As a mega-fire continues to burn in the Blue Mountains World Heritage Area near Sydney, concern about the future of some of the region's unique flora and fauna is increasing.

Key points: Experts say it could take centuries for the ecosystem to recover after the bushfires — if at all

Experts say it could take centuries for the ecosystem to recover after the bushfires — if at all Wildlife rescue groups have seen a large loss of kangaroos, wallabies, possums, insects and marsupials, and other groups fear relic plant species could be "wiped out"

Wildlife rescue groups have seen a large loss of kangaroos, wallabies, possums, insects and marsupials, and other groups fear relic plant species could be "wiped out" The Invasive Species Council is calling for culls to address feral animal populations while vegetation cover is reduced

Local plant and animal rescue groups have been swinging into action to help with recovery, but one expert has warned that the environment may "never recover".

"It will take decades or even centuries to recover," said Brajesh Singh, an ecosystem ecologist at the Hawkesbury Institute.

"And the rate of recovery will also depend on rainfall in the next few weeks, months and years.

"Action should be taken reduce greenhouse emissions, move to a carbon neutral economy and reduce the rate of global warming."

The Wild Plant Rescue Service is concerned about the survival of rare plants like Isopogon fletcheri which only grow in a small area in the Blue Mountains. ( Supplied: Wildplant Rescue Service )

Professor Singh has been studying biodiversity and how it has been affected by climate change and fire.

He warned that studies of similar environments in the United States show that more frequent and intense fires can destroy the seed bank and some areas never fully recover.

"Some of the forest area [in US studies] had almost no regrowth [because] there is not enough seeds in the system for the trees to germinate," Professor Singh said.

"So different [grassland] species of plants come into the picture."

Rare species under threat

The Gospers Mountain fire raged for 77 days across over 500,000 hectares until it was contained by firefighters in early January.

It had a devastating affect on wildlife according to Antonia Revece from the local Wildlife Information Rescue and Education Service (WIRES).

Huge numbers of animals have been either killed or displaced by the fires. ( Supplied: WIRES )

She said she had seen considerable loss of kangaroos, wallabies, possums, insects and marsupials.

"Potentially we've seen groups of animals completely wiped out and my sense is that this has completely changed the landscape," Ms Revece said.

"It's fairly bleak when you drive around — a lot of the smaller shrubs have been burnt into the ground.

"A lot of the larger birds have survived; we're seeing clusters of cockatoos, lorikeets, parrots.

"In the days after [the fire] it was difficult to tell what they [the birds] were because they were all black."

Ms Revece said the loss of vegetation was displacing the wildlife that had survived the fires.

"Small birds have less places to hide from predators," she said.

"With crowning fires, incredible heat, fast moving, there were very few places of safety or refuge and huge damage to nesting sites, while the ground was incredibly hot for days after.

"We've hardly found any sigs of possums. Considering the number that live out here, we're not seeing the equivalent of that being taken into care."

Plant species 'wiped out'

The Wildplant Rescue Service in Katoomba has been running a nursery and a seed bank to supply native plants from the local area to the public as well as Bushcare and Landcare groups, councils and state government agencies.

The coordinator, Tanya Mclean, was concerned about the survival of some of the unique species of plants that only live in the area.

"There are certain relic species of plants that are hanging on, like the isopogon fletcheri and the dwarf mountain pine, that could be wiped out by this fire because they have limited distribution," she said.

The intense heat and area of the Gospers Mountain fire means that some unique species may not recover. ( Image supplied: WIRES )

Ms Mclean was also concerned about the animals that depend on the forest.

"Lack of food will be a problem for the next three to five years, especially those that are arboreal like possums, sugar gliders and lizards that live and eat trees and plants," she said.

Native animals were also vulnerable after fire to predators like cats and foxes, so some food and water stations would be raised off the ground to provide some protection.

One expert has said it may be a good opportunity to cull feral animals.

Andrew Cox, the chief executive of the Invasive Species Council, said now is the time to reduce the population of deer, pigs and goats in New South Wales and Victoria while their cover is reduced and they gather around remaining water sources.

"If you really care about the wildlife we're going to have to get serious about the pest animals," he said.

"And aerial shooting should definitely be part of the mix."