Using Earth Observations to Map the Spatial Distribution of Buffelgrass in the Sonoran Desert

Abstract

The Sonoran Desert is recognized as an arid ecosystem with a year-round warm climate and biodiverse desert flora. The desert spans across the southwestern United States and northwestern Mexico. Much of the native flora, like the saguaro cactus (Carnegiea gigantea), are important members of the Sonoran Desert for native wildlife and human society. Currently, the ecosystem is being threatened by the rapid spread of an invasive grass species known as buffelgrass (Cenchrus ciliaris), as it is changing the desert landscape to a grassland and contributes to more flammable fuel of surging wildfires. This project, in partnership with the Tucson Sonoran Desert Museum’s “Save our Saguaros” initiative, utilized satellite imagery of Tumamoc Hill and Sentinel Peak from Google Earth to develop and assess an optimal workflow marking the spatial distribution of buffelgrass via manual mapping. This would aid in early detection and rapid response management not only within the study area but other areas of the Sonoran Desert. GIS analysts worked with a predetermined buffelgrass identification key to manually plot growth sites of the species across the study site. Satellite Imagery from 2016-2020 was found to provide the best visual reference for historical buffelgrass growth and through remote mapping and ground truthing a significant accuracy level was achieved.