Defoliation and mortality caused by western spruce budworm: variability in a Douglas-fir stand

Variation in Douglas-fir (<i>Pseudotsuga menziesii</i> [Mirb.] Franco) defoliation and mortality caused by the western spruce budworm (<i>Choristoneura occidentalis</i> [Freeman]) was measured in sequential annual surveys of a stand near Pemberton, British Columbia. The implications of this variability in designing defoliation and mortality surveys is discussed