Using Remote Sensing and Spatial Information Technologies
for Detecting and Mapping Chinese Tamarisk Infestations

James H. Everitt

Range Scientist
U.S. Department of Agriculture-Agricultural Research Service
Remote Sensing Research
2413 East Highway 83
Weslaco, Texas 78596-8344
Phone: 210-969-4824
FAX: 210-969-4823
E-mail: j-everitt@tamu.edu

Abstract

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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