Yield and financial losses associated with a jack pine budworm outbreak in Michigan and the implications for management

Stand-level merchantable volume and financial losses resulting from a 1991-1993 jack pine budworm (Choristoneura pinus pinus Freeman) outbreak were quantified for 99 jack pine (Pinus banksiana Lamb.) stands in the Race Plains area of the Hiawatha National Forest. Associations between standing value loss and stand inventory variables were evaluated. Stands were stratified into management groups based on age, site index, and stacking. Differences in standing value loss among groups were examined. Total standing merchantable volume loss and gross value toss were estimated to be 19 500 m(3) and $289 800, respectively, for the 1480-ha sample area. Standing merchantable volume loss averaged 13.3 m(3)/ha or 14% of standing volume. Standing value loss within stands averaged $194/ha. Losses were concentrated in only a few stands with eight stands accounting for over half the total standing value loss. Standing value loss was positively associated with stand age and basal area and negatively associated with the proportion of open-grown, full-canopied "wolf" trees in the stand. A significant interaction in standing value loss was observed between age-class and site index class. No significant differences in standing value loss were observed among stocking classes. Results confirm overstocked stands over 50 years of age should be prioritized for harvest.