Wildfire Patterns in Western Boreal Canada

The idea of using natural patterns as guides for policy and practices continues to gain favour in forestland management. Towards this, research activities in the boreal have been focusing on the patterns and processes of wildfires over the last 15-20 years. This project is the fourth phase of a long-term research study looking at natural wildfire patterns across the forested areas of Alberta and central Saskatchewan. This phase involved creating mortality maps from an additional 76 fires across Alberta, generating fire events from wildfires, and completing meta-analyses for all 129 fires. The event-defining algorithm defined an outer boundary for each event representing the general area of influence of each fire. This generated two types of remnants: island remnants as mapped by the original mortality maps, and 2) matrix remnants created by the algorithm, largely representing corridors between disturbed patches. The algorithm captured the entire area of each wildfire into a single event for all but five wildfires. Fires shared many key pattern characteristics across the entire data range, although some of the specifics varied. The average proportional area in remnants within each event averaged 41%, and was unrelated to event size. This finding challenges the notion of the boreal as having a so-called standreplacing fire regime. Less than 10% of the samples in this study technically qualify as stand-replacing, and at least as many would be considered standmaintaining based on mortality figures. One of the previously undocumented patterns noted in this study was the presence of multiple disturbed patches within individual wildfires. About half of all events had multiple disturbed patches, the number of which increased significantly with the log of event size. Furthermore, there tended to be one very large disturbed patch, the size of which was unrelated to event size. The shapes of both events and disturbed patches increased significantly as the log of event area increased, although disturbed patch shapes were more convoluted. Most of the island remnant area was partially disturbed, and small (<1 ha) islands account for 81% of the island numbers, but only 5% of island area. Probability of burning differentials were greater between major land types (such as nonforested versus forested), and less so for differences in forest ages, species, or