Leaf handling methodology and species classification of tropical tree leaf spectral reflectance

After leaves are clipped their reflectance properties change over time at variable rates depending upon species and wavelength. This study indicates that Visible reflectance from leaves does not respond until wilting is observed and that NIR and SWIR reflectance respond immediately. Wrapping leaves in moist paper towel and placing them within plastic bags maintained leaf reflectance longer (greater than 7 days) than equivalent leaves without treatment. Strong relationships between leaf water content and spectral shape were defined via theta ("angle difference") and the ratio 1187/1096 nm.; Leaf reflectance of twenty tropical tree species can be classified accurately (79% to 97%) using linear discriminant analysis. The species studied were classified best using bands or indices correlated with leaf water content, followed by pigmentation properties. While wavelengths between 350 to 2500 nm were important for overall classification accuracy, certain species were classified accurately using only one range (VIS or SWIR) of wavelengths.