A forest fire that has been raging for days in Yosemite National Park in California is threatening giant sequoias that grow there.

The fire near the Mariposa Grove redwood forest has spread to 644 hectares and has not yet been contained, Yosemite National Park said on Sunday (local time).

360 firefighters fought the flames and took protective measures for the "Grizzly Giant", the most famous and second largest giant sequoia in the national park, and other sequoias.

More than 500 giant sequoias grow in the Mariposa Grove alone.

Trees threatened by the forest fire were sprayed with water as a precaution.

An investigation has been launched into the fire.

Fire departments in the United States fear particularly severe forest fires in 2022.

"I'm predicting some very tough four, five, six months," said Orange County Fire Chief Brian Fennessy.

In 2020, 10,000 sequoias died in a fire

The giant sequoias, also called sequoias, are the largest trees in the world.

Their relatives, the California redwoods, can grow even taller at over 100 meters, but are not as large in diameter as the giant sequoias.

During their thousands of years of lifespan, sequoias experience wildfires from time to time.

The heat of the fire helps their cones open and the seeds to disperse.

However, longer, hotter and more aggressive fires, which are becoming more frequent as a result of global warming, can damage trees beyond repair.

In 2020, about 10,000 sequoias died in a huge fire.

That was up to 14 percent of the global population.