Invasion by non-native plant species can alter the composition of soil microbial communities resulting in the loss of mutualistic associations between native plants and arbuscular mycorrhizal (AM) fungi. Our previous research has indicated inoculation with native soils can increase success of grassland restorations. However, inoculating every plant across acres of a restoration is not feasible. Therefore, we planted inoculated native nurse plants, with the objective of re-constructing native soil microbial communities using limited native soil. We established restoration sites in Kansas and Oklahoma that were previously invaded by a non-native warm-season grass (Bothriochloa ischaemum). Invasive grasses were eradicated at each site and seven replicate (4m x 4m) experimental plots were planted with four individuals each of four nurse plant species (Andropogon gerardii, Amorpha cansecens, Allium canadense, Echinacea augustifolia). Nurse plants were inoculated either with whole soil from nearby native sites, AM fungi isolated from native whole soil, or received no inoculation. Soil was collected prior to transplanting and 1 month post-transplant at 0 m (nurse plant rooting zone), 0.5, 1.0, and 1.5 meters from nurse plants to assess relative abundances of soil microbial community functional groups using phospholipid and neutral lipid fatty acid (PLFA/NLFA) analysis.
Results/Conclusions
At the end of the first growing season, survival and growth of host plants were determined. Across the plots, we found significantly greater AM fungal abundance following transplant of whole soil-inoculated or AM culture-inoculated nurse plants, relative to non-inoculated nurse plants. Inoculation with native soil or AM fungal cultures significantly increased nurse plant survival and significantly increased leaf number of nurse plants. Variance in nurse plant survivorship can be attributed to greater competition in certain plots. Our initial results suggest successful introduction of AM fungi and that early seedling survival and growth was improved through the use of inoculated native nurse plants in post-invaded soil. These results indicate it is essential that restoration projects to re-establish the link between plants and native microbes that is often decoupled by non-native invasive species.