A review by The Bushfire Recovery Project has confirmed how it is that Australian eucalypt forests survive and regenerate after devastating wildfires like the 2019-20 Black Summer fires.
The expert review of published research on forest recovery following fire, undertaken by a group of five scientists from Griffith and Australian National Universities, reported that eucalypt forests typically bounce back well using two key tricks.
“Our key findings suggest that about 70 per cent of plant species within eucalypt forests survive bushfire using hidden ‘recovery buds’,” said Dr Patrick Norman, an ecologist with the Griffith Climate Change Response Program.
“These ‘recovery buds’ found in most eucalypts, as well as tree ferns and banksias, store energy and carbon reserves under their bark and in the ground and sprout new growth even when the entire tree has burned.
“Most of the remaining 30% shed large volumes of seed when their canopy is burnt. This fire adaptation known as ‘seeding’ creates a whole new generation of trees.”
Other key findings of the expert review include:
- Australian forests have evolved to recover after bushfires because fire has been part of the Australian landscape for 60 million years;
- Most Australian forest plant species are specially adapted to survive bushfires by either resprouting new growth using recovery buds, or dropping huge volumes of seed when their entire canopy is burnt (seeding);
- The fact most eucalyptus species survive fire and recover quickly by resprouting maintains vital old trees with hollows in them as homes for native gliders, kookaburras, goannas, parrots and more;
- Survival of many Australian animal and bird species relies on unburnt patches of forest for animals to live in while burnt forest recovers. Koalas can live off resprouting forest within months of a fire;
- Repeated mega-fires could change Australia’s forests, if fire occurs before seeding trees reach maturity and produce viable seed or if the recovery buds for sprouting trees their recovery buds are exhausted.
The team has also investigated forest along the south coast of NSW and east Gippsland.
“Having not been further disturbed one year on from the fire they appear to be recovering well,” Dr Norman said. “However, the same can’t be said for some subalpine woodlands near the NSW-Vic border which are seriously struggling.”
“Australian forest has lived with fire for 60 million years, and fire-prone ecosystems dominate much of Australia’s forest.”
“Even dead trees can be great habitat for our native animals and birds which need tree hollows for homes.
“Nearly all eucalyptus species can recover fully after fire even if all of their leaves were burned. Satellite imagery has shown the Sydney basin canopy cover recovered substantially within two years of a fire.
“Mammals such as sugar gliders and greater gliders often survive fires in their homes in tree hollows, and kookaburras, parrots and powerful owls can too. Other animals survive in unburned creeks and gullies as well as under bark, in wombat holes, under rocks and in hollow logs.
“For many of our iconic animals to survive after fire, we just need to leave the forest alone to recover.”
The science in this review found patches of unburnt forest such as in creeks and gullies become a refuge for surviving animals and birds, and are vital to ensure those species survive.
“Despite how well Australian species survive fire, our review has found that the number of species put at risk in the Black Summer fires was extraordinary,” Dr Norman said.
“Initial assessments have identified 119 animal species at risk following the Black Summer fires including 17 birds, 20 mammals, 23 reptiles, 16 frogs, 22 crayfish, 16 freshwater fish species and five invertebrate species.”