Mountain pine beetle in lodgepole pine: mortality and fire implications (Project INT-F-07-03)

Mountain pine beetle (Dendroctonus ponderosae Hopkins) has infested over 2 million acres of lodgepole pine (Pinus contorta Dougl. ex Loud.) forest since an outbreak began approximately in 2000 in north central Colorado. The tree mortality from mountain pine beetle outbreaks has the potential to alter stand composition and stand characteristics, along with fuel complexes. In general, it is assumed that these changes in stand structure from mountain pine beetle outbreaks in lodgepole pine forests increase fire hazard (Arno 1980, Jenkins and others 2008), though lodgepole pine fire regimes are characterized as having stand replacing high-severity fires, with nonlethal surface fires generally playing a lesser role in lodgepole pine ecosystems (Arno 1980, Kipfmueller and Baker 2000). To quantify the amount of mortality in infested lodgepole pine stands, along with identifying differences in stand characteristics and tree species composition before and after infestation, a study was conducted in Colorado lodgepole pine 7 years after mountain pine beetle outbreak initiation. Furthermore, litter, duff, and fuel bed depth along with downed woody debris loads and vegetation characteristics were examined in infested and uninfested stands. We also compared potential fire behavior and first order effects modeled with the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS) in uninfested stands, stands 7 years after mountain pine beetle outbreak initiation, and infested stands with projected fuel and stand characteristics that represent 10-percent and 80-percent tree fall.