The plants are lovely — their delicate, soft pink petals blooming on tall stems above the water. But pretty as it is, the flowering rush is an unwanted and uninvited lodger in Ohio waterways, displacing native species used by area fish and wildlife. An interdisciplinary BGSU team is developing a method of identifying the invader from satellite images in order to predict where it might go next, in hopes of thwarting its spread. It is already a problem from eastern Canada through the upper Midwest, said biologist Dr. Helen Michaels, the project leader.
“It was brought in as an ornamental plant and then gradually made its way into the Great Lakes. No one has clearly documented its economic impact on wildlife and recreation yet,” Michaels said.
Funded by the U.S. Fish and Wildlife Service, a group of graduate and undergraduate students led by Michaels has been braving the high heat and humidity this summer to find and map the plant in the waters of the Ottawa National Wildlife Refuge. Heading out in the early morning, going by canoe or in high waders where the growth is too dense to navigate by boat, they locate patches of the flowering rush for the “ground truthing” component of the project.
Arisca Droog, a second-year master’s student in geology, is participating in the research project for her master’s thesis, “Remote Sensing for Detection of Invasive Flowering Rush." She is mentored by Dr. Peter Gorsevski, School of Earth, Environment and Society.
“We use a Trimble GPS – a little yellow machine on a long pole — to precisely locate pre-selected sampling locations and ourselves in relation to those locations, and then mark off a one-meter by one-meter quadrant,” she explained. “We score the quadrant with marks for the rushes and the other plants. The biology students can identify them. And then we move on to another quadrant.”
Biology graduate students Jacob Meier and Mike Plenzler, and undergraduate Stephanie Kuck, an environmental science major, help create the map of the plants and their surroundings to yield a comprehensive picture.
The “ground truthing” is in preparation for gathering the “spectral signature” — the wavelength of light emitted — for the flowering rush and its neighboring plants, by which they can be identified in high-resolution images from aerial photography provided by the refuge, U.S. Fish and Wildlife Service, and, eventually, the LandSat satellite.
“Aerial photography is very expensive, so we want to be able to use the free LandSat images,” Droog said. “The whole idea is to be able to find flowering rush based on its spectral signature.”
Gorsevski is co-investigator along with Dr. Enrique Gomezdelcampo, environmental science, on the project. He will work on mathematically “decomposing” the aerial images, correlating them with the ground truthing data, to separate the flowering rush’s spectral signature from its surrounding plants and water.
Meanwhile, “the muskrats are starting to use it for their houses, and last week I noticed they had had a lovely supper on the flowers,” Michaels said.
Because flowering rush spreads so easily, on the feet of birds, by boats and through buds that break off near its rhizomes and float away, it is extremely difficult to control, Michaels said. “I wouldn’t be surprised to see it in drainage ditches in Bowling Green 15 years from now.”
In addition to the spectral signature grant project, Michaels and Kuck are also studying the effects of flowering rush on germination of native species from the marsh.