Numerous stands of western larch, Larix occidentalis, on the St. Joe, Coeur d'Alene, and Kaniksu National Forests, Idaho, show signs of gradual deterioration following repeated defoliation by larch casebearer, Coleophora Zaricella Hbn. (Tunnock et al. 1969). Stand deterioration can occur after 4 years of continued heavy defoliation. The main symptom...
Epidemic levels of the pine butterfly, Neophasia menapia (Felder and
Felder) have been evident in ponderosa pine stands in the Bitter Root
Valley since 1969. Evaluations of this infestation were initiated in
1970 to assess overwintering egg populations at 20 locations within
the infestation (Ciesla et al. 1971). Defoliation was...
Mountain pine beetle, Dendroctonus ponderosas Hopk., reached near epidemic levels in lodgepole pine stands in the Sulphur Creek-Black Butte area. Lodgepole pine are probably more susceptible due to the overstocked conditions of stands, and high incidence of girdling of the base of trees by porcupines. The infestation in this area...
Dwarf mistletoe is known to reduce both height and diameter growth and thus reduce the yield of an infested stand. This comparison of two similar stands--one healthy and the other infested--gives an indication of the impact of this parasite. The healthy stand has produced 1.5 times the board foot volume...
A multistage sampling survey to measure annual and cumulative mortality of lodgepole
pine by mountain pine beetle was conducted
on the Beaverhead and Gallatin National
Forests, 1978-79. The survey area, 270,000
acres, was stratified into three intensity classes
from aerial sketchmapping. This was followed
by large scale (1:6,000) aerial photography,...
Insect damage was extensive to Douglas-fir, ponderosa pine, western white pine, and western larch cones at most seed production areas surveyed in 1979. From 70 to 100 percent of the cones from several collecting periods were injured. Moderate damage (40-70 percent of cones injured) occurred to Douglas-fir, ponderosa pine, western...
An evaluation was made in 21 seed production areas and 1 seed orchard in Region 1 to identify the primary insect pests and to assess amount of injury caused. Cones from Douglas-fir, grand fir, western larch, lodgepole pine, ponderosa pine, and western white pine were collected periodically and examined. The...
An evaluation was made during midsummer 1972 to measure damage by the carpenterworm, Prionoxystus robiniae, and the ash borer, Podosesia syringae, to green ash in windbreaks in North Dakota. Intensity of infestation was determined in four land resource areas and four age classes of windbreaks. Of the 96 windbreaks examined...
We analyzed the effects of pathogens and insects on forest succession in the absence of
fire or management, addressing a number of related questions:
1. What is the rate of change in such forests?
2. How significant are the roles of pathogens and insects in the forest change?
3. How...