LAUSR

Alpine areas will likely experience an increase in non-native plant species invasions. Increased human activity and environmental changes are expected to lower the environmental constraints for their establishment and spread. To understand and prepare for high elevation plant invasions it is necessary to evaluate the changes in environmental factors that make alpine regions susceptible to potential invaders. The alpine of the Rocky Mountains has very few occurrences of non-native species to date, but anthropogenic environmental changes may facilitate invasion. We tested whether Bromus tectorum (cheatgrass or downy brome) invasion in the Rocky Mountain alpine could be facilitated by increases in mean and minimum growing season temperatures. We also tested whether nitrogen (N) deposition and alpine soil may modify B. tectorum ’s responses to climate warming. Our findings suggest that alpine soils inhibited growth of B. tectorum regardless of temperature or simulated N deposition. These results indicate that local alpine invasion by B. tectorum is unlikely in the near future. However, higher minimum growing temperatures and increased N addition did enhance B. tectorum growth for plants grown in upper montane soils. Such changes may promote population growth of B. tectorum within montane elevations.