According to recent study, the world's oldest tree may have been existing for millennia when the first rocks were constructed at Stonehenge.
A recent computer model estimates that the ancient giant, an alerce (Fitzroya cupressoides) known as the "Gran Abuelo" (or great grandpa in Spanish) that towering above a ravine in the Chilean Andes, is around 5,400 years old.
If that date is correct, the Gran Abuelo will be approximately 600 years older than the current official world record holder, a Great Basin bristlecone pine (Pinus longaeva) known as "Methuselah" in California.
However, the actual age of the alerce is still a matter of debate, as establishing it needs examination of the tree's rings - a procedure known as dendrochronology, and the gold standard for measuring a tree's age – yet the data is now lacking.
The model's underlying data has yet to be made public or submitted to a peer-reviewed journal.
The tree, regardless of its age, is in danger and must be safeguarded, according to Jonathan Barichivich, a climate and global ecology expert at the Climate and Environmental Sciences Laboratory in Paris and the model's creator.
"It's really in poor condition because of tourism," Barichivich said, adding that the tree has also been harmed by climate change.
How old is Gran Abuelo?
The Gran Abuelo, a conifer that stands 196 feet (60 meters) above the foggy forest floor in Chile's Alerce Costero National Park, was considered to be around 3,500 years old at first. But, according to Barichivich, experts have never conducted a comprehensive analysis of its age.
"We wanted to tell the story of the tree with the only aim to valorize it and protect it," Barichivich explained.
So, in 2020, Barichivich and Antonio Lara, a forestry and natural resources professor at Chile's Austral University, utilized a nondestructive technique to drill a small core from the tree, capturing 2,465 years' worth of tree rings.
The borer, on the other hand, was unable to reach the core of the tree's 13-foot (4-meter) diameter, preventing the counting of many of the alerce tree's growth rings.
The researchers built a mathematical model that took into consideration how F. cupressoides grows at varying rates from a sapling to a mature tree to account for the remaining years of growth. Variations in growth rate due to competition as well as changes in the environment and temperature were also factored into the model.
The scientists then used the model to recreate the tree's development 10,000 times, according to Barichivich. These simulations yielded a range of Gran Abuelo ages.
Barichivich indicated that the model assessed the tree to be roughly 5,400 years old. The tree might be 6,000 years old, with an 80% possibility of being older than 5,000 years, and all of the modelled development paths predicting it to be at least 4,100 years old, he added.
"Even if the tree was a very fast grower, for all that size, it cannot be younger than that," he remarked.
Another characteristic, according to Barichivich, indicates that the tree is very old: a biological law known as the growth-lifespan tradeoff. Slow-growing organisms are thought to live longer as a result of this tradeoff. And alerce trees grow very slowly, much slower than other long-lived species like gigantic sequoias (Sequoiadendron giganteum) or Great Basin bristlecone pines, according to him.
Some tree-dating specialists, however, cautioned Science Magazine against using modeling data to estimate a tree's age.
"The ONLY way to truly determine the age of a tree is by dendrochronologically counting the rings and that requires ALL rings being present or accounted for," Ed Cook, a founding director of Columbia University's Lamont-Doherty Earth Observatory in New York, wrote Science Magazine in an email.
Endangered tree
The tree has endured for thousands of years, but its future is uncertain, according to Barichivich.
According to him, the old tree has been ringed by a small platform walkway that is crushing its few live roots, and the thousands of people that visit the tree each year do additional damage by walking on it.
The majestic alerce has also been harmed by climate change and the accompanying 10-year drought, according to him; a second tree sprouting from the top of the towering monster is also withering.
To prevent additional harm to the Gran Abuelo, Barichivich and his colleagues recommend erecting a netting veil 10 feet (3 meters) high around the tree to keep people away. He told Live Science that they also propose relocating the walkway far away from the tree's ancient root structure.
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