time for 6 months. He should be able to complete the compilation of data and 
prepare the management plan in that time. In this case, therefore, it would appear 
possible to prepare an adequate management plan for a tract of 32,000 acres (50 
square miles, or 13,000 hectares) for a cost of 25 cents per acre ($ 160 per square 
mile or 61 cents per hectare). The completion of a detailed management plan, 
including partinent growth, volume and other inventory data, would hardly be 
possible under these conditions without using aerial photographs wherever and 
whenever possible throughout the project. 
Once a management plan is completed, the forest must be administered under 
the supervision of a forester in the field. Under American economic conditions, a 
conservative estimate is that one forester full time, can take care of and be paid 
out of the revenue from 30,000 acres of the type and stocking represented in Itasca 
State park. If the average cost of such a forester is $ 6000 per year, and the tract 
of 32,000 acres requires the services of 1.07 full-time foresters, the cost of admi- 
nistration is roughly $ 6,400 per year. If, however, large-scale photographic cove- 
rage was obtained for the construction of the forest management plan and was 
paid for out of sums allotted for that plan, these photographs would be available 
at no additional cost to the forester putting this plan into effect. A conservative 
estimate is that these photographs will allow a forester trained in photo-interpre- 
tation to accomplish 25 percent more work in the same amount of time. This 
saving will result from the reduction and field time in timber sales admistration, 
aquisition programs, timber appraisal, road and trail development, and the record- 
ing of damage by fire, insects and other agencies. A saving of 25 percent will allow 
the same forester to cover 37,500 acres with the same intensity that he covered 
30,000 acres without photographs. The cost of administration of 32,000 acres 
would then be $ 5,100 per year on the same basis as above. The savings resulting 
from the use of aerial photographs, therefore, would be $ 1300 per year simply by 
rendering the forester on the ground more efficient. 
Even on this conservative basis, the cost of the aerial photographs would be 
retired in the first year of actual management, and the cost of the entire manage- 
ment plan ($ 8000) would be paid off in a little over 6 years. 
In conclusion, the use of aerial photographs in forest management is practical 
and is growing rapidly. By using the photographs, not only for inventory, but also 
in preparing the management plan and in administering forest tracts, the costs of 
forest management can be reduced to the point where management is practical for 
many forested areas. [Under conditions similar to the example cited, where a 
management plan is being developed for a 32,000 acre tract, containing good tim- 
ber stands growing on an average site, the use of aerial photographs should go far 
toward introducing sound forest management on the ground]. 
BIBLIOGRAPHY 
The reader is referred to the two books by the author (see footnote 3) for 
a complete bibliography of the use of AERIAL PHOTOGRAPHS IN FOREST 
and FOREST INVENTORY. The following selected references are in addition 
to those previously cited. 
Backstrom, H., and E. Welander, 1948. En preliminir undersókning rórande 
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