Use of HYMAP image data to estimate sideroxylonal-A concentration of eucalypt foliage

Airborne HYMAP data were used to estimate the sideroxylonal-A concentration from the canopy reflectance of Eucalyptus melliodora. Modified partial least squares (MPLS) was applied to the extracted mean and maximum canopy spectra to estimate the sideroxylonal-A concentrations. The resultant coefficients of determination (R²) are high (e.g. 0.89 in one case), and the identified absorption features (wavelengths) are closely consistent with those identified in a previous study in which near IR spectroscopy was used to measure the sideroxylonal-A concentration of ground freeze-dried leaves, and a spectroradiometer was used to estimate the sideroxylonal-A concentration of whole oven-dried leaves and fresh whole leaves.