During 1959 a special study of logging operations on the Tongass National 

 Forest was started to determine the degree of utilization and relationships 

 between scaled and inventoried volumes. 



The net utilized volume of logs, scaled by Puget Sound Log Scaling and Grading Bureau 

 rules, was 26.4 percent less than the net inventory volume by Forest Survey standards. 

 But, logging residues accounted for only 9.4 percent of this difference. Differences in scal- 

 ing standards and practices accounted for most of the remainder. Loggers were not utiliz- 

 ing to the top diameter limit used in the forest inventory, but they were cutting a lower 

 stump than defined in Forest Survey merchantability standards . 



9 Chugach National Forest - -By January 1 , I960, Forest Survey work in the 

 Chugach area (fig. IB) was still primarily in planning stages. A preliminary 

 plan (much the same as followed in Southeast Alaska) was prepared and sample 

 form-class measurements were completed for volume table use. About 60 

 percent of the photo interpretation work on the Whittier and Copper River blocks 

 was completed on new 1:15,840 aerial photos. However, new photography is 

 needed for Afognak Island and the Kenai Working Circle. This was planned for 

 1959 but because of weather conditions and the priority of other aerial photo- 

 graphy the photos were not obtained. 



^ Interior Alaska--Because of the extensive nature of the survey to be con- 

 ducted in Interior Alaska, and because of the large acreage to be covered (some 

 229 million acres with tree cover), it was decided to rely upon aerial photographs 

 to a greater extent than in previous Forest Survey work. 



Area estimates of land classes will be determined by a dot-count on aerial 

 photos. The photography is near completion at a scale of 1:5,000 along flight 

 lines spaced 30 miles apart. One location per photograph will be classified. 

 These locations will be marked systematically along the flight lines. Area esti- 

 mates of commercial forest land will be determined for each unit by forest 

 types, stand-size classes, and crown-density classes. Estimates also will be 

 obtained for nonforest and noncommercial or protection forests. A statistical 

 sample of the photo locations will be examined by air to check the accuracy of 

 classification and, where necessary, the proportion of the various classes will 

 be adjusted. Estimates of area will be products of the area represented by 

 each location and the number of locations per class. 



Timber volume estimates will be determined from aerial photo stand volume 

 tables. These tables ar e related to photo measurements of stand height and 

 density and correlated with gross volume per acre by density-height classes. 

 Estimates of defect will be computed by applying factors to gross volume 

 according to species and height classes. Photo measurements will be made on 

 one-half-acre forest plots coincident with the areal sample. Estimates of 



