Assessing the Suitability of Landsat Satellite Data for Distinguishing Cheatgrass Infested Sites in Douglas, Wyoming

Cheatgrass (Bromus tectorum) is an invasive species that is threatening the rangelands of the Western US. By greening earlier in the season, Cheatgrass uses soil moisture that is normally available for native vegetation and poses fire hazards by drying in the middle of the growing season. Land management agencies are tasked with controlling Cheatgrass and mapping their distribution is essential for their management. Remotely sensed images are used for mapping vegetation condition however application of this technology poses some challenges for mapping Cheatgrass in Wyoming. This project assessed the suitability of Landsat 5 Thematic Mapper images for distinguishing Cheatgrass infested sites from those consisting of native vegetation. Satellite images acquired from April through August 2006 were evaluated to early season Landsat images for separating Cheatgrass from native vegetation based on their spectral reflectance. Sites from two privately managed ranches located 27 miles north of Casper were analyzed in this study. Spectral reflectance in the April and May Landsat images could be used for identifying Cheatgrass infested sites. However there is some overlap between reflectance from riparian vegetation and Cheatgrass which will require additional image processing to improve map accuracy.