Removing Invasive Plants Limits

Their Spread Through Wisconsin

A coalition of groups are combating the spread of invasive weeds in southeast Wisconsin to protect fish and wildlife habitat, water quality, and outdoor recreational opportunities.


Southeast Wisconsin is currently threatened by the spread of several invasive plant species that have the potential to completely alter natural ecosystems, with disastrous consequences for wildlife and people. The invasive plants are extremely aggressive, and once established their dense root systems can make it difficult for native plants to compete; invasives can take over an entire landscape to the point where they’re the only thing growing. This can significantly reduce the presence of fish and wildlife in an area, as the invasive weeds do not provide them with their ecological needs. The root systems of some invasives, such as Japanese knotweed, are so dense and aggressive that they have the ability to grow through concrete and pavement, damaging roads, basements, and other infrastructure. Invasives even have the ability to alter soil chemistry and degrade the quality of groundwater. It has been estimated that the annual economic impact of aquatic invasive plants in the U.S. is in the billions.

Thanks to a Great Lakes Restoration Initiative grant, the Ozaukee Washington Land Trust is combating the spread of four invasive weeds throughout southeast Wisconsin. Coordinating with 25 partner organizations across six counties, the trust is targeting so-called “pioneer colonies” of four invasive plants: phragmites; Japanese knotweed; purple loosestrife; and lyme grass. Pioneer colonies of these weeds are still young and small enough that they may be effectively controlled; if left unmanaged, eradicating them may quickly become unfeasible. The Land Trust is controlling these species with herbicides, mowing, prescribed burns, and biocontrols such as beetles that eat the non-native plants. With each treatment, care is taken to ensure that unintended residual effects are minimized. Treated sites are monitored for three years to guard against any re-sprouting plants and ensure that the control methods are effective. The Land Trust and their partner organizations are hosting workshops to train volunteers to remove the weeds, and to help the public learn more about the invasives in their area. The Trust is also creating an inventory of sites they’ve treated to inform future management efforts.

Resource Challenges Addressed

  • Lack of native habitat
  • Invasive species
  • Loss of native plants
  • Poor soil quality
  • Poor water quality


Phragmites reeds

Phragmites, shown here, are aggressive invasive species that out-compete native plants. Native plants are important for habitat restoration and resiliency. Credit: Ducks Unlimited.

Results and Accomplishments

The project is restoring the natural quality of hundreds of acres of shoreline and wetlands throughout southeast Wisconsin. So far, 130 acres have been treated; by the end of 2014, the Trust plans to have treated 1,500 acres in total. The restored areas are helping improve the quality of wildlife habitat and groundwater quality. Restoring native plants and wildlife enhances outdoor recreation for hikers, wildlife watchers, hunters, and anglers. Retaining aesthetically natural landscapes improves property values, and removing invasive root systems prevents significant property and infrastructure damage. An inventory of treated sites has been created to inform future management action.