region’s protracted, severe 2019/2020 fire season.
Last week, the Australian government released an initial report detailing how threatened ecological communities have been affected by bushfires in southern and eastern Australia since the drought-fueled fire crisis broke out in July 2019. Its conclusion: up to half of lowland subtropical rainforest in Queensland and NSW has been damaged.
To many, this comes as no surprise. New South Wales suffered its worst fire season in recorded history over the 2019/2020 summer, with widespread devastation across the state, while southeast Queensland was hit by early season fires following years of prolonged drought. Queensland alone saw approximately 6.6 million hectares burned, according to the Queensland State Government’s Department of Environment and Science (DES).
In a statement to Mongabay, a spokesperson from DES outlined that the scale and ferocity of the recent bushfires across the state was “unprecedented,” resulting in “significant impacts to local wildlife populations.”
Early findings from DES suggest the habitat of some 648 threatened species in Queensland has been damaged to some extent by the fires. Meanwhile, the federal government reports that 327 threatened species have had more than 10% of their habitat affected.
It has been difficult to determine the extent of the ecological damage and exactly which species have been affected. But as ecologists return to burned regions, the full impact of the fires is beginning to come to light.
Gondwana rainforests burn
Among the fires were ones that raged along the NSW and Queensland border. Here lie patches of rare, ancient rainforest that make up sections of the Gondwana Rainforests of Australia World Heritage Area (GRAWHA).
A UNESCO site, the GRAWHA contains the most extensive remaining stands of subtropical rainforest in the world, as well as the largest areas of warm temperate rainforest in Australia. However, this distinction may now be in jeopardy as the Australian government says that over half of the GRAWHA has been affected by this season’s bushfires.
Fire is extremely rare in any rainforest. However, David Keith, Professor of Botany at the Centre for Ecosystem Science at the University of NSW, said particular conditions were met in the border region that enabled the forest to burn.
“[A] severe and extended drought preceded the fires [and] caused moisture levels in soils and vegetation to decline to historically low levels,” he said. “Severe fire weather on particular days, in combination with low moisture levels, created a rare window of flammability.”
Keith identified the Nightcap Range in NSW and the Lamington plateau in Queensland as being among the most affected.
“The forests are burnt, severely in some places, but not lost,” he said. “Where fire has killed tree canopies, it causes major reorganisation of the rainforest that will require many decades or more than a century to recover.
“In other areas, the impacts may be confined to the edges of large forest patches or to the rainforest understory, which has the capacity to recover more rapidly, given follow up rains.”
Endemic, endangered tree species hovers on the brink
Nightcap National Park, inland from the famous surf town of Byron Bay, was burned by wildfire in November. A botanical hotspot, the Nightcap is home to many threatened animal species – including the endangered giant barred frog (Mixophyes iteratus) – and contains extremely rare plant species.
Among these is an endemic tree, the nightcap oak (Eidothea hardeniana). The species was first described in the early 2000s by Robert Kooyman, an evolutionary ecologist who works with the Royal Botanic Gardens, Macquarie University and the Missouri Botanical Gardens. The species has an extremely small known range, growing only along one creek within the Nightcap Range, and Kooyman has been monitoring the population in the wake of the fires. While the assessment is ongoing, he says that initial conclusions point to a significant impact on the species, which is already listed as critically endangered.
“In terms of numbers, perhaps as much as 30% of the habitat is affected,” Kooyman told Mongabay. “Rainforest trees are mostly thin-barked and not tolerant of fire, with some exceptions, while seedlings and saplings quickly succumb.”
Only around 125 sexually mature nightcap oaks are known to exist, which Kooyman calls “stems” to differentiate from saplings and seedlings. He warns that the small size of the population means that the loss of just one tree could be a big blow to the species’ genetic integrity.
“Each individual [nightcap oak] holds unique genetic material, with some stems or groups of stems retaining a higher proportion of genetic diversity than others,” Kooyman says. “So, this is not just about how many stems were lost, it is about how much of the 40 million years of evolutionary history has been lost.”
Some worry fires may become more common in the region, as flammable eucalypt species often regenerate and spread after bushfires. Nightcap, as well as other regions, were historically logged, resulting in the clearing of rainforest species and the accumulation of flammable material left by foresters. However, Kooyman said that although eucalypts have the potential to dominate post-fire areas, research does not indicate such an event at this stage in the Nightcap.
“For the most part, the problem seems to be mostly an increase in mountain wattle (Acacia orites) and some other more fire-promoting elements establishing in close proximity to the rainforest and key threatened species,” he said.
But if eucalypt expansion does happen in some areas of the border region, it may not be a bad thing. According to Rod Fensham, an associate professor at the University of Queensland’s School of Biological Sciences, it could even help save a species from extinction.
“The fires may stimulate germination of eucalypts that rarely regenerate and enhance the habitat of the highly threatened eastern bristlebird,” Fensham said.
This could be a boon to the eastern bristlebird (Dasyomis brachypterus), which is listed as endangered and is restricted to just a few small pockets of dense vegetation in Australia, one of which is on the Queensland/NSW border.
