Cheatgrass-associated AMF community negatively affects sagebrush root production but not C transfer to the soil

Abstract

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.

from Energy Ecology Environment Ambio via Terpsi Hori on Inoreader http://bit.ly/2SSYYGf