The oldest known tree in the world. Image source: GABRIEL POPKIN About 5400 years ago, when humans invented writing, a cedar (Chilean cypress) might have grown in the coastal mountains of Chile today. It hid in the cool and humid canyon, avoided the fire and felling, and now has grown into a gray white giant with a diameter of more than 4 meters. Most of the trunk of the tree has died, some of the crown has fallen off, and the tree is also covered with moss, lichen, and other trees have even rooted in its cracks.
Now, this tree, called Alerce Milenario or Gran Abuelo, may get a new and unusual title: the oldest living individual on the earth.
Jonathan Barichivich, a Chilean environmental scientist working at the Climate and Environmental Science Laboratory in Paris, estimated that this tree may be over 5000 years old, at least one century older than the current record holder, a foxtail pine in eastern California. It has 4853 growth rings under its rough bark.
Chilean cypress is an evergreen tree. Seen from a distance, it is similar to giant sequoia and redwood. Antonio Lara of Chile Southern University in Valdivia proved in the 1990s that Chilean cypress can grow to extreme age. In a 1993 study, Lara and colleagues reported that a Chilean cypress in southern Chile had 3622 growth rings. This makes this species the second oldest species after the foxtail pine, surpassing the redwood.
In 2020, Barichivich and Lara used a diameter increasing drill (a t-type drill, which scientists use to cut narrow cylindrical wood without harming trees) for coring. The tree core samples taken had about 2400 rings with very short intervals. Since the tools used at that time could not reach the tree core, Barichivich turned to statistical models to determine the complete age of this Chilean cypress. Using computer models and sampling data, he estimated that the age of the tree was about 5484 years old.
"This is amazing. It was thought that this tree was about 4000 years old," said Barichivich, who also wrote a short informal report. However, many scientists question this.
Tree ring scientists believe that the actual number of tree rings is the gold standard for determining the age of trees. Ed Cook, the founding director of the tree ring laboratory at Columbia University, wrote in an email: "The only way to truly determine the age of a tree is to calculate by the age of tree rings, which requires that all tree rings exist or be explained clearly."
In this regard, Barichivich said that his method explained this possibility. He plans to submit a paper to a magazine in the coming months.
Barichivich said that whether the tree is recognized as the oldest tree in the world or not, the Chilean government should better protect it. At present, the tree is located in the park. Tourists can climb down from the observation platform and walk around the tree, which will damage the root of the tree and compress the surrounding soil. At the same time, as the climate becomes drier and drier, it is more difficult for tree roots to absorb water, which puts pressure on trees.
Pablo Cunazza Mardones, head of the wildlife conservation department of Chile's National Forest Corporation, also believes that the tree is fragile. He said that budget restrictions hindered the protection work, but the agency still "multiplied" the protection of the tree and increased the number of forest rangers at the site from one to five.
Author: Li Muzi Source: China Science Daily
