—  áÓ— s 
Sweden also 1: 20 000. Usually the mapping work consists of revision of 
forest maps already existing. In working by this method, no changes need 
to be made in the basic features of the map and only stand boundaries 
and such details as roads and trails need to be brought up to date and new 
stand descriptions put in. Contour lines are very seldom used on these 
forest maps, but hatchings such as indicate mountains on ordinary maps 
are employed (see fig. 1, stand No. 4 and 9). These hatchings express in a 
more flexible manner the topographical details that are essential for hauling 
operations and for general orientation in the forest. For daily use, the 
forest maps are pasted on cloth and folded to pocket size. Every district 
forester and ranger is provided with his own copy of the map and there 
are further copies in the office for general study and as operational pro- 
gress maps. Sometimes there are separate progress maps for cutting 
operations and silvicultural measures. 
Use of aerial photographs in Swedish forestry 
In view of the natural conditions in Sweden, the forms of forest ad- 
ministration and the purposes for which forest maps are employed, it can 
well be understood that aerial photographs will be of great use throughout 
the country. In general when mapping projects are decided it pays to save 
part of the work of the personnel by utilizing aerial photographs, particularly 
when photographs are already available from general aerial surveys of the 
regions concerned. Aerial photographs can partly replace and partly supple- 
ment the information on conventional forest maps and in field notes. In 
Southern Sweden, however, the benefit is much less than in the north. In 
Norrland it pays to procure aerial photographs, even if these have to be 
made at one’s own expense. The cost of such special photographs can fre- 
quently be brought down if several forest managers in a region can utilize 
photographs from one order. 
Forest mapping in Sweden by means of aerial photographs has been 
much facilitated by the fact that large portions of the country have been 
photographed for this and other purposes, and that knowledge of photo- 
grammetry and particularly forest photogrammetry is extending and gain- 
ing a firm footing, owing to regular training and research. The bulk of the 
photo prints is of the standard in use since 1937 — vertical photos in black 
and white tone, photographed with wide angle RMK Topogone cameras, 
20/3030 em, on panchromatic film, on the scale 1: 20 000, and with nor- 
mal overlap (60 % front lap and 40 % side lap). More modern cameras, 
smaller size of photos and somewhat smaller scales have been used in recent 
years as well. 
New mapping methods 
The methods described below are significant, not only because they are 
already in use to a large extent over vast areas but because they throw a 
fairly general light on mapping questions in the transition time between 
the old and the new. 
The State forests 
The Swedish Forest Service has been promoting forest photogrammetry 
in Sweden since 1930 and has participated in various research projects