In the NIR strong influence of 
biomass or number of branches piled 
up of the same species on reflectance 
was confirmed. Saturation was reached 
for 5-7 branches. The measurement 
results of tree components of damaged 
beech and spruce trees emphasize the 
importance of the IR-region for 
damage classification. The spectral 
reflectance of beech branches 
decreases with increasing damage 
level. The reflectance curves of 
spruce branches show also in the IR a 
more consistent course. In the NIR 
the plateau level reduces with 
increasing degree of damage, 
yellowing is of minor importance. For 
wavelengths greater than 1,4 pm the 
curves for spruce branches raise with 
increasing degree of damage. This may 
be explained by augmented water 
stress, because also at the NIR- 
plateau attenuation in the water 
absorption bands reduces with 
increasing damage level. 
The spectral behaviour of the 
reflectance curves for beech and 
spruce in the visible region is 
largely influenced by discolouration, 
which seems not necessarely to be an 
indicator of damage. As already 
mentioned by Kenneweg, 1989, recent 
experience with damage interpretation 
indicates the important role of 
structural elements of tree crowns 
rather than colour. 
The interpretation of the curves in 
figure 6 and 8 for the visible as 
source of information on damage is 
difficult and may be misleading. For 
data evaluation additional statements 
on discolouration and its regional 
variation in respect to the degree of 
damage should be available. 
Caused by discolouration a red shift 
of the reflexion peak in the visible 
of about 10 nm and a variation of 
shape at the beginning of the slope 
to the NIR plateau was observed. 
These phenomena have to be further 
investigated, also with respect to 
their detection by future spectral 
high resolution instruments and their 
application in classification of 
forest species and forest decline. 
The results proved the influence of 
primary effects of damaged trees by 
measurement of tree components of 
beech and spruce. Secondary effects 
are mainly produced by crown struc 
ture change, increase of shadow areas 
and radiation from the background. 
Background radiation will be in 
fluenced by the degree of damage 
resulting in morphological and 
structural changes of the tree and 
its components. Higher amounts of sun 
and sky radiation will then penetrate 
to the undercover or the ground and 
will be reflected. It adds to the 
reflectance signal of the tree. As a 
consequence spectral reflectance of 
developing background or undercover 
vegetation may become an important 
factor for higher degrees of damage, 
as reported by Koch, 1987, and 
Herrmann, 1988, for beech undercover 
of severely damaged pines. 
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