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Climate change's impact on forests being measured via expanding tree trunks

By David A. Fahrenthold
Washington Post Staff Writer
Saturday, February 20, 2010; A01

Jess Parker hugs trees.

In the woods of Anne Arundel County, he throws his arms around tulip poplars, oaks and American beeches, and holds them so tightly that his cheek presses into their bark. This is not some hiker on a lark: anybody, hopped up on campfire coffee and exercise endorphins, might hug a tree once.

This is science. Parker has done it about 50,000 times.

Parker, a forest ecologist at the Smithsonian Institution, has spent the past 22 years on a research project so repetitive, so time-consuming, that it impresses even researchers with the patience to count tree rings. Since 1987, he and a group of volunteers have embraced thousands of trees, slipped a tape measure behind them, and wrapped it around to measure the trees' girth.

This year, after about 250,000 hugs between them, the work paid off.

Parker's data, which showed the trunks gradually fattening over time, indicated that many of the trees were growing two to four times faster than expected. That raised questions about climate change's impact on the age-old rhythms of U.S. forests.

It might also raise questions about Parker and members of his team, who say they enjoyed almost every minute of it.

"Are we all brain-dead?" asked Parker, 58, who is based at the Smithsonian Environmental Research Center in Edgewater, south of Annapolis.

That's one of the questions, yes. But Parker said that, even in a time where instantaneous is starting to feel slow, studying trees still means learning to live on their time.

"The beast," he said, "requires it."

This month, when Parker and his team published a paper on their work, it was received as a key piece of evidence about the ways that climate change could be having subtle but important effects on forests. Others have found similar growth in different parts of the world, as warmer weather and more carbon dioxide fuel tree growth.

In the tropics, however, some studies have seemed to show trees growing more slowly: It might now be too hot for some trees there.

Parker, a man with the wisecracking, constantly explaining manner of a good pediatrician, measured his first tree in Maryland in September 1987. It was his first day on the job at the Smithsonian center, 2,600 acres of forests and marshes at the edge of the Chesapeake Bay. He walked into the middle of those woods and slipped the tape around a tall tulip poplar.

Only 249,999 more to go.

This isn't tranquilizing wild grizzlies or tagging great white sharks: It's not even sexy by the standards of forest science, where West Coast trees such as redwoods are considered the glory species. But researchers say that East Coast forests have one important thing going for them.

They have a birth date.

Starting in Colonial times, much of the East was cleared to make room for agriculture.

After the Civil War, forests were allowed to grow back when easterners abandoned their pastures and moved West. Virginia, for instance, went from 25 to 30 percent forested in the mid-1800s to 62.5 percent now. Because of that, scientists can compare how big eastern trees have grown with how big they should have grown, given that start date and their species' usual patterns.

"The whole eastern U.S. is undergoing this amazing experiment," said David Foster, head of Harvard University's Harvard Forest. "We can gain invaluable insights by just going out and watching it."

That was Parker's plan.

He tracked about 50,000 trees on 55 plots between the District and the Chesapeake, typically returning every three years to measure them as they grew. His volunteers included an emergency room doctor in search of peace, trained scientists in search of a hobby and retirees following orders from their wives.

"My wife said I had to get out of the house and start dealing with live people," said Dale Morrow, 72, a former elementary-school teacher who had gotten deep into genealogy ("dead people," his wife said) in retirement. He volunteered at the Smithsonian, and people there sent him to Parker. "My wife's first comment was, 'I didn't want you interacting with trees; I wanted you interacting with people.' "

Morrow told her: " 'Trees are people, too.' "

The volunteers said they were sustained on their weekly outings by the dramas that showed themselves everywhere, once they learned to read the woods. This tree here, with tiny sticks poking out of its trunk, is desperate and dying, reaching crazily for the light. The two trees over there are a bully and its victim, a tall, straight tree and one that has corkscrewed around, looking for a way out of its neighbor's shadow.

"There's never a boring moment around here," Morrow said. "Even though it sounds like it."

They also had tree jokes. That tree is a poplar. The ones next to it are un-poplar (say it aloud). That's a beech tree. The one next to it?

A son-of-a-beech.

Last year, when Parker analyzed the mountain of data his team had collected, he found something surprising: Their trees were adding bulk at a surprisingly fast rate.

Parker said the best explanations for this all seemed to relate to climate change. Temperatures in the area have risen by three-tenths of a degree; the growing season has lengthened by 7.8 days; and the amount of carbon dioxide in the atmosphere has risen. All of those might speed up photosynthesis, the engine of tree growth.

Which sounds, at first, like a good thing. It would appear that trees were helping more than expected to reduce the world's greenhouse gases, sucking carbon dioxide out of the atmosphere and using it to make leaves and branches.

"The danger of that, of course, is that this can't go on forever," said Kenneth Feeley, a professor at Florida International University. He meant that, even if there was enough carbon dioxide to support more fast growth, the trees would eventually run out of water or plant food. Their growth would slow down, and they would stop absorbing so much carbon.

Other researchers, such as Feeley, say it wouldn't have been possible to notice this trend in the mid-Atlantic if Parker and his crew had not measured so many trees over so much time.

Looking back, Parker said, it was worth putting up with the tree-hugger jokes.

"It's kind of a soothing thing, you know, hugging lots of these," he said, standing next to a poplar he'd just measured. "You can't get too angry if you do a lot of that."

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