14
Leaf to Canopy Scale
., u
0.6
i 0.4
U . .
<;:
' "
0:: 0.2
0
350
Frank W. Davis and Dar Roberts
Light Soil
DxN Leaf
~----~~~---,I
850
1350
1850
2350
Wavelength (nm)
Populus resprou1s
0.7
0.6
LAI:4.8
0.5
., u
i 0.4
U
~ 0.3
.,
0:: 0.2
0.1
0
350
850
1350
1850
2350
Wavelength(nm)
FIGURE 1.2. Leaf and canopy scale spectra of natural materials. The photograph on the left shows Populus resprouts
(P. delta ides X P. nigra = D X N) located in the vicinity of Wallula, WA. Plants were flagged and placed in five
height classes covering a range of heights and LAIs. Multiple spectra were collected from each resprout. A subset
of 25 plants was destructively harvested to determine LAI for each plant and compared with canopy spectra and
several spectral indices. Example spectra of a leaf, bare soil, and a Populus stump are shown in the upper right frame.
Diagnostic absorptions for chlorophyll in the visible, liquid water in the NIR, and lignocellulose in the shortwave
infrared are marked by arrows. Four spectra, sampled from bare soil and three canopies with LAIs ranging from 1.8
to 4.8, are shown in the lower right frame. Note the general decrease in red reflectance and increase in NIR reflectance
with increasing LA!. Details on LAI sampling and spectral analysis are provided in Roberts et al., (1998b). (See
color plate.)
In December 1999 NASA launched the first earth
observing system (EOS) platform, which will include the much-anticipated moderate resolution imaging spectroradiometer (MODIS). MODIS can
observe most of the earth every two days via 36
spectral bands at nadir instantaneous-fields-of-view
of 250, 500, and 1000 m (Barnes et al. 1998). The
MODIS imagery will be acquired in concert with
LANDSAT 7 and ASTER (advanced spacebome
thermal emission and reflection radiometer) to allow multiscale sampling and land surface monitoring. The MODIS science team will derive and distribute several "standard data products" for
monitoring regional and global vegetation dynamics, including surface reflectance, land surface temperature, albedo, vegetation indices, fraction of absorbed photosynthetically active radiation (FPAR),
LAI, fires, landcover, and net primary productivity
(NPP) (see Justice et al. [1998] for details).
Radar Remote Sensing
Active microwave sensors yield a wide range of
information about earth surfaces, notably surface
topography, surface roughness, soil moisture, and
vegetation structure and composition (Henderson
and Lewis 1998). All active microwave sensors
share the advantages of being independent of solar
Leaf to Canopy Scale
., u
0.6
i 0.4
U . .
<;:
' "
0:: 0.2
0
350
Frank W. Davis and Dar Roberts
Light Soil
DxN Leaf
~----~~~---,I
850
1350
1850
2350
Wavelength (nm)
Populus resprou1s
0.7
0.6
LAI:4.8
0.5
., u
i 0.4
U
~ 0.3
.,
0:: 0.2
0.1
0
350
850
1350
1850
2350
Wavelength(nm)
FIGURE 1.2. Leaf and canopy scale spectra of natural materials. The photograph on the left shows Populus resprouts
(P. delta ides X P. nigra = D X N) located in the vicinity of Wallula, WA. Plants were flagged and placed in five
height classes covering a range of heights and LAIs. Multiple spectra were collected from each resprout. A subset
of 25 plants was destructively harvested to determine LAI for each plant and compared with canopy spectra and
several spectral indices. Example spectra of a leaf, bare soil, and a Populus stump are shown in the upper right frame.
Diagnostic absorptions for chlorophyll in the visible, liquid water in the NIR, and lignocellulose in the shortwave
infrared are marked by arrows. Four spectra, sampled from bare soil and three canopies with LAIs ranging from 1.8
to 4.8, are shown in the lower right frame. Note the general decrease in red reflectance and increase in NIR reflectance
with increasing LA!. Details on LAI sampling and spectral analysis are provided in Roberts et al., (1998b). (See
color plate.)
In December 1999 NASA launched the first earth
observing system (EOS) platform, which will include the much-anticipated moderate resolution imaging spectroradiometer (MODIS). MODIS can
observe most of the earth every two days via 36
spectral bands at nadir instantaneous-fields-of-view
of 250, 500, and 1000 m (Barnes et al. 1998). The
MODIS imagery will be acquired in concert with
LANDSAT 7 and ASTER (advanced spacebome
thermal emission and reflection radiometer) to allow multiscale sampling and land surface monitoring. The MODIS science team will derive and distribute several "standard data products" for
monitoring regional and global vegetation dynamics, including surface reflectance, land surface temperature, albedo, vegetation indices, fraction of absorbed photosynthetically active radiation (FPAR),
LAI, fires, landcover, and net primary productivity
(NPP) (see Justice et al. [1998] for details).
Radar Remote Sensing
Active microwave sensors yield a wide range of
information about earth surfaces, notably surface
topography, surface roughness, soil moisture, and
vegetation structure and composition (Henderson
and Lewis 1998). All active microwave sensors
share the advantages of being independent of solar