PARENT SESSION
Oral Session # 96: Disturbance Ecology: Wind and Water.
Presiding: L Battaglia
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 202.
Interactions between beech bark disease and wind disturbance with consequences to stand structure and composition.
Papaik, Michael *,1, 2, Canham, Charles 1, Woods, Kerry3, Latty, Erika4, 1 Institute of Ecosystem Studies, Millbrook, NY2 University of Massachusetts, Amherst, MA3 Benningon College, Bennington, VT4 University of Wisconsin, Madison, WI
ABSTRACT- Over the past century introduced pests and pathogens have caused widespread declines of a number of tree species in forests of eastern North America, including dominant species such as beech (Fagus grandifolia ). Most studies have focused on changes to forest composition and structure as a direct result of the mortality caused by the pest or pathogen. Our studies of the resistance of trees to windthrow in forests of northern New York and the upper peninsula of Michigan suggest the hypothesis that the resistance of beech trees to windthrow is strongly dependent on the presence of beech bark disease (BBD). The disease is absent from forests of northern Michigan, and in those forests, beech and sugar maple (Acer saccharum) have identical susceptibility to windthrow, while in northern New York, where BBD has been present for 50 years, beech trees have much higher susceptibility to windthrow. Within the New York population, there is a significant negative effect on resistance to windthrow of the level of BBD on individual trees. We tested potential consequences of this effect on long-term structure and composition in these forests using a computer simulation model, SORTIE. In the absence of BBD, beech is the competitive dominant of the 9 major tree species in this region. In simulations in which the hypothesized impact of BBD on the resistance of beech to wind was included, no competitive dominant emerged, species such as hemlock (Tsuga canadensis) and yellow birch (Betula alleghaniensis) increased dramatically in abundance, and the overall diversity of tree species increased. Our results highlight the effects that host-specific pathogens of dominant species can have on long-term competitive dynamics and species coexistence in forests.
Key words: wind disturbance, beech bark disease, forest dynamics