Chinese tamarisk (Tamarix chinensis Lour.) is an invader of riparian sites in the southwestern United States and northern Mexico. Studies were conducted to determine feasibility of using remote sensing techniques, global positioning system (GPS), and geographic information system (GIS) technologies for detecting and mapping this troublesome woody plant species.
Study sites were along the Colorado River in southwestern Arizona, the Rio Grande River in extreme west Texas, and the Pecos River in west-central Texas. Plant canopy reflectance measurements showed that Chinese tamarisk had higher visible (0.55- and 0.65-m wavelengths and 0.63- to 0.65-m waveband) reflectance than did associated woody and herbaceous plant species in the late fall-early winter period when its foliage turned a yellow-orange to orange-brown color prior to leaf drop. Chinese tamarisk had a yellow-orange color on conventional color aerial photography and videography during this phenological stage that made it distinguishable from other plant species.
Computer analyses of conventional color film transparencies showed that Chinese tamarisk populations could be quantified from associated vegetation. A GPS was integrated with the video imagery that permitted Chinese tamarisk infestations to be recorded on each image. The GPS latitude/longitude coordinates were entered into a GIS to map Chinese tamarisk populations along the three river systems.
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For information on the outcome of this workshop or integrated weed management in the Pacific Region (Region 1), U.S. Fish and Wildlife Service, Portland, OR, contact: Scott_Stenquist@fws.gov
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