Spectral Characteristics of Natural and ...

Two laboratory techniques (air drying and oven drying) were implemented to compare the spectral reflectance differences between laboratory-induced and natural leaf senescence. The spectral signatures of four common North American tree species were recorded over the 2011 summ er-autumn season. Natural ‘on-tree’ senescence was measured throughout the senescence period and simultaneously with the two laboratory methods. Two substantial differences were observed between the natural senescence and laboratory techniques: the persistence of the ‘green peak’ for the laboratory methods; and the much higher reflectance values throughout the middle infrared region for the laboratory methods. These results suggested that a more sophisticated laboratory method including the ability to export leaf constituents during senescence is required to accurately reproduce autumn leaf senescence in a laboratory setting. If achieved, this could greatly improve analyst’s ability to reproduce the spectral changes associated with vegetation health and leaf senescence.