Assessing wildfire effects with Landsat thematic mapper data

Abstract

We evaluated Landsat Thematic Mapper (TM) imagery to map forest survival after a wildfire using single-date and multi-date TM imagery. In addition, landscape patterns were measured to describe the wildfire effects on successional stage patterns, and their impacts on wildlife habitat. The study site was the 1991 Warner Creek Burn, covering 3669 ha, on the Willamette National Forest in western Oregon, USA. Regressions of TM band transformations were used to estimate forest survival. Single-date TM 4/5 accounted for 73% (P 0.0001) of the variation in post-burn canopy cover, whereas the TM difference (by ratio) imagery with stratification by pre-fire tasseled cap (TC) wetness explained 78% (P 0.0001). Verification of the best models using additional data in observed versus predicted post-burn canopy cover confirmed these results. The pre-fire landscape had a matrix of closed mature/old-growth stands comprising 77% of the area. After the burn, the early seral/rock stage expanded, the open mature/old-growth stage was created, and the closed mature/old-growth stage was reduced and fragmented. Overall habitat diversity and edge increased after the burn, but interior habitat decreased.