Analysis and experimentation on ecosystems

The cessation of mowing in subalpine grasslands promotes the dominance of Festuca paniculata leading to the reduction in plant diversity. Moreover, it affects positively the abundance of Epichlo€e sp. inhabiting F. paniculata leaves and negatively the soil density of arbuscular mycorrhizal fungi (AMF). We explored how the cessation of mowing influences root AMF communities in F. paniculata and the neighboring plants, and Epichlo€e sp alkaloids. Thirteen AMF operational taxonomical units were found. The neighboring plants affected positively the abundances of Aalpin and GLOM\_7 whereas the interaction plant/ management type influenced significantly Claroide\_1, GLOM\_1 and GLOM\_7. The N-formylnorloline, produced by Epichlo€e sp. increased in unmown grassland. Hence, the cessation of mowing, coinciding with the high abundance of endophyte alkaloid, affected root-associated AMF with differential responses at the abundance level. The N-formylnorloline could be one compound underpinning the dynamic of plant diversity with a resulting structuration of AMF in subalpine grasslands.