Evaluating the Vulnerability of Maine Forests to Wind Damage

Numerous factors, some of which cannot be controlled, are continually interacting with the forest resource, introducing risk to management, and making consistent predictable management outcomes uncertain (Birot and Gollier 2001, Wilson and Baker 2001). Included in these factors are threats or hazards such as windstorms and wildfire. Factors influencing the probability (risk) of windthrow or windsnap occurring can be grouped into four broad categories: regional climate, topographic exposure, soil properties, and stand characteristics (Mitchell 1995). Of these categories, stand characteristics are most commonly and easily modified through forest management. To augment our understanding of the interaction between forest management and wind damage vulnerability in Maine, we developed a wind damage model that reflects site and stand characteristics. Model calibration used information from published literature and experiences of regional managers. The model was evaluated using spatially explicit wind damage records from a 40,800-ha managed forest area in northern Maine. A comparison of means analysis identified significant differences in vulnerability index values between categorical populations of stands that have either recorded blowdown or no recorded blowdown during the last 15 years.