Glacier National Park Progress Report

Assal, Tim; Sibold, Jason

Developing a method that used archival remote sensing data to reconstruct the Mountain Pine Beetle (MBP) outbreak; eventually will produce a model of MPB severity in Glacier National Park. The final product of this analysis is a model of mountain pine beetle severity in Glacier National Park. We were able to identify a gradient of mountain pine beetle mortality on the landscape using changes in satellite imagery reflectance over time. Our findings confirm that outbreak severity was significantly heterogeneous across the landscape. We are now using this information to investigate the influence of mountain pine beetle mortality on fire severity. We are using GIS overlay analysis with our newly developed MPB outbreak severity map and maps of wildfire severity from the Monitoring Trends in Burn Severity data for all wildfires in the park between 1984 and 2006. Coupling these two data sets will allow us to gather additional information about the interaction of these two disturbances. For example, we can now calculate that 98% of the area that burned inside the park in the 1988 Red Bench Fire was impacted by some level of the mountain pine beetle outbreak. Of that area, 85% was impacted by mountain pine beetles as first detected in 1976. Moreover, we are comparing burn severity and mountain pine beetle outbreak severity to investigate how MPB outbreak severity interacts with wildfires to shape patterns of fire severity (Figure 3). Whereas it is only a single fire event, MPB-wildfire interactions in the Red Bench Fire indicate a positive relationship between MPB severity and fire severity. More specifically, forests that experienced no MPB outbreak or low-severity MPB outbreak experienced more low- and moderate-severity burned areas, and forests that experienced moderate- and high-severity MPB outbreak had more areas that experienced moderate- and high-severity fire. We are currently testing these relationships for all fires that burned in the study area to test if the relationships identified for the Red Bench Fire are consistent. Furthermore, we are testing if relationships between MPB and fire are contingent on the time interval between MPB outbreak and fire.

Glacier National Park Progress Report

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