history of 
frequently 
ions, wind- 
ying pocket 
y necessary 
d survey is 
er hectare). 
the growth 
(317/, miles 
unts should 
1anagement 
the mana- 
ind volume 
are assem- 
ese include 
ach period 
10ds and is 
t should be 
h age class 
the various 
erpretation 
an impor- 
nsideration 
: be located 
efficiently 
; and on the 
arcut areas, 
MI of these 
rial photo- 
ie planning 
costs here 
e of aerial 
yvement of 
pecies must 
artially cut 
die before 
t be plant- 
hotographs 
species can 
  
  
   
    
  
  
  
  
  
  
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
  
   
  
  
   
   
  
   
  
  
  
   
  
  
  
   
  
  
   
  
  
     
often be determined by stereoscopic examination of the photographs, especially if 
the desired crop is coniferous and the weed species are hardwoods. Crown size as 
measured on the photographs may be used to determine the relative vigor of the 
individual stems within a given age class, and thus to direct the forester to the 
stands requiring the most immediate thinning. Areas requiring planting can be 
located and mapped on the aerial photographs. The amount and kind of planting 
stock needed can usually be calculated from the photographic information, supple- 
mented by only a rapid field check. 
Finally, no management plan is of value unless it is put into effect and revised 
from time to time as needed. Aerial photographs play an important part in carry- 
ing out the management plan and in the routine management of the forest. They 
are of particular importance in normal aquisition and timber sale activities. Sup- 
pose a land-owner comes to the forester and offers to sell an outlying tract of 
timber. A quick look at the stereoscopic image of the tract will tell the forester 
more about the land and the timber on it than a field trip requiring several hours 
or even a full day. Again, take the case of the farmer or logger who wishes to pur- 
chase a small amount of stumpage on land under the supervision of the forester. 
If the area is one of extensive management and of low value, the arrangements for 
the sale may be completed purely from study of the photographs, as the profit 
from the sale might well be entirely consumed by the forester making a trip to the 
area in question. Even where intensive management or high values requires careful 
on-the-ground tree-marking and cutting supervision, much of the detail of the 
sale can be worked out from the photographs. 
The value of aerial photographs in maintaining records of the forest should not be 
overlooked. Complete precision coverage of the area may be justified only once 
every 10 years. In the intervening period, however, photography with a hand 
camera from a light aircraft will serve to record fires, insect defoliation, logging 
progress, and other changes in the vegetation of the tract. Such photographs can be 
matched in to the earlier precise photographic coverage to produce reasonably 
accurate maps. Timber-management concerns are increasingly finding that photo- 
graphy provides a cheaper and more accurate means of maintaining records than 
does ground survey. In many areas of relatively terrain, the photographs them- 
selves are being used as the vehicle of record, without the preparation of maps. 
Cutting areas, fires, road and trail development, and various management and 
silvicultural activities are inked in directly on the contact prints or mosaics, and 
these in turn are filed as permanent records. 
[In conclusion, let us return to the economic aspects of using aerial photo- 
graphs in forest management. As stated earlier, it seems probable that many forest 
land owners in the United States and Canada would be willing to pay 25 cents 
per acre for an accurate and detailed management plan. This sum presumes forest 
land containing at least some merchantable timber and at least partially-stocked 
with second-growth on favorable sites. Taking the Itasca forest management pro- 
ject as example, the aerial photographs (autumn panchromatic, 1 : 12,000) cost 2 
cents per acre. The photo-interpretation and the construction of the planimetric 
and the forest stand map is estimated to cost about 4 cents per acre. Ground survey 
to obtain volume, growth, and other forest information is planned for about 10 
cents per acre. The total thus far is approximately 16 cents per acre. For the 
remaining 9 cents per acre, it would be possible to pay a high-grade forester full 
7