soil fungal and bacterial community sequences from the 2011 Ossekampen experiment

Information on how the links between plant, bacterial and fungal communities in grasslands are affected by nutrient additions is limited. Management strategies such as long-term inorganic fertilization and mowing change soil factors with direct and indirect effects on the plant and soil microbial communities. Here, we explored the effects of long-term nutrient addition with nitrogen (N), phosphorous (P), NP-potassium (NPK) and liming (L) or no fertilization (C) and twice yearly mowing on the plant, bacterial and fungal communities and soil physicochemical factors. We combined topsoil 16S rRNA and 18S rRNA gene surveys with plant frequency and edaphic factor measurements at the treatment level using multivariate statistics and co-inertia analysis. Treatment grouping had a significant effect on the communities and soil factors; the treatments affected the grassland components differently. Based on Between-Class Analysis (BCA), we found that the plant and fungal communities were distinct in the NPK and L treatments, while the bacterial communities and soil factors were distinct instead in the N and L treatments. Furthermore, we found significant co-structures between the plant and fungal communities but not between the plant and bacterial nor bacterial and fungal communities. The NPK, L, N and P groupings were driven in the co-inertia analyses by co-variates between the individual groups such that plant species, bacterial groups and fungal groups co-varied along with soil factors. Our findings support the idea that the soil bacterial community composition is influenced more by edaphic factors than by plant composition. Our results also suggest that plant and fungal communities are more tightly linked than either community with the bacterial community. We found potential links between the plant, bacterial and fungal taxa attributed to the fertilization treatments that can be explored in future works.