A common misconception of wildland fires is that they affect all burned areas the same. In reality, the effects of fires across the landscape are highly discontinuous and varied. In any given fire, some areas of the landscape are radically changed due to intense scorching or sustained burning, while other areas are completely untouched. This varying burn severity results in a heterogeneous pattern or fire mosaic on the landscape. Burn severity is a measure of the ecological impacts of the fire, in terms of plant survivorship or mortality, depth of the burn in organic layers, or amount of biomass consumed. Information about burn severity helps fire and resource managers understand the effects of wildland fires on the fuel, vegetation and wildlife of Alaska’s national parks.
In order to better understand burn severity and wildland fire’s effects on Alaska’s national parks, the NPS Fire Management Program, in conjunction with the U.S. Geological Survey (USGS) EROS Data Center in Sioux Falls, South Dakota, have used remote sensing to map burn severity for all large NPS fires in Alaska since 1999. Burn severity maps and GIS datasets are created by analyzing the differences in Landsat satellite imagery collected before and after the fire. Burn severity maps are used by fire management staff to refine and improve final fire perimeters and to identify unburned islands within a burned area. In addition, these burn severity data products provide a means to update fuels and vegetation GIS datasets to reflect the changes on the landscape brought about by each passing fire season.
In order to test the accuracy of the satellite-derived burn severity maps, NPS fire management staff has installed nearly 300 plots within burned areas occurring in several NPS units in Alaska. The linear regression between these plots and the satellite-derived burn severity maps showed a positive correlation between ground and remote sensing measures of burn severity. These results have been published in both Alaska Park Science and the International Journal of Wildland Fire. Additional work continues on interpretation of burn severity maps and the application of burn severity data products in landcover and fuels mapping. Through burn severity mapping, NPS fire management staff are increasing their understanding of the effects of past fires and enhancing their ability to predict the behavior and consequences of future fires in Alaska’s national parks.
Contact: Brian Sorbel, Regional Fire GIS Specialist or Jennifer Allen, Regional Fire Ecologist
Phone: (907) 644-3413 or (907) 455-0652
*This story supports the National Fire Plan |
