California tree improbably becomes highest-growing in the state

The Jeffrey pine, one of the iconic trees of the Sierra Nevada, appears to have eclipsed other pines to become the highest-elevation tree growing in California.

A new study documents several Jeffrey pines well above 12,000 feet in Sequoia National Park, where they’re thought to be migrating from lower elevations — faster and farther than most trees — in a remarkable ripple of climate change.

The study suggests that the Jeffrey pines “leap-frogged” over other high-elevation trees with the help of a bird known as the Clark’s nutcracker: The bird scatters the seeds of the Jeffrey sometimes far and wide as it collects, transports and stows them for later feeding. The warming climate, in turn, made it possible for the trees to sprout and thrive at soaring elevations once too cold and snowy for them to bear.

“These were extraordinarily high Jeffrey pines,” said Hugh Safford, author of the study and a research forest and fire ecologist at UC Davis. “They’re moving uphill. This is a story of a tree that doesn’t belong there being dispersed by a bird and is only surviving because the climate is warming.”

The high-elevation Jeffreys were discovered last summer on the south slope of Mount Kaweah. They were as much as 1,860 feet above the highest Jeffrey pine previously recorded across the tree’s range. One tree was reported at 12,657 feet.

No other trees in California — even skyscraping stalwarts like the bristlecone, whitebark and foxtail pine — have been documented in the scientific literature or online databases at above 12,035 feet, according to the study.

Jeffrey pines, which are three-needled conifers similar in appearance to ponderosa pines and live for hundreds of years, are common in the Sierra Nevada. They’re dominant in such landscapes as the Lake Tahoe basin and Mammoth Lakes. The tree’s range spans from Baja California to Oregon, including parts of northwestern Nevada, but it’s primarily a California tree.

In the central and southern Sierra, Jeffrey pines have historically grown most abundantly at 6,000 feet to 9,500 feet of elevation, according to the U.S. Forest Service.

The higher-growing Jeffreys came to light serendipitously in September when Safford was hiking with his wife on the High Sierra Trail.

“I got up to the timberline where you bust out of the trees, and I stopped to get a drink and just look around, like anyone would,” he recalled. “Then I said, ‘What is that?’ and I walked over there and sure enough there was a Jeffrey pine.”

Surprised to find the trees, which were not known to exist much above 11,000 feet, Safford continued to investigate and discovered more than a dozen above 11,800 feet.

He collected enough information on the Jeffreys to return to UC Davis and write up what he calls an “exploratory study.” (He plans to go back to Sequoia National Park for further examination this summer.)

Safford’s study was published in March in Madroño, a journal of the California Botanical Society.

In the paper, Safford hypothesizes that the preference of the Clark’s nutcracker for Jeffrey seeds over other types of seeds is why the trees have moved more than other trees, sometimes thousands of feet uphill. He also theorizes that the earlier snowmelt and warmer temperatures observed in the Sierra in recent decades is why the tree is flourishing at higher elevations.

The trees he found were all younger than 25 years old.

Safford doesn’t believe that the highest Jeffrey pine he found will hold the elevation record for long. Because extensive surveying hasn’t been done and satellite imagery is too coarse, he said there are probably more trees, possibly both Jeffrey pine and other species, that are growing at even higher elevations in the Sierra, especially with climate change.

“Unless we have people out there working in the natural world, you’re not going to find these things,” he said. “The world works in complex and mysterious ways, and we need to be out there to try to understand it.”

Reach Kurtis Alexander: kalexander@sfchronicle.com Twitter: @kurtisalexander Bluesky: @kurtisalexander.bsky.social