Bj. Yoder et Re. Pettigrewcrosby, PREDICTING NITROGEN AND CHLOROPHYLL CONTENT AND CONCENTRATIONS FROM REFLECTANCE SPECTRA (400-2500 NM) AT LEAF AND CANOPY SCALES, Remote sensing of environment, 53(3), 1995, pp. 199-211
An experiment was designed to determine whether chlorophyll and nitrog
en concentrations could be predicted from reflectance (R) spectra of f
resh bigleaf maple leaves in the laboratory, and, if so, whether the p
redictive spectral features could be correlated with chlorophyll and n
itrogen concentration or content of simple canopies of maple seedlings
. The best predictors for nitrogen and chlorophyll of fresh leaves app
eared with first-difference transformations of log 1/R, and the bands
selected were similar to those found in other studies. Shortwave infra
red bands were best predictors for nitrogen, visible bands best for ch
lorophyll. In the shortwave infrared region, however the absolute diff
erences in reflectance at critical bands was extremely small, and the
bands of high correlation were narrow. High spectral and radiance reso
lution are required to resolve these differences accurately. The best
shortwave infrared bands from the leaf scale were not good predictors
of chemical content or concentration at the canopy scale; variability
in canopy reflectance in the shortwave infrared region was at least an
order of magnitude beyond that necessary to detect signals from chemi
cals. The variability in first-difference log 1/R on the canopy scale
was related to the arrangement of trees with respect to direct solar r
adiation, instrument noise, leaf fluttering, and small changes in atmo
spheric moisture.