Fall rate of lodgepole pine killed by the mountain pine beetle in central Oregon

Abstract

The fall rate of nearly 600 lodgepole pines(Pinus contorta) killed by the mountain pine beetle (Dendroctonus ponderosae) in central Oregon was investigated in thinned and unthinned stands. Estimates were obtained by fitting a complementary log-log model to the conditional probabilities of trees falling within a given year. Snags began falling 3 y r after death In thinned stands and 5 yr in inthinned stands. Small trees fell slightly faster than large trees in thinned stands, but tree size was not a factor in the fall rate in unthinned stands. In thinned stands, 50% were down in 8 yr and 90% were down in 12 yr. In unthinned stands, 50% were down in 9 yr and 90% were down in 14 yr. Nopartici dar calendar year had tree fall that was significantly greater than average. All beetle-killed trees broke off at the ground when they fell. The rate that trees fall in different environments may be related to the speed of bole decay at the ground level.