Abstract

The social, economic, and ecological costs of plant invasions are vast, through their ability to alter ecosystem structure and function. Invasive annual grasses are a nuisance in the American Southwest through promotion of the grass-fire cycle. Annual grasses such as Bromus rubens, Bromus tectorum, Schismus barbatus, and Schismus arabicus have invaded the Mojave Desert and increased fire occurrence, thus it is important to identify and characterize the areas where persistent invasion has occurred and subsequently fire risk is increased by understanding the distribution of these invasive grasses. Previous plot and landscape-scale research has revealed anthropogenic and biophysical correlates with the establishment and dominance of invasive annual grasses in the Mojave Desert. However, these previous studies have been limited in spatial and temporal scales. Here we use a remote sensing framework to map persistent and productive populations of invasive annual grass, called hot spots, in the entire Mojave Desert ecoregion over 12 years, identify important variables for predicting hot spot distribution, and identify the most invaded subregions. Hot spots were identified in over 5% of the Mojave Desert, and invasive grasses were detected in over 90% of the desert at least once. Our results indicate that soil texture, aspect, winter precipitation, and elevation are the most important predictive variables of invasive grass hot spots, while anthropogenic variables were the least useful. The most invaded subregions of the Mojave Desert were western Mojave basins, eastern Mojave mountain woodland and shrubland, western Mojave low ranges and arid footslopes, eastern Mojave basins, and eastern Mojave low ranges and footslopes.

Degree

College and Department

Life Sciences; Biology

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