753 
Where for classification purposes discoloura 
tion i3 taken into account in addition to de 
foliation, the following system is used: 
Defoliation class Discolouration class 
12 3 
Resulting damage class 
0 0 12 
1 12 2 
2 2 3 3 
3 3 3 3 
1.2 Actual Situation and Extent of Damage 
Extensive forest die-back due to the immedi 
ate effect of SO 2 emission, for example, can 
be observed mainly in the Erzgebirge-mountain 
range (CSFR, GDR), and Isergebirge-mountain 
range (GDR). For the most part of Europe, ho 
wever, slight to moderate damage prevails. In 
the Federal Republic of Germany nearly half 
of the forest area is affected by the new ty 
pes of damage but only 15 per cent are seri 
ously affected or dying (Fig. 1) /3/. 
FOREST AREA X 
g 3-4 severely 
Q2 moderately 
[7)1 sligntly 
[jO without 
damaged and dead 
damaged 
damaged 
visible danage 
Fig. 1: Extent and development of forest da 
mage in the Federal Republic of Ger 
many 
What is certain is that the damage depends on 
species, age of trees, altitude and expositi 
on. Seriously affected trees can be found 
especially in the Alps and a number of low 
mountain ranges. 
Considering the progress 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 Euro 
pean Community (EEC.) was to establish a stan 
dardized terrestrial inventory at permanent 
sample plots in all member countries. The as 
sessment method used is basically identical 
to the method described above. First results, 
relevant for the years 1987/1988 are now 
available through the EEC /12/. Mention must 
also be made of an international survey of 
forest damage in Europe which is coordinated 
by the United Nations Economic Commission for 
Europe (UN-ECE). This survey assesses forest 
damage not only in western, but also in 
eastern Europe and uses similar methods /18/. 
2 AERIAL INVENTORIES BY COLOUR INFRARED 
PHOTOGRAPHS 
2.1 Regional Pilot Projects 
In addition to inventories taken in field 
work, remote sensing methods based on the in 
terpretation of Colour-Infrared (CIR) photo 
graphs is a common practice since 1982. 
Aerial inventories in EEC countries started 
in 1985 with pilot projects conducted in Bel 
gium, France and West Germany to develop and 
apply a modular inventory and monitoring 
system based on CIR-photographs /10/. 
One of the main results of these pilot pro 
jects was to define common parameters for the 
unitary classification of damages. These pa 
rameters can now be applied individually in 
the different countries /9/. Under the 
guidance of teams involved in the pilot pro 
ject, Danish, Irish, and Italian foresters 
have successfully taken aerial inventories 
and it is expected that other countries will 
follow their example in the near future /5/.