Australia’s massive bushfires, which were contained in mid-February and declared over in early March, left eucalypt forests scorched and the ground, too dry to absorb the following rainfall. But now, the burnt trees are beginning to show signs of recovery as small, leafy branches sprout from their sides.
The welcome sight comes after more than one-fifth of the country’s eucalypt forests were burned in the most recent wildfire season, and a report published in National Hazards and Earth System Sciences provides evidence that climate change has increased the likelihood of bushfires by 30 percent since 1900. Now, experts are considering how Australia will recover—and change—in the long-term.
"Far from seeing ecosystem collapse, I think we could see ecosystem change," plant ecologist Michael Doherty tells Nathan Rott at NPR. "And that change may or may not be desirable from a human point of view."
Per NPR, historian and ecologist Stephen Pyne describes Australia as “a fire continent” in his book “World Fire.” The continent’s trees have evolved strategies to handle intermittent fire seasons. Eucalypt trees grow tufts of emergency foliage called epicormic leaves from their blackened trunks, which provides a boost of photosynthesis until their canopy leaves grow back.
"Notwithstanding climate change, we're still seeing the ecosystems recover as we might expect they would," Doherty tells NPR.
The sprouts show that under the burnt bark, the trees are still alive. But because the fires were so severe, it’s likely that they need a break in order to fully recover. As fires become more frequent, even fire-adapted tree species won’t get the break they need, Marta Yebra, an expert in fire severity, tells NPR.
The fires followed months of drought in Australia, and left behind an environment ripe for floods. Hot air can hold more moisture than cooler air, which meant that the clouds collected more water before releasing a deluge on the dry landscape. The soil couldn’t absorb the water quickly enough, and communities flooded.
“We’ve been writing about climate change being a stress multiplier for many years,” Macquarie University climate scientist Lesley Hughes tells the New York Times. “It’s absolutely been foreseen that our climate is becoming more variable and more severe.”
To calculate the contribution of human-caused climate change to the 2019-2020 bushfire season, researchers used climate models to calculate the high "fire weather index" seen this year compared to about a century ago. They found that the heat wave that happened at the same time as the fires is ten times more likely now than it was in 1910, and that 30 percent of the rise in the region’s "fire weather index" is due to climate change.
“It is always rather difficult to attribute an individual event to climate change,” but this study is well done, climate scientist Wenju Cai, who works at Australia’s scientific research agency, told Carolyn Gramling at Science News earlier this month. Cai said the link is reasonable, and not a surprise.
Other fire-prone regions like the Western United States are already seeing the long-term impacts of severe fires. When hit by a blazing wildfire, parts of California’s Sierra Nevada forests are turning into fields of shrubs, though other parts of the Sierra Nevada are so overgrown from lack of fire that they’re interfering with bats’ hunting abilities. Pine forests around Yellowstone may also turn into permanent grassland.
If Australia were to lose its forests, species like koalas—highly specialized to live high in eucalyptus trees—would be at high risk.
“Unfortunately, we have now reached such a tipping point in Australia,” Rebecca Montague-Drake, an ecologist with the Koala Recovery Partnership, tells Romina Castagnino at Monga Bay. “With so many runs of hot, dry seasons, that even planting programs to reverse habitat loss are fraught with difficulty.”