Modeling the effects of emerald ash borer on forest composition in the Midwest and Northeast United States
The nonnative invasive emerald ash borer (Agrilus planipennis Fairmaire; EAB) has caused considerable damage to the ash (Fraxinus spp.) resource in North America. While there are methods to mitigate, contain, control, or even eradicate some nonnative invasive insects, EAB continues to spread across North America. Considering strong evidence suggesting >99 percent probability of host tree mortality, the loss of the North American ash resource is possible. To examine anticipated effects of EAB on tree species composition, we modeled future spatial and temporal changes in forest composition over the next 50 years with and without ash mortality anticipated from EAB spread. We used U.S. Forest Service Forest Inventory and Analysis (FIA) data, the current extent of EAB in the United States and Canada, estimated spread rate and host mortality data, and a suite of human population, energy, consumption, land use, and economic models to project the future condition of forests in the Midwest and Northeast United States. Our results suggest that in most cases EAB will not have a substantial effect on ecosystem function of future forests measured by FIA because of the replacement of ash by other species. The transition from ash to other species may take many decades, but forests can eventually recover when a variety of associated species replace ash.