Ancient Oaks Help Scientists Study Climate in Southwestern Wisconsin

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July 10, 2013

By Marie Zhuikov

In the first comprehensive tree coring study for the area, researchers from the University of Wisconsin-Platteville will analyze ring-width patterns within cores taken from old oak trees found in southwestern Wisconsin’s Driftless Region. The effort is for a two-year study funded by the University of Wisconsin Water Resources Institute into signs of long-term variability in rainfall and climate conditions.

“Trees are excellent recorders of their environment,” said Evan Larson, assistant professor of geography and co-director of UW-Platteville’s Tree-Ring, Earth and Environmental Sciences (TREES) Laboratory. “Wide rings indicate years of good growth while narrow rings represent stressful times. Using these patterns of growth, we can expand our perspective on climate beyond what instrumental records can tell us, moving further into the past to build a more complete picture of the range of potential drought conditions we may face as a region. These data will help community planners understand a broader range of climate variability, including the frequency of extreme events, and will provide context for climate change predictions that incorporate uncertainty into water resources management in a changing world.”

Inspiration for the project came in the form of a bike ride.

“I was riding through the Platteville countryside and I saw all these beautiful old oak trees,” said Larson. “I realized the area had a lot of trees that have lingered on the landscape since before European settlement, and that those trees could tell us the history of the climate in this region.”

Although Larson and Christopher Underwood, adjunct research faculty member at the TREES Lab, are the lead investigators on the project, Establishing the Long-term Range of Variability in Drought Conditions for Southwest Wisconsin, Sara Allen, a UW-Platteville geography and history double major, will spearhead it as a post-bachelor research fellow, along with six to eight undergraduate students.

“Southwestern Wisconsin is an agricultural area, and the drought that affected crop production last year had a negative impact on the farmers throughout the region. Looking into historical drought patterns can help us better prepare for possible water deficits in the future,” Allen said. “This project will give me the opportunity to move into a mentoring role.”

Researchers plan to take samples from 400 living trees with increment borers – essentially a hollow drill bit, turned by hand, that removes a pencil-width piece of wood from the tree.

Drilling into the tree, Larson said, is akin to taking a blood sample in a person and does not cause the tree lasting damage. Although Larson’s bike ride helped pinpoint the location of some trees, the researchers need help from the public to find others.

Landowners in southwestern Wisconsin who have oak trees they suspect may be hundreds of years old on their property are invited to contact Larson if they would like their trees considered for the project. The researchers hope that in exchange for permission to sample the rings of old oaks, they can offer property owners a glimpse into the environmental history of their land.

Larson can be reached at (608) 342-6139 or