Elevated CO2, warming, N addition, and increased precipitation affect different aspects of the arbuscular mycorrhizal fungal community

The functional diversity of arbuscular mycorrhizal fungi (AMF) affects the resistance and resilience of plant communities to environmental stress. However, considerable uncertainty remains regarding how the complex interactions among elevated atmospheric CO2 (eCO2), nitrogen deposition (eN), precipitation (eP), and warming (eT) affect AMF communities. These global change factors (GCFs) do not occur in isolation, and their interactions likely affect AMF community structure and assembly processes. In this study, the interactive effects of these four GCFs on AMF communities were explored using an open-top chamber field experiment in a semiarid grassland. Elevated CO2, eN, eT, eP, and their interactions did not affect AMF biomass. The relative abundance of Paraglomus increased with N addition across treatment combinations, whereas that of Glomus decreased with N addition, especially combined with eT and eCO2. Precipitation, temperature (T), and N affected AMF phylogenetic α-diversity, and the three-way interaction among CO2, T, and N affected taxonomic and phylogenetic α-diversity. N addition significantly affected the composition of AMF communities. Both variable selection and dispersal limitation played major roles in shaping AMF communities, whereas homogeneous selection and homogenizing dispersal had little effect on AMF community assembly. The contribution of variable selection decreased under eCO2, eN and eT but not under eP. The contribution of dispersal limitation decreased under eCO2, eT, and eP but increased under eN. The assembly of AMF communities under the sixteen GCF combinations was strongly affected by dispersal limitation, variable selection and ecological drift. Elevated CO2, warming, N addition, and increased precipitation affected different aspects of AMF communities. The interactive effects of the four GCFs on AMF communities were limited. Overall, the results of this study suggest that AMF communities in semiarid grasslands can resist changes in global climate.