• MacLean, D.A.
  Maritimes Forest Research Centre
  

Tree mortality resulting from a severe spruce budworm outbreak which began in 1974 on the Cape Breton Highlands was analyzed at five locations. Five permanent sampling plots at each location were measured for initial tree and stand characteristics, and assessed for tree mortality as of September 1977 and September 1978. Mortality varied considerably among and within sampling locations, with three broad groupings emerging: one location with <1% of the basal area dead by 1978, three locations with 10-15% of the basal area dead, whereas the fifth area had 36% of the basal area dead. Examination of increment cores from several trees at the sample locations indicated the growth during the infestations was considerably lower than and correlated with, growth before the infestation. Mortality on the sample plots generally increased with increasing values of a variety of stand characteristics, including basal area, total volume, mean dbh, and mean basal area, but considerable variability was present, possibly because the infestation was more advanced at certain sampling location than at others. Undoubtedly, further mortality will occur on these plots since budworm populations are still high and many of the tress presently surviving are in advanced state of defoliation.