Depending on where you are in Wisconsin, you may have heard of non-native Phragmites. In most of western Wisconsin, it’s a plant you might only recognize from an invasive species watch list. If you are in the far eastern part of the state, you would probably recognize it as a tall grass with a large, brown, feathery plume, and can be seen in many roadside ditches. In fact, if you happen to own property along western Green Bay, you almost certainly know it as the reason why you can no longer see the Bay, or why it may be difficult to use your dock.
Phragmites australis, also known as common reed, is a large perennial grass found throughout temperate and tropical regions around the world. In fact, native Phragmites has been common to the Great Lakes region for thousands of years. Brock Woods, wetland invasive species specialist for the DNR and the University of Wisconsin Extension, had previously known all Phragmites as a natural part of the Wisconsin wetlands. “The strain native to Wisconsin has co-occurred with other plants for many generations,” explains Woods. “It generally grows in low density stands with a diverse array of native organisms.”
However, a European strain of Phragmites (subspecies australis) was observed on the Atlantic coast in the early 1800’s and has been spreading west throughout the country ever since. In Wisconsin, the Lake Michigan coast has been the focal point of this invasive Phragmites. According to Woods, non-native Phragmites likely first arrived along Lake Michigan in the late 1970s. It may have arrived in ballast as free-floating seeds, or root, rhizome and stem fragments. Unfortunately, its many dispersal mechanisms have also allowed it to start spreading north and west across the state, establishing first in roadside ditches through vehicular traffic, construction activities and mowing. This subspecies grows much more densely and often taller than native Phragmites. It outcompetes and eliminates native plants, leaving very poor habitat for any native animals. It also causes undesirable site changes for people, including safety issues along roads and fire hazards from biofuel accumulation, especially along lake shores.
There is an area of the state where non-native Phragmites populations are still very young and small. This is the plant’s invasion frontline, and it occurs in a north-south tier of counties through which Highways US 51 and I-39/90 run, along with the next tier of counties to the east. Areas east of these central counties are often so infested with Phragmites that significant investment are needed to reduce the impacts of those invasions. Areas to the west have almost no known populations, and education with early removal of new infestations is the tool of choice there. But the counties in this central area represent a manageable invasion front where non-native Phragmites stands are present, but small enough that control work, maybe even elimination, is still feasible with a comprehensive and strategic treatment plan. Jason Granberg, a water resource management specialist for the DNR, has been implementing just such a plan over the past growing season, and he is excited about the progress made in a few months of work.
Part two will feature the DNR’s Great Lake Restoration Initiative efforts to control pioneer Phragmites populations.
For information on the differences between native and nonnative Phragmites, visit this resource from the Great Lakes Phragmites Collaborative.