Issue 9

Return of the American Chestnut?

On the same plots in the Bankhead National Forest where the SRS upland hardwoods unit tests different treatments to promote hardwood regeneration, research forester Stacy Clark has set out American chestnut and hybrid seedlings to see how well they will do under the different treatments.

American chestnut dominated the forests of the Southeast until most of the mature trees were wiped out by chestnut blight by the 1950s. Though a few mature trees remain, efforts to reestablish the tree have been stymied by the nature of the blight itself. Chestnut blight attacks the tree stem; because the roots remain, sprouts can come back year after year. But the blight also returns, usually killing the tree around the time it starts to flower and before it produces nuts.

Chestnut breeders have been crossing the American chestnut with Asian and European varieties to produce blight-resistant hybrids that look and act as much like the American chestnut as possible. They've managed to produce hybrids that are 94 percent American. The seedlings planted on the Bankhead plots were grown from a mixture of pure American nuts from The American Chestnut Foundation and hybrid nuts containing DNA from four other chestnut species. The study is part of a cooperative agreement with Scott Schlarbaum, professor and director of the University of Tennessee's Tree Improvement Program.

Clark and other Forest Service researchers are planting selections of pure American chestnut and hybrids in plots across the Southeast to test their survival. In addition to seedlings on the Bankhead sites, Clark has planted chestnuts on oak regeneration research plots in Jackson County, AL, and will plant more in the Daniel Boone National Forest in Kentucky next year.

On the Bankhead, the chestnut seedlings out in the sun in a 25- percent retention plot are doing well. "We're finding that chestnut seedlings grow well out in the full sunlight, but we don't know whether the tree is advance-growth dependent," says Clark. "Does it need to be established before disturbance, or can it come in after? How does it respond to competition? We control the competition now to keep the seedlings alive, but eventually we want to know how we can use silviculture to help restore this tree to the forests of the Southeast." - ZH

Back to: The Forest For The Trees Connecting Silviculture and Wildlife