蘑菇短视频

For 467 years, an eastern hemlock in the mountains of Western North Carolina has counted the seasons ring by ring. Now, Highlands Biological Station scientist Liam Stiefel has translated those rings into music, allowing us to listen to the tree鈥檚 centuries-old record.

By translating measurements of its growth into musical notes, and by combining its tune with those of three younger neighbors, Stiefel has distilled more than four centuries into a 4-minute, 19-second melody.

COK021, the first member of this creekside quartet, is the oldest eastern hemlock yet documented in the southern Appalachians, with its first ring dating back to 1559.

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The professors and faculty at HBS conduct all manner of research atop the Highlands-Cashiers plateau, from microplastics to bats to endemic plant species, and the station is visited by research groups throughout the University of North Carolina system for its unique biological offerings.

Stiefel, a dendrochronologist and tree ecophysiologist, came to HBS this April as a temporary program associate.

鈥淒endrochronology is the study of the patterns of tree rings, and what they can tell us about the conditions that a tree experienced during its life, and what those rings might tell us about what might have been going on in the climate, particularly when we were talking about really old trees that predate the time period when folks were keeping weather records,鈥� Stiefel said.

鈥淭ree ecophysiology is basically just the study of the way trees respond to their environment, particularly stressors in their environment 鈥� We might be interested in the way photosynthesis responds to drought, or the way water moves through a tree. It's focused on those kinds of questions of the physiology of the tree in relation to its growing conditions,鈥� he said.

Researchers like Stiefel are given freedom to devote their expertise to topics of their choosing while working at HBS. When Stiefel looked about the 24-acre campus, its three acres of old-growth forest immediately caught his attention.

鈥淚 decided that there was still a lot of potential there. There were parts of the forest that had not been studied,鈥� Stiefel said. 鈥淎nd so, as I've had time over the last few months, I've gone out and taken a few samples with an increment borer, which basically allows you to drill into a tree and collect a little pencil of wood called a tree core.鈥�

This delicate core, once sanded, can be studied to determine the tree鈥檚 age. Removing an intact core requires precision and teamwork once the hollow body of the increment borer reaches the tree鈥檚 center.

蘑菇短视频student Aidan Holton, who worked this summer as a botanical gardens assistant at HBS, was invited by Stiefel to assist with coring at the undisclosed location where COK021 stands beside a creek and its three fellow performers.

鈥淚've cored trees in my forest ecology class, which I鈥檇 taken in the spring semester of this year. So, I鈥檇 just got finished with learning how to core trees and using increment borers,鈥� Holton said.

He described the hard work it took to penetrate deep into the wood with the small metal tool.

鈥淚t definitely took us a good 30 minutes to get it all the way in, and then it was usually a little longer to get it out.

鈥淵ou're sitting there and you鈥檙e hand-cranking it 鈥� you put it onto the tree, and you turn it gently, and then it's like a screw,鈥� Holton said. 鈥淵our hands will get tired after a minute, so one of us would swap off. You could do it with one person, but it would take you a very long time because you'd need to take a few breaks.鈥�

While a core can provide a detailed picture of a tree鈥檚 life, the number of rings scientists can count doesn鈥檛 necessarily represent the tree鈥檚 full age. The location of the tree鈥檚 center can vary based on its growing angle and location, and coring is typically performed at chest height, with the borer aimed toward the center as best as scientists are able. That means samples are often off by inches, and that the core removed may contain fewer years than the tree鈥檚 true age.

COK021 is at least 467 years old; the tree itself is almost certainly older.

Other factors can also make a tree鈥檚 history more difficult to read. Many of these towering giants are rotten inside where water has found its way into the trunk, alive but decaying, and in these instances, scientists find it difficult or impossible to distinguish individual lines from the soft rot.

This is natural, Stiefel explains, and many trees eventually succumb to this weakness in time when their great towering height proves too weighty for the remaining trunk to sustain.

Eastern hemlocks also face a far more immediate threat: the hemlock woolly adelgid, an invasive insect that has devastated the species throughout the southern Appalachians.

