^ Southeast Alaska--The survey of Southeast Alaska forests was based on 

 the study of aerial photographs, followed by field measurements to check the 

 accuracy of the photo interpretation and to obtain supplemental tree measure- 

 ments. A sampling technique was used, designed to determine the commercial 

 forest area within / 3 percent per million acres of forest land and the timber 

 volume within / 5 percent of the total net board-foot volume in each forest man- 

 agement unit. 



The photography was 1:40,000 vertical photos and twin oblique photographs at 

 a scale of 1:20,000, flown in 1948 by the U. S. Navy. Randomly selected plots 

 of ten acres each were interpreted on the photos and a portion of these were 

 sent to the field for examination. In the field three one -fifth-acre plots were 

 measured at each location. 



Table 1 gives a few highlights of the work that has been accomplished to January 

 1, I960 on the Tongass National Forest and adjoining public and private areas 

 (fig. lA). The photo plots were randomly distributed over the gross land area, 

 but the ground and air check plots were confined to the forested area which is 50 

 percent of the total area. 



Table 1. --Total land and forest areas and number of plots studied, by 

 Forest Survey units for southeastern Alaska, July 1954 to 

 January 1 , I960. 



Survey 



Gross 



Total forest 



Photo plots 



Ground plots 



Air checked 



unit 



land area 



land 





studied 



inventoried 



plots 





M acres 



M acres 



No. 



No. 



No. 



Juneau 



3, 832.5 



1,652. 



5 



5, 830 



164 



485 



Sitka 



2,433.3 



1, 740. 



2 



3,314 



129 



328 



Petersburg 



3,286.6 



2,356. 



6 



4,347 



129 



663 



Ketchikan 



5,531.5 



3, 892. 



9 



8,902 



227 



594 



Yakutat 



795.9 



315. 



2 



872 



57 



109 



Glacier Bay 



2,037.0 



361. 



1 



3,424 



-- 



-- 



Haines - 



928.4 



226. 



2 



1,486 



16 



-- 



Gustavus 















Public 



1,992.3 



52. 



3 



3,316 



-- 



2 



Domain 















Total 



20,837.5 



10, 597. 







31,491 



722 



2, 181 



Data compilation has been completed for all except the Ketchikan Unit. 



