By SAM CORDEN
Capital News Service
Instead of removing plants like phragmites and switchgrass, they harvest them. These plants are a threat to biodiversity, they say, but invasive plants can benefit farmers and even power homes.
Scientists are working in the middle of the Shiawassee National Wildlife Refuge which has 10,000 acres of marshes, bogs, forest and farmland. Everywhere you look, there’s a hawk or a herring. Bushes rustle with rodents, and the air is filled with mosquitoes and a thick humidity. To put the size in perspective, Manhattan is roughly 15,000 acres.
Brendan Carson, a researcher from Loyola University Chicago, and Eric Dunton, wildlife biologist at the Shiawassee refuge, are researching invasive cattails.
“The hybrid’s called Typha x glauca,” Carson says. “And the hybrid can become fairly dominant – or extremely dominant in a lot of wetlands – especially where there are excess nutrients like nitrogen and phosphorus.”
The cattails occupy space, which means less room for native biodiversity, and without plant variety, the wetland suffers. The system loses its ability to filter nutrients, and all wildlife – from fish to migratory birds – are affected.
Carson and his colleagues are collecting cattails. Their goal is to deal with invasive species and address pollution at the same time, one reason this research so innovative.
Rummaging through cattails that stretch taller than a person, the bright red roof of the harvester pushes forward, spitting out cattails as it moves. The machine looks like a tiny snow plow that clears the sidewalks, but it is built on tank treads rather than wheels. It’s specially made for projects where low environmental impact is crucial. With its weight evenly dispersed, it glides over marshland, consuming every cattail in its path.
This method of eradication removes the invasive plants and the unwanted nutrients they’ve absorbed.
“Anytime throughout the growing season when the cattail has gotten to the point where it’s a mature plant, it’s taking nutrients through its roots,” Carson says. “It’s taking them out of the soil and the sediment, and incorporating them into growing tissue. So as long as you can remove that tissue while it’s still green, you’re going to be removing quite a bit of nitrogen and phosphorus.”
A possible source of energy
Once these nutrients have been harvested, they’re put to good use. The harvested cattails are shredded and applied directly to crop fields where the biomass breaks down, providing organic material as well as recycled chemical fertilizer.
This can help farmers reduce their need for fertilizers in future years, resulting in lower operating costs and less environmental impact.
The invasive plants may have other economic uses as well.
Greg Zimmerman, a professor at Lake Superior State University, has started using invasive biomass to make fuel pellets. They can be used in pellet stoves, which are similar to wood burning stoves, as a clean alternative heat source.
At the University of Wisconsin-Oshkosh, Brian Langolf is using a mechanical digester that breaks down the material at an accelerated rate. When the invasive biomass is paired with food or other organics, it turns into a rich compost, and the methane released during the process can be converted to electricity.
Langolf says they have “roughly the capacity to produce up to 10 percent of our university’s power consumption equivalent, or roughly 220 average American homes year-round [that] we can provide heat and power to.”
The economic opportunities on the horizon look promising, but the true potential is still unknown.
Although energy rates in the United States remain unfavorable to alternative sources, other countries have already begun to implement similar methods.
This story was produced as part of a partnership with Great Lakes Echo and Interlochen Public Radio where it first appeared.