Twenty-five variable sample plots were examined in mature white spruce (Piceaglauca (Moench) Voss) stands, in southcentral Alaska. These stands, located in the Canyon Creek – Quartz Creek valley on the Kenai Peninsula, have been infested by spruce beetle, Dendroctonusrufipennis (Kirby), since 1978. Diameter was not an important criterion for spruce susceptibility to attack or death unless large diameter was coupled with slower than average radial growth in the last 5 years, an apparent indicator of current tree vigor. A sigmoid transformation of percent mortality of spruce was inversely related to the logarithm of mean cumulative radial growth of spruce in the last 5 years and was directly related to number of spruce per hectare greater than 24.1 cm in diameter. This relationship is portrayed graphically as a rudimentary stand hazard rating model.
Two stands of white spruce (Piceaglauca (Moench) Voss), one on a south aspect and one on a north aspect on the Kenai Peninsula of Alaska, were sampled intensively to determine site and host variables associated with high attack densities by spruce beetle, Dendroctonusrufipennis (Kirby). Attacks peaked during the early phase of tree radial growth on both aspects as the rate of tree expansion slowed. Generally, the first trees attacked, also the most heavily attacked, expanded more slowly before and after beetle attack than did trees attacked later or not at all. High attack densities were concentrated in trees on dry, cold soils. Mean percent basal-area growth of plots was inversely related to stocking of live spruce and to percentage of sample trees attacked and killed.
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