Large natural disturbances have important implications for both short and long term ecosystem function and dynamics. Among the most important attributes is severity, a combined function of disturbance intensity and the relative susceptibility of ecosystem elements, such as vegetation and soils. The Pagami Creek Fire of August 2011 in the Boundary Waters Canoe Area Wilderness of Minnesota presents an historical opportunity for understanding spatial heterogeneity in fire effects and its consequences for future ecosystem recovery within a fire dependent ecosystem in the eastern United States. This large fire exhibited a wide range of behaviors across an ecologically diverse area for which unprecedented levels of pre-fire forest conditions were documented. The seasonal timing requires a rapid field response so that fire intensity, severity, and initial soil impacts can be accurately measured prior to the onset of winter.
Transects of plots will be sampled across major forest types for data on live and dead vegetation amounts and distribution and chemical attributes of the soils in burned and unburned plots that will also be compared to data obtained before the fire. Satellite imagery will be used to characterize tree and shrub burn severity and vegetation loss. This information will be used to scale the plot level data to the entire burned area and will enable the scientists to examine the feedbacks among forest structure and fire disturbance and to better predict future ecosystem recovery.
Opportunities for studying the behavior and ecological impacts of major fire events in forests of the eastern United States are dramatically less than in the west. This research will provide a foundation for programs that will increase public safety, facilitate reintroduction of fire into fire dependent eastern forests, and provide guidance for forest and wilderness management in the face of major natural disturbances.
Scientific Merit. The Pagami Creek fire was the largest in Minnesota in nearly 100 years. Fires of this magnitude are large sources of CO2, oxidized forms of N, and gaseous Hg to the atmosphere. Based on the area of the fire and our mean pool loss rates when compared to unburned controls, we estimate over 500,000 Mg of C, nearly 5,000 Mg of N and over 250 kg of Hg was emitted to the atmosphere as a result of the Pagami Creek Fire. For C that amount is similar to the amount of C that 52,000 Sport Utility Vehicles emit into the atmosphere every year. The amount of N is equal to about the fertilization rate of 31,000 ha of corn. The Hg emissions are comparable to about 18% of the 2010 annual emissions for the state of Minnesota. In addition, we were able to show the capacity of remotely sensed imagery to detect early successional forest and herbaceous species, and even detect different varieties of herbaceous species following a fire. This shows the potential of remote sensing for tracking invasive species distributions following disturbances at a landscape scale. The results of our study are novel and represent a significant addition to the literature on the benefits of using remote sensing and rapid field sampling to detect and quantify early patterns of forest ecosystem response to wildfire disturbance. We are not aware of any similar studies that have attempted to use remote sensing in a similar fashion or have had the wealth of pre- and post-fire data, especially in a sub-boreal forest ecosystem. Our results show considerable promise for the use of multiple remote sensing types for characterizing fire severity and ecosystem response (Figures 1 and 2). Broader Impacts. Because of the magnitude of the Pagami Creek fire, it had a major influence on the management of the Superior National Forest and the associated Boundary Waters Canoe Wilderness Area (BWCWA). The BWCWA is the most visited wilderness area in the US and, as such, our research will help inform how to manage such areas following fire, and provide critical information on a) how pre-fire landscape characteristics influence fire severity and then b) how these affect post-fire recovery, not just of vegetation, but soils and other components of the system.
