Differential Impacts of Emerald Ash Borer (Agrilus planipennis Fairmaire) on Forest Communities Containing Native Ash (Fraxinus spp.) Species in Eastern North America

Invasion by emerald ash borer (EAB; Agrilus planipennis Fairmaire), an exotic pest, is disrupting natural processes and hindering our ability to conserve genetic diversity and perpetuate ash ecosystem services and functions. The goal of this project was to identify forest communities most at risk in terms of having altered ecosystems following EAB invasion. Using recent data available from the USDA, Forest Service, Forest Inventory and Analysis program, we calculated Shannon-Wiener species diversity index values for forests containing each of the six native ash species found in the eastern United States. These forest communities differed in their species diversity index values, and diversity indices varied across ecosystem provinces and states. In addition, communities containing ashes that are restricted by a narrow range of suitable environmental conditions consistently had lower diversity index values than communities of ash species with greater geographical ranges. Finally, forest stand cohorts (i.e., seedlings, saplings, and canopy trees) had similar species diversity indices across forest communities containing a single ash species. The tree species diversity index values quantified for communities with a single ash species will provide managers with additional information for prioritizing EAB control measures and restoration efforts following EAB invasions.