28 
Finland: 
Aerial pictures are used for administration questions. 
France: 
Aerial photographs are used when preparing the programs of replanting, because they 
allow a simple and rapid determination of the situation and importance of the bare spaces. 
Germany: 
The use of aerial photographs for these purposes has now been taken up again. 
Sweden: 
Aerial photographs can offer much valuable information when planning clearances, 
regeneration measures, etc., in the daily administration of the forests. When making visits 
to the forests, aerial photographs facilitate one's personal orientation, and this is of great 
value in the large forests, as well as giving a good notion of the conditions to be studied. 
U. S. A.: 
Most U. S. Forest Ranger headquarters have files of photos of the areas under their 
jurisdiction. These photos in most cases were not taken for forestry purposes and are 
mostly at a scale of 1:20.000. They are used in innumerable ways such as to locate 
timber trespass, locate section corners, decide on fishing rights, etc. 
Question No. 9: 
After how many years are the photographs considered too old for the dif- 
ferent purposes referred to? 
Austria: 
As the aerial pictures give informations about the stand at the time of 
the aerial photography, this must be made immediately before a general 
forestry surveying. Old aerial pictures are only of stand-historical interest. 
Finland: 
Most of the aerial pictures in Finland are taken recently, and the 
question of when they must be considered as too old is therefore not yet 
topical. 
Germany: 
For forest planning purposes the aerial pictures must not, if possible, 
be more than one year old. 
Italy: 
At the skirts of the forest, aerial photographs more than ten years old, are 
in Italy considered as useless, considering that forests with trees of different 
ages, now and then marked out for cutting, and brush-wood of the Medi- 
terranean type, gradually cut away, causes a never-ceasing variation of 
the composition of the wooded grounds. 
This 
own pl: 
areas u 
12 year 
Has 1 
increme 
Terre 
Terre 
Finland 
of takir 
Groui 
in large 
have 
»No. 
Inves 
tion. Fi 
The | 
to put t 
detailed 
training 
Foun 
metry à 
sche Ze