Report: Quantifying and mitigating the impacts of emerald ash borer on black ash forests in the upper Great Lakes region

The emerald ash borer (EAB) poses a tremendous threat to ash forest habitats across the upper Great Lakes. Of particular concern is the impact EAB will have on the ecology and functioning of black ash ( Fraxinus nigra) forested wetlands, which cover over 500,000 ha in Michigan, Minnesota, and Wisconsin and represent the region’s most common ash forest habitat. Black ash often occurs in relatively pure stands on poorly drained sites where it serves as a foundation species exerting a strong control over ecosystem structure and functioning. Correspondingly, extirpation of this species by EAB could have negative cascading effects, including dramatic rises in water tables and shifts in vegetation composition towards shrub- and graminoid-dominated wetlands with little to no tree component. Such changes would have negative impacts on the myriad wildlife species that use these habitats, as well as the ecosystem services provided by these forests, such as flood regulation and carbon sequestration. Much of our understanding of EAB impacts on ash forests in the Lake States comes from upland and/or urban green ash ( F. pennsylvanica) and white ash ( F. americana) forests, limiting our understanding of how EAB will affect black ash wetlands, the most vulnerable forest type in the region. Moreover, little is known regarding the management strategies and tools that may mitigate EAB impacts.

This project is designed to increase our understanding of the potential, regional impacts of EAB on black ash forest habitats and associated wildlife by leveraging funding and existing research experiments and field trials located across Michigan, Minnesota, and Wisconsin. These experiments and trials are designed to quantify EAB impacts on vegetation, wildlife, and hydrology and to identify potential mitigation strategies. Findings from this broad array of sites will be coupled with remote sensing and geospatial analyses to quantify the true extent and vulnerability of these critical habitats across the upper Great Lakes region. Results from this project would include management recommendations aimed at mitigating the impacts of this exotic insect, including the identification of potential replacement species for these areas.