PARENT SESSION
Oral Session #44: Disturbance ecology of forests: Animals, wind, gaps, edges. Presiding: S. Archer.
Wednesday, August 8, 2001. 8:00 AM to 11:45 AM. Hall of Ideas G.
Pre- and post-disturbance conditions in an old-growth forest: catastrophic wind in Wisconsin's hemlock-hardwoods.
Schulte, Lisa1, Guntenspergen, Glenn2, Mladenoff, David1, 1 2
ABSTRACT- Although predominant throughout the Great Lakes region prior to European settlement, old-growth hemlock (Tsuga canadensis) - northern hardwoods forests are presently limited to a few small tracts. We discuss a long-term dataset that chronicles the effects of catastrophic wind disturbance and offer insights into past and future dynamics within this forest type. In the mid-1900s, the 61-ha Flambeau River Hemlock-Hardwood Scientific Area was an old-growth forest dominated by large eastern hemlock with a strong component of yellow birch (Betula alleghaniensis). In 1977, hurricane-force winds struck the region and toppled nearly all canopy trees. Despite a post-disturbance presence of hemlock and yellow birch as trees and saplings, data gathered over the last 22 years show that forest recovery is not proceeding toward its pre-disturbance state. In locations where regeneration has occurred, American basswood (Tilia americana) and sugar maple (Acer saccharum) dominate the forest; yellow birch is a minor component and eastern hemlock is absent from all structural classes. Of all forest layers, only the herb layer exhibits partial recovery to the pre-disturbance state, but only where canopy closure has occurred. In addition to offering insights into a major disturbance process within hemlock - northern hardwood forests, this study highlights the difficulty in predicting ecosystem recovery from catastrophic disturbance and the importance of long-term ecological data sets.
KEY WORDS: disturbance, hemlock (Tsuga canadensis) - northern hardwoods, catastrophic wind, Wisconsin