Comparison of in situ measurements of forest decline symptoms in Vermont (USA) and the Schwarzwald (FRG)

Field analyses were conducted at spruce/fir sites in the U.S. and Germany undergoing forest decline. Data gathered from common branch samples included reflectance curves, fluorescence measurements, and pigment concentrations. Similar reflectance signatures are seen for specimens from all sites. Reflectance spectra from specimens collected from high damage sites in both countries show a characteristic reflectance drop in the near infrared and a shift (5 nm) of the red edge to shorter wavelengths. Fluorescence data suggest altered state of health of photosynthetic pigments only in specimens from German high damage sites, and pigment extraction and analysis indicate a reduction in total chlorophyll, a decrease in chlorophyll b when compared with chlorophyll a, and a relative increase in carotenoids.