Occurrence of wildfire in the northern Great Lakes Region: Effects of landcover and land ownership assessed at multiple scales

Risk of wildfire has become a major concern for forest managers, particular ly where humans live in close proximity to forests. To date, there has been no comprehensive analysis of contemporary wildfire patterns or the influen ce of landscape-level factors in the northern, largely forested parts of Mi nnesota, Wisconsin and Michigan, USA. Using electronic archives from the USDA Forest Service and from the Departm ents of Natural Resources of Minnesota, Wisconsin, and Michigan, we created and analysed a new, spatially explicit data set: the Lake States Fire Data base. Most of the 18 514 fires during 1985-1995 were smaller than 4 ha, alt hough there were 746 fires larger than 41 ha. Most fires were caused by deb ris burning and incendiary activity. There was considerable interannual var iability in fire counts; over 80% of fires occurred in March, April, or May . We analysed the relationship of land cover and ownership to fires at two di fferent fire size thresholds across four gridded spatial scales. Fires were more likely on non-forest than within forests; this was also true if consi dering only fires larger than 41 ha. An area of National or State Forest wa s less likely to have experienced a fire during the study period than was a forest of equal size outside National or State Forest boundaries. Large fi res were less likely in State Forests, although they were neither more nor less likely to have occurred on National Forests. Fire frequency also varie d significantly by forest type. All results were extremely consistent acros s analysis resolutions, indicating robust relationships.