A summer in the woods
"It looks more silvery as the wind blows,” he said. “The silvery side of the leaf flips over in the breeze, and then it shimmers.”
Calvin College professor of biology David Dornbos is giving his aesthetic take on the shrub thriving on both sides of the highway en route to Pierce Cedar Creek Institute, near Hastings. The shrub he is describing is the autumn olive, an invasive species that Dornbos and Calvin sophomore Rachel Hesselink have learned is pretty good at taking over the landscape.
Summer researcher
Hesselink, 20, spent her summer researching the autumn olive at the institute, a natural area of 661 acres of wetlands, forests, marshes, streams, lakes and prairies crisscrossed by seven miles of trails and anchored by a spacious, modern visitor’s center.
The species is thriving at the institute too, and what her research, and that of Dornbos has shown, is that autumn olive—a woody shrub introduced to America from Asia in the 1830s as an ornamental plant—aggressively colonizes both meadows and the forest understory. “This academic project is to figure out why it’s so competitive is these different areas,” said Hesselink. “If we figure that out, we can figure out what areas are risk areas.”
Gobbling CO2
Key to the autumn olive’s aggression is the rate at which it does photosynthesis, the conversion of light energy and carbon dioxide (CO2) into sugar. Dornbos and Hesselink are measuring the rate of photosynthesis of the invasive species versus its woody shrub competitors.
“In the meadow,” he said, “there are two or three plants that can do photosynthesis as fast as autumn olive, but there’s nothing faster.”
Reading the trees
The real story, however, is the forest understory, where Dornbos took readings from leaves on a variety of shrubs, using a device that measures CO2 going into a leaf and water coming out: Beech; 27. White Ash; 29, 30. Red Maple; 31, 26. Oak; 37, 34. Autumn Olive; 55, 52, 56, 57. (Hesselink also grinds up leaves from the plant and measures the result for chlorophyll.)
“Everybody in land conservancy, they know about autumn olive in the meadows…,” said Dornbos. “I don’t think that’s the real problem. I think the problem is in the understory of the native forest.” He gestured toward the more heavily forested area nearby: “In two years time, this went from 40 percent un-infested to 20 percent un-infested,” he said.
It isn’t possible to eradicate autumn olive altogether, said Dornbos. “It’s like zebra mussels …; you’re can’t get them out of Lake Michigan.” The solution, he said, is to prevent the invader from getting started.
Researching through URGE
Hesselink, who was given a $3,000 stipend from Undergraduate Research Grants for the Environment (URGE), a program of the institute, has handled the majority of the research on the autumn olive; her work will be published in an academic journal.
She spent the summer living in Hyla House, a farmhouse belonging to the institute with student researchers from Aquinas College, Grand Valley State University, Western Michigan University, Valparaiso University and Albion College. The students work on a range of biology projects. “We’re hoping to raise the next generation of scientists,” said Matt Dykstra, the education director for the institute.
When she’s not stalking invasive species, Hesselink is fishing and hiking with her colleagues. “I went frog catching with the frog catchers,” she said. “They have to go out at night.” She enjoys the rural setting and pastimes, she added.
Hands-on learning
“It’s not an opportunity for everyone,” said Dornbos, who has worked with two other students over the previous summers, researching autumn olive. “It’s a little remote. It can be a little scary. I don’t know that everyone would gravitate toward it.” He does think the URGE program is an effective teacher: “You can’t learn biology unless you do it. It’s not a bunch of facts,” he said. “That’s what any summer research program is all about.”
