A summer wildflower with dark secrets, a Grand Valley researcher working to unlock them

In July the spotted knapweed springs forth, its spindly bright pink flowers and thin, elongated stems with spare foliage adding a delicate-looking feature to the summer landscape and an attraction for bees and butterflies.

But the plant has a dark side.

Anything but delicate, this invasive plant from Europe and Asia is an aggressive species with both its own weapon and armor to secure dominance in its territory, said Todd Aschenbach, associate professor of biology. The species deploys a chemical called catechin that inhibits the growth of other plants while harboring silica in its stems that thwarts attempts at burning. 

Left unchecked in the grasslands it favors, spotted knapweed will cause harm by overpowering other plants and throwing the ecosystem out of balance. That is why Aschenbach, who researches the restorative ecological benefits of using controlled burning, was involved in a recent study to see if fire can manage the spotted knapweed.

"When you have only that one species, it outcompetes other plants and, for instance, fewer insects can utilize that ecosystem," Aschenbach said.

The study, which was the subject of a recent article in the research publication Ecological Restoration, was conducted at Pierce Cedar Creek Institute in Barry County, southeast of Grand Rapids. Aschenbach said the institute, which has an interest in ecological management, has an ongoing competitive undergraduate research program. Zachary T. Pitman, an article co-author, started the research as an undergraduate and continued at a graduate level. 

Researchers worked to determine the optimal conditions for burning spotted knapweed; the temperature had to be particularly high and sustained to get past the silica in the stems. They also checked the soil to see if burning affected the chemical that inhibits other plants but the evidence of that was limited, Aschenbach said.

The latter outcome is driving his hope for further research of the soil to pinpoint the concentration of the chemical. He also wants to find native plants that can be established with the spotted knapweed to help facilitate fire management of the invasive species and its surroundings, allowing for multiple species to grow.

Overall, having an ecosystem that is more readily managed by fire is beneficial, Aschenbach said.

"Burning is a natural and necessary disturbance in fire-adapted ecosystems such as prairies and savannas," he said. "When we suppress fires we end up with prairies that turn into woodlands."

Prairies are an endangered ecosystem, with less than 1 percent of original tall grass prairies still in existence in the U.S., Aschenbach said. He noted prairies are part of our ecological heritage and provide important habitat for creatures such as pollinators.

The plight of pollinators is another important reason to control spotted knapweed and diversify the plant population, he said. The blooming time for the invasive species is only about a month, so if Aschenbach could, he would want the pollinators that are attracted to the plants to know: "There are other things I can give you so that rather than having a one-month feast, you can have a buffet throughout the season." 

Aschenbach is passionate about helping students understand the professional fire science and fire management opportunities that are increasingly important for management of natural resources. Besides studies determining the best timing and conditions for fire affecting what is above ground, an emerging research area also seeks to understand how burning can affect carbon storage in the soil, he said.

He is equally passionate about educating the public on the ecological benefits of burning. He noted that public awareness campaigns about the human danger of fire and news stories about wildfires, such as the recent ones in Australia, can taint people's perspectives about burning, but controlled fires can also have benefits from a human context, especially for those living near grasslands or other areas prone to wildfires.

"Prescribed burning is also a way to prevent loss of life and property," Aschenbach said. "You can have low-intensity controlled burns where you decide when to add fire to the landscape as opposed to high-intensity massive burns that are not controlled and have a lot of fuel."