led elucidating re- 
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roved too limited. 
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cut of the U. S. A. 
pes principally — 
, parallax bar. For 
cre classes on the 
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sults. This means 
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nd concentrate on 
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d, certain types of 
ing of the ground 
maps and descrip- 
h the forest types 
height classes and 
23 
Italy: 
The examination of the forest was made in two parts: 
(1) Determination of tree species, density and fertility. 
(2) Plotting for measurement of the trees. 
Sweden: 
The quality of the site can only be uncertainly estimated for isolated 
stands; on the other hand, the average for a larger number of stands may 
be of practical value. To provide a basis for site quality estimates it is 
generally required that pictures of stands that have already been studied 
from the ground shall be used. 
U. S. A.: 
Broad types identified at 1:20.000 with infra-red photography. Sites 
difficult to identify largely due to lack of trained ecologist-photogram- 
metrists. 
Question No. 3: 
Determination of tree species. 
Finland: 
It has been difficult to determine the tree species on the pancromatic 
film used up to now. In the summer of 1951 photographing with infra- 
film was made, but a report of the result of the experiment is not yet 
available. 
France: 
It is possible to distinguish between deciduous and coniferous trees on 
aerial photographs, especially in winter. The coniferous trees are disting- 
uished amongst themselves from the silhouettes. To distinguish between 
the different deciduous trees, aerial photographs are taken in spring with 
suitably chosen intervals. The leafing of oak, beech etc. occurs at diffe- 
rent dates, and it is thus possible to determine with enough accuracy the 
relative importance of each tree species in the stand. 
Germany: 
Plotting is made in connection with field-work (revision of draft) and 
complementary interpretation. Infra-red photographs are also used. 
Italy: 
The determination of tree species was made on paper positives, enlarged 
4 times from the negative, and through stereoscopic studies small forest 
regions were detached with regard to growth, degree of mixture of the 
species and density of the forest.