A wildfire threatening the largest grove of giant sequoias in Yosemite National Park more than doubled in size in a day, with firefighters working to protect the iconic trees.
More than 500 mature sequoias were threatened in the Mariposa Grove in the sprawling park in California but there were no reports of severe damage to any named trees, including the 3,000-year-old Grizzly Giant.
The cause of the Washburn fire was under investigation. It had grown to nearly 2.5 square miles (6.7 square kilometres) by Sunday morning.
Beyond the trees, the community of Wawona, which is surrounded by parkland and a campground, was under threat, with people ordered to leave their homes and campsites on Friday night.
The blaze was proving difficult to contain, with firefighters throwing “every tactic imaginable” at it, including dropping fire retardant from the air, said Nancy Phillipe, a Yosemite fire information spokeswoman.
Firefighters planned to use bulldozers to create fire lines protecting Wawona, she said. About 600 to 700 people who were staying at the Wawona campground in tents, cabins and a historic hotel were ordered to leave.
Temperatures were expected rise in the coming days, but fire crews working in steep terrain were not contending with intense winds, Jeffrey Barlow, senior meteorologist with the National Weather Service in Hanford, said.
Smoke had settled across large swaths of the park but the fire was not sending up huge plumes seen a day earlier, Mr Barlow said on Sunday.
Given the relatively small size of the fire and minimal winds, smoke impacts were not expected to stretch far beyond the park, he added.
So far in 2022, over 35,000 wildfires have burned nearly 4.7 million acres, according to the National Interagency Fire Centre, well above average for both wildfires and acres burned.
The giant sequoias, native in about 70 groves spread along the western slope of California’s Sierra Nevada range, were once considered impervious to flames but have become increasingly vulnerable as wildfires fuelled by a build-up of undergrowth from a century of fire suppression and drought exacerbated by climate change have become more intense and destructive.
Ms Phillipe, the park spokeswoman, previously said some of the massive trunks had been wrapped in fire-resistant foil for protection, but she corrected herself on Sunday and said that was not the case for this fire.
Lightning-sparked wildfires over the past two years have killed up to a fifth of the estimated 75,000 large sequoias, which are the biggest trees by volume.
There was no obvious natural spark for the fire that broke out on Thursday next to the park’s Washburn Trail, Ms Phillipe said.
Smoke was reported by visitors walking in the grove that reopened in 2018 after a 40 million US dollars (£33 million) renovation that took three years.
A fierce windstorm ripped through the grove over a year ago and toppled 15 giant sequoias, along with countless other trees.
The downed trees, along with massive numbers of pines killed by bark beetles, provided ample fuel for the flames.
The park has used prescribed burns to clear brush around the sequoias, which helps protect them if flames spread farther into the grove.
