Dendrochronology study of fire history, 1475 to 1996, Blue River watershed, Oregon (Weisberg thesis)

Fire history and fire regimes were reconstructed for a 450 square meter area in the central western Cascades using tree-ring analysis of fire scars and tree origin years at 137 sampled clearcuts. Temporal patterns of fire frequency, severity, and size, and interpreted topographic influences on fire frequency are described. Influences of fire history and topography on the development of forest structure are evaluated. Ninty-four fire episodes were reconstructed for the 521-year period from 1475 to 1996. The average mean fire interval, Weibull median probability interval, and maximum fire interval of 4-ha sites were 97 years, 73 years, and 179 years, respectively. Fire frequency and severity patterns were weakly but significantly associated with spatial variation in hillslope position, slope aspect, slope steepness, and elevation. Fire frequency was lower for higher elevations, lower slope positions, and more mesic slope aspects. Fre severity was lower for higher elevations, lower slope positions, more north-facing slopes, and more gradual slopes. Three fire regime classes are defined and mapped. Study parameters include several variables describing fire scar and tree origin years, reconstructed fire history, fire frequency, fire severity, fire size, forest stand structure.