Over the last century, forests of the eastern U.S. have been plagued by a series of devastating introductions of exotic pests. Among the most well-known examples are: the chestnut blight, which effectively eliminated from the landscape the American chestnut, a former forest dominant; Dutch elm disease, which has nearly eliminated a major riparian and shade tree species; gypsy moth, which feeds preferentially on oaks and is now the major defoliator of eastern forests; and the beech bark disease, which is causing a serious decline in American beech, one of the dominants of the northern hardwood forest type.
In each case, a considerable body of scientific research exists on the life cycle of the pest and its mode of action on the tree, but less work has been done on the long-term effects of these pests on the community composition of the forests, and very little is known about the ecosystem-level implications of the pest invasions.
We have been studying two pests common in Northeastern forests-the gypsy moth and beech bark disease. In a 2006 paper in Bioscience (Lovett et al. 2006), we summarized knowledge of ecosystem effects of exotic forest pests and pathogens in eastern North America.