SEQUOIA CREST, Calif. – Kristen Shive glanced around the blackened forest and started counting.

She stopped at 13 — the number of giant sequoias she spotted with charred trunks, scorched crowns and broken limbs. The towering trees had grown on this Sierra Nevada ridge top for well over 500 years. They had lived through many wildfires and droughts. But they could not survive the Castle Fire, which swept into the Alder Creek Grove in the early hours of Sept. 13.

One of the monster wildfires birthed by California's August lightning blitz, the Castle Fire burned through portions of roughly 20 giant sequoia groves on the Sierra's western slopes, the only place on the planet they naturally grow.

Sequoia experts may never know how many of the world's most massive trees died in the Castle Fire, but judging by what they have seen so far, they say the number is certainly in the hundreds — and could easily top 1,000.

"This fire could have put a noticeable dent in the world's supply of big sequoias," said Nate Stephenson, a U.S. Geological Survey research ecologist.

The Castle Fire is just the latest in a string of wildfires since 2015 that have fried monarch sequoias — trees that nature designed to not only withstand fire but thrive with it.

Shocking destruction

They are armored with thick bark. Their high branches are out of reach of most flames. Their cones — no larger than a chicken egg — release seeds when exposed to a burst of heat.

The problem is that the wildfires chewing through sequoia groves these days are not the kind that the long-lived giants evolved with.

A century of fire suppression, the 2012-16 drought and rising temperatures have combined to produce more intense fires that are taking an alarming toll on the copper-hued behemoths.

Shive had been watching the growth of the Castle Fire since it started Aug. 19 with a lightning strike on the edge of the Golden Trout Wilderness in the Sequoia National Forest.

By the weekend of Sept. 12, it had spread westward to the doorstep of the 530 acres of the privately owned Alder Creek grove that the Save the Redwoods League purchased less than a year ago.

"We thought we were in the clear; the fire was on the other side of the ridge," said Shive, the conservation group's science director.

But the fire made a major run that Sunday morning, blasting down drainages as 60 mph winds pushed flames into the grove's southern end. Shive spent much of the day on the phone, gathering information about fire behavior and studying maps. She knew the Castle Fire had burned extremely hot in places.

But when she drove the grove's dirt roads a few weeks later, she was shocked by what she saw in some places.

Old sequoias can survive even if just 5% of their crowns remain green and unscorched by a fire's heat. There was no green on the sequoias that Shive counted on the ridge west of Jordan Peak.

Their broccoli tops were roasted. One giant was decapitated, the upper trunk and branches strewn at its base in a tangled heap.

There were more bleak scenes elsewhere. The league estimates that on its property alone, the Castle Fire killed at least 80 monarchs, ranging in age from 500 years old to well over 1,000 years old. "We shouldn't have lost so many. I think it's unacceptable," said Shive, a former fire ecologist with the National Park Service.

In Sequoia Crest, a small vacation-home community developed in the grove in the 1960s, chimneys and foundations are all that remain of about a third of its 104 houses.

Glimpses of hope

Remote-sensing satellite images indicate that much of the league's Alder Creek land didn't burn in the Castle Fire or experienced light fire that will do some ecological good.

One of those good burns was in the vicinity of the grove's star, the 3,000-year-old Stagg tree, the fifth-largest giant sequoia on record.

As tall as a 25-story building and wider than a two-lane road, the Stagg remained untouched with the help of a hose sprinkler system laid around its base by firefighters.

Near the Stagg, the Castle Fire did a bit of forest housekeeping, burning undergrowth, young white fir trees and incense cedars. Seventy feet of black trunk traced the path of flame on a younger sequoia, but "I don't think it will even notice," Shive said.

At another spot in the grove, Shive pointed to little sequoia seeds that newly opened cones had showered on the ash-coated ground. "I suspect we're going to have a lot of regeneration," she said. When big sequoias die in a wildfire, it is usually because heat has scorched all their needles, which are still on the tree. This was different. All-consuming flame had turned the giants into sequoia skeletons.

"Nobody was really worried" about the Castle Fire in its first weeks, said Christy Brigham, science chief of Sequoia and Kings Canyon National Parks. "We have a lot of lightning fires. I was not overly concerned."

In early September, the Castle Fire made some major runs toward the parks.

"At that point, we started to think it could get into some of our sequoia groves," Brigham said. "But I still had the mental model that these trees are very fire adapted. ... This is going to be OK from the sequoia perspective."

'A gut punch'

That notion began to fade as she heard more about the Castle Fire's erratic behavior. "To see those giant sequoia, monarch, blackened toothpicks was a gut punch," Brigham recalled.

When big sequoias die in a wildfire, it is usually because heat has scorched all their needles, which are still on the tree. This was different. All-consuming flame had turned the giants into sequoia skeletons.

Brigham has known since she arrived in Sequoia-Kings Canyon five years ago that the parks' average of 1,000 acres a year of controlled burns is not enough.

Now she has a new sense of urgency, realizing that "if we don't get prescribed fire in those groves that have not had any for 100 years, we lose 2,000-year-old monarchs in a fire."