Invasive species are expected to spread under all alternatives. Surface disturbance can increase invasive species by either damaging native vegetation and creating a space for the establishment of invasive species, or introducing invasive species seed and plant matter from machinery and other equipment. Correspondingly, alternatives projected to involve the greatest amount of surface disturbance would have the greatest potential to increase the spread of invasive species. Stringent reclamation requirements, especially reclamation plans before surface disturbance, would decrease long-term disturbance and the likelihood of invasive species establishment. Based on projected surface disturbance, Alternative C would result in the greatest potential spread of invasive species, followed by alternatives A, D, and B respectively. Alternative D is projected to result in greater surface disturbance than Alternative A, but contains more stringent reclamation requirements that would result in a reduced potential for the spread of invasive species.

Fire and fuels management, motorized vehicle use, and livestock grazing would have the greatest impact on the spread of invasive species. Though disturbance caused by fire can spread invasive species, when conditions are favorable and proactive management to reestablish native plants follows closely after, fire can be a tool to reestablish historic fire regimes that favor native plants over invasive species. Alternative C would result in the greatest short-term adverse impacts from disturbance due to fire and fuels management and the greatest potential long-term benefits from restoration of historic fire regimes, followed by alternatives A, D, and B respectively. Closing areas to motorized vehicle use can help prevent the unintentional spread of invasive species; Alternative B restricts travel across the largest portion of the Planning Area, and would provide the greatest potential reduction in the spread of invasive species from motorized vehicles, followed by alternatives D, A, and C respectively. The potential adverse impacts from livestock grazing related spread of invasive species would be greatest under Alternative C due to fewer management options to control their spread (e.g., the option to require livestock flushing); alternatives A, D, and B, respectively contain more management options to control livestock grazing related invasive species spread.