California wildfires: World's biggest tree wrapped in special 'blanket' for protection

The majestic General Sherman and other giant sequoias are under threat from the Paradise and Colony files

Firefighters working to protect the world's largest tree have said they are hopeful they can protect it from wildfires raging across the US state of California.

The Paradise and Colony fires, which began more than a week ago, have destroyed more than 4,600 hectares of land. They are drawing closer to Giant Forest, a grove of about 2,000 sequoias that includes five of the largest trees on the planet, some up to 3,000 years old.

The biggest of them all, General Sherman, is 83 metres tall.

On Thursday, General Sherman was wrapped in fireproof blankets to protect its giant trunk from the worst of the flames.

The enormous trees of the Giant Forest are a tourist draw, with visitors travelling from all over the world to marvel at their imposing height and extraordinary girth.

Although not the tallest trees – California redwoods can grow to more than 91 metres – the giant sequoias are the largest by volume.

"We have folks up in the Giant Forest protecting structures and preparing everything," said Mark Garrett, communications officer for the region's fire department, of the operation in Sequoia National Park.

"The fact is that they've been prescribed burning for the past 25 or 30 years, so it is really prepared."

Scientists say global warming, stoked by the unchecked use of fossil fuels, is making the area more vulnerable to bigger and more destructive wildfires.

Brian Klatt, a Ukiah Valley Fire Authority firefighter in California, pauses as a helicopter makes a drop on a fire.

Thick, acrid smoke envelops firefighters as they battle a brush and timber slash fire north of Ukiah, California.

Fires burn in Doyle, California.

A firefighter sprays water while trying to stop a blaze from spreading to neighbouring homes in Doyle, California. Pushed by heavy winds amid a heatwave, the fire came out of the hills and destroyed several residences.

Flames consume a vehicle in Doyle, California.

Fire consumes a home in Doyle, California. Pushed by heavy winds, fires came out of the hills and destroyed several houses in central Doyle.

Pushed by heavy winds, fires came out of the hills and destroyed several homes in central Doyle.

Fire consumes a home in Doyle, California.

Fire burns an electricity pole as blazes tear through Doyle, California.

US Forest Service firefighter Chris Voelker monitors a fire burning in Plumas National Forest, California.

Smaller fires generally do not harm the sequoias, which are protected by a thick bark and often have branches only 30 metres above the ground.

But the larger, hotter blazes that are laying waste to the western US are dangerous to them because they climb higher up the trunks and into the canopy.