LOS ANGELES — “Increased fire activity” was expected Tuesday as crews continued to battle the 3,221-acre Washburn fire in Yosemite National Park, but officials were growing more confident that the Mariposa Grove of ancient sequoias would survive the blaze.
“Although there’s a lot of smoke with this, it seems to be progressing slowly and it seems to be doing predictable things,” U.S. Forest Service district ranger Jennifer Christie said during a community meeting late Monday night.
Nearly 700 firefighters were battling the blaze from the air and the ground, including setting backfires, laying hand lines and using bulldozers to create barriers, officials said. The fire was 22% contained Tuesday morning.
For days, all eyes had been on two high-priority areas threatened by the creeping flames: the community of Wawona, which remains under mandatory evacuation orders, and the Mariposa Grove, home to more than 500 mature sequoias, including the 3,000-year old Grizzly Giant.
There remains some cause for concern, as recent years have seen more of the ancient trees decimated by hot, fast fires fueled by climate change. Last year’s KNP Complex and Windy fires in California killed an estimated 3% to 5% of the world’s sequoias, and firefighters at the Washburn fire have set up sprinkler systems to help protect the Grizzly Giant and other at-risk trees.
But sequoias have also evolved with wildfire, and in fact rely on extreme heat to help release their seeds. Crystal Kolden, a fire scientist at the University of California, Merced who has been tracking the blaze, said she was “not worried” about the trees in Mariposa Grove.
“They’ve been doing prescribed burns in that grove for over 50 years, and it’s early in the season yet,” Kolden said via email. “This fire should actually be pretty beneficial for them, and it is much better for them to burn in July — which is normally when most of the lightning ignitions are in Yosemite, so it’s the natural fire timing — rather than in September.”
Indeed, many fire experts in recent years have extolled the virtues of “good fire,” which can help clear the century’s worth of dead vegetation that has built up in the state’s forests due to past fire suppression policies. Forest Service spokesman Stanley Bercovitz said Yosemite has a good track record of letting fires do their natural work on the landscape, as well as a history of prescribed burns and mastication with heavy machinery.
“The nervousness and the threat level of the Mariposa Grove has dropped way down,” Bercovitz said Tuesday morning. “Fire did go through the lower portion of the grove, but it was low- and medium-intensity and the kind of fire you like.”
While it was too soon to officially declare the grove safe, he said there are early indications that most trees will survive. A younger tree, about 200 years old, may have been lost, he said, but its fate won’t be clear for some time.
But while the Washburn fire has the potential to be beneficial for the grove if current conditions hold, that doesn’t mean crews can relax. The fire grew by about 1,000 acres between Monday and Tuesday mornings, and high temperatures were expected to remain in the area through week’s end.
The fire has also given several indications of its power, including forming a massive pyrocumulus cloud on Monday signaling intense heat. Officials said the cloud was visible for miles, and areas from Sacramento to the Bay Area reported impacts from the fire’s smoke.
Additionally, the blaze was so intense that at one point a tree branch was “sent into the air from the powerful updraft produced by the fire,” the Forest Service said, and “as it dropped back to earth, it narrowly missed two firefighting aircraft.”
There are other concerns, too. While the Forest Service has yet to release the official cause of the fire, Yosemite National Park Superintendent Cicely Muldoon indicated that it was not naturally caused.
“As you all know, there was no lightning on that day, so it’s a human-start fire and it’s under investigation,” she said during Monday night’s community meeting. “That’s all I can really say.”
Bercovitz said he confirmed that there were no strikes recorded on the lightning map when the fire sparked Thursday, and that there was no wind and there are no power lines in the area. But he cautioned that “human start” doesn’t necessarily mean arson, and that it’s still too soon to declare anything for certain.
“As soon as you start talking like that, it automatically points to a person, and who knows?” he said.
What was clearer was the immense value of the forestland that firefighters were working to protect.
“The Mariposa Grove was set aside in 1864 by Abraham Lincoln. It predated both the creation of Yosemite National Park and the National Park Service itself,” Muldoon said during the meeting. “It’s really the root of the whole national park system — a very important place to us, to the community.”
