Windthrow Hazard Mapping using GIS, Canadian Forest Products ...

ApplicationsThese models predict the probability of damage to clearcut edges under givencombinations of environmental and management conditions. Because these maps usestand level information from broad scale inventories, they indicate conditions at thestand level not at the microsite or tree level. Furthermore, aerial photographinterpretation of wind damage does not detect low levels of damage which might beimportant in riparian areas or areas of unstable terrain. These maps are intended forstrategic planning during the development plan stage. Windthrow risk and potentialimpacts should be assessed in the field during cutblock layout. Since partiallyharvested stands were not represented in the model fitting dataset, predictions are notreliable in these stand types.ConclusionsAdequately fitting, local windthrow risk prediction models can be developed usingstand, site, topographic, wind and management variables. Spatial autocorrelation, animportant issue to consider when analysing spatial data was also taken intoconsideration and was handled more rigorously in this study than in previous studies.The availability of extreme wind data substantially improved the model. In ourinvestigations of models from coastal and interior BC locations, we are findingconsistency in the variables selected and general portability of empirical models toareas with similar conditions. This reflects consistency in the underlying factors thatcontribute to windthrow risk. However windthrow prediction models work best forlandscape sub-units whose attributes fall within the area from which data wasgathered. The resulting hazard map for TFL 30 should be useful for strategicdevelopment planning.18