Firefighters used a heavy aluminum wrap to protect the entrance sign to Sequoia National Park, and to wrap the base of some giant sequoia trees/NPS

Rolls of aluminum foil -- heavy, heavy duty foil -- were being used at Sequoia National Park to protect structures, and some giant sequoias, from wildfires that were bearing down on the Giant Forest.

Perhaps not since 1988, when a firestorm appeared ready to descend on the Old Faithful Complex in Yellowstone National Park, has such a national park icon been threatened by fire.

In the case of Yellowstone 33 years ago, sprinkler systems were erected on the roof of the historic Old Faithful Inn to defend the massive log structure from the North Fork Fire. The inn was indeed saved, though 16 surrounding cabins fell to the flames.

At Sequoia, crews resorted to the heavy reflective foil, also known as Aluminized Structure Wrap that has a glass/polyester backing, to protect park signs, buildings, and even the base of sequoias from the flames and heat of the Colony and Paradise fires. The material can withstand temperatures to 1,200° Fahrenheit for short periods, according to manufacturers.

The two fires, which combined covered more than 9,300 acres Thursday, were ignited by a lightning storm that passed over the park on September 9-10. The Colony Fire was said to be just a mile from the Giant Forest area as daylight arrived Thursday. The two fires, neither of which had any containment lines carved into the earth around them, were expected within 24 hours to burn into one huge blaze and advance on the Giant Forest complex.

"Crews are preparing the Giant Forest before the fire reaches that area, by removing fuel and applying structure wrap on some of the iconic monarch sequoias that characterize the most famous area of Sequoia National Park," park staff reported Thursday. "The fire continues to grow in all directions."

Though sequoias evolved and adapted to fire, a trilogy of threats -- fire, drought, and insects -- have made them more vulnerable to flames than they have been in recent history. 

As Traveler contributor Rita Beamish noted earlier this year, devastating wildfires have spiked since 2015, culminating in last year’s fire-season inferno. In a little over a century, from 1910 through 2014, wildfires burned 25 percent of the giant sequoia range, forest and fire ecologist Kristen Shive found when analyzing the state’s Cal Fire data. Then in 2015 through 2020, wildfires burned 65 percent of the range: 2020 alone accounted for half of that, 16,000  grove acres, dwarfing the 1910-2014 combined acreage burned.  

Last year's Castle Fire, sparked by lightning in Sequoia National Forest, took out thousands of old-growth monarchs -- a data point from satellite and aerial imagery that is most stunning when considered alongside historical losses of zero to just a few trees a year, Beamish reported. As the Castle Fire blasted through Sequoia, about 3,550 acres of sequoia groves suffered high-severity burning, she added, noting that park officials estimated that an unprecedented 340 monarch trees -- those with trunk diameters of four or more feet – were lost.

The Paradise and Colony fires were burning through stands of live timber, intermixed with stands of 10-year-old dead trees, and brush. Nearly 500 firefighters were battling the flames and working to protect structures. They were supported by 11 engines, two water tenders, and one helicopter. The weather was not helping their efforts, with westerly afternoon and evening winds gusting to as much as 40 mph.

According to the park staff, the area of Three Rivers under mandatory evacuation was the Mineral King Road in its entirety, areas along Sierra King Drive, Crest Lane, Hammond Drive, and Oak Grove Drive, and areas along Highway 198 from the intersection with Mineral King Road to the Sequoia National Park entrance station. The remainder of the community of Three Rivers was under evacuation warning, a message the residents should be ready to leave at a moment's notice.

Sequoia National Park is closed to the public, and employees who lived within park boundaries have been moved out of the park. Kings Canyon National Park remained open, but air quality impacts were likely.