Aim: Cheatgrass (Bromus tectorum) invasion can alter community structure of arbuscular mycorrhizal fungi (AMF) in the sagebrush-steppe ecosystem. The feedbacks and underlying mechanisms of a changed AMF community on sagebrush (Artemisia tridentate ssp. wyomingensis) remain unclear. We assessed how 'own' versus 'foreign' AMF impact plant biomass, C transfer to AMF, and decomposition rates.Methods: To evaluate the impact of different AMF communities on plant biomass and C transfer, sagebrush and cheatgrass were grown in sterilized soil amended with 'own' or 'foreign' AMF. Sagebrush plants were labeled with 13C-CO2 to assess changes in allocation of C belowground (13C-PLFA & NLFA) and decomposition (soil respired 13C-CO2). Community structure and alpha-diversity of AMF were examined in native and cheatgrass-invaded communities.Results: Cheatgrass invasion changed AMF community structure and decreased AMF taxon richness. Sagebrush C transfer and decomposition were not altered, but sagebrush root and cheatgrass shoot production was reduced with 'foreign' AMF and no AMF, respectively.Conclusion: Our results from the greenhouse experiment suggest that sagebrush performance declines with cheatgrass invasion. This may be caused by a disadvantageous AMF community shift, where 'foreign' AMF received the same amount of C but provided fewer benefits to sagebrush, as shown by decreased root biomass. These findings provide insight into the feedback mechanism that may contribute to decreasing native plant performance upon invasion. [ABSTRACT FROM AUTHOR]