Geoscientist Sean Bemis, undergraduate student Madeleine Kronebusch, and Dhari Alharbi '22, who was a student at the time, review data collected by their ground-penetrating radar system. Photo courtesy of Sean Bemis
Virginia Tech scientists study how vegetation helps create soil on bare rock outcrops
Lon Wagner is senior director of communications and marketing in the Virginia Tech College of Science.
BLACKSBURG — In the forests of the southeastern United States, dense tree cover dominates most landscapes. That’s why the Appalachian Trail is sometimes nicknamed “The Green Tunnel.”
But avid hikers know that often in the Southeast, they’ll emerge from the green tunnel.
“When you walk out of the forest onto the rock, the contrast is immediate,” said Sean Bemis, a geoscientist and lead author of a study that uses these unique outcroppings as a natural laboratory to examine fundamental connections between rock weathering and vegetation. “You are standing on solid rock and you wonder where did all the trees go?”
Because of the lack of vegetation, these outcroppings are known as “balds.” But on geologic time scales, these balds have not always been devoid of vegetation. When bedrock is stripped of soil, it presents an extreme environment — hard, dry, and nutrient-poor — yet plants eventually take root. The study, published in the Journal of Geophysical Research-Earth Surface, reveals how this process unfolds during the earliest stages of what scientists call the critical zone: the life-supporting system of the Earth’s surface extending from bedrock to the tops of trees.