Mountain pine beetle populations increased in 1979 in the Thompson River drainage to levels predicted following the 1978 attack period. New attacks in 1979 averaged 27 per acre. Current estimates indicate another 25 percent of the remaining lodgepole pine could be killed in 1980.
A pilot survey was conducted to evaluate the effectiveness of using multistage sampling techniques to measure annual and cumulative mortality on a State-wide basis with acceptable statistical reliability, timeliness, and cost. Within the State of Montana, aerial surveys showed about 986,000 acres of lodgepole pine infested with mountain pine beetle....
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,...
During December 1978 and January 1979, temperatures reached all-time lows in some parts of Montana. Overwintering mountain pine beetle populations were sampled at 11 sites during February and March 1979. Effects of the extreme cold varied from site to site, with larval mortality ranging from 6 percent to 100 percent....
The mountain pine beetle infestation on Bureau of Land Management lands in Centennial Valley has increased from about 500 acres in 1977 to more than 7,000 in 1979. Average number of trees per acre killed has more than quadrupled, increasing from 9.8 in 1977 to 47.8 in 1979. Predictions for...
Thirty permanent mountain pine beetle population trend plots were established in each of six areas in the state in 1979. Infestation levels ranged from 0 to 47.8 new attacks per acre. The potential for increased mortality is considered high for all areas. Each area will be evaluated for 5 years...
Mountain pine beetle populations developed to epidemic level in 1970 on the Hebgen Lake Ranger District. Infested acreage increased from 78,000 in 1977 to 79,061 in 1978. More than 4 million trees (238 MMBF) were killed in 1978. Cold temperatures during December 1978 may cause a significant decline in the...