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California’s ancient redwoods face new challenge from fires, warming climate

by Eric Westervelt, National Public Radio |

After this year's historic wildfires, California's oldest state park — Big Basin Redwoods — looks more like a logging village than an iconic hiking and camping mecca.

There's a near constant buzz of chainsaws. Rumblings from trucks and logging skidders fill the air as crews busily cut charred, fallen trees and chop down "hazard trees" rangers worry will topple on to the park's roadways.

It's estimated the wildfire, awkwardly named the CZU Lightning Complex Fire, burned through 97 percent of Big Basin's more than 18,000 acres, scorching its 4,400 acres of ancient redwoods and obliterating most of the park's infrastructure for camping and recreation.

"All of the historic structures in the park, totally destroyed, save one residence," Joanne Kerbavaz says. The California state park senior environmental scientist is standing in ashes and bits of charred beams. This is where a log-cabin-like visitors center and museum once stood, built by the Civilian Conservation Corps during the New Deal.

"It's truly tragic from the perspective of all of the generations of people who grew up coming here and enjoying this," she says.

Big Basin – and big swaths of California – are still recovering from historic wildfires that ravaged the state this year, displacing tens of thousands of people and wildlife, burning more than 4 million acres and killing at least 33 people. They also ripped across groves of giant, coastal, old-growth redwoods here in the Santa Cruz Mountains. And while these trees are incredibly resilient, there's concern that even they may find it harder to rebound amid the mounting impacts of climate change.

>> Capturing fog drip to adapt to fire

These ancient trees are among the oldest and tallest on earth. Some are 1,000 to 2,000 years old. Redwoods capture more carbon dioxide than any other tree, and provide critical habitat for birds and scores of other species. Many of Big Basin's old growth will be just fine, Kerbavaz says. "A lot of the constituents of this forest are very much able to deal with fire.”

Wildfire, of course, is a vital, natural part of forest regeneration. Burning away underbrush and built-up fuel helps replenish forest nutrients and opens paths to new growth. Redwoods have evolved to adapt. Their tall crowns capture moisture from fog, mist and low clouds, called fog drip, that helps them survive drought and infernos. Water from fog, studies show, can be more important to redwoods than winter rainfall.

But now, Kerbavaz and other scientists who study the trees worry the redwoods will face new challenges rebounding in hotter, drier conditions than they're used to, and with radically changing weather patterns.

"As the climates changes, [redwoods] could be restricted to just areas that really meet their needs," Kerbavaz says, while walking near Opal Creek in Big Basin's historic core. That would be "areas that get summer fog, that helps give them extra water, and also helps mediate the moisture loss from the temperature.”

It's estimated the state's recent five-year drought killed more than 120 million trees across wide swaths of California's forests. Redwoods, experts say, survived better than many mixed conifer forests. Scientists are now tracking how California's redwoods are being affected by a warming climate, especially fog patterns past and present.

>> ‘It’s the fire climate feedback that's really driving this’

The trees here at Big Basin are hardly the only ones at possible risk.

"I'm concerned that we're seeing much more of the forest impacted by these issues," says Greg Asner, who runs the Center for Global Discovery and Conservation Science at Arizona State University. "It's the fire climate feedback that's really driving this.”

Asner has studied and mapped California's forests for more than two decades, flying airplanes with cutting-edge technology to track just how much water is in trees' canopies, and other key markers of environmental change.

He worries that more catastrophic wildfires, combined with warmer temperatures and the potential for ever decreased fog and rain, may be altering the playing field for California's forests.

"These issues are recurring so frequently," he says, "that the system cannot go through some sort of rebound or recovery that we all ... in Biology 101 learned about in high school.”

Four years of devastating, historic wildfires, Asner says, should be a loud alarm bell for the region. To save more of the forests, he says California must dramatically expand targeted forest thinning and intentional burning.

"It's kind of like sacrificing something for the greater good," he says. "Without that, it's just all reactive – it's all putting out fire.”

But how California does that at scale, across its vast forests and in the wake of a deadly pandemic, remains a huge financial, logistical and political challenge.

One silver lining: the fire this time affords forest experts a great chance to study and map how this ancient and complex ecosystem bounces back.

>> Hopeful signs of endurance

"This is the kind of event we wouldn't wish on the park," Big Basin's Kerbavaz says. But "hopefully we're going to learn more about these trees, this forest, and how to maintain it well into the future.”

We walk across forest ground blackened to a crunchy charcoal, up to what's called a "fairy ring" – a circle of towering old-growth redwoods with an opening in the middle where an even larger tree, call it a parent tree, once stood.

We gaze at trees blackened far up their towering trunks. Yet just a few months since the fire, Kerbavaz points to signs of new life.
"That looks like at least 200 feet up, there are green sprouts coming out of the stems on the side of the tree there," she says.

Elsewhere are other hopeful signposts of endurance and resurgence. At the base of a cluster of near-dead tanoak trees, 4 feet high green offshoots are jutting skyward. Huckleberry and manzanita bushes are sprouting.

Big Basin will recover, she says, but the park will be different.

"We only have about 5 percent of the old-growth trees that we had at the time of the Gold Rush" in the mid-19th century, she says. That makes it all the more important to protect them for the good of the larger landscape. "You can lose a few icons and still keep the forest.”

Not long after the latest big fire, the 30-year veteran of the state parks went to one of her favorite spots in the woods for a little inspiration in a tough year. In a grove of old growth that had survived the blaze, she says she just stood and took in the quiet. And she watched the sunlight come through those giant trees.