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Title: Mapping Broom Snakeweed Through Image Analysis of Color-infrared Photography and Digital Imagery

Author
item Everitt, James
item Yang, Chenghai

Submitted to: Environmental Monitoring and Assessment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2007
Publication Date: 10/15/2007
Citation: Everitt, J.H., Yang, C. 2007. Mapping broom snakeweed through image analysis of color-infrared photograpy and digital imagery. Environmental Monitoring and Assessment. 134:287-292.

Interpretive Summary: The invasion and spread of undesirable plant species on rangelands present serious problems to range managers and ranchers. Broom snakeweed is a short woody-based shrub that invades rangelands in the western United States and northern Mexico. It is poisonous to livestock and suppresses growth of grasses. A study was conducted in southern Texas to evaluate aerial color-infrared (CIR) photography and digital imagery combined with computer image analysis to map broom snakeweed. Unsupervised image analysis of CIR photographs had mean producer’s and user’s accuracies for broom snakeweed of 98.3% and 88.3%, respectively; whereas, image analysis of CIR digital images had mean producer’s and user’s accuracies for broom snakeweed of 98.3% and 92.8%, respectively. These results should be useful to rangeland resource managers who are interested in controlling this noxious weed and monitoring its spread or contraction over large and inaccessible rangeland areas.

Technical Abstract: A study was conducted on a south Texas rangeland area to evaluate aerial color-infrared (CIR) photography and CIR digital imagery combined with unsupervised image analysis techniques to map broom snakeweed [Gutierrezia sarothrae (Pursh.) Britt. and Rusby]. Accuracy assessments performed on computer-classified maps of photographic images from two sites had mean producer’s and user’s accuracies for broom snakeweed of 98.3% and 88.3%, respectively; whereas, accuracy assessments performed on classified maps from digital images of the same two sites had mean producer’s and user’s accuracies for broom snakeweed of 98.3% and 92.8%, respectively. These results indicate that CIR photography and CIR digital imagery combined with image analysis techniques can be used successfully to map broom snakeweed infestations on south Texas rangelands.