Stable colonization of native plants and early invaders by arbuscular mycorrhizal fungi after exposure to recent invaders from the Asteraceae family

Arbuscular mycorrhizal fungi (AMF, Glomeromycota) are globally distributed symbionts of plant roots. Relationships with arbuscular mycorrhizae can provide crucial support for the establishment of any plant in an unfavorable environment. We hypothesized that invasions of neophytes are associated with changes in the colonization of native plants and early invaders (archeophytes) by AMF. We examined changes in AMF colonization in yarrow Achillea millefolium, wild carrot Daucus carota (native plants), tansy Tanacetum vulgare and false oat-grass Arrhenatherum elatius (archeophytes) in response to the invasion of four neophytes from the Asteraceae family, namely great globe-thistle Echinops sphaerocephalus, New York aster Symphyotrichum novi-belgii agg., annual fleabane Erigeron annuus, and Canada goldenrod Solidago canadensis. We found that the AMF colonization of the Asteraceae neophytes was high in the studied monodominant invasions, and the AMF colonization of the neophytes was higher than or equal to that of the studied native plants and archeophytes. Changes in plant dominance did not serve as predictors of the extent of AMF colonization of the native plants and archeophytes despite the invaded plots being associated with strong changes in the availability of primary and secondary mineral nutrients. The absence of a response of AMF colonization of native and archeophyte plant species to the invasion of neophytes suggests that AMF are passengers, rather than drivers, in the course of Asteraceae invasions in central European environments.