Does the oldest tree in the world grow in a ravine in Chile? | Science

ALERCE COSTERO NATIONAL PARK IN CHILE –About 5,400 years ago, around the time humans invented writing, an alert tree (Fitzroya cuppressoides) may have started growing here in the coastal mountains of present-day Chile. Sheltered in a cool, wet ravine, it has avoided fires and logging that have caused many more of its kind, and has grown to become a grizzled giant of over 4 meters. in diameter. Much of the trunk has died, part of the crown has fallen, and the tree has been festooned with moss, lichen, and even other trees that have taken root in its crevices.

Now, the tree, known as the Alerce Milenario tree or Gran Abuelo (great-grandfather), could claim a new and extraordinary title: the oldest living individual on Earth.

Using a combination of computer models and traditional methods to calculate the age of trees, Jonathan Barichivich, a Chilean environmental scientist working at the Laboratory of Climate and Environmental Sciences in Paris, estimated that the Alerce Milenario is likely to have more than 5000 years. That would make it at least 1 century older than the current record holder: Methuselah, a bristled pine in eastern California with 4,853 years of annual growth rings under its gnarled bark. (Some clonal trees that come from a common root system, such as that of the Utah-based aspen colony known as “Pando,” are thought to be older, but dendrochronologists tend to focus on single trunks with countable rings.)

Many dendrochronologists are likely to be skeptical of Barichivich’s claim, which has not yet been published, because it does not provide a complete count of tree growth rings. But at least some experts are open to the possibility. “I fully trust Jonathan’s analysis,” says Harald Bugmann, ETH Zürich dendrochronist. “Sounds like a very smart approach.”

Alerce are conifers in the same botanical family as giant sequoias and sequoias, and from afar, they can resemble those giants. And warnings can grow to extreme times, Antonio Lara of the Austral University of Chile, Valdivia demonstrated in the 1990s. In a 1993 study, Lara and a colleague reported an alert strain in southern Chile that had 3622 growth rings. This made the species the second oldest ever recorded after bristlecone pines, beating redwoods.

But that study did not include the Alce Milenario, which stands out from other ancient trees in a rainforest west of the city of La Union. Barichivich says his grandfather discovered the tree around 1972. His grandfather and mother both worked as rangers in the park where the tree lives and he suspects he was one of the first children to see it. “It’s a tree that is very, very dear to us,” he says.

In 2020, just before the pandemic, Barichivich and Lara cored part of the Alerce Milenario with an incremental auger, a T-shaped auger that scientists use to remove thin wooden cylinders without damaging the tree. “In a way, the tree told me it was time” to take the core, says Barichivich. The wooden thorn produced around 2400 closely spaced growth rings.

Since his borer could not reach the center of the tree, Barichivich turned to statistical modeling to determine the full age of Alerce Milenario. He used complete cores of other erroneous trees and information on how environmental factors and random variations affect tree growth to calibrate a model that simulated a possible age range the tree had reached early in the core period. partial, along with a probability for each age. The method yielded an overall age estimate of 5,484 years, with an 80% probability that the tree lived for more than 5,000 years.

“It was amazing,” he says; he expected the tree to be about 4000 years old.

Barichivich presented his findings at meetings and conferences and wrote a short informal report on his methods. Some on the pitch are intrigued. “The prospect is certainly exciting,” says Nathan Stephenson, a scientist emeritus at the US Geological Survey who reviewed the report. But he’s withholding judgment until he sees more. “As a scientist, you want the peer-reviewed publication with all the dirty and dirty details.”

Others will be more difficult to convince. Dendrochronologists have traditionally regarded the actual ring count as the gold standard for determining the age of a tree. “The ONLY way to truly determine the age of a tree is to dendrochronologically count the rings and that requires ALL rings to be present or accounted for,” Ed Cook, founding director of the Tree Ring Laboratory at the Columbia University. And deducing growth rates during a tree’s youth can be challenging, adds Ramzi Touchan of the University of Arizona’s Laboratory of Tree-Ring Research, because the young tree may have had less competition and grown faster than in years. subsequent.

Barichivich says his method explains such possibilities. He plans to submit an article to a newspaper in the coming months.

Meanwhile, he says the possibility that the Alerce Milenario could be the record holder should also spur the Chilean government to better protect it. Currently, visitors to the tree, which is located here in the park, can get off a viewing platform and walk around it, which Barichivich says damages the roots and compacts the surrounding soil. The climate is also becoming drier, making it more difficult for the roots to absorb water and putting stress on the tree. “People are killing him,” Barichivich says. “He urgently requires our protection.”

Pablo Cunazza Mardones, head of the department of protected natural areas of the Chilean National Forest Corporation, which oversees the country’s national parks, agrees that the tree is vulnerable. He says budget limits have hindered protection efforts, but adds that the agency has still increased tree protections “exponentially” and increased the number of rangers at the site from one to five.

Regardless of whether Alerce Milenario is accepted as the oldest tree in the world, the finding highlights how some trees can live much longer than most of their peers, for reasons scientists don’t fully understand, Bugmann says. “Some species do things we think should be impossible,” he says. “There are still mysteries out there in the forest.”

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