Distribution of residual vegetation associated with large fires in Alberta

Abstract

Fire size and shape, number and size of islands of residual vegetation, amount of edge, and distances to residual vegetation were analyzed for 69 fires that burned in Alberta between 1970 and 1983. These fires ranged in size from 21 to 17 770 ha. Distribution of residual vegetation was compared among five fire size classes. Fires in the smallest size class (20–40 ha) did not contain any islands of unburned vegetation. Percent of area within the fire perimeter that was actually disturbed decreased with increasing fire size. The number of unburned islands per 100 ha was highest for the third and fourth largest fire size classes (201–400 and 401–2000 ha). Median island area per fire, fire shape index, and edge index increased with fire size. Percentages of burned area within 100, 200, 300, 400, and 500 m of residual vegetation decreased with increasing fire size. These results indicate decreased potential for natural reforestation and increased benefits to some wildlife habitats as fire size increases.