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Chestnuts Could Slow Climate Change06-11-09 | News

Chestnuts Could Slow Climate Change

The American chestnut is an incredibly fast-growing tree. Generally the faster a tree grows, the more carbon it is able to sequester. And when these trees are harvested and processed, the carbon can be stored in the hardwood products for decades, maybe longer.

If ever there was a tree that has inspired devotion, it’s the American chestnut, once one of the most common trees in East Coast forests. Thoreau considered it among the “noblest” trees he encountered in his walks through the Lincoln woods, while settlers in the southern Appalachians found the nuts and timber such valuable allies in their struggle to survive that the tree became a regional icon. When an imported plague, the chestnut blight, all but eradicated the tree in the early 20th century, people mourned from Georgia to Maine. A Purdue University study shows that introducing a new hybrid of the American chestnut tree would not only bring back the all-but-extinct species, but also put a dent in the amount of carbon in the Earth’s atmosphere.

Douglas Jacobs, an associate professor of forestry and natural resources, found that American chestnuts grow much faster and larger than other hardwood species, allowing them to sequester more carbon than other trees over the same period. And since American chestnut trees are more often used for high-quality hardwood products such as furniture, they hold the carbon longer than wood used for paper or other low-grade materials.

New efforts to hybridize remaining American chestnuts with blight-resistant Chinese chestnuts have resulted in a species that is about 94 percent American chestnut with the protection found in the Chinese species. Jacobs said those new trees could be ready to plant in the next decade, either in existing forests or former agricultural fields that are being returned to forested land.

The American chestnut grew faster, having as much as three times more aboveground biomass, than other species at the same point of development. American chestnut also sequestered more carbon than all the others. The only exception was black walnut on one site, but the American chestnut absorbed more carbon on the other study sites.

Jacobs said trees absorb about one-sixth of the carbon emitted globally each year. Increasing the amount that can be absorbed annually could make a considerable difference in slowing climate change, he said.