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METHODS 
In connection with an evaluation of the insect outbreaks on 
Anticosti Island, a remote sensing study was initiated by the Laurentian 
Forest Research Centre in Quebec, and the island was photographed in 
July 1973, at an altitude of 35000 feet (10670 m), with a RC-10 camera 
loaded with a Kodak Aerochrome infrared 2443 film; the 6-inch focal- 
length lens used gave an approximate scale of 1:70000. In October 1973 
aerial photos were also obtained with the same sensor at 5000 feet 
(1525 m) over a part of the island where heavy damage occurred. Unfortu- 
natly these photos at an approximate scale of 1:10000 were taken with a 
very low sun angle of about 20°. 
All the island, which has an area of about 3,100 sq. miles 
(8000 km 2 ), was examined through the small scale transparencies with a 
custom mirror stereoscope of a possible 3X magnification. An attempt 
was made to map tree mortality in balsam fir stands, following the two 
distinct outbreaks (1929 and 1971), in classes of 25%. Since nearly 
all attacked trees died at the time of the outbreak, and as defoliation 
was at its peak in 1971-72, it was impossible to see partially defoliated 
trees. Killed stands were quite easily detected through their blue, blue- 
green color as compared to healthy balsam fir which appeared in various 
tones of magenta. 
Ground truth was obtained by a single crew of two men working 
for a period of three weeks. All areas accessible by road were visited. 
Stand composition was described for about 150 check points, 40 of which 
were sampled with a relascope (point sampling method) (Kendall and Sayn- 
Wittgenstein 1964) as an aid to evaluate the percentage of tree species 
and dead trees. Ground truth data were also taken from existing aerial 
sketch mapping records and from the color-IR medium-scale photographs» 
ERTS-I imagery for mapping forest cover types and damage was 
also investigated by visual analysis on a light table of custom black 
and white and color composite transparencies. 
RESULTS AND DISCUSSION 
Aerial color-IR photos 
Quality of imagery from both scales was excellent. Tree mor 
tality, following the 1971 outbreak, could readily be evaluated on 
small-scale photographs (1:70000) with a mirror stereoscope. Heavily 
damaged stands were clearly visible without the aid of stereoscopic 
viewing. A map, showing the proportion of dead trees in balsam fir 
stands, is now in preparation. Medium scale photos are really an 
excellent ground truth tool as each individual dead tree is clearly 
visible.