Variation in Surface and Crown Fire Hazard With Stand Age in Managed Coastal Western Hemlock Zone Forests in Southwestern British Columbia

Abstract

Surface and crown fuels were measured in 186 stands ranging in age from 0 years after clearcutting to old-growth forests > 300 years old in Douglas-fir (Pseudotsuga menziesii) – western hemlock (Tsuga heterophylla) – western redcedar (Thuja plicata) – dominated forests in southwestern British Columbia. Indexes of surface fire hazard based on woody debris loads, and of crown fire hazard based on 5 factors (canopy foliar bulk density, height to live crown, woody debris loads, ladder fuels, and snag quantities), were developed. Using the indexes developed, surface fire hazard followed a U-shaped trend with stand age, being highest for the first few years after clearcutting, declining to a minimum 20 to 40 years after harvesting before increasing. Crown fire hazard was lowest for the first few years after clearcutting, rose to a maximum 20 to 90 years after harvesting and then declined to low values in 100 to 150 year old forest, before rising to higher values in old-growth. In the absence of fuel reduction treatments, some post-harvesting age classes of forests will have higher surface or crown fire hazards than old-growth forests.

Parent Publication

• Fuels Management-How to Measure Success: Conference Proceedings

Citation

Feller, Michael C.; Pollock, Stefanie L. 2006. Variation in Surface and Crown Fire Hazard With Stand Age in Managed Coastal Western Hemlock Zone Forests in Southwestern British Columbia. In: Andrews, Patricia L.; Butler, Bret W., comps. 2006. Fuels Management-How to Measure Success: Conference Proceedings. 28-30 March 2006; Portland, OR. Proceedings RMRS-P-41. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 367-380