Tree rings reveal climate secrets

Maia Cuddy’s dad and grandfather were surveyors for logging companies in the Clearwater Forest, and she heard their outdoor tales of marking trees with a surveyor’s stamp and swinging machetes to slice through saplings and bushes clearing a path for line-of-sight instruments.

By the time she enrolled in the College of Natural Resources to pursue a degree in environmental science and conservation biology, she admired trees and loved to sojourn in North Idaho’s vast forests. She could climb trees or split their wood for campfires, but she had not studied their rings.

At University of Idaho, Cuddy, who grew up in Lewiston, learned how to drill and read tree cores in Department of Earth and Spatial Sciences Associate Professor Grant Harley's tree ring lab — part of the College of Science —which led to a summer field experience in Virginia.

“I love dendrochronology, because it offers a deep and interesting story of climate,” Cuddy said. “Analyzing tree rings can show years of climate history in specific ecosystems.”

The study of dendrochronology uses slim tree cores, removed with a boring instrument, to extract a sample of the tree’s growth rings. The rings can tell a researcher a lot about forest history, weather patterns and even sunspots.

At a dendrochronology field school at the edge of the Appalachian Mountains, Cuddy and her colleagues explored the effects of woolly adelgid bugs on eastern hemlock trees. The small invasive aphid-like species introduced from Japan is adept at killing trees. Tree ring samples showed how the aphid-like insects affected hemlock trees, how the trees recovered by covering wounds made by the insects, and the rings provided researchers with patterns — showing how often over the years the trees sustained bug attacks — that may help predict future outbreaks.

Her weeks in Virginia were followed by a stint in Idaho and Yellowstone National Park where Cuddy and the graduate students she was helping pulled core samples from ancient trees and woody plants.

The experience and skills she acquired in Summer 2024 have led to a new interest and opened avenues for a new career, said the junior who attained two years of dual credit coursework at Lewis Clark State College before enrolling at U of I.

“I really wasn’t well versed in dendrochronology,” Cuddy said. “The only experience I had from the tree ring lab was scanning cores. I had not collected cores or analyzed them for historical data.”

Cuddy, who earned a Hill Undergraduate Research Fellowship through the College of Science and a scholarship from the University Honors program to pursue the summer tree ring research said her U of I experience, so far has been phenomenal.

“Maia was such a great candidate because she really had a desire and passion to learn about the environment through the lens of dendrochronology,” Harley said. “As a second-year undergrad student, she got plugged into the Idaho Tree Ring Lab, where she was taught the basics of dendro, and she really got some hands-on and applied learning from that environment. So, when she expressed the interest in going to the Virginia field school, this was the perfect next step for her to increase her skills and learning.”

Cuddy flourished at the field school, Harley said, which set her up for additional dendrochronology field work including a stint along the Salmon River, and she traveled to East Yellowstone to help a graduate student with field work.

“After only a semester at U of I, I entered a new world of opportunities,” Cuddy said.

Her love of trees and the stories they can tell, has kept her — at least for the summer — out in Idaho’s forests where she feels the most at home.

“I have learned so much in such a short amount of time and have created a network of incredible and inspiring people,” she said. “The opportunities just keep coming.”

Although dendrochronology is a subskill — there are few jobs for full time dendrochronologists, Harley said — knowing how to collect core samples, and how to use them for a variety of research projects, is a valuable tool for any conservation biologist, he said.

“She just really took advantage of everything Dendrochronology Field School had to offer, from participating in other’s field research while at the same time conducting her own research,” he said. “I was really proud of her, she really exemplified what I think of as a true Vandal.”