As little as 1% of the original expanse of North America’s tallgrass prairie remains intact. The remaining extent of tallgrass prairie is currently threatened by invasions of non-native plant species. Restoration of native biodiversity is often minimally successful following eradication of non-native plants. While much attention has focused on aboveground processes, considerably less research has assessed the role of belowground microbial communities in restoration success. Our research investigates effective establishment of late-successional native plant species by incorporating native tallgrass soil microbial communities.
Our study was conducted at Konza Prairie Biological Station (LTER KNZ) in Manhattan, Kansas, in areas heavily invaded with Bothriochloa bladhii, a non-native warm-season bunchgrass. After eradicating B. bladhii, we established 24 replicate plots to assess the benefits of inoculation with native soil or selected arbuscular mycorrhizal (AM) fungi. Seedlings of five native prairie plant species (Andropogon gerardii, Pascopyrum smithii, Asclepias syriaca, Ratibida columnifera, and Lespedeza capitata) were established in the greenhouse (nurse plants) with one of three soil inocula: whole prairie soil, AM taxa selected as beneficial to warm-season grasses, and sterile prairie soil (control). Nurse plant survival was assessed for three years following transplant, and plant community diversity was assessed at the end of year three.
Results/Conclusions
Responses to microbial inoculations were species-specific. Grass species (A. gerardii, P. smithii) survival was generally not improved following inoculation with whole soil or selected AM fungal taxa (collectively, native soil microbes). However, survival of R. columnifera or L. capitata was significantly improved when inoculated with native soil microbes, compared to nurse plants inoculated with sterile prairie soil. Survival of A. syriaca was generally low, and did not differ between soil inoculation treatments. Future restorations may benefit from identifying and cultivating AM fungal taxa specifically beneficial to A. syriaca, as some plant species display a greater degree of plant-fungal specificity. Generally, inoculation with native soil microbes improved native plant diversity over time, as compared to inoculation with sterile soil. Our results show aboveground restoration success is linked with belowground microbial communities, and transplanting mycorrhizal nurse plants can improve restoration success following removal of non-native species. Furthermore, as few differences occurred between whole soil inoculum and selected AM fungal taxa, successful restoration may be achieved through propagation of AM fungal taxa specifically selected for target native species, with fewer disturbances to native grasslands.