which are compatible with forest damage inventories 
based on ground measurements and aerial photo 
interpretations this definition was suggested by the TWG 
as base for the standwise damage class. 
| not defoliated 0-10% 
slight defoliation 10-25% 
moderate defoliation | 25-60% 
severe defoliation > 60% 
dead 
  
Tab. 1: Damage class definition according to AFL 
interpretation key 
7.3.1.2 Damage Class Definition According to Needle 
Loss of stands or pixles 
It was the consistent opinion of the members of the 
technical group that the damage cannot be defined as 
one single damage class, because of the 
unhomogeneous distribution of damages within stands or 
picture elements of the satellite data. The classes must 
rather be defined as the portion of differently damaged 
trees. There are different possibilities to describe the 
damage of stands or pixels, which are all based on 
definitions describing the damages of single trees 
(7.3.1.1). After intensive discussions, the TWG decided 
to accept Forster's damage-class definition for 
determining standwise needle loss (Förster, 1989). This 
class definition which is shown in table 2 was developed 
in the first phase of the German Harz project. In this 
definition the defoliation categories are defined as the 
portion of strongly damaged trees belonging to the 
defoliation classes S2, S3 and S4 (AFL, 1988). 
   
  
0-10% of strongly damaged trees (S2+,S2-,S3, and S4, AFL) 
  
  
  
  
  
11-33% of strongly damaged trees (S2+,S2-,S3, and S4, AFL) 
  
34-66% of strongly damaged trees (S2+,52-,S3, and S4, AFL) 
  
67-100% of strongly damaged trees (S2+,S2-,S3, and S4, 
AFL) 
  
  
  
  
Tab. 2: Standwise needle loss categories 
The advantages of this damage class definition is, that all 
potential damage conditions in the stand are included. It 
is not optimised for one region and thus can be applied 
universally. This advantage is of special importance for 
small-scale forest-damage mapping not limited to a 
single country, as it is the case in this project. Apart from 
that the definition is easy to be understood by everyone. 
738 
7.3.2 Classification of deforestation / crown density 
The question of the necessity and practicability of 
integrating deforestation stages as a damage symptom 
into the classification was also discussed intensively in 
the TWG. The members of the TWG decided to integrate 
this parameter into the damage-class definition. 
It was suggested that deforestation due to decreasing 
crown density can be defined as the percentage of crown 
cover. It was decided to test the following combined 
damage class definition, that integrates standwise 
damage classes (see table 2), and deforestation 
symptoms. 
  
Crown closure more | Classification into Defoliation Classes 
than 60 % C0, C1, C2, C3:1/- 
  
Crown closure 
41-60% Deforestation class 1 
  
Crown closure 
21-40% Deforestation class 2 
  
Crown closure 
below 20% Deforestaion class 3 
  
  
  
  
Tab. 3: Damage class definition by combination of 
standwise needle loss and deforestation 
By this definition, damages with a crown closure of more 
than 60% are classified exclusively according to needle 
loss as proposed by the TU Berlin (CO to C3). Those with 
a crown closure below 60% are classified exclusively 
according to deforestation symptoms expressed by the 
canopy density. The advantages and the disadvantages 
were also discussed intensively. 
Advantages of the damage class definition: 
The term 'deforestation' is appropriate for a canopy 
density below 60%, since the stability of stands below 
this range is no longer guaranteed, and only a few 
silvicultural procedures are intended to operate at such a 
low canopy density. 
As in former forest-damage inventories, the important 
information on needle loss of single trees in terms of the 
portions of different damage classes (S2-S4) will be 
integrated. 
The very important information of the stand density which 
indicates the stability of a stand will also be considered. 
For a correct interpretation of these new damage 
classes, knowledge of the classified area must be taken 
into account, or digitised forest maps must be 
superimposed on the classification results in order to 
know which state the stand is supposed to be in. 
There is a consensus among the members of the 
working group that a classification according to needle 
loss categories of stands with a crown closure of below 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996 
  
— PN 4 9 IN ra 0 Se 
(o n) rr n "Ty ed