| This investigation on fire mosaics addressed several aspects: (1) quantifying the role of terrain variables in fire-related mortality and historical mean fire return interval (MFRI), (2) comparing post-burn Landsat Thematic Mapper (TM) imagery, TM difference imagery, and aerial photo interpretation to map forest survival after wildfire, and (3) to describe and discuss wildfire effects on successional stage patterns and wildlife habitat.;Historical MFRI, terrain, and vegetation data were input into a geographical information system. Random sampling was conducted on all layers, and was also used to ground truth forest survival, primarily with aerial photography. Relationships of terrain to forest survival and historical MFRI were analyzed with regression. Regression was also used to model forest survival with TM data. Error matrices were used to compare classified TM data and aerial photo interpretation in mapping survival.;At both sites, terrain variables accounted for more variation in forest survival (12-62%) or historical MFRI (4.8-21.9%) within individual physiographic areas, than across the respective study areas. Moreover, the significant topographic variables differed among individual physiographic areas.;Regressions of TM band transformations were used to evaluate forest survival. The TM difference imagery with stratification by pre-fire tasseled cap (TC) wetness explained 75% of the variation in live canopy ratio, and post-burn TM Structural Index (SI) accounted for 72%. Classification of the TM difference imagery with pre-fire TC wetness had an overall accuracy of 68%, that of the post-burn SI was 63%, and that from aerial photo interpretation was 56%.;The two study sites were located on the Willamette National Forest in the Oregon Cascades. The Warner Creek burn was the location of a 1991 wildfire covering 3669 ha; the Upper McKenzie site was the location of ecological and historical fire studies.;Before the burn, landscape matrix was closed mature/old-growth. After the burn, the early seral/rock stage expanded, the open mature/old-growth stage was created, and the closed mature/old-growth was reduced and fragmented. Thus, overall habitat diversity and edge increased, but interior habitat decreased. Also, patches of early seral/rock were more variable in size and complex in shape than staggered setting clearcuts on public lands. |
