Wednesday, December 12, 2007
D0552

Predicting post-fire bark beetle attack and tree mortality in ponderosa pine forest type three years following prescribed and wildland fires in the northern Rocky Mountains

Ryan S. Davis, ryan.davis@biology.usu.edu, USDA Forest Service Rocky Mountain Research Station, 860 North 1200 East, Logan, UT, Barbara J. Bentz, bbentz@fs.fed.us, USDA Forest Service, Rocky Mountain Research Station, 860 North 1200 East, Logan, UT, and Sharon M. Hood, shood@fs.fed.us, USDA Forest Service Fire Ecology/Fuels Project, 5775 US W Highway 10, Missoula, MT.

459 fire-injured ponderosa pine were monitored for mortality and bark beetle attack three years following one prescribed and one wildland fire in Idaho and Montana, respectively. Logistic regression was used in the construction of four predictive ponderosa pine mortality models and three predictive bark beetle attack models. Diameter at breast height (DBH), post fire live-crown proportion (LCP), presence of Ips and/or Dendroctonus beetles (ATK), and an interaction between DBH and ATK were significant in predicting tree mortality. Tree mortality rates increased with the presence of primary bark beetles independent of dbh, and increased at lower diameters because of susceptibility to fire-caused mortality. Mortality also decreased as LCP increased. DBH, LCP, cambium kill rating (CKR), bole char proportion (CHIP), and the interactions of DBH and LCP, and CHIP and LCP were significant in predicting bark beetle attack probability. Increased frequency of attack occurred as LCP increased and CHIP increased, indicating that beetles prefer to attack trees with damaged boles and slightly injured crowns. Attacks also increased as LCP decreased and DBH increased indicating that beetles also prefer to attack larger diameter trees with greater crown fire injury. Classification tables for all predictive models were presented for application in post-fire management development.


Species 1: Coleoptera Curculionidae Dendroctonus brevicomis (western pine beetle)
Species 2: Coleoptera Curculionidae Dendroctonus ponderosae (mountain pine beetle)
Species 3: Coleoptera Curculionidae Ips emarginatus (emarginate ips)