More than a hundred years ago, naturalist John Muir took President Theodore Roosevelt camping under a majestic ancient tree in Yosemite National Park.
Known as the Gray Giant, the tree was over 2,000 years old and 61 meters tall, with branches a few meters in diameter. President Roosevelt described the tree and surrounding grove as a “temple”, and shortly thereafter granted federal protections to the park in Sierra Nevada, California.
But in recent days the Gray Giant has come under threat from the Washburn fire, which has already ravaged more than 3,000 acres of undergrowth and trees in the southern part of the national park, prompting an evacuation order for residents and tourists in the Wawona community.
“We have to go to the ends of the earth to protect this tree,” said forest ecologist Garrett Dickman, who works in Yosemite National Park and is helping to manage efforts to protect Mariposa Grove from Giant Sequoias, the largest and most visited three sequoia clusters in the park, with over 500 ancient trees.
“The last two years have been a serious wake-up call,” he added. “We never imagined that giant sequoias were in real danger of catching fire.”
California’s giant sequoias have been facing especially fierce fires since 2015, a consequence of climate change and a lack of frequent fires over the previous century, according to the National Park Service. The looming threat — now reaching some of the state’s most admired and oldest trees — is prompting scientists and firefighters to take exceptional measures to protect them.
Dickman explained that to protect the Gray Giant, authorities set up a sprinkler irrigation system that works intermittently, pumping between 70 and 90 liters of water per minute at the base of the tree. Debris from the ground around the tree is being cleared, and smaller trees that could set fire to the giant sequoias are being felled.
In other recent fires, firefighters have wrapped trees in flame retardant tarps, sprinkled fire retardant foam over them and doused them in pink flame retardant. Dickman said he considered the possibility of directing thin jets of water into the air around the trees at risk, to create a “wall of water”. In other cases, he explained, arborists climbed giant trees to check for possible embers or to cut branches that might have caught fire.
During last year’s Windy Fire, which destroyed more than 1,700 acres at Giant Sequoia National Monument, expert firefighters known as “smokejumpers,” who parachute into an active fire zone, spent two days climbing a tree that was burning in slow fire.
It took a lot of planning, Dickman said. “How do you climb a tree that’s burning?”
Scientists say Bosque Mariposa is likely to be less at risk than some other giant sequoia groves, given the decades of controlled fires prescribed by the National Park Service that they hope will have prepared it well to avoid the more serious consequences of an uncontrolled fire.
As of Tuesday, the fire was 22% contained and was advancing north, a spokesperson for the US Forest Service said. More than 600 firefighters participate in the firefighting effort.
The fire has already smoldered on parts of the forest floor. Scientists and officials say the priority is to ensure it doesn’t reach the treetops. Sequoias are able to withstand some heat and scorching from their trunks, but if flames reach their tops they can cause them to be devoured by fire, as if they were matchsticks.
Once the leaves of a giant sequoia disappear, the tree can lose its ability to photosynthesize and it can die, said Nate Stephenson, scientist emeritus in forest ecology with the US Geological Survey. He explained that while giant sequoias need some fire to regenerate, “the conditions of the fires that are burning right now have changed.”
Wildfires occur every year across the western United States, but scientists see the influence of climate change in the extreme heat waves that have been contributing to the intensity of the fires seen this summer. Most of Mariposa County also experiences exceptional drought — the most severe classification of droughts in the country. Trees affected by drought compete for limited water, and the resulting stress makes them more susceptible to insect infestations.
In a 15-month period between 2020 and 2021, an estimated 13% to 19% of the world’s sequoias died or were fatally injured, according to a report by the National Park Service. To scientists, this number is especially shocking given how few redwoods have died in previous centuries.
“I’ve counted a lot of dead giant sequoias, and I don’t like it,” said Dickman, the forest ecologist, who spent last fall counting the trees destroyed by the Windy Fire. At the end of each day, he would get into his car, lay his head on the steering wheel, and cry.
“It’s like counting dead people,” he said. “That left me devastated.”
On Tuesday morning, officials said Bosque Mariposa’s ancient giant sequoias had not been seriously affected by the fire so far and said they were confident they could be saved.
The cause of the Washburn fire was under investigation, but most likely it was human, Cicely Muldoon, superintendent of Yosemite National Park, told a community meeting Monday night. “As you all know, there was no lightning that day,” she explained.
The fight to save the redwoods is a war against the relentless force of global warming, but it is also an attempt to save a piece of ancient history and the cultural legacy of the West. Muldoon pointed out that Bosque Mariposa, first protected by Abraham Lincoln in 1864, was “the root of the entire national park system”.
According to the Metropolitan Museum of Art in New York, an image of the Graying Giant taken by Carleton Watkins in 1861 was one of the first photos of Yosemite to be sent to the east of the country and “helped to cement the idea that Yosemite was a relic of the Garden of Eden in North America”.
According to the National Park Service, it was the night he spent camped under the Gray Giant that inspired Theodore Roosevelt to establish several more national parks, monuments, and forests. In 1905 he created the US Forest Service.
Bosque Mariposa, Roosevelt said at the time, is “a temple more majestic than any human architect could ever erect.”
Translation by Clara Allain
