Native soil microbial amendments generate trade‐offs in plant productivity, diversity, and soil stability in coastal dune restorations

Abstract

Given the important role that soil microbes play in structuring plant communities and mediating ecosystem functions, there is growing interest in harnessing microbial communities to restore degraded ecosystems. Dune restorations, in particular, may benefit from native soil amendments because microbial diversity and abundance are very low in unvegetated areas. In an outdoor mesocosm experiment simulating Texas Gulf Coast dune restorations, we tested how native soil microbial amendments and restored diversity of foundational grasses influenced three key restoration responses: plant performance, plant diversity (including the colonization of native forbs), and soil stability. We found that native microbial amendments increased plant diversity and have the potential to increase soil stability, but this came at the cost of decreased plant biomass. Our results suggest that soil enemies in the native microbial amendments increased plant diversity by decreasing the performance of the dominant grass species and that arbuscular mycorrhizal fungi in the native microbial amendments increased the density of fungal hyphae in the soil, which can increase soil stability. Depending on the goals of the restoration, native soil microbial amendments may be a simple and inexpensive method to provide restoration benefits.