Inner Workings: How saving some of the Southeast's oldest trees might help scientists monitor climate change.

In the swampy floodplains of North Carolina’s Black River stand ancient trees with a story to tell. Many of these bald cypress (Taxodium distichum) were well over a millennium old when Columbus discovered the Western Hemisphere. As it turns out, their locale has greatly promoted their longevity: by being relatively inaccessible, the trees have been spared from loggers’ saws. But the inexorable sprawl of humans is threatening to breach their mucky moats and disrupt habitats for these trees, many of which have stood for hundreds of years. The true value of these small patches of largely undisturbed forest may not lie in their wood, however. It may stem from what scientists can glean about how such ecosystems respond to ongoing and future climate change. A few thousand acres of such cypress-studded wetlands are now protected along the lower reaches of the Black River. But researchers are mobilizing to build a consortium that will locate, map, and raise money to purchase hundreds of additional acres of these majestic old trees. Climate Chronicles The southeasternUnitedStates onceboasted anestimated 40 million acres of bald cypress forests. Cypress wood is prized for its strength and rot-resistance, so these massive trees—the largest of which can contain six homes’worth of lumber—quickly became a logger’s favorite. Cypress is highly valued among scientists for other reasons. For one thing, its growth rings are clear andeasy to read, saysDavid Stahle, who analyzes tree rings to discern past trends in climate, at the University of Arkansas in Fayetteville. Bald cypress is a widespread species, living in wetland habitats from Delaware to eastern Texas and throughout the lower Mississippi Valley (1). Its longevity ranks in the top 10 among trees in the Western Hemisphere; ancient rot-resistant trees that have died and fallen into oxygen-poor swamps offer researchers the ability to assemble a series of rings from trees that lived during overlapping intervals, thus generating uninterrupted chronicles of climate that can stretch back hundreds if not thousands of years, says Stahle.