Tallgrass prairie ecosystems are one of the most endangered ecosystems in North America. Due to this loss there is substantial interest in restoring tallgrass prairies in the Midwest and Great Plains regions to recover aboveground ecosystem services. However, most prairie restorations focus on improving plant community and animal diversity, with little focus on how restoration impacts soil microbial communities. Soil microorganisms provide important ecosystem services such as controls over nutrient cycling and carbon sequestration, as well as improving establishment of late successional plants. Traditional aboveground-focused restoration practices do not restore soil microbial communities to one that resembles a remnant prairie soil community, but instead to restores to a new community that still reflects the legacy of agriculture. To incorporate microbially-focused restoration strategies into standard restoration practices, methods must be affordable, easy to implement and effective. The objective of this study was to determine if inoculation with a recalcitrant substrate or a microbial community enhanced the restoration process. We tested several possible treatments to improve microbial restoration using a field-level inoculation experiment. We added biochar and remnant prairie soil amendments alone, as well as a combination of the two amendments to plots within a new prairie conservation corridor in southwest Michigan. We sampled soil in the experimental plots, prairie and adjacent agricultural field in August and October 2018 and examined changes in bacterial 16S rRNA amplicon-based community composition using an Illumina Mi-Seq approach. We also determined soil respiration and extracellular enzyme activities for key enzymes involved in carbon degradation.
Results/Conclusions
Bacterial communities in prairie conservation corridors differed significantly from those found in the agricultural fields. However, there was not an increase in the abundance of Verrucomicrobia, a slow-growing bacterial phylum that is thought to cycle carbon slowly. Soil respiration rates and enzyme activities also did not differ between the agricultural field and the prairie corridor, indicating a need for microbially-focused restoration strategies. However, our results indicate that neither biochar amendment nor remnant soil inoculation changed soil bacterial diversity or any enzyme activity rates or respiration. We hypothesize that adding a dried plant-based amendment to the soils will be a more effective strategy for microbial-focused restoration.