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: “A 
7. U.S. FOREST SERVICE RESEARCH NOTE WO-2 
U.S. DEPARTMENT OF AGRICULTURE. . .WASHINGTON, D.C. 
MARCH 1964 
An Aerial Survey of Spruce and Fir Volume 
Killed by the Spruce Budworm 
in Northern Minnesota 
U. S. DEPT. OF AGRICULTURE 
NATIONAL ASRIC'! ">"! LIBRARY 
By Frederick P, Weber, Research Forester 
Forest Insect Laboratory, Forest Service 6 - 1964 
U.S. Department of Agriculture 
Since the beginning of the current spruce budworm (Cho- 
ristoneura fumiferana (Clem.)) infestation in northern Minnesota, 
over three-fourths of a million acres of white spruce (Picea glauca 
(Moench) Voss) and balsam fir (Abies balsamea (L.) Mill) type have 
received varying degrees of defoliation. This includes approximately 
274,000 acres of severely defoliated stands, characterized by ex- 
tensive top killing and tree mortality. 
Early operation recorder surveys beginning in 1957 showed 
where the damage was occurring; however, operation recorder sur- 
veys provide information only on where the host type is, the degree 
of defoliation, and the location of dying trees. They do not tell the 
volume of timber that has been killed. To estimate the volume loss, 
a new type survey was designed which incorporates both the opera- 
tion recorder method and a new photomeasurement method sup- 
plemented by ground sampling. It was conducted in July 1962, and 
the results are presented in this note. 
METHODS 
Operation Recorder Survey ! 
Figure 1 shows the location of spruce budworm damage to 
spruce-fir type in northeastern Minnesota, based on operation 
* For details of making an operation recorder survey, see Heller, R. C., 
Bean, J. L., and Marsh, J. W. Aerial survey of spruce budworm damage in 
Maine in 1950, Jour. Forestry 50: 8-11, illus, Jan, 1952, 
