The invasion of semiarid Mediterranean sites by Nicotiana glauca mediates temporary changes in mycorrhizal associations and a permanent decrease in rhizosphere activity.
Background and aims: Exotic invasive plants may have adverse effects on native plant communities and ecosystem functions by altering communities of belowground mutualistic mycorrhizal fungi. However, little is known about how such alterations change over time. The aim of this work was to determine the arbuscular mycorrhizal fungi (AMF) communities colonizing the roots of Nicotiana glauca populations of distinct ages (1 and 20 years old), and of co-occurring native plants, growing at four different Mediterranean semiarid locations. The short-term and long-term effects of the invader on rhizosphere activity and nutrient pools were also determined. Methods: Illumina MiSeq technology was used for high-throughput sequencing of AMF communities and basal respiration and enzymatic activities were determined for assessing rhizosphere activity. Results: The composition and structure of AMF communities differed according to the invasive character of plant and the invaded site. The AMF community belonging to the young invasive plants had a significantly different structure and composition in comparison to the native plants and the adult invasive plants. However, the native plants and the adult invasive plants harboured a similar AMF community. In general, basal respiration, enzymatic activities and nutrients of the rhizospheres of two populations of N. glauca of distinct ages were significantly different from those of the rhizosphere of native plants, but these differences were independent of the time after the invasion. Conclusions: The invasion of semiarid Mediterranean sites by N. glauca mediated temporary changes in mycorrhizal associations, whereas the early effect of this invasive plant decreasing rhizosphere activity remained across time.