Abstract: Weedy and invasive plant species can dominate prairie restorations, creating management problems. The early-successional, often non-native, species may be suppressed by initial establishment of high diversity of late-successional native prairie plants that are highly conservative and highly sensitive to the soil microbial community. In particular, many late-successional grassland species rely on their symbiotic relationship with arbuscular mycorrhizal fungi (AMF) for establishment and reproductive success (Koziol et. al, 2019). To study how to the soil microbial community and established plant diversity influences community assembly, we developed a large field experiment using a randomized-factorial design. We planted 18 native plant species: six from three different families (Asteraceae, Fabaceae, and Poaceae). The design of this experiment includes the manipulation of several ecological factors: two levels of phylogenetic dispersion (over/under), five levels of species richness (1, 2, 3, 6, and 18), and three levels of soil community treatments (sterile, prairie whole soil, and AMF inoculated). We collected a biomass strip harvest and percent cover data annually to analyze the effects of diversity and soil microbial community manipulation on the abundance and composition of volunteer species. This data was collected on all species present in the plot distinguishing ‘weeds’/volunteers as species that were not of the 18 planted. Four years after initiation native AMF inoculated plots had consistently lower and consistently decreasing invasive species richness compared to the sterile and prairie whole soil treatments. With increased diversity, there was an increase in the abundance of planted species and a decrease in the abundance of volunteers. In the first two years of the experiment, there was a result of inoculation on the abundance of volunteer species; those inoculated with AMF had significantly less volunteer abundance than those in the other two soil treatments. This result diminished and in the last three years, the abundance of planted and volunteer species was better explained by the diversity treatments. Our results suggest that planting high native plant species richness and native AMF inoculation can effectively suppress early-successional and non-native species, thereby facilitating management of future restoration efforts.
