The trunks of giant sequoia trees in Sequoia National Forest are being wrapped in aluminum foil insulation today to help protect them from the oncoming flames of the Colony Fire, which continues burning in the direction of Giant Forest.

Another looming threat to one of California's most treasured natural resources, its ancient giant sequoia trees, has spurred headlines around the globe, as the KNP Complex fires are burning dangerously close to Sequoia National Forest.

One of the two fires in the lightning-caused complex, the Colony Fire, is still about a mile away, and Cal Fire estimates it will arrive at the edge of the famed sequoia grove by Friday morning. As the Chronicle reports, fire crews today are digging protective lines around the trees, and wrapping as many as possible with the aluminum foil, as well as starting back burns to potentially shift the movement of the fire.

The Visit Visalia Twitter account posted a photo Wednesday of fire crews wrapping the Sequoia National Forest sign in foil.

On Tuesday, a spokesperson for Sequoia and Kings Canyon national parks had said the threat to the sequoias was not yet imminent, and the Colony Fire has moved steadily but slowly since then. It stood at 439 acres on Tuesday, and then as of Thursday morning it had grown to 1,683 acres. The entire complex is now 7,039 acres, with the further-away Paradise Fire at 7,257 acres.

While giant sequoias are mostly immune to most wildfires — and these 2,000 or so specimens that are upwards of 1,000 years old have likely seen many — some fire behaviors can threaten them, and indeed one fire did just last year. The Castle Fire, which burned south of the KNP Complex, is estimated to have killed upwards of 10% of the world's entire stock of sequoias, or between 7,000 and 10,600 trees.

Among the trees killed in the Castle Fire was the King Arthur Tree, also once known as the California Tree, which stood 270 feet tall and was upwards of 2,000 years old.

Among the trees now being threatened is the General Sherman Tree, which is around 2,300 to 2,700 years old, is the largest known living sequoia and has a base diameter of 36.5 feet.

Photo: Jim Bahn/Wikimedia

The Colony Fire is now less than a mile from Giant Forest, and it was about a mile away on Tuesday.

Part of the community of Three Rivers is under a mandatory evacuation order, while the remainder of the community is still under an evacuation warning.

According to an incident update from Wednesday, within the next 48 hours, through Saturday, the Colony Fire is expected to continue upslope to the northeast into Giant Forest, and then spread upslope to the north and east and up the East Fork of the Kaweah River into Mineral King and west towards the national park's Ash Mountain headquarters.

The KNP Complex fires were both sparked during lightning storms on Friday, September 10, in remote, largely inaccessible areas in Tulare County.

Previously: Lightning-Caused Fires Threaten California's Giant Sequoias In Two National Parks