WWETAC Projects

Project Title: Evaluating interactions between insect infestations and fire extent and fire severity: A preliminary investigation in Washington and Oregon

Principal Investigators: Penny Morgan, Department of Forest Resources, University of Idaho; Zachary A. Holden, USDA Forest Service; Eva Strand, Department of Rangeland Ecology and Management, University of Idaho; Jeff Hicke, Department of Geography, University of Idaho; Alan Ager, WWETAC, USDA Forest Service

Status: Ongoing

E-mail Contact: pmorgan[at]uidaho.edu

Summary: Fire activity and insect infestations in western forests are both expected to increase with climate change. Interactions between these two important disturbance agents (e.g. how insect-infested stands will influence fire behavior and post-fire ecological effects) are relatively unknown.  This study will assess the effects of insect infestations on fire extent and fire severity using data available for Oregon and Washington. A 22-year burn severity atlas databases developed from pre and post-fire Landsat images will be combined with historical aerial insect survey data.

Hypotheses include:  1. Timing of insect disturbance and fire occurrence matter. Fires that occur soon after initial insect attack will increase the probability of severe fire occurrence.  2.  Fires that occur long after insect attack and tree mortality may burn intensely (i.e. high fire line intensity and crowning in dead needle laden trees) but will show a decrease severity inferred from satellite imagery due to lack of green vegetation at infested sites, despite the potential for severe understory effects (e.g. soil heating and post-fire erosion.  3.  Post-fire effects will depend on the intensity of the insect infestation. Low-to moderately infested stands will show higher post-fire severity response inferred from satellite data, due to increased crown fire risk, higher surface fuel loading and presence of green canopy.  4. Fire effects on soil characteristics will be higher in insect infested stands due to increased surface fuel loading and low packing ratios of those fuels.

See related WWETAC project: Fire, bark beetles and salvage logging in the Greater Yellowstone Ecosystem

Project ID: FY08AA41