Newspaper article The Christian Science Monitor

The Secret Life of Ancient Trees

Newspaper article The Christian Science Monitor

The Secret Life of Ancient Trees

Article excerpt

A thousand years ago, the steep slopes of Vietnam's southern highlands were cloaked by forests of towering pines and other trees. Tribesmen roamed the forests, hunting wild boar and deer under a lush canopy of laurels and oaks.

In their quest for sustenance, they moved slowly through an understory of tangled bamboo and palms. Thick layers of moss and decaying leaves muffled their footsteps as they stalked their prey.

On the forest floor, the seed of a Fokienia hodginsii tree sprouted in the moist detritus. As it grew, a chronicle of each year of its life was locked into narrow bands inside its trunk - light for the beginning of a growing season and dark marking winter.

Now, a thousand years later, Vietnamese forest specialist Le Canh Nam and American tree ring scientist Brendan Buckley are hunting in the forest. But their quarry isn't wild boar or deer. It's the tree that grew from the Fokienia hodginsii seed and has survived for a millennium, growing into an ancient giant.

Like the hunters of the past, Mr. Nam walks deliberately through prickly stands of rattan palms and over downed trees in what is now Bidoup-Nui Ba National Park near Da Lat, Vietnam.

Nam's quest began two years ago when he was asked by Dr. Buckley to find ancient Fokienia hodginsii trees from which he and a team of scientists could extract tree rings to help with climate studies.

Buckley and his colleagues have spent the past five years working with collaborators in more than a dozen countries to reconstruct information about historical monsoons from tree rings. Such data is useful for climate modelers, who want to find out how global warming might affect monsoon rainfall.

The models that predict rising temperatures are "very iffy" about precipitation patterns, says Edward Cook, director of Columbia University's Lamont-Doherty Earth Observatory (LDEO) Tree- Ring Laboratory. That puts a premium on figuring out how much it rains from year to year in Asia's densely populated river deltas. Tree rings help scientists understand past climate variations.

Nam spent a week in the forest searching for big trees. Now he is guiding the group back to a promising site.

"A tree that is beautiful to me is probably ugly to most people, says Buckley. "Mine are twisted and have been through hell on a weathered ridge or dry slope. Those are the trees I'm interested in."

Buckley is considered the foremost tree-ring scientist (dendrochronologist) working in Southeast Asia and is a research scientist at LDEO's Tree-Ring Laboratory. Nam consults his map, a global positioning system, and a compass, and relies on an intuitive sense of direction developed through years in the forest.

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.

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. …

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