Reviving American chestnuts may mitigate climate change

American chestnut trees are very fast growing and produce a hard wood suitable for furniture. They're good at sequestering carbon. In the early 1900s a blight nearly wiped out chestnut trees. They've never come back. But Douglass Jacobs, an associate professor of forestry and natural resources at Purdue University, has hybridized American chestnuts with blight-resistant Chinese chestnuts. The tress are 94 percent American chestnut, yet retain the blight resistance of Chinese chestnuts.

(Photo by Nicole Jacobs)

Jacobs studied four sites in southwestern Wisconsin that were unaffected by the blight because they are so far from the tree's natural range. He compared the American chestnut directly against black walnut and northern red oak at several different ages, and also cross-referenced his results to other studies using quaking aspen, red pine and white pine in the same region.

In each case the American chestnut grew faster, having as much as three times more above ground 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.

"Each tree has about the same percentage of its biomass made up of carbon, but the fact that the American chestnut grows faster and larger means it stores more carbon in a shorter amount of time," Jacobs said.

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.

Reviving American chestnuts may mitigate climate change