CR 20:41-54 (2002)  -  doi:10.3354/cr020041

ABSTRACT: Major ice storms are significant forest disturbance agents and natural hazards in eastern North America. Studies of forest damage suggest that ice storm severity varies among topographic positions, but little climatic information is available to evaluate fine-scale variations in ice storm climatology. Our study assesses the utility of tree-ring analysis for identifying fine-scale spatial patterns and long-term temporal variations in the frequency of major ice storms. We looked for ice storm signals in tree-ring chronologies of chestnut oak Quercus prinus L. and black oak Q. velutina Lam. at 2 sites in southwestern Virginia that were affected by known ice storms in 1979 and 1994. Radial growth of these species exhibits a dual response to ice storm disturbance. Trees with substantial canopy loss show reduced radial growth for several years following an ice storm. Other trees display increased growth due to the loss of competitors. We identified thresholds of ring-width increase and decrease that distinguished ice storms from other events, permitting a preliminary attempt to reconstruct ice storm history at each of the 2 study sites. For our Gap Mountain site, ring-width chronologies spanning the period 1914-1998 record apparent signals of major ice storms in 1920, 1979, and 1994. For the Walker Mountain site, our results suggest that during the period 1901-1998 the stand was affected by major ice storms in 1918 and 1994. This study suggests that dendrochronology provides a promising method for understanding fine-scale spatial patterns of ice storm disturbance in hardwood forests.

KEY WORDS: Dendrochronology · Tree rings · Freezing rain · Ice storms · Forest disturbance · Appalachian