Doctoral student Sonja Schmoyer is using drone-based hyperspectral imaging and AI to detect invasive pests that are endangering one of America’s keystone species.
The National Geographic Society has awarded a grant to Sonja Schmoyer, a doctoral student at the University of Tennessee, Knoxville, for research designed to help protect endangered hemlock trees.Schmoyer is one of the first 20 recipients of conservation grants under National Geographic’s American Keystones initiative, which supports efforts to protect the country’s ecological, cultural, and economic pillars as the United States prepares to celebrate its 250th anniversary. Other grants sup
“I remember growing up reading National Geographic magazines and watching documentaries about the incredible work their Explorers were doing around the world; I never imagined that I could one day be part of such an inspiring community,” said Schmoyer, a third-year doctoral student in UT’s Department of Earth, Environmental, and Planetary Sciences (EEPS). “Being named an Explorer now feels like a validation that someone believes in both me and my work, and that what I am doing has real significance, which motivates me to work harder every day.”
Eastern and Carolina hemlocks, called the “redwoods of the east,” can live hundreds of years and are one of the most important tree species in the Great Smoky Mountains National Park. For more than 50 years the tiny aphid-like hemlock wooly adelgid has been killing eastern and Carolina hemlocks across the Appalachian Mountains, and their damage now extends from Maine to the Carolinas and as far west as Michigan.
Devastation to the hemlocks could be comparable to the blight that struck American chestnut trees in the 20th century. Loss of hemlocks can affect everything from birds that nest in the branches to trout that swim in the cool pools created by their shade.
“This research highlights the importance of hemlocks not just as a species, but as a foundation of the ecosystems they support, both ecologically and culturally,” Schmoyer explained. “In losing our hemlocks, this would result in drastic changes in forest structure, biodiversity, and landscape processes across the region.
“My goal is not only to study that decline, but to contribute to tools that can help monitor, manage, and ultimately preserve these fragile and important systems.”
Research Partnerships
Schmoyer began using unmanned aerial vehicles and hyperspectral imaging to examine hemlocks in May 2025. She will be leading visual tree assessments through spring 2027, visiting field sites and evaluating tree health metrics such as live crown ratio, foliage transparency, and crown density. She also collects branch samples to assess evidence of new growth, dieback, and the presence of hemlock woolly adelgid ovisacs.
Tree health metrics are used to assign each hemlock a physical stress value on a scale from 0 to 6. The stress value and the spectral signatures of the hemlocks derived from fixed-wing hyperspectral imagery, along with thermal signatures collected by drones, are used to train a machine learning algorithm. “As more sites and scenes are collected, the accuracy of the algorithm improves, which enhances its ability to predict the stress level of the tree using only remote sensing,” Schmoyer said.
“The broader impact of this work is the ability to extend observation beyond what is logistically possible with ground surveys across large and remote areas of land,” she said. “Maps resulting from this project would serve as a critical tool for land and forest management and support more informed decision making and monitoring.”
Schmoyer is working with multiple organizations, including the Tennessee Department of Agriculture’s hemlock woolly adelgid strike teams and the Great Smoky Mountains National Park, where one of four study sites across Tennessee is located.
EEPS undergraduate research assistant Ainsley Starkey has been helping conduct visual tree assessments, and Schmoyer hopes more undergraduates will volunteer to join her ground-based monitoring team this fall and winter and learn remote sensing techniques as part of the project.
“I am also interested in interdisciplinary collaboration by incorporating research on the cultural and historical significance of eastern and Carolina hemlocks in Tennessee, especially within the context of Native American communities,” she said. “This broader perspective will help contextualize the importance of hemlocks within both environmental and cultural frameworks.”
From Earth Analogs to Mars
Schmoyer chose UT for graduate school because of its strong combination of Earth-based geologists and planetary scientists. “I was especially drawn to the EEPS department’s emphasis on interdisciplinary research, which has allowed me to learn new methods and perspectives across multiple fields and collaborate with students and faculty both within the department and across UT,” she said.
For her dissertation, she is using remote sensing techniques from satellites, fixed-wing aircraft, and drone systems to study Earth environments in Utah, Nevada, and California that serve as analogs for Martian terrains, as well as to assess forest health.
“My research portfolio brings together geology, environmental science, and planetary science,” Schmoyer said. “I use remote sensing techniques to study planetary analog environments, combining both remote sensing data and ground-based geologic analyses to better understand surface processes. At the same time, I apply these same methods to a more applied Earth-based problem by assessing the health of eastern and Carolina hemlocks across East Tennessee.”
Schmoyer had first noticed the trees’ decline as an undergraduate in Pennsylvania. She was introduced to the work using drone imaging to study the issue through a member of her dissertation committee, Christopher G. Tate (PhD physics ’17), a researcher at Oak Ridge National Laboratory.
“Dr. Tate has long been interested in this topic and is now working on a related project that tracks changes in hemlock health over multiple years using datasets from the National Ecological Observatory Network (NEON), an NSF-funded program, across the Oak Ridge campus,” Schmoyer said.
“This project is driven by personal motivation to better understand and help protect the ecosystems we call home,” she said. by personal motivation to better understand and help protect the ecosystems we call home,” she said.
by Amy Beth Miller