In this study we used information from topographic, vegetation inventory and ecosystem databases, aerial photographs, field surveying and wind flow modelling to explore the relationships between wind regime, topographic location, soil conditions and stand structure and composition. We compiled these data for eight 1:20,000 NTS mapsheets on south coastal Vancouver Island in a geographic information system. We evaluated associations, and constructed predictive models for risk of whole or partial disturbance by wind in natural stands. Patches originating from stand replacing wind disturbance occupied 1% of the landscape within the overall study area, increasing to 4 % in mapsheets near the coast. Patches ranged in size from 0.3 to 59 ha, averaging 8.5 ha. They occurred more frequently on higher topographic exposure and on well-drained fertile soils. Hemlock and amabilis fir were strongly associated with these types both in field and forest cover data. Well fitting logistic regression models were produced, enabling creation of maps showing the distribution of susceptibility to stand replacing wind disturbance across the landscape. The improved knowledge of the processes underlying stand and landscape conditions will assist natural resource managers in the development of ecologically-based management plans for coastal stands and landscapes.
Stephen J. Mitchell
Mitchell, Stephen J., Pearson, Audrey F.; Kimmins, J.P. (Hamish); Lanquaye, Naa; Ortlepp, Stephanie. 2004. Investigation of windthrow as a natural disturbance agent in coastal BC forests. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report