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In Minnesota, Anticipating the Loss of a Million Acres of Ash Forests to Emerald Ash Borer

Photo of A wood frog sitting within decaying black ash leaves in a wetland forest in northern Minnesota on the Chippewa National Forest. A wood frog sitting within decaying black ash leaves in a wetland forest in northern Minnesota on the Chippewa National Forest. Snapshot : Black ash is a foundational species in the wetland forests of the northern Great Lakes region, affecting nearly all aspects of ecosystem function. A nonnative insect that has killed millions of ash trees in more than 25 states is edging closer to Minnesota’s black ash forests. USDA Forest Service scientists have unraveled the complex relationships between black ash and ecosystem functions and how loss of the species from emerald ash borer, and potential replacement by new tree species, will impact these relationships.

Principal Investigators(s) :
Eggert, Sue 
Research Location : Chippewa National Forest, Minnesota
Research Station : Northern Research Station (NRS)
Year : 2019
Highlight ID : 1612


Emerald ash borer is approaching Minnesota’s 1 million acres of black ash wetlands. USDA Forest Service scientists at the agency's Northern Research Station and collaborators developed a framework to understand how black ash, a foundational species, affects ecosystem functions, including hydrology and food webs. They used this framework to determine how loss of black ash to emerald ash borer (EAB), a nonnative insect, and replacement with new tree species will impact these functions. Their work uses a large-scale manipulation of wetlands on the Chippewa National Forest to simulate death of black ash from EAB and to evaluate replacement tree species. A key finding is that hydrologic function is closely tied to tree cover and loss of black ash without aggressive replacement with other species leads to marsh conditions. Moreover, leaves of black ash decompose faster than other species, readily becoming food for aquatic invertebrates. Conversion to replacement trees or marsh vegetation will alter food webs and the amphibian communities that depend on them. Promising replacement trees include swamp white oak and balsam poplar. These species will maintain hydrologic function but not aquatic food webs based on black ash leaves. These findings are changing the way that black ash wetlands are managed by state and federal agencies and tribes in Minnesota and Wisconsin.

Forest Service Partners

External Partners

  • Chippewa National Forest
  • Minnesota Forest Resources Council
  • University of Minnesota
  • University of Vermont
  • Virginia Technological University
  • Wisconsin Department of Natural Resources