The Targhee and Black Hills infestations were sketch mapped from light 
aircraft during July and early August, respectively. Numbers of current 
faders were estimated for units of land bounded by natural features such as 
ridges, major drainages, or roads, and recorded on planimetric maps. These 
data were converted to trees per acre and used to classify the infestation 
into three broad strata. 
Aerial photography was acquired approximately three weeks later. Photo plots 
were distributed to provide for representative sampling within each of the 
three strata defined by the sketch map survey. Color aerial Ektachrome (SO- 
397) 9 x 9 inch (3.54 x 3.54 cm) stereo triplets were taken at each plot 
location at a scale of 1:6,000. Sample plots were established in the stereo 
portion of each triplet. In the Targhee test site, all photo plots were 40 
acres (16.2 hectares) in size. In the Black Hills, photo plot size varied 
according to stratum with 90-, 62.5-, and 40-acre (36.4, 25.3, and 16.2 hect- 
ares) plots being assigned to the light, intermediate, heavy strata, respec- 
tively. Photo plots were subdivided into 2.5-acre (1.01 hectare) subplots, 
and counts of discolored crowns were made in each subplot with an Old Delph 
scanning stereoscope. 
A series of 2.5-acre (1.01 hectare) subplots were randomly selected within 
each stratum for ground sampling. Number and diameter of all trees killed by 
mountain pine beetle during 1976 were recorded. In addition, a 5 point 
variable plot cluster (BAF 10) was taken in each subplot to sample the green 
stand and to estimate green infested trees and residual stocking. 
The surveys provided the desired statistical summaries (Tables 2 and 3). 
Sampling errors where less than 107 for estimates of number of trees and 
volume loss in lodgepole pine stands on the Targhee National Forest where the 
distribution of infested trees tended to be more uniform (Table 2). In the 
Black Hills test site, where infestations are clustered, sampling errors were 
approximately 407% (Table 3) indicating that additional refinement in sampling 
strategy is required for estimating losses in ponderosa pine with an acceptable 
sampling error. 
High Altitude Photography for Stratification of Infestation Intensity 
When potential users reviewed this methodology they were quick to point out a 
potential logistical problem. If this survey method is to be used over large 
areas for statewide loss estimates, there is a possibility that there will be 
insufficient time to complete sketch map surveys and stratification in time 
to plan, design, and conduct aerial photo and ground surveys before heavy 
snows make many infested areas inaccessible to ground crews. In addition, 
aerial sketch mapping is highly subjective: there is often considerable 
variation between observers and, therefore, it may not provide a consistent 
stratification. 
During 1976, the National Forestry Applications Program of the U.S. Forest 
Service, headquartered at the National Aeronautics and Space Administration's 
(NASA) Lyndon B. Johnson Manned Spacecraft Center in Houston, Texas, conducted 
a special survey designed to estimate volume of dead salvageable timber on 
the Clearwater National Forest in northern Idaho (Duggan et al. 1977). Color 
aerial photography (Ektachrome S0-242) at a scale of 1:30,000 at nadir was 
    
  
  
  
  
  
  
    
   
    
   
    
   
    
   
   
  
  
  
  
  
  
  
   
     
   
  
  
  
  
  
  
  
  
   
  
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