Susceptibility of lodgepole pine stands to the mountain pine beetle: testing of a rating system

A system for rating the susceptibility of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stands to the mountain pine beetle (Dendroctonus ponderosae Hopkins) was field tested in 38 stands in the Cariboo forest region of British Columbia in a retrospective study. A linear relationship was defined between the percentage of basal area killed by the mountain pine beetle and the susceptibility indices for the sample stands. The system was further tested using an independent data set of 41 stands from across southern British Columbia. Forty of the 41 stands fell within the 95% prediction interval of the original model data for stand susceptibility. This study provides validation for a susceptibility rating model described in 1992. The regression model and associated confidence interval also provide a useful tool for landscape level loss predictions due to the mountain pine beetle.