Conclusion

Wind damage to forests in Maine is a continual consideration for forest managers across the region. The importance of wind damage in the State is likely to increase as large areas of forest that were regenerated during the spruce budworm outbreak of the 1970s and 80s continue to mature. In addition, the vast majority of harvesting in the State utilizes partial harvesting techniques that increase stand susceptibility to windthrow. If these trends in stand height and area thinned continue, managers will need tools and techniques to help them manage the growing wind damage threat. Spatial risk index modeling with GIS provides an alternative view of the landscape, allowing for threat assessment and more informed decision making. The wind vulnerability model developed for this project can be used as a tool to assist in forest planning and provide insight into historic trends in forest dynamics and habitat associations. This tool should be portable to other regions because it contains variables that are frequently identified as critical in predicting windthrow vulnerability. The stand level variables are general enough to adapt to similar forest typing schemes used by other managers in the State.

There are multiple complexities associated with modeling vulnerability to wind damage in forests. Foremost among these is modeling the interaction of rare regional wind events, chaotic local wind behavior, changing soil conditions (saturation and freezing), and dynamic stand characteristics (growth and manipulation). One approach for managing the uncertainty surrounding wind damage is to develop relatively simple models of vulnerability based on past observations of factors influencing damage. These more general models, like the one developed for this project, would not be expected to predict past wind damage as well as models developed directly from damage information collected after a particular storm or in a specific landscape. However, they may prove less biased towards particular sites, stand conditions, or individual wind events and, therefore, be more useful for guiding forest management across a large region or as stand conditions change through time.