Plant-Microbial Interactions Change Along a Prairie Restoration Chronosequence

Soil microbial communities are critical in determining the performance and density of species in plant communities. However, their role in regulating the success of restorations is much less clear. This study assessed the ability of soil microbial communities to regulate the growth and performance of two potentially dominant grasses and two common forbs in prairie restorations. Specifically, I examined the effects of soil microbial communities along a restoration chronosequence from agricultural fields to remnant prairies using experimentally inoculated soils. The two grass species, Andropogon gerardii and Sorghastrum nutans, produced larger biomass with the agricultural inoculates and experienced a decline in performance in later stages of the chronosequence, indicating that the microbial community shifted from being beneficial to grasses in the early stages to inhibiting grasses in the later stages of restoration. The forb, Silphium terebinthinaceum was largely unaltered by the inoculation or position along the restoration chronosquence. Baptisia leucantha growth appeared limited by nodule formation in agricultural soils, peaked in young restoration soils along with module formation, but decreased in older soils as the microbial community became more antagonistic. Overall, this experiment showed strong site variability, representing patchiness in microbial interactions, though older soils consistently had the strongest inhibitory effect on growth. Negative feedbacks tended to be less important in the beginning stages of succession in these restorations but appear important in remnant and restored prairies. My results provide evidence that it maybe advantageous for management practices to take negative feedbacks into consideration when trying to recreate the diversity of prairies