Evacuations for Camp Nelson..Ponderosa due to Fire..

This is not their first rodeo.

The ponderosa pine had taken root decades before the Revolutionary War, making a stately stand on this western Sierra Nevada slope for some 300 years, Nate Stephenson figures. Then came the beetle blitzkrieg. Now the tree is a dab in the gray and rusty death stain smeared across the mountain range.

At the base of its massive trunk, a piece of bark has been cut off, revealing an etched swirl of insect trails. Higher up, naked branches reach out, as if from a many-armed scarecrow.

“This was alive until the drought killed it,” Stephenson says mournfully.

The U.S. Forest Service estimates that since 2010, more than 102 million drought-stressed and beetle-ravaged trees have died across 7.7 million acres of California forest. More than half of those died last year alone. Exacerbated by anti-wildfire policies that produced a crowded forest more vulnerable to drought, the massive dieback is unprecedented in the recorded history of the Sierra.

The beetle epidemic is transforming the 4,500-foot to 6,000-foot elevation band of the central and southern range for decades to come, if not permanently. The sheer scale of mortality means that outside of developed areas, it’s likely that most of the tree corpses will be left to topple over.

It will takes centuries to replace the legions of majestic old pines that have succumbed — if that is even possible in a warmer future that promises to alter the forest in ways ecologists can only guess.

“We don’t know under the new conditions what things will do well,” says Christy Brigham, the top scientist and acting superintendent of Sequoia and Kings Canyon national parks.

But she’s pretty sure of one thing: The western Sierra pine forest as it was 100 years ago is not coming back.

“The world has changed…” Brigham says. “We’re never going to be able to get back to where we were before.”

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When the first big patches of forest turned a fatal orange in 2015, “We were agog,” says Stephenson, a federal research ecologist who has worked in Sequoia National Park for nearly four decades. “It was hard to get over.”

Now he’s used to it.

And he finds comfort in a simple observation: “Most of the forest is still there.”

Higher elevations have largely escaped the beetle damage. Even in heavily infested areas, there is a mosaic of the living and the dead — patches of green and burnt sienna that from a distance suggest autumn in New England.

by Bettina Boxall