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Blue Mountains Natural Resources Institute
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Key Science Findings of Fiscal Year 1999
Advances in chemical ecology of bark beetles. Progress is being made in understanding the chemical ecology of the spruce beetle and Ips engraver beetles in Alaska, and the Douglas-fir bark beetle in the Pacific Northwest. Preliminary results with new commercially available release devices for dispensing bark beetle pheromones are promising.
Thinning will provide some protection against spruce beetle in Alaska. Thinning to reduce basal area of white spruce stands in south-central Alaska offers some protection against spruce beetle when beetle populations are at low to medium densities.
Long-term effects of spruce beetle tree mortality in Alaska. Twenty-year-old plots in spruce beetle outbreak areas in south-central Alaska have shown major changes in tree species composition and forest structure as well as a buildup of large woody debris, plus a reduction in diversity of ground vegetation, all as a result of tree mortality. Further, very little natural regeneration of spruce is occurring in these areas.
Wind not the key factor in causes of small-scale disturbance in southeast Alaskan forests. Tree death in old-growth forests of southest Alaska most commonly leaves trees standing dead with broken stems, with uprooting occurring less frequently. This indicates that factors other than wind are the chief causes of small-scale disturbance for the area.
Dead yellow-cedar in southeast Alaska highly resistant to decay. Yellow-cedar is a decay-resistant tree that deteriorates slowly after death. Strength properties, volume and grade recovery, and decay resistance of usable wood show no or only modest change even 80 years after a tree dies.
Dwarf mistletoe in Alaska correlated to numbers and characteristics of residual hemlocks on sites. Dwarf mistletoe levels in managed forests in southeast Alaska are strongly correlated with the number, size, and infection levels of residual hemlocks left at the time of harvest. Managers can use this information to manipulate dwarf mistletoe to desirable levels.
Wide-area control of bark beetles with pheromones. Ongoing studies with pheromone methods to reduce and allocate the effects of Douglas-fir beetle outbreaks across a landscape continue to show promising results.
Spring and fall prescribed burning affects arthropods. Species diversity of ground beetles increased after fall burns, with no differences in their abundance associated with season of burn. Spider abundance dropped following spring and fall underburning, but their species diversity also increased in the fall burned areas.
Minimal effects of timber harvesting on soil arthropods. Nematodes and metabolically active fungi and bacteria did not appear to have been affected by mechanical timber removal, and little change in numbers of soil microarthropods and microbes occurred at the levels of compaction and displacement experienced in the study. Compaction did have a negative effect on abundance of microarthropods in the litter layer.
An insect attractant of logs and stumps is strongly affected by precipitation. Ethanol accumulates in logs and stumps exposed to winter precipitation. Protecting logs from rain greatly reduces the amount of ethanol and number of insect attacks. Understanding ethanol production in woody residues may lead to new options for managing some insects.
Stump fumigation with chloropicrin shows no nontarget effects. Chloropicrin applied to Douglas-fir stumps in an attempt to eliminate laminated root rot fungal disease had no significant adverse effects on ectomycorrhyzal fungi or vegetative composition or cover 5 years after application.
Nitrogen availability influences alkaloid concentrations in ponderosa pine foliage. Piperidine alkaloids in pine foliage are potential defensive chemicals. Nitrogen fertilization was found to be an effective means for significantly increasing foliar alkaloid concentrations in ponderosa pine growing on both low- and high-quality sites.
Pheromone trapping to estimate populations of a biological control agent of knapweed. Preliminary results indicate that pheromone-baited traps can be used to estimate populations of a biological control agent of spotted knapweed in Montana without unduly affecting the beneficial insect's population numbers.
US Forest Service - Pacific Northwest Research Station, Blue
Mountains National Resources Institute