A 39,000-ha semi-arid rangeland test site in Starr and Zapata Counties, Texas, was used to compare rangeland inventory and other landuse categories estimated by digital pattern recognition methods (maximum likelihood ratio classification) with percentages estimated from a ground-correlated print enlarged to 1:100,000 scale from a LANDSAT color composite transparency. Five land-use categories were identified (grassland, mixed brush rangeland, saline rangeland, cropland, and water). We found a highly significant correlation (r = 0.997**) between the photo- and computer-estimated hectarage for the June LANDSAT-2 overpass. The correlation was not significant for the August overpass largely because a large percentage of the most extensive rangeland category (mixed brush rangeland) was misclassified as cropland. The misclassification was probably related to some of the spectra in the rangeland area resembling that of crop residue, and volunteer plants and weeds on the idle cropland. Computer-estimated hectarages for grassland, saline rangeland, and water were similar to the photo-estimated hectarages for both the June and August overpasses, indicating the feasibility of estimating these landuse categories for either date.
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