CANOPY LIGHT REFLECTANCE AND REMOTE-SENSING OF SHIN OAK (QUERCUS-HAVARDII) AND ASSOCIATED VEGETATION

Shin oak is a deciduous shrub that forms dense stands of brush on sand y soils in rangeland areas of the Rolling and High Plains of Texas. Pl ant canopy reflectance measurements made on shin oak showed that it ha d both low visible (0.63- to 0.69-mum waveband) and near-infrared (0.7 6- to 0.90-mum waveband) reflectance values, a characteristic generall y not shared by associated plant species or mixtures of species. The l ow reflectance values of shin oak caused it to have dark-red, reddish- brown, or brown image tones on color-infrared photographic, videograph ic, and SPOT satellite images that made it distinguishable from associ ated vegetation and other land use features. The optimum time to remot ely distinguish this noxious shrub is during the mature phenological s tage from June to September. Computer-based image analyses of video an d satellite images showed that shin oak populations could be quantifie d. This technique can permit ''percent land area'' estimates of shin o ak on rangelands. The aerial imagery is useful for detecting shin oak on smaller rangeland areas, whereas the satellite imagery is applicabl e in mapping large areas of shin oak distribution.