Last summer's daring fire-fighting efforts to save the world's last stand of Wollemi pines prevented significant loss of the larger, mature trees but left many juvenile plants severely burnt, prompting expert calls for permanent fire-dampening measures to protect the ancient grove.
Of the total of 49 large trees, just four escaped without some scorching but most of the stems of less than two metres in height were badly burnt, with only a small portion so far beginning to resprout.
Aerial view of the main Wollemi Pine grove immediately after the bushfire. Credit:Phil Lamrock / NPWS
One year on from the remarkable attempt to shield the secret location from the giant Gospers Mountain fire, the Herald can reveal researchers studying the trees' recovery fear more frequent and intense bushfires from climate change could doom a species that dates from the age of dinosaurs.
Berin Mackenzie, a member of the fire crew and one of the ecologists leading the post-fire study, said "extraordinary efforts" by the National Parks and Wildlife Service and the Rural Fire Service definitely prevented the fire reaching the canopy of most of the larger trees.
"We definitely breathed a sigh of relief," Mr Mackenzie said. "It was an excellent sign that they would recover."
Of concern, though, has been the state of the seedlings and smaller juvenile plants, with most trees shorter than 8 metres showing 100 per cent canopy scorching. While laboratory testing had indicated smaller plants would recover from fire, many of them are yet to do so in the wild.
Only 2 per cent of the plants between 5 centimetres to 2 metres have started to resprout.
Scorching of lower canopies of mature Wollemi pines during last summer’s bushfires.Credit:John Spencer/ NPWS
"We'd expect them to have a good capacity to resprout," Mr Mackenzie said. "So far, we've observed very few resprouting."
Mr Mackenzie cautioned that, as the pines are coming out of drought and seasonal in their growth patterns, it was too soon to declare the one-third of juvenile plants yet to recover to be dead.
With just four sites of Wollemi pines clustered within a small area deep within the Wollemi National Park, the ancient species remains vulnerable to a severe impact, such as from a bushfire as intense as last summer's.
Mr Mackenzie, who estimates he has made as many as 20 visits to the site since the fires, first aired some of his findings at the annual conference of the Ecological Society of Australia late last year. The research has been submitted for peer-review and publication.
Berin Mackenzie (left) was part of the team behind the successful saving of the rare Wollemi pine trees in the Wollemi National Park during the 2019-20 bushfires. Some of the others include Lisa Menke (second from left), Steve Clarke, and Tony Auld (right). Credit:Janie Barrett
He said that, given the slow growth rates of the plants, the risk was that the coppicing plants or seedlings wouldn't attain a so-called minimum escape height to avoid total canopy loss before the next fires come.
In fact, the pines may need "extended fire-free intervals spanning many decades for post-fire recovery, recruitment and persistence", Mr Mackenzie told the gathering.
"This presents significant challenges for conservation managers in the current climate where wildfires are expected to increase in frequency and severity," he said.
Cris Brack, an honorary professor at the Australian National University who has studied the pines, said the damage from the fires for juvenile plants was "worse than I had been led to believe".
A Wollemi pine begins its recovery by coppicing, or resprouting.Credit:Berin Mackenzie / DPIE
"Now that we know that solved the problem, with a bit more forethought, they may be able to get a better system down there provided the water keeps running in the creek," Professor Brack said.
Mr Mackenzie said the sprinklers, water-bombing helicopters, use of fire retardant and the critical deployment of remote area firefighters after the front had passed showed what can be done.
"I can say with very high confidence [those firefighters] saved the trees," he said, adding "it's the first time globally that such a massive effort to protect an important biodiversity asset during a national crisis".
Rachael Gallagher, a Macquarie University researcher, said it was not surprising the plants would take some time to recover.
One of the first Wollemi Pine seedlings to emerge after the fires. Credit:Berin Mackenzie/DPIE
She noted that the bushfires had also affected many of plants, with more than 250 species having more than 80 per cent of the range burnt out by last summer's fires.
Many of them will suffer especially if there are multiple fires in the future, not just from climate change but increased prescribed burning to reduce hazards.
"It's not just this one fire event but the cumulative impact of inappropriate fire regimes on species that really will drive them to extinction," Dr Gallagher said.
Heroic fire-fighting efforts managed to limit the damage from last summer’s bushfires but the impacts were still significant.
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