Epidemic populations of the western spruce budworm persist in the Northern Region. Aerial surveys made in August 1976 showed a decline in the acreage of aerially visible defoliation. In northern Idaho, the defoliated area dropped from 831,487 acres in 1975 to 655,711 acres in 1976, down 21 percent. Surveys in...
Preliminary analysis of data from this study in the mountains southwest of the Anaconda Copper Smelter, an industrial source of SO2 and heavy metal particulate, reflects a complex pattern of pollutant impact. The differential effect of smelter emissions on plant life in the study area is best explained by the...
Mountain pine beetle populations began increasing in Glacier National Park in 1970. Numbers of infested trees increased steadily from an average of 12 to 115 per hectare from 1972 to 1976. Total hectares of infestation have increased from 445 in 1972 to 40,419 ha in 1976. Predictive equations estimate a...
We conducted a combination road/plot impact survey for dwarf mistletoe in lodgepole pine on six East Side National Forests in 1978. The road survey showed infestation percentages ranging from 28.2 on the Custer to 52.4 on the Beaverhead. The plot survey showed annual cubic foot volume losses ranging from 106M...
Based on per acre costs, plantation establishment is one of the most expensive silvicultural practices (Pfister 1976), but only token studies have been done on frequency and causes of seedling injury and mortality in Region 1 plantations (Wenner 1976). Therefore, we conducted a survey in 1978 on four National Forests...
Mountain pine beetle developed to epidemic levels in lodgepole pine stands in the Thompson River drainage in 1971. Approximately 506,616 trees are infested on 4,444 hectares. Based on buildup ratios, infestations are expected to intensify; develop in uninfected stands; and kill about 1,763,024 trees in 1977. Salvage logging of infested...