Synergistic changes in AM fungi and soil abiotic properties in rhizosphere soils of invasive Solidago canadensis may confer its stronger dominance in communities

Background and aims Arbuscular mycorrhizal fungi (AMF) promote uptake of nutrients by plants; inversely, soil abiotic properties determine relationships between AMF and hosts. Although multiple hypotheses have suggested the importance of AMF or soil nutrients alone for plant invasion success, few studies have examined the relative importance and synergistic effects of AMF and soil abiotic properties at the community level. Methods Eighteen pair-wise plots with or without by Solidago canadensis invasion were surveyed and 72 rhizosphere and bulk soils were sampled to evaluate changes and the relative importance of AMF and soil abiotic properties. Assembly communities were constructed with native or invasive AMF inoculation into sterilized soils with no phosphorus (P) addition (low P), and with inorganic and organic P added to evaluate plant soil feedback-mediated synergistic effects. Results AMF community structure and composition in the rhizosphere soils of S. canadensis differed greatly from those in the bulk and native soils. Soil abiotic properties changed synergistically with lower pH, higher conductivity, and higher P content. S. canadensis dominance was explained more by interactions between AMF and soil abiotic properties than AMF alone, but was lower than that of abiotic properties alone. In low P and added organic P conditions, synergistic changes in AMF and soil abiotic properties provided positive feedback to the invader but neutral feedback in conditions with added inorganic P. Conclusion S. canadensis produced strong rhizosphere effects on the AMF community and soil abiotic properties, which supported its growth and competition, especially under low and organic P conditions.