Trees giving bizarre clues to climate change
CARSON, Skamania County — Suspended 20 stories in the air, Ken Bible looks down on the crown of a 500-year-old Douglas fir and ponders a mystery.
It's not the obvious one: How does a man without superpowers hover above the treetops?
That's easy. The University of Washington forest ecologist rose to his lofty perch in a metal gondola hoisted by a 285-foot-tall construction crane.
The vantage point allows Bible to study the upper reaches of this old-growth forest, where a reproductive orgy is under way.
"We've never seen anything like this here," he says, reaching over the edge of the open-air gondola to grasp a limb laden with cones.
He counts at least 30.
"Normally, a branch like this would have about three," he says. "Why so many this year? We really don't know."
Maybe global warming nudged the trees to procreate. Perhaps it's a natural cycle.
In either case, Bible wants to pinpoint the trigger. Did the forest crank up cone production in response to temperature? Is moisture the key? Or could the flush of fertility be traced to high spring winds that whipped up a sexy cyclone of pollen?
The work is part of a bigger effort to figure out what climate change, both natural and man-made, will mean for the Northwest's iconic forests. The UW's Wind River Canopy Crane, erected in 1995 near the Columbia River, is proving an ideal tool.
The crane and the research area that surrounds it have already helped answer several fundamental questions about forests and their ability to counteract global warming. A cooperative venture with the Forest Service, the crane is the largest in the world dedicated to forestry research, and the only one in North America.
It was here that scientists put to rest the myth that mature forests are biologically moribund. By rising above the treetops, they were able to take measurements that showed old forests continue to grow and act as a sink for carbon dioxide, a major greenhouse gas.
Studies here also proved it doesn't make sense from a global-warming perspective to cut older forests and replace them with seedlings, which grow faster and had been thought to absorb more carbon dioxide. Old forests are storehouses for such vast amounts of carbon that it would take many decades for new forests to catch up on the carbon balance sheet.
"If you want to measure these kinds of things, you need to be able to get up in the tops of the trees and out at the ends of the branches where processes like photosynthesis are really going on," says UW forestry professor Jerry Franklin, who pioneered the study of old growth. "The canopy crane gives you that ability."
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Trees giving bizarre clues to climate change
