USING REMOTE-SENSING AND SPATIAL INFORMATION TECHNOLOGIES TO MAP SABAL PALM IN THE LOWER RIO-GRANDE VALLEY OF TEXAS

This paper describes an application of airborne video data with global positioning system (GPS) and geographic information system (GIS) tech nologies for distinguishing and mapping the distribution of sabal palm (Sabal mexicana) in the lower Rio Grande Valley (LRGV) of southern Te xas. Field reflectance measurements suggested that sabal palm may be r emotely distinguished fr om associated vegetation during the late summ er and fall as a result of the presence of senesced (brown) leaves and mature fruit clusters within the canopy. Sabal palm could be distingu ished on aerial color-infrared (CIR) video imagery during this phenolo gical stage because it had a brownish-red image response. integration of GPS with video imagery permitted latitude/longitude coordinates of sabal palm populations to be recorded on each image. Global positionin g system coordinates were entered into a GIS to produce maps depicting the distribution of sabal palm in the LRGV.