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McCormick’s Creek tornado aftermath provides chance to study ‘tree throw’ and its effect on soil

Feb 28, 2024

Aerial photos of trees flattened and on the grown after a tornado A drone captured an aerial photo of tree damage in McCormick's Creek State Park in Spencer, Indiana, after the park was hit by an EF-3 tornado on March 31, 2023. Photo courtesy of Brian YanitesAfter a tornado leveled trees in a south-central Indiana state park last year, an Indiana University professor began studying the forever-changed forests to conduct first-of-its-kind research on natural disasters’ impact on the environment.

On the evening of March 31, 2023, McCormick’s Creek State Park in Spencer, Indiana, was hit by an EF-3 tornado hurling 138 mph winds. More than 280 acres of the 1,961-acre park were seriously damaged, and two people died in the park’s campground. Brian Yanites, an associate professor of earth and atmospheric sciences in the College of Arts and Sciences at IU Bloomington, drove to the park and saw hundreds of destroyed trees.

Brian Yanites Brian Yanites is an associate professor of earth and atmospheric sciences in the College of Arts and Sciences. Photo courtesy of the Department of Earth and Atmospheric SciencesYanites, who studies how the Earth’s surface and topography are shaped by atmospheric and geologic processes, and his colleague Doug Edmonds had just been awarded a grant from the National Science Foundation to establish a process for mapping tree throw, or the deep depressions made in soil once a tree is uprooted by extreme atmospheric events, and to investigate the implications it has on the surrounding soil and biosphere. What happened at McCormick’s Creek State Park would give them an important opportunity to do so.

After receiving permission and permits from the park and the Indiana Department of Natural Resources, Yanites surveyed the tree wreckage, collecting data with a lidar drone. The drone is equipped with high-powered lasers that shoot more than 100,000 pulses per second at targets below. Pulses travel to the ground and bounce off the surface, allowing drone sensors to map pits and elevations on the ground. With the images the drone captures, Yanites can reconstruct the magnitude of disturbed soil, and the velocity and direction of the wind during the storm.

Yanites plans to revisit the park this spring to continue collecting data, joined by undergraduate students in IU’s Arts and Sciences Undergraduate Research Experience. ASURE is a freshman-year research program in the College of Arts and Sciences where students earn credit toward their degree through project-based learning and lab work. Yanites said he values the program, its mentorship and how it sparks creativity in first-year students.

“As a first-generation college student, I struggled with the concept of belonging my freshman year,” he said. “It was when a professor reached out to me and asked if wanted to do research that gave me the confidence that I do belong. Now, as a professor myself, I will never forget the power that gesture has on undergraduates ­— that you are valued for your mind and are an important intellectual part of our academic community.

“I’m really excited about the ASURE program because it does exactly that and provides this impactful opportunity to first-year students in the College.”

Yanites and ASURE students will analyze laser points captured from the drone to identify the size and shape of the trees' root balls.... Yanites and ASURE students will analyze laser points captured from the drone to identify the size and shape of the trees' root balls. Photo courtesy of Brian YanitesThe Department of Earth and Atmospheric Sciences has a course in the program. Through Yanites’ drone data collection project at the park, students will map laser points from the drone, find where the thrown trees’ root balls are and use specialized software to calculate the volume of the depressions.

I could envision doing this year after year with the ASURE students,” Yanites said. “Over the next five or 10 years we can build a data set that not only captured how the landscape was impacted by a tornado, but how it heals, or responds and evolves after the damage is done.”

Yanites and his colleagues also plan to work with Educating for Environmental Change, an IU program providing professional development to K-12 science teachers. Through a hands-on, weeklong workshop, educators will gain better understanding of how to effectively teach extreme weather and topography. Yanites and Edmonds will be hosting a workshop April 20.

Little is known about the effects that natural disasters, like tornadoes and extreme wind, have on forests and the soil. The research Yanites and his students are conducting will produce some of the first quantitative data on how soil horizons, or the layers of soil beneath trees’ roots, affect the environment when uncovered.

When trees are blown over, the soil horizon becomes exposed to elements such as rainwater, which can weather and erode the soil, potentially contaminating surrounding areas’ drinking supply, Yanites said. Moreover, forested soils also hold roughly 30% of the carbon on the earth’s surface. The weathering processes induced by tree throw can facilitate carbon storage in the soil and act as a sponge for atmospheric carbon dioxide.

Researching the frequency and volume of soil disturbance by these rare but high-magnitude events is critical to understanding the significance of natural processes in mitigating increases in carbon dioxide by human activities.

“Especially in the context of a tornado, it’s an extreme event that doesn’t happen very often,” Yanites said. “We don’t have a lot of observations, so these opportunities are really important to advancing that science and to better understand the natural processes that regulate carbon dioxide in our atmosphere.”

McCormick’s Creek State Park, the oldest state park in Indiana, has experienced storm damage before. In 2003, straight-line winds flattened trees in a portion of the park.

Currently, several of the park’s trails remain closed as park staff and the Indiana Department of Natural Resources clear debris. Dependent on regrowth from existing seed banks in the soil, the DNR may plant new native hardwood trees to replace the forests’ canopy.

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Jaleesa Elliott

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