Partial cutting lodgepole pine stands to reduce losses to the mountain pine beetle
Partial cutting prescriptions were applied in the fall of 1978 through the early winter of 1980 to lodgepole pine stands (Pinuscontorta Douglas var. latifolia Engelmann) threatened by mountain pine beetle (Dendroctonusponderosae Hopkins) in the Kootenai and Lolo National Forests in western Montana, U.S.A. Partial cutting prescriptions consisted of removing from separate stands all trees 17.8, 25,4, and 30.5 cm and larger diameter at breast height (dbh), and prescriptions leaving 18.4, 23.0, and 27.6 m2 basal area per hectare. In thinned stands, the first 5 years' results following cutting showed greatly reduced tree losses to mountain pine beetle when compared with untreated stands (P < 0.01) on both forests. There were no significant differences in tree losses among partial cut treatments (P > 0.05). Post treatment mortality of lodgepole pine 12.7 cm and larger dbh to mountain pine beetle averaged 4.0 to 38.6% on the Kootenai and 6.0 to 17.1% on the Lolo in treated stands, compared with averages of 93.8 and 73.1% in untreated stands. Partial cutting appears to be useful for reducing lodgepole losses to mountain pine beetle.