Hemi-marsh is a condition or state of marsh that offers well intermixed areas of open water and emergent vegetation, and provides the optimal conditions for breeding marsh birds. Hemi-marsh condition is dynamic in nature, driven by ecosystem engineers (largely muskrats and beavers) and fluctuations in water levels; in general hemi-marsh conditions exist in about 3-6ft of water. Across the Great Lakes, the extreme and rapid fluctuations in water levels combined with the impacts of non-native plant species have limited the availability of hemi-marsh. This project seeks to increase marsh bird habitat quality in Allouez Bay by increasing hemi-marsh conditions and overall structural diversity.
Major goals for this project include:
Increase and sustain the extent of hemi-marsh habitat by increasing interspersion across at least 150 acres in Allouez Bay
Create conditions that allow for a dynamic and resilient marsh that provides sustainable breeding habitat for American Bittern, Least Bittern, Marsh Wren, Pied-billed Grebe, Sora, Swamp Sparrow and Virginia Rail.
Create conditions that allow for a dynamic and resilient marsh that provides shorebird and fish spawning habitat, and the potential for occasional or regular breeding by Black Tern and Yellow-headed Blackbird.
Challenges and Opportunities
The project team used the Adaptation Workbook to and the draft menu of Great Lakes Coastal Adaptation Strategies and Approaches to develop several adaptation actions for this project. One of the main outcomes of this discussion was altering the sequence of each restoration phase in the Bay, in order to reduce the vulnerability of restored marsh to climate change impacts. The three restoration phases planned for this project include:
- Light touch invasive control, enhancement of native vegetation, more detailed bathymetry mapping
- Reducing exposure by constructing wave attenuation structures and gradualizing slope of the bay in some areas
- Heavier cattail management in areas protected by phase 2 actions to create hemi-marsh conditions
Some of the specific Adaptation Approaches discussed by the project team include: