Black Hills National Forest N F Bugtown Gulch Mountain Pine Beetle And Fuels Project

Mountain pine beetle-killed ponderosa pine trees in three stands of different stocking levels near Bear Mountain in the Black Hills National Forest were surveyed over a 5-year period to determine how long they persisted as unbroken snags. Rate of breakage varied during the first 5 years after MPB infestation: only one tree broke during the first 2 years in the three stands; breakage increased during the third year; the highest percentage of snags broke during the fourth year; and 10% to 14% broke in the fifth year. Cumulatively, snag breakage was 76%, 91%, and 95% in a GSL 80/90, GSL 100/110, and unmanaged stand, respectively. On average, 56% of the snags broke below 25 ft. The rate and height of breakage in mountain pine beetle-killed trees indicates that they are unlikely to persist as suitable snags for more than 5 to 10 years after infestation.

Diesel fuel oil was applied to mountain pine beetle (Dendroctonus ponderosae Hopkins) infested bolts of ponderosa pine (Pinus ponderosa Lawson) in early June. Just prior to the fuel oil application and 6 weeks later, 0.5 ft|p2|s bark samples were removed from each bolt and the numbers of live beetles counted. Beetle survival was 8.3% in bolts arranged in a single layer and 4.8% in bolts arranged in 2 layers.