While hiking on the slopes of Mount Kaweah in Sequoia National Park last September, Professor Hugh Safford, a forest ecologist at the University of California Davis, made a surprising discovery. At over 11,500 feet (3,505 metres), he came across a tree he didn’t expect to see at such lofty heights. It was a Jeffrey pine.
On his way up Kaweah, Safford passed a foxtail pine, then a lodgepole pine – both known to grow in mountainous environments. "Then I thought, 'What's that?'" says Safford. "It made no sense. What is a Jeffrey pine doing above 11,500 feet?"
The Jeffrey pine is commonly found at mid to high elevations in California's High Nevada, especially around Lake Tahoe and Mammoth Lakes. It’s not normally considered a tree of the uppermost mountain zones – those harsh, windy areas above the tree line. But after discovering the first Jeffrey pine, Safford found more specimens growing at even higher elevations of 12,657 feet (3,858 metres) – that's nearly 1,900 feet (579 metres) higher than the previously known record for the species.
In fact, none of the six traditional subalpine tree species have been recorded above 12,034 feet (3,668 metres), suggesting the Jeffrey pine may now hold the title of California’s highest-living tree.
The findings, published in the Madroño journal, point to a changing environment in California’s highest peaks.
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The high life
During his hike, Safford found 14 Jeffrey pines above 11,800 feet (3,597 metres), some of them over 20 years old. He also spotted at least a dozen more he couldn’t reach at the time.
The unexpected presence of Jeffrey pines so far above their known range may be a sign of a warming climate, says Safford. As snow melts earlier and air temperatures rise, these hardy trees are managing to take root in places that were once too cold and icy.
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Role of the nutcracker
Safford believes the Clark’s nutcracker, a bird known for storing pine seeds at high altitudes, may be helping the Jeffrey pine spread uphill.
Much like it does for the whitebark pine, the bird could be carrying seeds from lower elevations and stashing them in cooler, higher zones for later eating. Some of those seeds then take root, growing into the surprise trees Safford found.
With earlier snowmelt and warmer summers, more of these seeds are now able to germinate and survive.
Trees on the move
Climate models suggest many tree species aren’t moving uphill fast enough to keep up with rising temperatures. But Safford’s discovery hints that these models might be missing something important – like the role of animals in spreading seeds or the ability of hardy species to suddenly thrive in new spots.
"I'm looking at trees surviving in habitats where they couldn't before, but they're also dying in places they used to live before," Safford says. "They're not just holding hands and walking uphill. This crazy leapfrogging of species challenges what we think we know about these systems reacting as the climate warms."
What's next?
Safford’s findings weren’t picked up by satellite images or AI tools, proving that you can’t always rely on technology to tell you where life is changing. "People aren't marching to the tops of the mountains to see where the trees really are," Safford says. "Instead, they are relying on satellite imagery, which can't see most small trees.
"What science does is help us understand how the world functions. In this case, where you see the impacts of climate change most dramatically are at high elevations and high latitudes. If we want our finger on the pulse of how the climate is warming and what the impacts are, that's where it will be happening first. We just need to get people out there."
That’s exactly what Safford and his students plan to do this summer. They’ll be trekking across Mount Whitney, Mount Kaweah and the Sequoia-Kings Canyon National Parks, measuring trees, identifying seedlings, and mapping how the forest is moving with the climate.
Find out more about the study: New elevation records for Jeffrey pine (Pinus jeffreyi a.murray bis & al.)
Main image: Jeffrey pine with view of the Chagoopa Plateau, Big Arroyo Creek Canyon and the Great Western Divide. A peak in the middle background is Needham Mountain, where another Jeffrey pine was observed at very high elevation, underlining that this is not simply an anomaly on Mount Kaweah. Credit: Hugh Safford, UC Davis
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