Outdoors: Can We Heal Our Hemlocks?
By Ken Czarnomski
The magnificent Eastern and Carolina hemlocks, which represent Appalachian culture, are also a keystone contributor to the mountain forest ecology. Foresters estimate that nearly 80 percent of our southern hemlock forests may be gone already. They seem to be losing their ongoing fight to survive the invasive hemlock wooly adelgid (or HWA), which feasts only on them. This aphid, less than 1/32 inch (about the size of a poppy seed), has dramatically increased its rate of infestation in the last decade.
But hope remains. In the Western North Carolina region, we are fortunate to have several inspirational initiatives supported by grants through federal, state, regional and private contributors that are determined to make a difference, sharing the goals of the Hemlock Restoration Initiative (HRI), headquartered in Asheville.
The mission of the HRI “is to work with a variety of partners to restore hemlocks to long-term health throughout North Carolina and ensure that both the Eastern and Carolina hemlocks can withstand attacks by the invasive HWA and survive to maturity on public and private lands,” says Margot Wallston, HRI statewide coordinator. New research on the physiology of hemlocks and how they respond to severe conditions such as HWA, drought, air quality and warming temperatures is being conducted. “We have not lost all of the hemlocks,” says Wallston. “There are stands throughout Western North Carolina that have not been as heavily hit by HWA.”
Currently, the primary method of treatment is chemical. But these treatments are only a temporary solution since they are costly and often difficult to accomplish. Ben Smith, research scientist of the Forest Restoration Alliance (FRA) in Waynesville and Albert Mayfield, research entomologist and project leader with the Forest Service, Southern Research Station in Asheville, are looking beyond chemical treatment. Both organizations work with HRI.
One initiative being researched by the FRA includes a hybrid program that would develop a cross between a Carolina and a Chinese hemlock. “The Carolina hemlock is capable of a cross with the Asian, but the Eastern hemlock is not,” says Smith, who is exploring development of breeding a naturally resistant species. He does this by taking cuttings from found specimen trees resilient to HWA, transplanting them into labs and test plots where they eventually can be exposed to field conditions. “It takes about seven years just to turn a generation,” he says. Yet he remains optimistic because the HWA does not genetically modify as quickly as some other insects.
Mayfield’s research into growing seedlings in degraded hemlock stands “resists the idea that only one solution will solve all the problems.” Developing restoration methods is the Forest Service’s first critical step. This silvicultural strategy is being tried “even before we explore other methods, [to see] what we might do with the tools we already have,” Mayfield explains. Dupont State Forest and Cold Mountain hemlocks are being restored and studied using various methods including clearing, opening gaps, fertilization and soil composition. The Forest Service’s second initiative in combination with universities is a two-pronged approach introducing two different insects from the Pacific Northwest.
Each of the programs operates from the belief that the health of the remaining trees can be improved, especially those in the far north where HWA is not as severe. They also share the idea that chemical treatment works and can help stabilize trees, which would give scientists more time to develop their research.
There will be a free presentation by Margot Wallston, “The State of the Hemlock,” on Tuesday, February 21, at 5:30 p.m. at the West Branch of the Asheville Public Library, sponsored by the Blue Ridge Naturalist Network. Learn more about the hemlocks and events by visiting savehemlocksnc.org and srs.fs.usda.gov. Ken Czarnomski is vice president of the Blue Ridge Naturalist Network, which is dedicated to connecting people who love the natural world.