Colin Orians, Missy Holbrook, Kristin Lewis

Harvard University

Primary Interests:

plant ecophysiology, plant-insect interactions, carbon balance, plant defenses

HWA Objectives:

Eastern hemlock (Tsuga canadensis (L.) Carriere) is an important component of eastern forests, both because of the unique microclimate found in hemlock stands and the habitat those stands provide for wildlife. This species is currently being eliminated in the southeastern part of its range by the introduced hemlock woolly adelgid (Adelges tsugae (Annand)), which is spreading northward through New England. Most researchers assume that T. canadensis is uniformly vulnerable to attack by and mortality from HWA. Nevertheless, there is variation in susceptibility - for example, T. canadensis expeiences more rapid adelgid-induced mortality on western-facing and dry slopes (Orwig et al. 2002). Thus, we are interested in what ecological factors may affect both susceptibility to and effects of the HWA in Eastern hemlock. Furthermore, the physiological effects of the adelgid on the hemlock tree are poorly understood, and may hold clues to the mechanism by which the adelgid kills hemlock. We will be investigating the ecological and physiological factors that are correlated with adelgid infestation and mortality.