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Wildfire threatens historic trees at Sequoia National Park. Fireproof blankets are the defense.

Firefighters wrapped the historic General Sherman Tree, estimated to be more than 2,300 years old, with fireproof blankets in California's Sequoia National Park. (National Park Service/AFP/Getty Images) (Handout/AFP/Getty Images)

A week after California’s KNP Complex Fire was sparked by lightning strikes, the blazes continue to threaten Sequoia National Park, prompting crews to wrap fireproof blankets around the bases of several giant sequoias, known to be among the tallest and oldest trees in the world.

Firefighters on Thursday were seen covering the base of several trees in the protective aluminum wrap, including the 275-foot General Sherman, the world’s largest tree by volume, according to the National Park Service. General Sherman grows in the park’s Giant Forest, a grove of ancient giant sequoias where some trees are estimated to be as much as 2,700 years old.

“The fire continues to grow in all directions,” NPS said in a statement Thursday. “Crews are preparing the Giant Forest before the fire reaches that area, by removing fuel and applying structure wrap on some of the iconic monarch sequoias that characterize the most famous area of Sequoia National Park.”

The fire had burned 9,365 acres as of Thursday with zero containment, according to the park’s incident information system.

Anatomy of a wildfire: How the Dixie Fire became the largest blaze of a devastating summer

The KNP Complex Fire is made up of The Colony and the Paradise Fires, which were sparked by a lightning strike in the rugged, high elevation of the Sierra Nevada on Sept. 9. Employees living in the park and portions of the nearby Three Rivers community were been evacuated before the park closed to visitors on Wednesday.

A day before the park shuttered, crews were spotted using the same protective aluminum wrapping for the trees to cover the historic Ash Mountain Entrance, the park’s 85-year-old sign welcoming visitors to Sequoia National.

Though wildfires are part of the natural regeneration process for sequoias, experts say intensifying blazes fueled by climate change are instead destroying them.

Wildfires typically help the natural regeneration process of giant sequoias: the blazes burn up competing plants, enrich the soil and dry out the tree cones until they burst and release their seeds. The bark on great sequoias grows between six inches and as thick as two feet in the oldest trees to provide natural insulation from routine fires.

But the trees are now contending with conditions they likely haven’t faced in their hundreds — and in some cases — thousands of years on Earth.

“The current generation of wildfires are certainly different,” Joanna Nelson told The Washington Post on Wednesday. Nelson, director of science and conservation planning at Save the Redwoods League, which works in collaboration with NPS and other conservation groups, said giant sequoias have evolved with “low-to-moderate intensity fire.”

In the past 100 years, only a quarter of the groves, or areas with sequoia in it, have experienced a fire, Nelson said. By contrast, in the past six years, four large fires burned two-thirds of the giant sequoia range.

The damage from last year’s Castle Fire is still being tallied, but Nelson said early estimates indicate 10 to 14 percent of all giant sequoias were killed. The high-elevation western slopes of the Sierra Nevada are the only place in the world giant sequoias grow, where they thrive in patchy, disjointed groves, Nelson said.

“The estimate that we lost 10 to 14 percent in one year is really devastating and worrisome — and not sustainable,” she said.

The newer fires burn too hot for even the thickly insulated mature trees to survive. “The seeds burn up and the soil burns,” Nelson added. “So you don’t have a way to regenerate the forest; there’s not a way for it reseed itself.”

The Paradise Fire had burned almost 6,000 acres as of Wednesday, and has been difficult to fight due to the steep terrain. NPS said “a total lack of access has prevented any ground crew operations.” Fire crews have largely fought the blazes with aircraft that drop fire retardant and water.

Clay Jordan, superintendent of Sequoia and Kings Canyon National Parks, said during a community news conference Tuesday that air teams “literally started painting the mountains red with retardant.”

Wildfires need fuel to burn. A key way to get rid of that fuel is to set it ablaze, very carefully.

Nelson said the Save the Redwoods League and other conservation groups are advocating for the expansion of wildfire mitigation practices like prescribed burning, a scientifically backed process that Indigenous communities like the nearby Tule River Tribe and others had practiced for thousands of years pre-colonization.

The practice, while effective, has historically run into a complex web of challenges ranging from underfunding to resistance from local residents hesitant to add more smoky days to a wildfire season that is already sprawling into a year-round occurrence.

Nelson is hopeful the trees can be saved this season and protected by coordinated efforts in the future because the trees are natural habitat to many rare and endangered species and help stem the tide of rising global temperatures by storing “incredible amounts of carbon.”

Beyond their benefits, Nelson said the trees themselves are natural wonders that are one of the few living artifacts from ancient history.

“What’s special about them is that a 3,000 year-old tree was there while Indigenous people were here tending them,” she said. “The same time the Roman Empire was flourishing and people were building viaducts.”

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