Mountain Pine Beetle Killed Trees As Snags In Black Hills Ponderosa Pine Stands

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.