By Sam Corden
Standing in the middle of Michigan's Shiawassee National Wildlife Refuge, it’s hard to comprehend the size. It’s about two-thirds the size of Manhattan – some 10,000 acres of marshes and bogs, forest and farm land.
Everywhere you look; there’s a hawk or a heron. Bushes rustle with rodents; and the air is filled with mosquitos.
Here, researchers are tackling invasive cattails -- a common problem in wetlands across the Great Lakes.
Their target is a European cattail that’s crossed with a native cattail to make a hybrid. They grow about 10 feet high and cover much of the wetland.
“The hybrid’s called Typha x glauca," says Brendan Carson, a University of Loyola Chicago researcher working on a cattail project at the refuge. " 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.”
He says when there are too many cattails in one place, they can crowd out native plants.
A wetland can lose its ability to filter water, and birds and fish can suffer from a lack of food and shelter.
That’s why Carson and his colleagues are collecting the cattails. Their goal is to deal with invasive species -- and address pollution at the same time.
That’s part of what makes this research so innovative.
To mow down the cattails, the researchers turned to a harvester that pushes forward, spitting out cattails as it moves.
The machine looks a lot like one of the tiny snowplows that clears sidewalks, but is built on tank treads rather than wheels.
It’s specially made for projects where low environmental impact is crucial.
And with its weight so evenly dispersed, it seems to glide over the marshland, consuming every cattail in its path.
This method removes the invasive plants from the wetland, while also removing the unwanted nutrients that they’ve absorbed.
Carson says the project is designed to let the cattails grow all summer, absorbing the nutrients like a sponge, before harvesting takes place. , "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.”
Once these nutrients have been harvested, they’re put to good use.
Working with local farmers, the harvested cattails are shredded and applied directly to fertilize crop fields.
The invasive plants may have other economic uses as well.
A professor at Lake Superior State University in northern Michigan has started using invasive plants to make fuel pellets.
Pellet stoves, similar to wood burning stoves, can burn plant matter as a clean source of home heat.
And at the University of Wisconsin Oshkosh, Brian Langolf is mechanically breaking down the material to create a rich compost. That process releases methane that can be converted to electricity.
By combining the cattails with other material the university has “roughly the capacity to produce up to 10% of our university’s power consumption equivalent, or roughly 220 average American homes year round we can provide heat and power to.”
Using invasive plants in these ways is still pretty new, and it may take several years to assess the impact on farms and wetlands.
But the researchers say farmers and businesses could work together to create markets for them.
And that could result in healthier wetlands around the Great Lakes.