Abstract: Tamarisk Pilot Mapping Inventory Study

A collaborative project between the US Forest Service, Remote Sensing Application Center (RSAC) and the Tamarisk Coalition, evaluated different sources of digital imagery for mapping the invasive species tamarisk. Costs for collecting and analyzing the imagery as well as ease of use were considered in the evaluation. Digital images with differing spatial and spectral resolution were collected during 2002 at two study sites along the Colorado River near Grand Junction, CO. This project focused on the analysis of natural color and color infrared data collected with Kodak digital cameras as well as hyperspectral data collected with HyMap sensor. The digital camera images were classified using Feature Analyst, a spectral-spatial image analysis program. The hyperspectral data were classified using a partial unmixing method for which the input spectra were extracted from image pixels corresponding to field documented tamarisk sites. The results indicate that the higher spatial and spectral resolution data collected during the summer can be used to differentiate larger stands of tamarisk from other riparian vegetation. The field-based accuracy assessment of the hyperspectral classification resulted in overall accuracies of 76% and 89% for dense mature tamarisk stands on the two study site. Younger and smaller tamarisk shrubs, important for detecting early infestations, were more difficult to map accurately.

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