At the beginning of February the Victorian state government took the extraordinary step of capturing and evacuating as many eastern bristlebirds as they could find in the state’s bushfire-plagued Gippsland region, transporting them back to Melbourne Zoo to be housed until the bushfire threat has cleared. Researchers believe that if the species’ habitat recovers and expands, it could help to increase its numbers in northern NSW.
Rain: a double-edged sword
Many fires were extinguished with the aid of torrential rain that hit Australia’s east coast in the second week of February. However, while the rains have eased stress in some areas, they have worsened it in others, washing ash and soil from burned areas into sensitive river ecosystems.
Mount Barney National Park, which suffered significant forest loss to fires in December, remains closed, with Queensland Parks and Forests staff reporting “heavy rainfall and flooding have now impacted the fire damaged landscape.”
Stuart E. Bunn, professor of Ecology and Director of the Australian Rivers Institute at Griffith University spoke to Mongabay and said that burned areas are more prone to erosion, and large quantities of ash and charcoal are being washed into waterways. This sediment runoff is entering streams and smothering aquatic life adapted for clearer, cleaner water.
“If the surface of the water is covered, this limits the rate that oxygen can be exchanged from the air to the water,” Bunn said. “Oxygen levels in the water can fall below critical levels and most fully aquatic animals die.”
Bunn added that the fires have also affected the vegetation growing along rivers.
“This allows more light to enter the streams, and also more heat,” he said. “More light, coupled with nutrients that are washed in can stimulate algal production, can lead to further water quality problems. The increased water temperatures stress species [that are] adapted to cool habitats.”
Among the species threatened is the critically endangered smooth crayfish (Euastacus girurmulayn), which is endemic to the Nightcap area. Included in the federal government’s register of animals requiring urgent management intervention, research indicates the smooth crayfish is particularly susceptible to localized impacts, such as bushfires, given its highly restricted range.
There are similar concerns for freshwater fish. The northern Gondwana Rainforests area houses the Clarence River cod, (Maccullochella ikei), a large, predatory species that was once abundant but is now restricted to the upper reaches of the Clarence River along the NSW/Queensland border. While its IUCN profile says that it is increasing in number, the Richmond Range National Park in northern NSW where it is located remains closed due to fire damage, and ecologists are still trying to ascertain the status of the species.
Invasive species move in
Fires may also make it easier for invasive species to move in and displace native plants and animals. Australia already has one of the worst extinction rates in the world, with an estimated 100 species lost since European colonization.
Candice Bartlett, a conservation officer at the Invasive Species Council, said that the threat of permanent extinction is now very real for endangered species.
“The bushfires have burnt through the forest undergrowth which leaves any surviving native species exposed and vulnerable to predation from cats and foxes,” she told Mongabay. “While feral animals living in our forests are not impervious to the fires, they recover faster, they will be hungry and they are fierce predators. Predators like feral cats will travel further for prey and move into burnt areas where the landscape is an open hunting ground.”
Nor are flora species immune. Invasive grasses such as serrated tussock (Nassella trichotoma) and molasses grass (Melinis minutiflora) are of great concern to conservationists, as they typically thrive after fire and readily outcompete native species.
Additionally, hoofed feral mammals such as deer, horses and pigs compact the ground and consume new growth. “This inhibits the recovery of vegetation and reduces the already limited food resources available for surviving native herbivores, like kangaroos and wallabies,” Bartlett said. “[Threatened] species will suffer unless feral animals are removed from the environment.”
In its report released last week, the federal government’s Department of Agriculture, Water and Environment included a list of 113 animal species across Australia identified by experts as the highest priorities for urgent management intervention. These species have potentially lost upwards of a third of their ranges to the fires. The list includes marsupials such as the hastings river mouse (Psuedomys oralis) and the Parma wallaby (Macropus parma), which live along the Queensland/NSW border.
Additionally, the NGO Birdlife’s Australia chapter says that 77 bird species have lost more than a third of their habitat as a result of the fires. Borderland inhabitants on this list include the rufous scrub bird (Atrichornis rufescens) and Albert’s lyrebird (Menura alberti), which is found nowhere else in the world.
David Keith warns that that while the fires have been quelled for now, there is still a major risk of “flammability feedbacks” – a process whereby a fire-affected tree canopy reduces the ability of the surrounding, unaffected forest to maintain a moist microclimate. This allows the forest to dry out and become more likely to burn than it was in the past.
“When combined with a drying climate and more extreme fire weather, these processes have the potential to end the 100-million-year history of these magnificent relict forests,” Keith said.
Banner image of December fires in Queensland courtesy of Planet Labs.
Editor’s note: This story was powered by Places to Watch, a Global Forest Watch (GFW) initiative designed to quickly identify concerning forest loss around the world and catalyze further investigation of these areas. Places to Watch draws on a combination of near-real-time satellite data, automated algorithms and field intelligence to identify new areas on a monthly basis. In partnership with Mongabay, GFW is supporting data-driven journalism by providing data and maps generated by Places to Watch. Mongabay maintains complete editorial independence over the stories reported using this data.
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