鈥淭here is an invasive insect pest, the hemlock woolly adelgid, that came through the Highlands area, probably starting around 2003, and killed an enormous number of hemlocks within a decade,鈥� Stiefel said. 鈥淎nd so any living trees, like all of the living trees that we have here on site, were all treated with an insecticide.鈥�

鈥淭he only reason they're still alive is because they've probably been treated at least four or five times over the last 20 years, and there's an organization called Hemlock Restoration Initiative which does great work and volunteered their time and chemicals to treat the trees earlier this season,鈥� he said.

The Hemlock Restoration Initiative, in addition to providing chemicals used to treat the trees, works with HBS faculty on programming for students and members of the public.

鈥淗emlock Restoration Initiative operates through collaborative partnerships with many different entities, such as federal and state agencies, private land trusts, and other nonprofits,鈥� said Olivia Hall, educational outreach manager for HRI. 鈥淚n communities located a considerable distance from our home base in Asheville, local organizations, such as the Highlands Biological Station (HBS) in Highlands, help us connect with local community members and strengthen our presence in the region.

鈥淗BS, in particular, has served as an exceptional venue for some of our educational programs and a useful home-away-from-home while we're working in nearby Nantahala National Forest,鈥� Hall said.

鈥淟iam Stiefel's recent research has helped expand our understanding of this old-growth stand, and we are now able to share that knowledge with our team, partners, and audiences. In turn, our partnership has allowed us to support HBS in managing and protecting the hemlocks across its campus. This exchange is a truly symbiotic partnership, one in which HBS, HRI and the communities we serve all benefit.鈥�

Stiefel sent the data he collected from the old-growth forest at HBS to the National Oceanic and Atmospheric Administration鈥檚 Paleoclimatology Data Repository, where future researchers will be able to compare his measurements against their own specimens throughout the tree鈥檚 broad range, from southern Appalachia all the way up to Canada.

By translating the trees鈥� long lives to song, he hoped to make their stories accessible beyond the numbers.

In the quartet recording, each tree becomes an instrument, with one note representing one year of growth. Wider rings produce higher pitches, while narrower rings produce lower pitches. The four trees began their lives in 1559, 1725, 1795 and 1843, with the first full year represented in the recording being 1560.

The oldest tree, COK021, plays the bass. COK019 joins on cello, COK018 on viola and COK521 on violin. Together, their growth from 1560 through 2025 becomes a 4-minute, 19-second composition.

鈥淚 think that the novelty of listening to the years and the changes through time emphasizes how cool these trees are in a way that you might not feel if you just look at the data,鈥� Stiefel said.

鈥淔inding other ways to present data, particularly to the public, can be really helpful to get people to relate to it in a new way.鈥�

In the music, listeners can hear the conditions changing around the trees.

In the early 2000s, when the hemlock woolly adelgid reached the mountains, all four trees recorded unusually thin growth rings between 2005 and 2007.

鈥淚n fact, neither COK018 or COK019 grew at all in 2007, a year of drought and heavy adelgid infestation,鈥� Stiefel said.

COK021, however, responded differently after neighboring hemlocks died.

The loss of surrounding trees allowed more light to reach its canopy, and its growth increased.

For Stiefel, the trees鈥� long record offers a window into another world.

鈥淲hen it comes to these old-growth forests, just looking at the trees themselves, the tree canopy, they are structurally different from younger forests. I also think our experience of these forests is different if we pay attention; these trees are not replaceable in the span of a human life,鈥� Stiefel said.

鈥淲hen I core some of these trees, my entire lifetime has occurred within the last quarter inch of the tree core 鈥� I think it really does hammer home the need to try and preserve these little remnant hemlock forests, both the second growth and especially the old-growth ones.

鈥淣ot only for their ecological value, which is really important, but also for how folks coming to the station here get a chance to experience what an old-growth hemlock forest would have been like---that this kind of forest used to be all over the southern Appalachians before logging and before the adelgid.

鈥淪o, I think, more than anything, we've just gotten an extra sense of how special this particular tract of land is.鈥�

Stiefel鈥檚 research is a powerful reminder of the role of science in expanding our experience of the world and our sense of appreciation for home.