THE ROLE OF TERRAIN IN A FIRE MOSAIC OF A TEMPERATE CONIFEROUS FOREST

This investigation focused on the role of terrain variables in fire-re lated mortality. The study area was the location of a 1991 wildfire, t he Warner Creek Burn, on the Willamette National Forest in western Ore gon. Forest survival at the Warner Creek Burn was interpreted from aer ial photography. Terrain data were generated from digital elevation mo dels (DEM), and from digitized stream, ridge, and vegetation layers, w hich were input into a geographic information system (GIS). We randoml y sampled all layers, and investigated the relationship of vegetation and terrain to mortality using regression analyses. Vegetation and ter rain variables accounted for more Variation in forest survival within individual physiographic areas (5.4-61.9%) than across the entire stud y area (3.7-24.4%). Moreover, the significant topographic variables di ffered among individual physiographic areas, and included ridgeline pr oximity, elevation, stand age, and aspect. Factors such as fire fighti ng, fuel loading, weather conditions, and neighborhood effects probabl y affected forest survival at Warner Creek along with terrain. Observa tional studies such as this one could identify the topographic variabl es meaningful for inclusion in probabilistic models of wildfire behavi or. (C) 1997 Elsevier Science B.V.