The role of arbuscular mycorrhizal fungi in the competition between invasive and native plants depends on the soil nitrogen form

Studies show that arbuscular mycorrhizal fungi (AMF) facilitate invasion of alien plants. AMF prefer to take up and transfer more ammonia (NH4+) than nitrate (NO3−) to plants. However, few studies have investigated the response of AMF to soil N forms. Therefore, two invasive and two native plants in the Asteraceae family were selected for a common garden experiment involving different N forms (NH4+ vs. NO3−), AMF treatments (−AMF, +AMF, mycelium) and competition conditions (monoculture vs. mixture).