vegetation. The absorption band of
Phragmites australis
was
mainly centered at 380 to 400 nm, 680 to 720 nm, 1420 to
1450 nm, 1900 to 1940 nm, and 2450 to 2500 nm, and the
spectral curves of different leaf water contents were not sig-
nificant. The spectrum of 45% to 60%
VWC
in the range of 550
to 675 nm and 1400 to 2500 nm was highest, followed by 30%
to 45%, while the minimum was 60% to 75%. Therefore, the
550 to 675 nm and 1400 to 2500 nm bands could be used to
identify the water content of
Phragmites australis
leaves. In
the first order differential spectrum, the spectral ranges could
not be easily distinguished (Figure 6).
The absorption band of
Nitraria tangutorum
mainly cen-
tered on the water content layer of 60% to 75%; thus, there
was only one spectral curve. The
Nitraria tangutorum
reflec-
tance curve was determined by characteristics of the vegeta-
tion, which was similar to that of other desert vegetation.
The absorption band was mainly centered at 380 to 400 nm,
680 to 720 nm, 1420 to1450 nm, 1900 to 1940 nm and 2450
to 2500 nm. Because there was only one spectral curve in the
first order differential spectrum, the difference between the
different water content could not be effectively distinguished
(Figure 7).
Figure 5. Reflectance and first order differential spectra of
Phragmites australis
under different leaf water contents.
Figure 6. Reflectance and first order differential spectra of
Nitraria tangutorum
under different leaf water contents.
Figure 7. Reflectance and first order differential spectra of
Populus euphratica
under different leaf water contents.
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
September 2018
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