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SURVEY MAPPING OF SWEDISH VEGETATION FROM THE INTERPRETATION
OF AERIAL PHOTOGRAPHS
Margareta Ihse
Department of Physical Geography, Stockholm
AIMS
Up to the present day there has been an almost complete lack of vegetational
survey maps in Sweden. A Start has now been made with the production of maps
to cover an area 50.000 km“ of the central mountain chain on the Swedish-
Norwegian border (Scandes) and plans exist for producing vegetational maps
covering an entire province in many parts of the country. The aim in produc-
ing such maps of the vegetation cover is to provide a basic material for use
in planning in such fields as:
- decisionmaking in questions of nature conservation priorities, both from
botanical and zoological points of view
- to be able to follow the changes occurring after such decisions have been
made and as a check on boundary and other transgressions of already exist-
ing nature reserves and national parks
- in the assessment of the suitability of different areas for outdoor
recreation
- assessment of the preconditions for land utilisation and of the probable
consequences of changes in land usage.
The only realistic possibility of rapidly producing such basic maps has been
by aerial photographic interpretation. Methodological studies were commenced
in 1973 at the Dept. of Physical Geography of Stockholm University, financed
by the Swedish Environmental Protection Board, to investigate the possibility
of mapping vegetation by interpreting aerial photographs. The aim of these
studies was to establish the most suitable types of films and photographs to
use as well as to provide guidance on the most suitable flying altitudes, and
time of season and to assess the degree of precision obtained in relation to
the time involved in preparing such survey maps.
Two main types of photographic material were investigated, viz. black-and-
white (panchromatic) film on a scale of 1:30,000 and IR colour film on scales
varying from 1:10,000 to 1:50,000. Previously, black-and-white (panchromatic)
aerial photographs had mainly been used for such interpretational studies of
vegetational units. Such aerial photographs in fact exist for the whole country.
IR colour film had also been used in special circumstances, since it yields
photos on which different kinds of vegetation are discernible with a much
better degree of contrast than on those made from black-and-white film. Further-
more, it yields good quality phétos even when flying at high altitudes, since
haze present no obstacle.
Research into the most appropriate methods of producing such vegetation maps
has been carried out in two different areas, one involving mountain and up-
land vegetation and another comprising the typical vegetation cover of the
southern and central parts of Sweden.