Australia's Fire-Ravaged Forests Are Recovering.

Australia's Fire-Ravaged Forests Are Recovering.
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澳大利亚受火灾破坏的森林正在恢复

Australia's Fire-Ravaged Forests Are Recovering
By Nathan Rott | NPR

In the back corner of a burned lot in Australia's fire-ravaged South Coast stands a torched tree. It's uppermost branches reach into a cloudless sky, brittle and bare. Against its charred trunk rests half-burned rubble, remains from the gift shop it used to shade.

But that's not where local resident Claire Polach is pointing. She gestures to the middle part of the tree, where lime green leaves sprout from blackened bark, as if the tree is wearing a shaggy sweater.

To Polach, the burst of regrowth is a sign that despite a months' long assault of flame and smoke, the second-hottest summer on record and a multi-year drought, Australia's nature "is doing its thing."

As for people like her, recovering from the same? "We'll follow the nature," she says.

This cycle of fire, rain and recovery has played out in Australia for millennia. The majority of the country's forests are uniquely adapted to fire. Some species need it. "Australia is, more than any other, a fire continent," writes ecologist and historian Stephen Pyne in his book "World Fire."

But scientists have long warned that a warming climate could mean more severe fires, more often. Now there are concerns that even a fire continent will struggle to recover from the scale and severity of recent events.

New research published in the journal Nature Climate Change found that a staggering 21 percent of Australia's forested area burned in the 2019-2020 fire season, a figure the authors say is "globally unprecedented" and may indicate "the more flammable future projected to eventuate under climate change has arrived earlier than anticipated."

The question now is whether Australia's nature can keep pace.

A different landscape

A chief concern for ecologists is that as the climate warms and fire conditions become more common, the time between wildfire events will shorten. This is problematic for species that have evolved to cope with fire on an irregular basis.

"If we get more and more frequent fires, this vegetation might not have the break it needs to recover," says Marta Yebra, a research fellow from ANU who studies fire severity.

Compounding the problem, as climate change brings hotter temperatures and more erratic precipitation, recovery for some species might take longer than normal. That could give less dominant species an upper-hand.

Scientists have already documented this happening in the Western U.S.

Patches of California's Sierra Nevada forests are morphing from mixed conifer to shrub fields. Ecologists say the lodgepole pine forests that dominate the Greater Yellowstone Area could become more permanent grassland.

Research in Australia has found that shrub growth after severe fires can promote further fire, creating the potential for a runaway effect.

"Far from seeing ecosystem collapse, I think we could see ecosystem change," Doherty says. "And that change may or may not be desirable from a human point of view."

Desirable in that a forest will still exist. Not desirable in that some of the species humans love may not.

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  • 来源:NPR 2020-03-19