The secret life of ancient trees
An ancient evergreen tree reveals its secret life to scientists, helping them decode climate history.
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Close on Nam’s heels, Buckley twists his lanky body to avoid low-hanging limbs. Tucked safely inside his pack are two hollow corers used to extract narrow dowels of wood showing a tree’s growth rings. The air is heavy with humidity, and the climb is unrelenting.Skip to next paragraph
Then Nam breaks through a clump of brush and stops, looks to his left, and says simply, “Fokienia.”
It is a massive evergreen tree. Lichens hang from the 6-foot-wide trunk and thick vines climb 120 feet to limbs hosting orchids, ferns, and mosses. It is exactly the kind of ancient tree that the researchers had hoped to find and whose climate history can now begin to be unlocked.
“A tree like this could be as old as the oldest ones we’ve gotten,” says Buckley. “The idea is so simple ... there is this organism sitting here and kind of recording what is going on in its environment and reliably so. When you find that right site that has whatever characteristic is necessary to give it an imprint of the overall climate and it just locks in, that’s a pretty special thing.”
Teak was once the most studied tree in the tropics, but it’s been backdated reliably only 400 years. Then, in the late 1990s, Japanese researchers discovered that Fokienia hodginsii had all the characteristics they were looking for in a tropical species. The tree had identifiable rings that were produced annually, the ring samples could be cross-dated between trees, and the ring patterns over time recorded the climate in which it grew.
LDEO research fellow Kevin Anchukaitis rests a hollow coring device against the trunk of a tree the team has labeled Tree No. 12 and turns it slowly to sink the bit. Within seconds, the corer begins its journey through time.
The forest silence is broken by a rhythmic “uRR, uRR, uRR,” as the 32-inch corer drives into the wood. Soon, the drill can go no farther. A quick spin in the opposite direction breaks off the end of the one-fifth of an inch piece of wood inside the hollow corer, and it is ready to extract.
Dr. Anchukaitis slowly pulls the core out, and his eyes widen as he quickly studies it.
“Oh, wow!” exclaims Buckley. “That’s incredible. [The growth ring pattern] just doesn’t stop. It’s slow growing all the way back.”
Tree No. 12’s growth rings are compacted tightly and nearly imperceptible, about 1/40th of an inch or narrower. The only way to reliably determine the tree’s age is to mount the sample, finely sand it, and painstakingly count the rings under a microscope back in the lab.
But Buckley knows that the tree is very old. “If I had to put my bets, I would say this is close to a thousand years old,” he says.
Buckley’s guess is confirmed months later when the cores from Tree No. 12 are analyzed at the LDEO lab in New York. The tree is dated back to 1029.
In Asia, the monsoon has long dictated the rhythms of life. More than 40 percent of the world’s population relies on water from the seasonal rainfall to grow food and for drinking. If there are disruptions to the monsoon, there are serious potential economic and social consequences.