The high temperature hydrothermal convection system underlying northwestern Dixie Valley, Nevada, is probably responsible for the development of certain geobotanical anomalies in the area. A large
ìdie-offí of Baileyís greasewood (Sarcobatus baileyi) has been observed over the last several months and appears to be related to activity that
preceded the appearance of a new fumarole. AVIRIS (Advanced Visible and Infrared Imaging Spectrometer) airborne hyperspectral data was
acquired for this area in May 1995, several months before the die-off was first recognized. Analysis of hyperspectral remote sensing data using polytopic vector analysis has resulted in the characterization of
vegetal-spectral anomalies in the area of the die-off. Four spectral ìfingerprintsî were resolved and mapped. One of the four appear related to the S. baileyi die-off. Its spectrum closely matches spectra
of healthy S. bailey. EM-1 was largely absent in the present area of the die-off at the time of the AVIRS image was collected. The fact that the analyzed AVIRIS image was taken months before the die-off
was observed in the field suggests that spectral unmixing may prove an effective tool in anticipation of vegetative stress.

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