Crown loss and subsequent branch sprouting of forest trees in response to a major ice storm.

BROMMIT, A., N. CHARBONNEAU, T. A. CONTRERAS and L. FAHRIG (Department of Biology, Carleton University, Ottawa, Ontario, Canada, K1S 5B6). Crown loss and subsequent branch sprouting of forest trees in response to a major ice storm. J. Torrey Bot. Soc. 131: 169-176. 2004.-In January of 1998, a severe ice storm hit much of eastern Ontario, western Quebec, and the northeastern United States. The objective of this study was to determine whether this disturbance could result in short-term changes in canopy dominance by different tree species. We measured canopy loss in 1998 of 2,919 trees in 164 forest plots distributed across the Ottawa, Ontario region. In 2000, we measured branch sprouting in the same trees. We found a positive cross-species relationship between the proportion of stems damaged by the ice storm and the proportion of stems showing branch sprouting in response to damage (r = 0.498, P = 0.01). Prunus serotina and Acer rubrum showed exceptionally high sprouting-to-damage ratios, whereas Fagus grandifolia and Populus tremuloides showed exceptionally low ratios. Mean percent crown loss and mean number of branch sprouts on damaged stems were also correlated across species (r = 0.404, P = 0.04). Prunus serotina and Quercus macrocarpa showed exceptionally high mean number of branch sprouts and Carpinus caroliniana showed exceptionally low mean number of branch sprouts compared to other species. No conifer species showed any branch sprouting. We predict that due to these different sprouting-to-damage ratios, species such as Prunus serotina, Acer rubrum, and possibly Quercus macrocarpa, may become better represented in the forest canopy while Fagus grandifolia, Populus tremuloides, and conifer species may become less well represented in the canopy in the short-term. These changes in canopy dominance may be prolonged if ice storms become more common due to climate change.