between the species is more than within them. We calculated 
these vegetation indices listed in Table 2, that are based on 
the chlorophyll absorption band in the 680- 850 region of the 
spectrum. 
Statistical analysis 
The differences between sunlit and shaded leaves in each 
species were tested by comparing the mean of vegetation 
index values. We also used Analysis of Variance (ANOVA) 
to test the differences among the species both in sunlit and 
shaded leaves. Statistical analyses were performed with SAS 
software. 
3. RESULT AND CONCLUTIONS 
3.1. Spectral fingerprinting of forest species 
The sampling plan in acquiring spectral measurement is very 
important to get a reliable spectral library. Because of large 
altitude gradient in the Caspian forest and complex 
topography as well as uneven aged stands we sampled the 
species in different diameter from dominant stairs to cover 
the variety of the spectral signature between different 
samples. 
The spectra of the collected species show the typical pattern 
of vegetation (Figure 2). A visual discrimination of the 
species by their reflectance alone must be regarded as 
difficult for most species. Figure 2 shows the mean spectra of 
all five species in two illumination conditions. Although we 
could distinguish that sunlit leaves shows less reflectance 
values for some species verse shaded leaves, it must be 
statistically tested to prove the differences between them. 
In order to remove the noise spectra in water absorption 
feature wavelength we calculated the standard deviation of all 
reflectance values in each wavelength and omitted the values 
which were more than twice of standard deviation (Figure 3). 
Since a non-noisy reference spectrum does not exist, we 
focused on those wavelengths that had values less than twice 
of standard deviation. 
Alder 
(Alnus subcordata) 
wavelength (turn) 
Hornbeam 
(Carpinus betulus) 
| 0, 
1 03 
0,2 
550 »0 ?50 950 * *50 1350 1550 1?5Q 1950 2150 2350 
wavelength (nm) 
wavelength (nm) 
Common Oak 
(Quercus castaniafolia) 
I « 
£ 
f 0.3 
m «o m m 
11» \m 1560 1W0 1950 2150 2350 
wavelength (nmj 
Figure 2: Spectral fingerprints of five tree species in two 
exposed conditions (shaded vs. sunlit leaves). Black lines 
represent sunlit leaves and gray line shaded leaves. 
1150 1350 1550 1750 1950 2150 2350 
Wavelength (nm) 
1.4E+16 
1.2E+16 
3 1E+16 
c 
J 
I 8E+15 
« 
I 6E+15 
T) 
c 
w 4E+15 
2E+15 
b 
4$ 
% 
■ standard 
deviation 
i 
} 
i 
ft 
I ; 
Figure 3: Standard deviation (b) calculated for all reflectance 
values in each wavelength to remove the noise spectra in 
water absorption bands (a).