Susceptibility of white spruce to attack by spruce beetles during the early years of an outbreak in Alaska

Abstract

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.

The effectiveness of vegetation management practices for prevention and control of bark beetle infestations in coniferous forests of the western and southern United States

“…Periodic annual increment (last 5 years) was 0.25 cm for infested and 0.51 cm for uninfested trees. These data agree with those of Hard et al (1983) who indicated that spruce beetle exhibited a preference for slow growing trees. Holsten et al (1995) reported that, following a spruce beetle epidemic, increased radial growth in surviving trees, primarily as a result of reductions in tree density and competition, reduced stand susceptibility to future infestations in the shortterm.…”

“…Dymerski et al (2001) reported similar results in spruce beetle-affected Engelmann spruce stands in central Utah. In Alaska, Hard et al (1983) and Hard (1985) examined conditions during the beginning of a spruce beetle outbreak in white spruce, P. glauca (Moench) Voss. Attacked trees were characterized by low radial growth, which was inversely related to tree density.…”

Spruce beetle outbreaks on the Kenai Peninsula, Alaska, and Kluane National Park and Reserve, Yukon Territory: Relationship to summer temperatures and regional differences in disturbance regimes

“…Spruce beetles selectively attack mature spruce, because large, slow-growing spruce are less able to resist the establishment of adult spruce beetles in the inner bark or phloem layer (Hard et al, 1983;Hard, 1987). After the overstory spruce are killed by spruce beetles, the smaller surviving spruce have less competition for light, soil moisture, and nutrients, and often increase their growth abruptly (Veblen et al, 1991a,b).…”

Fine-scale disturbance and stand dynamics in mature, spruce-subalpine fir forests of central British Columbia.

“…suggested that the identification of canopy disturbance based on release, measured as the percent change in radial growth, should be fairly accurate because uncertainty and ambiguity associated with the pattern is low. Ring-width series of gap-making trees, however, show a range of ring-width patterns prior to death, including slow decline resulting from root disease , to abrupt death of healthy trees with wide rings, resulting from windthrow or bark beetle outbreaks (Hard et al 1983, Holsten 1984. When canopy trees decline before death, gap-filling trees may show complex or ambiguous growth patterns.…”