Ecologist is pessimistic

about hemlock’s future
By Scott Nicholson
nicholson@wataugademocrat.com

Though different weapons are entering into the battle against the hemlock woolly adelgid, it appears the pest may end up winning the war.

Chris Ulrey, a plant ecologist with the National Park Service, said the combined approach of using chemicals and natural predators to attack the adelgids have proven successful on a limited scale, but it’s unlikely that enough resources can be mustered to beat back the threat in time to save the hemlocks. Mother Nature is also not providing much assistance to adelgid opponents, since the dry and warm weather has helped the adelgids spread and thrive.

The National Park Service recently approved the Finding of No Significant Impact (FONSI) for the Hemlock Woolly Adelgid Control Strategies along the Blue Ridge Parkway. The FONSI has determined that there will be no significant environmental impacts that would occur by implementing a combination of chemical and biological controls to treat individual hemlock sites throughout the park.

Ulrey said, “There’s not a whole lot new. We’re really worried about what this past season means to the hemlocks. The trees were already stressed because of the dry weather. We expect accelerated mortality in the the following summer and the summers to come.”

Parkway superintendent Phil Francis said using a combination of chemical and biological controls will allow more areas throughout the park to be treated; thus, park managers can more effectively use limited funds and resources to treat a greater area across the landscape.

Ulrey agreed that the combination had shown visible results, and the chemical treatments had shown an effectiveness cycle of about three years. That means areas targeted for focused protection will probably have to be continually treated.

However, it’s impossible to save all the hemlocks, even inside limited borders such as those of the parkway.

Adelgids are attacking hemlocks all over the Eastern seaboard, and private land managers and public forest rangers have to largely fight their own battles. While some imported beetles and insects that feed off the adelgids have shown promise, it’s not only difficult to find enough beetles, each species has a unique seasonal cycle. Ulrey said that means different predators will have to be brought into the same areas to help vanquish the adelgids.

The hemlock woolly adelgid, an insect accidentally imported from Asia to the United States in the 1920s, fatally attacks the Eastern and Carolina hemlock trees found in the Southern Appalachians. In the Eastern United States, it was first seen in Virginia in the 1950s. Since then, it has spread north and south, first spotted in the Great Smoky Mountains National Park in 2002.

The insect has appeared throughout Western North Carolina from Virginia and points north, producing potentially “devastating impacts” in the region and some of its most prized forest attractions including Joyce Kilmer National Forest and Linville Gorge bordering the High Country.

The National Park Service has determined that the proposed project will not significantly affect the human environment within the project area; therefore, an environmental impact statement will not be prepared. Ulrey said while the red tape is wrapped up, the footwork will be ongoing, and because of the intensity of the battle, the park service is selecting areas where the remaining trees appear to be the healthiest.

“It was a fairly dry spring, so spraying wasn’t as effective as it might have been,” Ulrey said. “We may find that we have to spray those trees again. Usually, the adelgid population builds until the tree is stressed. When it’s dry, and then having insects suck the sap, a lot of trees are dying out.”

In Watauga County, the park service is focusing on stands of hemlock near Simms Pond and around the Cone Manor Estate. “They are looking pretty rough and we’re not sure we can save them,” Ulrey said. “Some near Camp Catawba look okay still, and we hope to target more out near the Cone Estate next year.”

Ulrey said those that have been chemically treated were marked with a dot, but he said that was unnecessary since the treated trees are so much obviously healthier than their infested counterparts.

The weather has also not helped contain the adelgids, because the recent winters have been warm. Ulrey said in northeastern areas, the adelgid has reached a natural upper limit to its territory because of low temperatures. “An unusually cold winter might help,” he said. “The adelgids can’t tolerate real low temperatures.”

Because it’s now basically a losing battle, Ulrey and other biologists hope to maintain the trees they’ve already been protecting and treating, while simultaneously trying to bring new beetles and other natural predators into the mix.

“We only treat those that are still alive, but it will never be enough,” Ulrey said. “We are hoping to keep some alive as a seed source for future generations. We really hoped the trees would hang on long enough for the treatments to take effect, but we could see a bunch of trees dying this summer.”