干旱区生态环境知识资源中心

Management of semi-arid rangelands in the western United States for sustainability requires objective methods for monitoring large areas; the goal of the Wyoming Hyperspectral Imagery Pilot Project (WHIPP) was to determine if hyperspectral remote sensing can provide the capability for rangeland assessment. Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) data obtained during the Geology Group Shoot over the Nature Conservancy's Red Canyon Ranch near Lander, WY, were compared with Landsat Thematic Mapper data for classification of vegetation communities. Using the same training areas, supervised classifications from the two sensors were significantly different. The amount of vegetation cover from unconstrained linear spectral unmixing was highly correlated to normalized difference vegetation index (NDVI). The flight lines were east-west, vegetation on the north side of the image had significantly higher reflectances compared to similar vegetation on the south side of the image, possibly due to differences in the bidirectional reflectance distribution function. These results indicate hyperspectral imagery can provide better data on community composition, but equivalent information on the amount of vegetation. Thus, infrequent collection of AVIRIS data combined with other sensors provides an optimal solution for monitoring rangelands.