Predicting leaf and canopy 15N compositions from reflectance spectra

[1] We explored whether N-15 concentration could be predicted from reflectance spectra of fresh leaves, and, if so, whether the spectral features were related to the N-15 concentration on a canopy scale. Leaf scale reflectance (R) measurements were conducted in Ghanzi, Botswana using a spectrophotometer in March 2005 and canopy scale leaf R was measured in a series of successional fields in Northern Virginia, USA using the same instrument in September 2005. Results showed that there was a strong correlation between foliar N-15 concentration and spectral data in both visible and near-infrared wavelength regions. Stepwise regressions showed that the first-difference of the log1/R [(log 1/R)'] could explain 76 to 92% of the variation in foliar delta N-15, providing the most reliable correlations with foliar N-15 at bands near 600 and 700 nm. The present study indicates the possibility of estimating fresh leaf N-15 abundance from high-resolution reflectance at leaf and canopy levels.