Restoration of Non-Native Cattail Dominated Wetlands in Border Waters

We mapped areas in the park using field mapping and remote sensing methods to establish areas needing restoration. These parcels were surveyed using one-meter quadrats in a grid pattern corresponding to plot size for cover class, select plant species, floating mat presence, floating mat depth, water depth, soil type and other vegetation characteristics. Vegetation surveys allowed us to determine severity of need and hybrid cattail presence and assess which methods would be used for treatment. The focus of this project was to test new and previously used methodology to remove invasive cattails. Several treatments were experimental, and early trials led to useful techniques for later in the grant period.

Total Removal: Sixty-three acres of floating cattail mats were mechanically destroyed and piled on shore.

Under Water Cutting: Rooted cattails were cut near their base, limiting regrowth and survival. Underwater cutting occurred on 37 acres.

Surface Cutting: In drier areas, cattails were cut above water surface, or above ground, to limit growth. This trial method proved ineffective, however, as plants regrew. Surface cutting was used on 7.8 acres.

Prescribed fire was implemented on 38.5 acres during early spring burning which took place in 2021 and 2022, and in 2024 for an additional 49 acres of newly treated burned areas.

Tilling and Flattening: Tilling cattails on inundated soils and flattening cattail debris on the soil surface was performed on 3.53 acres.

Seed was purchased or collected to deploy at project sites as well using either a handheld seeder, the Mobitrac seeder, or spread by hand. The purchased seed mix was a native pesticide-free seed mix, purchased from Minnesota Native Landscape. Seed collection of wild rice utilized volunteers as well as park employees to collect wild rice seed in the fall. Seed collected by National Park Employees and volunteers included wild rice, woolgrass, bur reed, blue flag iris, various sedges, and soft stem bulrush. The acres seeded were 11.3, however, some overlap of seeding did occur in those acres, decreasing the number of total acres somewhat. Seeding sites were predominately tilled sites. Natural seeding was allowed to take place in areas where natural seed load was high from appropriate neighboring mature plants.
Treated areas were mapped in the field and data incorporated into analysis to record treatment history and acreage treated. These sites were later revisited, many on an annual basis, to measure vegetation changes which occurred in treated areas. Marshbird surveys were performed to assess environmental impacts on wildlife.

Data collection: Quantified spoil, mapped treatment areas, surveyed vegetation pre/post treatment (for SGCN/T&E), surveyed secretive marsh birds. Survey sites were selected based on presence of persistent emergent vegetation. Plots were randomly selected and located at least 400 m apart. Teams of observers performed three rounds of call back surveys and visual surveys. Species include least bittern, yellow rail, sora, Virginial rail, American Bittern, & pie billed grebe. Proximity, bearing, and time of each marsh bird was recorded. Data are used to quantify bird habitat quality.