Fire in Western Forest Ecosystems

Major forest types that are characterized by nonlethal understory fire regimes include those where ponderosa pine or Jeffrey pine has been a major component either as a fire-maintained seral type or as the self-perpetuating climax (table 5-1). This includes extensive areas throughout the Western United States from northern Mexico to southern British Columbia, Canada (Little 1971). Also, sizeable areas of open woodlands dominated by Oregon white oak, California black oak, blue oak, or Digger pine were characterized by frequent understory fires largely due to deliberate burning by Native Americans (Boyd 1986; Lewis 1973). These occurred in relatively dry areas west of the Cascades and Sierra Nevada from the southwest corner of British Columbia to southern California. Recent studies suggest that large areas of the redwood forest in coastal northern California were characterized by frequent understory fires resulting from burning by Native Americans (Brown and Swetnam 1994; Duncan 1992; Finney and Martin 1989; Greenlee and Langenheim 1990). Additionally, portions of other forest types may also have had understory fire regimes. For example, some areas of interior Douglas-fir near the drought-caused lower timberline in the higher valleys of the Rocky Mountains may have been maintained in open condition in understory fire regimes (Arno and Gruell 1983; Arno and Hammerly 1984). Nevertheless, most of this type is best represented by the mixed regime.