Western spruce budworm defoliated area in the Northern Region has differed significantly across three discrete geographic zones during the past decade. Aerially visible defoliation in northern Idaho increased from 1.7 million acres in 1969 to a high of 2.2 million acres in 1974, and declined to none in 1979. Defoliated...
The objective of my study was to examine differences in riparian tree and shrub composition associated with adult aquatic emergence and implications for terrestrial spiders in these sites. Seasonal abundance and biomass of adult emergent aquatic insects, riparian arthropod abundances and spider densities were compared between conifer- and hardwood-dominated sites...
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...
Mountain pine beetle populations developed to epidemic level in Glacier National Park in 1972. Buildup ratio of old to newly attacked trees was 1:1.8 from 1976 to 1977. More than 12 million trees are infested on 142,871 acres. Buildup ratio is expected to exceed 1:3 from 1977 to 1978. Management...
Mountain pine beetle infestations in second-growth ponderosa pine developed in 1973 in the Little Rocky Mountains. In 1976, increasing numbers of attacked trees were observed. Current infestation intensity averages 7.1 trees per acre. Losses are expected to continue as long as stands remain overstocked and stagnated. Reduction of basal area...
Mountain pine beetle infestations in second-growth ponderosa pine have been chronic in the Little Belt and Big Snowy Mountains since 1947. In 1976, increasing numbers of attacked trees were observed. Current infestation intensity averages 82 trees per hectare. Losses are expected to continue as long as stands remain stagnates. Commercial...