Biogeosciences News

North Carolina Bald Cypress Tree Is at Least 2,674 Years Old

Researchers say it’s the oldest-known living tree in eastern North America. If it hadn’t been protected, it could have ended up as garden mulch.

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Wired to survive in dry, wet, or even swampy soil conditions, bald cypresses are hardy, tough, and adaptable. Yet even the hardiest of these rugged, magnificent conifers can’t guard against tree-killing humans.

Less than 1% of bald cypress forests have survived periods of heavy logging, according to David Stahle, a geoscientist at the University of Arkansas who uses dendrochronology, radiocarbon dating of tree samples, and other information (such as rainfall data) to reconstruct ancient climate conditions.

Like rhino populations decimated out of desire for their horns, humans have ruthlessly “hunted” almost all of the otherwise resilient bald cypress trees for their timber.

However, many bald cypresses 1,000 or more years old along southeastern North Carolina’s Black River (a tributary of the Cape Fear River) have managed to escape this fate. Stahle and his collaborators now report their discovery of the oldest-known tree among those at Black River in a study published in Environmental Research Communications on 9 May 2019. The tree is at least 2,624 years old, according to their analysis, which included tree ring chronology and radiocarbon dating of nondestructive core samples.

The bald cypress is also the oldest-known living tree species in eastern North America and the oldest-known wetland species of tree in the world, the researchers wrote.

Surprise and Gratification at an Ancient Tree

“We were surprised and gratified” to discover the minimum age of this ancient tree, said Stahle, who has studied Black River bald cypresses since 1985.

Photo of a man knee-deep in a muddy river lined by cypress trees
A bald cypress in the Black River, above, is the oldest-known living tree in eastern North America. Credit: Dan Griffin

When he first arrived at the Black River, Stahle was stunned by the sheer number of ancient trees found there. To find that many trees that appear to be at least 1,000 years old in one place is “pretty rare,” he said.

“Dave is a pioneer in our field, particularly in the eastern U.S. and with bald cypress. His discovery of a truly ancient bald cypress is a natural trajectory of his career and his lab’s efforts over the decades,” Neil Pederson, a senior forest ecologist at Harvard University’s Harvard Forest in Petersham, Mass., wrote in an email to Eos. Pederson wasn’t involved with this study.

“I was pretty sure Dave and his lab would find a 2,000-year-old bald cypress. With this discovery, I [now] kind of expect that they [will] find one that is over or very close to 3,000 years old. (No pressure, Dave),” wrote Pederson.

The study also revealed that the area of old-growth Black River bald cypress is about 10 times larger than Stahle previously thought. Pederson actually considers that the most surprising finding of this study.

“It gives hope that there is more forest out there that has mostly escaped the heavy logging of the last four centuries,” he wrote.

Preserving Ancient Wonders

In a 1988 study published in Science, Stahle shared his discovery of a Black River bald cypress that was at least 1,700 years old. This work inspired The Nature Conservancy to act.

“We began protecting land on the Black River because of Dr. Stahle’s original research, which found trees dating from Roman times,” Katherine Skinner, executive director of the organization’s North Carolina chapter, wrote in an email to Eos. (The Nature Conservancy provided funding for Stahle’s recent research.)

“There really is no other place like it in the world,” Skinner added.

The Nature Conservancy has protected 19,000 acres (77 square kilometers) in the Black River basin. “The ancient forest is totally protected at this time, which was our top priority,” Skinner wrote.

A River Region Bursting with Natural Treasures

In the 1980s, Stahle primarily studied the Black River bald cypresses to learn more about the area’s climate record. He continues to focus on this aspect of his research, and his team’s paper extends the paleoclimate record in the southeastern United States by 900 years.

However, Stahle’s work with these trees has evolved over time to include dating individual Black River trees, especially older ones, and the conservation of the river and its floodplain.

That ecosystem is home to black bears, bobcats, river otters, rare fish species (including the Santee chub and broadtail madtom), the Cape Fear spike and other rare mussels, and neotropical songbirds, including the prothonotary warbler and the yellow-throated vireo.

Protected from Harvesting

Before The Nature Conservancy protected the ancient Black River bald cypresses, these trees were probably spared because they were too worn and weathered to attract loggers, Stahle said.

However, it is now common to harvest trees for their biomass. “With nations labeling biomass as carbon neutral, there has been renewed logging that has been pretty destructive of the productive and rich ecosystems in the southeastern U.S.,” Pederson wrote. “Ironically, one part of the green economy movement is a real threat to forests. Do not misunderstand. We need to change our economy to battle human induced climatic change [but] one early approach has become a threat to forests,” he added.

Another unexpected threat? The garden mulch industry. “Recently, other cypress forests in North Carolina were logged for cypress mulch. What a tragedy it would have been to lose these trees to mulch in someone’s yard,” Skinner wrote.

—Rachel Crowell (@writesRCrowell), Science Writer

Citation: Crowell, R. (2019), North Carolina bald cypress tree is at least 2,674 years old, Eos, 100, https://doi.org/10.1029/2019EO126031. Published on 11 June 2019.
Text © 2019. The authors. CC BY-NC-ND 3.0
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