Although mixed-pine forest ecosystems once dominated almost 40% of eastern Upper Michigan, few relatively undisturbed mixed-pine forest ecosystems remain. The legacies of turn-of-the-century logging, catastrophic wildfires, and fire suppression have resulted in altered structures, and increased fuel loadings that have reached potentially dangerous levels. To better understand how these legacies have influenced these forest ecosystems, we are quantifying the differences in fire-history regimes, fuel loadings, and forest compositions and structures between pre-European settlement and post-settlement mixed-pine forest ecosystems. Concurrently, we are examining the current fire hazard and forest management planning efforts of different land management agencies in the region, including the USDI Fish and Wildlife Service, USDA Forest Service, Michigan Department of Natural Resources, and The Nature Conservancy. Our overall goal with this integrated research program is to develop restoration-based fuel reduction recommendations for mixed-pine forest ecosystems of eastern Upper Michigan.
Results/Conclusions
Our preliminary results, based on extensive fire-scar analyses of sites located at the Seney National Wildlife Refuge, the Two Hearted River Forest Reserve, and the Hiawatha National Forest suggest that the natural fire regimes of mixed-pine forest ecosystems in eastern Upper Michigan were dominated by frequent small (< 100 ha) fires with a fire return interval (FRI) of 20-30 years and large (5,000-10,000 ha) surface fires with a FRI of 50-70 years. However, widespread logging led to an increase in small fires in the first half of the 20th century while active fire suppression resulted in a decrease in fire frequency in the non-wilderness areas in the second half of the 20th century. Surprisingly, we find little evidence of differences in fire regimes between two major landform types (glacial outwash channels vs. sand ridges). However, our analyses do reveal that stand composition, structure, diversity, and fuel loadings are closely related to past fire history. Finally, our analysis of the decision-making process used by federal and state agencies and non-government organizations when deciding how to manage both natural and prescribed fire suggests that these processes involve complex tradeoffs and are largely driven by both fundamental management objectives and external drivers (e.g., public perception, tradition, industry standards). Our results also suggest that the potential and perceived risks associated with fire vary both within individual organizations as well as among them. Currently, we are working to integrate our ecological analyses with the decision-making analyses to aid land managers in the development of comprehensive restoration-based fuel reduction techniques across the region.
