The giant sequoias, native in only 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 fueled by a buildup of undergrowth from a century of fire suppression and drought exacerbated by climate change have become more intense and destructive.
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 Thursday next to the park's Washburn Trail, Phillipe said. Smoke was reported by visitors walking in the grove that reopened in 2018 after a $40 million renovation that took three years.
The fire had grown to about 1.9 square miles (4.8 square kilometers) by Saturday evening.
A fierce windstorm ripped through the grove a year-and-a-half 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.
Meanwhile, most evacuation orders were lifted Saturday in the Sierra foothills about 80 miles (128 kilometers) to the northwest of the Yosemite fire, where a fire broke out on July 4. The Electra Fire that began near Jackson was mostly contained, and only areas directly within the fire's perimeter remained under evacuation orders, according to the California Department of Forestry and Fire Protection.
