Looking belowground: The role of soil symbionts in tallgrass prairie invasion and restoration

Abstract

Tallgrass prairies of North America are under threat from a number ofanthropogenic disturbances including the introduction and expansion of nonnative plant species. One potential mechanism for successful invasion by nonnative plants is alterations of native soil microbial communities, including symbiotic arbuscular mycorrhizal (AM) fungi. Restoration projects typically focus on aboveground processes with less focus on altered belowground aspects. However, to successfully restore prairiesfollowing invasion by non-native plants, a deeper understanding of belowground alterations facilitating invasive dominance and hindering native reestablishment is needed. A restoration project focused on repairing belowground processes following invasion by Bothriochloa bladhii was established at the Konza Prairie Biological Station near Manhattan, KS. This study evaluated the influence of native AM fungal communities on establishment and survival of reintroduced native plant species following eradication of the invasive. Seedlings received one of three soil microbial inoculants (whole prairie soil, selected AM fungi, or sterile soil), prior to introduction into the study site. Evaluations of species diversity, survival, and return of the invasive plant were conducted for five years following transplant. No significant differences in diversity were observed, which likely stemmed from a high rate of return of the invasive. Overall, whole soil and selected AM fungal inoculum significantly improved survival of native species, but survival was species-specific. A second project tapped into the plant-soil feedback (PSF) framework to determine the reciprocal effects of interactions between plants and root-associated microbes. Previous research indicates PSFs driven by invasive plants can be buffered by management practices. Therefore, I investigated the influence of herbivory as a potential restoration tool. In a greenhouse study, PSF responses of cooland warm-season native and non-native grasses were examined to determine how herbivory (clipping) impacts PSF dynamics. My findings suggest herbivory alters the strength and direction of PSFs, and these changes may impact interactions of plants and associated soil microbes. Reintroducing herbivory into invaded areas may be a pathway to reset PSFs established by invasive grasses, potentially negating soil legacies by buffering the benefits established through soil microbial alterations.