MELBOURNE, Australia — From the sheer cliffs of the Blue Mountains that rise beyond Sydney to the tropical Daintree and Kimberley wilderness regions, Australia is one of the most bio­diverse places on Earth.

Across this variety of terrain, one genus dominates the landscape: the eucalyptus tree.

The hardy eucalyptus, native to Australia and the favored food of koalas, has an ancient relationship with fire. Scientists have found that in most cases eucalyptuses, commonly known as gum trees, thrive in the continent’s fire-prone environments, having adapted and evolved over 60 million years.

Woody capsules known as gumnuts — technically a fruit — protect the tree’s seeds. When a fire sweeps through a forest, the gumnuts act as insulation and eventually open up, showering seeds onto beds of ash and beginning the process of regrowth.

But Australia in recent weeks has confronted a wildfire crisis of unprecedented scale. The blazes have raged since October, left 28 people dead, destroyed 2,000 homes and razed an area the size of Virginia. Scientists estimate 1 billion animals have perished.

The eucalyptus tree — immortalized in one of the country’s best-known folk songs — is facing a challenge like never before.

David Bowman, a fire ecologist and director of the fire center at the University of Tasmania, said swaths of eucalyptus forests that were fire-resistant have been starved of carbon amid prolonged drought. That means they are not as healthy, and when fires arrive, many are dying.

“With these fires we’re going to see ecological systems barely recover, or they won’t because the adult trees are exhausted and then there’s no rain,” he said. “The fires are like a disease ravaging a prisoner-of-war camp: You’ve got all these emaciated people — trees — and then this terrible disease — fire — goes through and they just die.”

Burning rainforests

This season’s fires are transformative, Bowman said, because they have affected rainforests that don’t typically burn.

“When the rainforests start burning, they are telling you that the system is being taken right outside its operational framework and it’s flipping into a new state,” he said. “It’s the equivalent of an ice cap breaking up. The fact that some of these systems are now collapsing is again telling us things have changed.”

Home to ancient plants and animal species, Australia’s Gondwana rainforests are the world’s most extensive subtropical rainforests.

In September, members of an advisory committee on rainforests met at a lodge in a national park to draft a letter to Australia’s environment minister about the threat posed by climate change, urging the government to act to protect World Heritage areas.

The next day they were evacuated when a bush fire — later revealed to be caused by a discarded cigarette — ignited in the rain­forest around them. The lodge was destroyed.

David Camroux, a research fellow at the Center for International Studies at SciencesPo in Paris, agreed that the impact on Australia’s unique ecosystem has been unprecedented.

“Now we see a rich country that is overwhelmed and incapable of dealing with the effects of climate change,” he said.

Indigenous knowledge

Australia’s dense eucalyptus forests produce a blue hue in the air, the result of eucalyptus oil mixing with dust particles, water vapor and sunlight. This effect is commonly seen in the Blue Mountains area of New South Wales.

In this Australian summer, however, a more familiar image is of a sky choked with smoke.

As the blazes fuel a political debate about climate policy, the traditional role of fire in the landscape has also come into focus, drawing on the expertise of Australia’s indigenous people, whose interaction with fire goes back 40,000 years. Much of that knowledge was lost, however, when European colonization decimated Aboriginal culture.

Controlled burning is an ancient technique used by indigenous people to manage the land under certain circumstances. Since European settlement, fire agencies have adapted the practice and refer to it as hazard reduction, but some critics say it lost the integrity of historic practices.

“If we’re just using Western mentality to manage landscapes — where they just fly over the top and drop water bombs, or hazard reduction, or solely for the protection of people — we’re going to miss all those layers and we’re going to continue to see a degraded landscape,” said Victor Steffensen, an indigenous expert on cultural burning practices.

Steffensen told the Australian Broadcasting Corp. recently that many of the nation’s forested areas have become overgrown because they have not been managed. “People have been calling for better fire management for a long time,” he said.

Traditionally, he said, small, controlled fires would be lit to clear invasive species or to trigger regeneration.

Fire authorities have defended their approach. At a recent news conference, Shane Fitzsimmons, rural fire service commissioner in New South Wales, said hazard-reduction burns were hampered by longer fire seasons and extreme weather.

“They are not the panacea some may be looking for to temper bush fires,” he said, adding that controlled burns were conducted with the priorities of people, property and the environment in mind.

Bowman laments what he says is an “ideological civil war” that has broken out over the issue of fire management. He also laments the loss of indigenous know-how.

“We really missed out on capturing a lot of Aboriginal knowledge,” he said. “Had we captured that knowledge 100 years ago, we’d be in a better place.”