70 
Reflectance 
Figure 1 
Reflectance of beech branches with 
shadow leaves for single and up to 
seven stacked branches. The numbers 
indicate the quantity of piled up 
branches. 
Figure 2 
Reflectance of five stacked branches 
of 1 = beech with sun leaves, 2 = 
beech with shadow leaves, 3 = beech 
with discoloured leaves (yellowing), 
4 = spruce. 
rise of the spectral curve of beech 
branches with yellowing in respect to 
green beech branches with shadow 
leaves. 
For the visible the influence of 
needle age on spectral reflectance is 
shown in figure 4. Even for needles 
gathered on July 20, 1988, in Ober 
pfaffenhofen near Munich, the in 
fluence of young current year's 
needes on the spectral reflectance of 
branches is still important. A high 
amount of sprouts increases reflec 
tance in the visible and NIR, in the 
SWIR reflectance decreases. Disregar 
ding this and simular saisonal 
effects will produce classification 
errors. 
Information for the understanding of 
spectral trends in reflectance 
measurements of damaged beech trees 
can be derived from figures 5 and 6. 
In figure 5 spectral reflectance of 
beech branches in the IR decreases 
with increasing damage level. Spec 
tral analyses of multispectral 
scanner data of beech and oak stands 
Figure 3 
Ratio spectra, each spectrum of five 
stacked branches of 1 = beech with 
sun leaves, 2 = beech with yellowing 
and 3 = spruce divided through the 
corresponding spectrum of beech with 
shadow leaves . 
53 
Figure 4 
Reflectance spectra of spruce, 
measured at one branch with 1 = 
current year's needles, 2 =1 year 
old needles, 3 = 2-4 year's old 
needles, 4 = total sample. 
in the Stadtwald Frankfurt, gathered 
by the airborne Deadalus scanner from 
flight altitudes 2000m and 4000m at 
September 9, 1986, indicated an 
decrease of reflectance in the 
infrared with increasing damage. 
These analyses described by Guttmann 
et al., 1987, Kirchhof et al., 1988; 
presented the overall spectral be 
haviour of surface areas composed of 
5m x5m or 10m xlOm image elements. 
These results let to the working 
hypothesis - that in case of no 
significant change of vegetation on 
the surface layer-primary and secon 
dary effects of damage of the same 
species and the same age should 
result in a decrease of reflectance 
in the IR. In case of no discoloura 
tion of leaves the same tendency 
should apply for the visible region. 
In figure 6 the variation in spectral 
reflectance in the visible for 
branches of the same damage class 2/3 
is rather important. We have to keep 
in mind, that within the frame of 
these measurements only primary 
effects of damage are considered,