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Professor Hugh Safford from UC Davis embarked on a hiking trip in California’s High Sierra that led to an unexpected discovery: a potential new elevation record for the Jeffrey pine, which may now hold the title of the highest tree in the state. This intriguing finding has been detailed in the journal Madroño, published by the California Botanical Society.
While hiking last September along the south slopes of Mount Kaweah within Sequoia National Park, Safford stopped to enjoy the sight of a foxtail pine and a lodgepole pine, both of which are common at such high altitudes.
“Then I thought, ‘What’s that?'” Safford recalled, noting his surprise when he discovered a Jeffrey pine at an elevation of over 11,500 feet. “It made no sense. What is a Jeffrey pine doing above such heights?”
Typically found in upper montane regions across the Sierra Nevada, the Jeffrey pine thrives around areas like Lake Tahoe and Mammoth Lakes. It is not categorized as a conventional subalpine species, which are typically confined to the most extreme elevations. Remarkably, Safford documented sightings of Jeffrey pines reaching heights of 12,657 feet, surpassing the previous record by 1,860 feet and exceeding even the altitudes recorded for lodgepole, limber, and foxtail pines.
Notably, none of the six widely recognized subalpine species have been recorded above 12,034 feet, suggesting that the Jeffrey pine may indeed be California’s highest tree at this point in time. This finding raises questions about other species potentially growing at greater heights than current databases reflect.
This discovery is indicative of the shifting climate affecting California’s highest altitudes. With earlier snowmelt and rising air temperatures, seeds of Jeffrey pine are beginning to germinate in areas that were once frozen and inhospitable.
Moving on up
During his research-hiking adventure, Safford identified and studied 14 Jeffrey pines at elevations exceeding 11,800 feet, some estimated to be over 20 years old. Although he observed at least a dozen additional Jeffrey pines from a distance, he could not examine them all. He and his research team plan to return to the southern Sierra Nevada this summer to delve deeper into the dynamics of Jeffrey pines in the subalpine zone and the factors influencing their migration.
Safford hypothesizes that the Clark’s nutcracker, a bird known for its role in high-altitude seed distribution, may be instrumental in this process. Just as it aids in the propagation of whitebark pine, initial evidence indicates that this bird transports Jeffrey pine seeds from lower elevations to the higher mountain areas, where they may be cached in cooler conditions for use in the early summer.
The combination of earlier snowmelt and rising temperatures allows these seeds not only to germinate but to thrive, forming new populations in elevations previously deemed unsuitable.
Leapfrogging trees
While research suggests that many species are moving uphill in response to climate change, the pace is often too slow to keep up with the changing environment. Current climate models, however, may not adequately account for the impact of seed dispersal by animals and their role amid the evolving ecological landscape.
“I’m observing trees thriving in new habitats where they couldn’t survive before, but they are also vanishing from their traditional habitats,” Safford noted. “It’s not as if they are simply relocating in a coordinated manner; instead, this phenomenon of ‘leapfrogging’ species challenges our conventional understanding of ecological responses to warming climates.”
Given the Jeffrey pine’s resilience to both cold and drought conditions, their unexpected presence along the slopes of Mount Kaweah presents a hopeful outlook, according to Safford.
Trees in real life
This discovery emphasizes the importance of combining advanced technologies with hands-on observation. The Jeffrey pines Safford documented were not identified by existing databases, artificial intelligence tools, or satellite imaging.
“Researchers are not always venturing to mountainous areas to accurately gauge tree populations,” Safford explained. “Instead, reliance on satellite images often misses smaller trees. True scientific understanding hinges upon direct observation and engagement with the environment. The most dramatic impacts of climate change are evident in high-altitude and high-latitude regions. If we wish to grasp the effects of warming climates, monitoring these areas will be crucial. It’s essential that we conduct on-the-ground assessments.”
This summer, Safford and his students will engage in fieldwork across Mount Whitney, Mount Kaweah, and Sequoia-Kings Canyon National Parks, where they will catalog seedlings, measure trees, and contribute to developing elevation models as part of their effort to better understand the evolving dynamics of the High Sierra’s landscape.
Source
www.sciencedaily.com