Tree mortality caused by the western hemlock looper in landscapes of central British Columbia

An outbreak of the western hemlock looper, Lambdina fiscellaria lugubrosa ( Hulst) (Coleoptera: Geometridae), caused tree mortality in central British Columbia, Canada, to stands composed of alpine fir, Abies lasiocarpa (Hook. ) Nutt., western hemlock, Tsuga heterophylla (Raf.) Sarg., white spruce, Pi cea glauca (Moench) Voss, and western red cedar, Thurja plicata Donn. After 4 years, high levels of tree mortality (51-96% of all trees with DBH great er than or equal to 7.5 cm) occurred in areas of severe defoliation classif ying this pest as a serious depletion agent of British Columbia forests. Tr ee mortality occurred rapidly, mostly within 2 years of the start of the in festation. Equations are provided to allow foresters to determine expected mortality levels with reasonable precision. A higher proportion of mortalit y occurs on alpine fir rather than on other species. (C) 1999 Elsevier Scie nce B.V. All rights reserved.