PARENT SESSION
Poster Session 11: Disturbance Ecology
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

A comparison of mortality risk factors associated with large, infrequent wind disturbances of Carolina Piedmont forests.

Xi, Weimin^*,1, Peet, Robert¹, DeCoster, James ², Urban, Dean ³, ¹ Department of Biology, Chapel Hill, NC 29599-3280, USA² U.S. National Park Service, Midwest Regional Office, Omaha, NE 68102, USA³ Nicholas School of the Environment and Earth Sciences, Durham, NC 27708, USA

ABSTRACT- Past studies of large, infrequent wind disturbances have shown how meteorological, topographical, and biological factors interact to generate damage patterns, but have left open the extent to which these limited previous findings are representative and can be used to predict damage. We present a multiple-scale comparative analysis and evaluate the consistency in mortality risk factors associated with three major wind events: the Umstead tornado (1988), Hurricane Hugo (1989), and Hurricane Fran (1996). Our results reveal distinct differences in the damage caused by hurricanes relative to the tornado, and to some extent consistency between hurricanes. As compared to hurricanes, the tornado caused significantly greater and less species-specific mortality. Within-stand hurricane damage was more patchy, indicating tree morality risk must be conditioned on occurrence of unpredictable individual gusts. Differences in associated rainfall have strong influences on damage patterns with high rain increasing the risk of blow down relative to breakage. Landscape-scale analyses show relatively predicable patterns controlled by a combination of wind speed, topography, and pre-disturbance species composition, in contrast to local patterns, which can be understood only in the context of site conditions and small-scale wind patterns.

Key words: Mortality risk factors, wind disturbances, multi-scale analysis, Piedmont forests