In Knoxville, we’ve had two back to back years of rather harsh winters complete with several weeks of significant snow fall and temperatures that fell well below freezing. Having seemingly made it through these dark times, it’s now relevant to assess the impact of an all too real winter. The benefits of these cold winters stems beyond snow days, this time reaching up to the highest peaks in the Smoky Mountains. With longer periods of below-freezing temperatures, the hemlock trees of the National Park’s highest peaks have been given a second chance.
Many of you may have heard of the hemlock woolly adelgid, Adelges tsugae, an invasive insect that bores into the base of the needles on hemlock trees and sucks out the sap. When infested, these adult trees cannot produce enough sap to acquire enough nutrients to satisfy their own needs. The result is hemlock forests filled with the skeletons of old growth trees with a scattering of younger trees that will soon meet the same fate.
While the insect reached Great Smoky Mountains National Park in 2002, the park’s forest health monitors and visitors can already see the decimation of hemlock forests at the top of Clingmans Dome and other high elevation peaks in the park. The park rangers are employing biological and chemical strategies to improve tree defenses and fight the presence of the insect, but ultimately, Mother Nature has the most effective tool in this effort.
The population size of the woolly adelgid goes through distinct boom and bust cycles typical of most insect species. During the warmer spring and summer, the insects pillage the hemlock trees for nutrients and then reproduce, releasing large pulses of offspring, before dying. As cold winter temperatures arrive, the insect populations take a huge hit, meaning that the population must grow from nearly nothing again each spring. This yearly culling of the adelgid populations is the most effective check on the growth and spread of the insect’s impact on hemlock forests.
These past two winters have been abnormal, though. When compared to the warming trend clearly seen in the last decade of winters as a whole, these winters have been unique in that we have experienced sustained periods of below-freezing temperatures, especially in the high-elevations of the park. While previous warmer winters have simply caused a small dip in the size of adelgid populations, this past winter and the one before that dealt a hefty blow to the invasive pest that’s sucking the life out of our hemlock forests. More snow days, a bigger appreciation for the spring that’s slowly arriving and healthier forests: I’d say that’s a win for everyone.
Kenna Rewcastle is a senior in College Scholars. She can be reached at [email protected].
