Ecological Impacts of Emerald Ash Borer in Forests at the Epicenter of the Invasion in North America
Department of Entomology, The Ohio State University, Columbus, OH 43210, USA
Daniel B. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
Department of Entomology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, OH 44691, USA
Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
The Davey Tree Expert Company, Kent, OH 44240, USA
Author to whom correspondence should be addressed.
Forests 2018, 9(5), 250; https://doi.org/10.3390/f9050250
Received: 31 March 2018 / Revised: 3 May 2018 / Accepted: 3 May 2018 / Published: 5 May 2018
(This article belongs to the Special Issue Understanding and Managing Emerald Ash Borer Impacts on Ash Forests)
We review research on ecological impacts of emerald ash borer (EAB)-induced ash mortality in the Upper Huron River watershed in southeast Michigan near the epicenter of the invasion of North America, where forests have been impacted longer than any others in North America. By 2009, mortality of green, white, and black ash exceeded 99%, and ash seed production and regeneration had ceased. This left an orphaned cohort of saplings too small to be infested, the fate of which may depend on the ability of natural enemies to regulate EAB populations at low densities. There was no relationship between patterns of ash mortality and ash density, ash importance, or community composition. Most trees died over a five-year period, resulting in relatively simultaneous, widespread gap formation. Disturbance resulting from gap formation and accumulation of coarse woody debris caused by ash mortality had cascading impacts on forest communities, including successional trajectories, growth of non-native invasive plants, soil dwelling and herbivorous arthropod communities, and bird foraging behavior, abundance, and community composition. These and other impacts on forest ecosystems are likely to be experienced elsewhere as EAB continues to spread.