Sweden 17 
Forestry Institutions 
Since 1952 air photos have been used to an ever increasing extent in 
Swedish forestry practice, especially by the large scale forest owners 
(the Board of Crown Lands and Forests and the big forest companies), 
who work intensively on rationalizing and simplifying the methods 
hitherto used. Even in small scale forestry with limited financial re 
sources the possibilities of using air photos for practical purposes are 
being more and more appreciated. Air photos are most extensively used 
in North and Central Sweden, where the wooded areas are largest. See 
[6], [7], [24], etc. 
Important Applications of Air Photos. Air photos have been used 
primarily for mapping purposes and to some extent for ascertaining 
the conditions of ground and forest. The results are sometimes checked 
and supplemented by helicopters and slow-flying planes (Piper Cub). 
In addition, photos are used for various kinds of planning work, e. g. 
planning of roads and ditches, logging operations, stand tending, rege 
neration, etc. Air photos have also been experimentally used for forest 
assessments. Promising results have been obtained in volume estimates. 
The Board of Crown Lands and Forest and the big forest compa 
nies are nowadays usually making their maps from air photos, at least 
in North and Central Sweden. 
Air photos taken for the Economic Map of Sweden are increasingly 
used as the basis for forestry projects on individual forest properties 
and for localizing and recording progress. Contact prints or enlarged 
pictures, sometimes rectified, are used for this purpose. These are usu 
ally first stereoscopically interpreted, the observations are recorded and 
later checked and supplemented in the field. Occasionally the details of 
the pictures are entered by direct copying on the map drawn. 
It has been found that the field work in planning forest roads can 
be considerably reduced by the study, especially stereoscopic, of photos. 
Preliminary reconnaissances can be made with pocket or mirror stereo 
scopes and different alternatives marked out for further examination 
in the field. Stereometric elevation measurements have hitherto only 
been made exceptionally. 
Some County Forestry Boards have been using air photos for pro 
jecting drainage systems in their districts. 
Stereoscopically viewed air photos have proved useful to large scale 
forestry in the requisite division of the forest into areas for lumbering 
operations, stand tending and regeneration. 
Large forest companies have been using air photos for administrative 
purposes. Operations of different kinds are roughly outlined, using air 
photos, often stereoscopically viewed. 
Air photos were most useful for surveying the damage caused by the 
winter gales in 1954. Special photographs were taken and the pictures 
used for planning the recuperative actions.