Accuracy of Defoliation Estimates from Aerial and Ground Surveys in a Boreal Forest during an Outbreak of the Hemlock Looper, Lambdina fiscellaria (Guenée)

Annual estimates of defoliation are important tools for managing forest insect defoliators such as the hemlock looper, which feeds on conifer needles all age classes. We tested accuracy classes obtained from aerial surveys by comparing them with ground-based during a recent outbreak this insect. used an approach derived Fettes method to estimate current-year shoots well four previous years. Defoliation provided accurate overall and strength relationship gradually decreasing one-year-old four-year-old foliage. The survey light moderate first year outbreak, but was lower both ends gradient much less reliable after second outbreak. All levels were then observed in stands where had not been detected survey. Cumulative foliage brings new challenge crews assigned programs. Ground-level can help appraise risk tree mortality following year.