Pests, Pathogens, and the Death of Dominant Forest Trees: What are the Effects on Forest Ecosystems?

At the beginning of March, two-dozen scientists from the Andrews Forest, Coweeta, Harvard Forest, Hubbard Brook, and Luquillo Long-Term Ecological Research sites, and the Institute for Ecosystem Studies met at Harvard Forest to explore opportunities for collaborative research. Sponsored by the LTER Network Office, the "Workshop on the Impact of Removal of Foundational Species by Pests and Pathogens on Structure and Dynamics of Forested Ecosystems" examined case studies of pest- and pathogen-induced changes in the composition of forests across North America. Over the course of two snowy March days, participants presented overviews of beech-bark disease, sudden-oak-death, fungus-induced declines in Port-Orford cedar, large-scale defoliations during gypsy-moth outbreaks, and the death of eastern hemlock in response to the hemlock woolly adelgid. Researchers discussed scientific questions common to northern forests, the middle-Atlantic states, the southern Appalachians, and the Pacific northwest and considered opportunities for cross-site research on the effects of species losses on forest composition, streamflows and energetics, and ecosystem processes such as cycling of nutrients and carbon. The results of the discussions are being written up as a review paper summarizing the effects of major forest pests and pathogens on trees, and the associated impacts of large-scale changes in forest composition.