Cheatgrass and AMF: Impacts of Invasion and Mitigation for Restoration.

Cheatgrass (Bromus tectorum) invasion in the western United States has caused a dramatic shift from diverse shrublands to annual grass monocultures. Cheatgrass is considered a facultative AMF associate, but little is known about specific interactions with AMF, how these interactions differ from native vegetation, and how changes to the AMF community due to invasion might be overcome. Results from multiple studies will be presented assessing AMF colonization of cheatgrass, comparing AMF diversity associating with cheatgrass and big sagebrush across multiple sites using molecular and morphological methods, and greenhouse and field studies that seek to overcome AMF alterations due to cheatgrass invasion. Cheatgrass was found to be a poor AMF host throughout its life, have lower AMF diversity associated with individuals compared to big sagebrush, significantly alter AMF composition compared to big sagebrush, and alter the heterogeneity of individual AMF associations in plant populations. However, native plant species were identified that interact with AMF associated with cheatgrass invasion in ways that not only provide them a competitive advantage, but also rapidly improve AMF density in invaded soils. Further, plant species exhibiting a positive response in the greenhouse had much higher establishment at the invaded site, indicating that AMF interactions can be used to screen for forbs that are most likely to establish at a particular invaded site.