STANDARDIZED METHODS - COMPARABLE RESULTS:
THE EEC - MANUAL ON AERIAL FOREST - CONDITION INVENTORIES
C.P. Gross
Albert-Ludwigs-Universität
Abteilung Luftbildmessung und Fernerkundung
Werderring 6, 7800 Freiburg, Germany
Commission No. :
ABSTRACT:
Since 1985 six study groups from six European
countries have developed a method under the
coordination of the Directorate Agriculture of the
Commission of the European Communities to observe
and monitor the state of forest health with aerial
colour-infrared photographs. One result of this
research is a practice oriented MANUAL "Remote
Sensing Applications for Forest Health Status
Assessment" (Commission of the European
Communities, 1991) compiled under the supervision
of Prof.Hildebrandt, Freiburg University. The
MANUAL summarizes the experience gathered so far
and documents the state of research in Europe.
KEY WORDS: Aerial Forest Damage Inventories, Color-
Infrared Photographs, Interpretationkeys, Inventory
Concepts, Statistics, Standards.
1. INTRODUCTION
The last decade saw a new type of forest decline in
many forests in Europe. The damage is widespread
and independent of site conditions or proximity to
industrial centres. Symptoms vary but generally
point to air pollution.
The main visible symptoms of such damage include
progressive loss of needles or leaves, dis-
coloration of sections or the entire crown, and
even crown deformation. Decreasing vigour leaves
the afflicted trees unprotected against biotic as
well as climatic stress. Furthermore a remarkable
decrease in timber increment can be observed.
Considering the progression of forest decline in
Europe, inventories limited to individual countries
are no longer adequate to monitor the scope of this
pandemic process. The first measure taken by the
Commission of the EEC was to establish a standar-
dized terrestrial inventory at permanent sample
plots in all member countries.
The assessment method is stipulated by the manual
of the United Nations Economic Commission for
Europe and equally applies to the annual UN-ECE
coordinated forest damage inventory in European
countries outside the community (UN-ECE, 1986)
2. AERIAL FOREST DAMAGE INVENTORIES IN THE EEC
In addition to inventories taken in fieldwork,
remote sensing methods based on the interpretation
of Color-Infrared (CIR) photographs have been
widely applied since 1982.
In 1985 the EEC Council of Ministers decided to
develop a method to observe and monitor the state
of forests using CIR-assisted inventories which
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could be applied individually in the various
regions of the Community. It was meant to draw on
the experience gathered so far in select member
countries. The General Directorates VI
(Agriculture) and XI (Research) commissioned three
study groups with the task: the Université
Catholique Louvrain (Belgium), the INRA Télédétec-
tion in Cestas (France) and the Albert-Ludwigs-
Universität in Freiburg (Germany). Other inventory
groups in Denmark, Italy and Ireland have since
then worked with the results of this pilot project
and have successfully taken CIR-assisted forest
inventories.
The application was paralleled by the improvement
of the hitherto established methods in a number of
follow-up-projects. For instance, research has been
carried out to optimize photo scales, to test the
usability of various infrared films for the pur-
poses of forest damage inventories, to incorporate
analytical photogrammetry into the assessment
method, to develop standardized interpretation keys
and to provide the basis for the statistical
analysis of the interpretation results.
3. THE AIM OF THE EEC - MANUAL
Final reports fully document the results of the
various projects (Constantini, 1990; Giot, 1989;
Giot-Wirgot, 1986; Hildebrandt et al. 1986,
Hildebrandt et al. 1989; Jensen et al. 1989; Riom
et al. 1987; Walphot, 1990). It seemed useful
however to summarize the cardinal results and
dispersed individual information in such a way as
to provide potential users with a transpicuous
presentation of the experience gathered in the
various projects. The result of this effort is the
MANUAL Remote Sensing Applications for Forest
Health Status Assessment which has been worked out
by a team from the Abt. Luftbildmessung und
Fernerkundung at Freiburg University and the
Belgian company WALPHOT under the direction of
Prof .G.Hildebrandt. It is primarily designed for
use by foresters assigned with forest inventories
who are obviously well-acquainted with the basics
of forestry and biometry. These forest practicians
should be supplied with all relevant information to
enable them to plan and conduct aerial forest
inventories on their own. Nevertheless the MANUAL
is not conceived as a recipe-book which contains
clear-cut solutions to all possible problems.
Rather, it provides the technical, statistical and
organisational basics, highlights potential snags
and specifies research conditions and minimal
standards which must be observed in successful
inventories. As far as the concept of the
inventory, its design and the analysis of its
results are concerned the MANUAL provides a choice
of possibilities which may be applied, combined or
even modified independently and under the sole
responsibility of the interpreters in accordance
with environmetal, technical and personal
conditions of the inventory. The authors of the
