Battling Phragmites: How Science is Restoring Metroparks Wetlands

Written By: Julie McLaughlin

Healthy wetlands are some of the most valuable ecosystems in our Metroparks. They provide habitat for wildlife, improve water quality, help reduce flooding, and create beautiful places for people to explore. But these important landscapes face ongoing threats from invasive species like Phragmites. Through science, collaboration, and long-term stewardship, the Metroparks are working with partners across the Midwest to better understand how to control this invasive plant and restore healthier wetlands for future generations.

Phragmites (pronounced “frag-MIGHT-ees”) is a large, invasive wetland grass with distinct tassels at the top of a 6–15-foot-tall plant. Although most of us associate it with roadside vegetation, it can be extremely invasive in natural areas.  One key to its success is spreading by rhizomes, which are horizontal underground stems (rhizomes). Phragmites rhizomes can grow up to 10 feet per year, with shoots coming up continuously along the way.

This makes it difficult to manage, because many of the treatments used (fire, flooding, herbicide, mowing) do not address the underground parts and often have no long-term impact on the size and density of the Phragmites. Climate change adds to this difficulty – many stands are only possible to reach if the ice is frozen, and the unpredictable and intense spring storm events and summer droughts can impact the ability of native plants to compete for space. There is currently no agreed upon method or series of steps that work better than others – but that is on the way!

This is the mission of the Phragmites Adaptive Management Framework (PAMF). PAMF applies a scientific modeling approach to develop management protocols and timelines for Phragmites throughout the Midwest, working with partners including the Chicago Park District, Wisconsin DNR, and the City of Toledo. Each enrolled group’s individual data contributes to the strength of the modeling. And not only does this type of community or participatory science provide enough data to do robust research, but it also reminds us that we are connected to a community of people who have been dealing with similar issues. This is a large-scale problem, and we all rely on each other to develop best management strategies.

The Metroparks’ Natural Resources Crew collect data like density, size, and hydrology from several stands, which are sent to PAMF for use in the modeling process. In return, PAMF provides a customized (adaptable) annual management plan for each stand enrolled in the program.

With funding from the Great Lakes Commission, the Metroparks were able to hire an ecological restoration contractor to implement the management recommendations at Stony Creek Metropark for 2025 – 2026.  Five Management Units totaling 33 acres were created in areas with continuous areas of Phragmites. After each management action, the Natural Resources Crew collect the monitoring data. For monitoring, they walk along a transect – an invisible line through the longest part of the stand – and collect data at 5 areas along the line using a small plot sampling frame. The last treatment of this annual cycle was completed in early June, and the final monitoring was completed earlier this month, with the project period officially ending in August. In total, two of the five Management Units had significant decreases in plant stem density and in the percent of the Management Unit made up of Phragmites.

So what now?

Metroparks staff and contractors will continue annual Phragmites treatments in units where treatments have been successful, and where native biodiversity is highest. We have also begun hand-seeding in bare areas that are not dominated by phragmites, using species that have been resilient in light of the invasive pressure.

And, best of all, Metroparks has been selected to receive another year of funding for PAMF management! This time the work is located at Lake St. Clair Metropark in the Point Rosa Marsh. The Point Rosa Marsh is a 50-acre part of a 525-acre Clinton River Delta wetland along the west and north sides of the park. Black Creek Marsh to the north is 220 acres of Emergent Marsh. This wetland complex has historically been home to several rare wildlife species including Blanding’s turtle, Marsh wren, Eastern fox snake, Common gallinule. It can be daunting to think about the area and density of wetland invasive species – but it also gives us a reason to continue working in the areas that have the best chance of success.