SPATIOTEMPORAL ANALYSIS OF CONTROLS ON SHRUBLAND FIRE REGIMES: AGE DEPENDENCY AND FIRE HAZARD

Large fires in chaparral-dominated shrublands of southern and central California are widely attributed to decades of fire suppression. Prehistoric shrubland landscapes are hypothesized to have exhibited fine-grained age-patch mosaics in which fire spread was limited by the age and spatial pattern of fuels. In contrast, I hypothesize that fires during extreme weather conditions have been capable of burning through all age classes of the vegetation mosaic. Using the mapped fire history (1911–1995) of Los Padres National Forest, I analyzed burning patterns for hundreds of fires using a geographic information system (GIS). To estimate the degree of age dependency exhibited by the fire regime at different spatial scales, I employed methods of fire frequency analysis (i.e., fitting a generalized Weibull function to fire interval distributions). Statistics were also calculated using a temporal breakpoint of 1950 to assess possible effects of suppression. Results indicated that shrubland fires have frequently bur...

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