Fire Influences in Abies-Dominated Forests

Abstract

Abies-dominated forests have a relatively low fire hazard when compared with vegetation types dominated by Pinus or Picea species. Although large quantities of fuel are present, the humid climate of Abies-dominated areas reduces the probability of fire. When fires occur after prolonged drought periods, fir can be essentially eliminated from an area because it is not resistant to fire. Abies spp. tend to be shade-tolerant, late successional species and only in the absence of fire do they compete successfully with species established early in the post-fire pattern. Abiesdominated forests are more susceptible to fire following disturbance which damages or removes tree crowns, and in turn permits solar energy to reduce the moisture content of forest floor fuels. Forest harvesting is one of the recent disturbances, but it is thought that defoliation and tree mortality caused by insects also increase fire hazard. This 'insect-wildfire hypothesis' has been raised in a number of Abies-dominated areas around the world and seems intuitively plausible; yet there is little field evidence and very little experimental evidence to support the hypothesis.