COMMUNITY TYPE DIFFERENTIATION USING NOAA/AVHRR DATA WITHIN A SAGEBRUSH STEPPE ECOSYSTEM

We assessed the ability of AVHRR/NDVI data to record intrabiome variability of phenological and structural characteristics of three dominant vegetation communities in the intermountain northwest. Seasonal NDVI signatures were developed from biweekly composite data for two grass and one shrub community within a sagebrush-steppe ecosystem. The signatures were found statistically separable (p = 0.01) among all three communities in three of 19 composite periods, and between shrub and grass in 15 of 19. Integrated NDVI provided the greatest differentiation among the communities due to ordinal consistency of the three signatures throughout the growing season. A supervised classification of adjacent regions with contrasting topography and substrate was tested for accuracy, and results indicate a strong potential for AVHRR applications to community-level vegetation differentiation. Classification errors are primarily caused by subpixel scale topographic and soil background variations that may not be correctable for coarse resolution imagery.