We've Moved!
Visit SDSU’s new digital collections website at https://digitalcollections.sdsu.edu
Description
Tallgrass prairie once covered approximately ten percent of the contiguous United States, but only a small fraction of the highly diverse ecosystem remains, largely having been replaced by row crop monocultures. Representing over a quarter of the global terrestrial landscape and storing 20% of global soil carbon stock, grasslands and their soils are essential natural resources for carbon sequestration. Elucidating the soil microbiome composition and functions of restored grassland soils may aid in future restoration efforts and climate change mitigation. A previous study of the Nachusa Grasslands in Illinois, USA, used 16S amplicon rRNA sequencing to uncover convergence of restored soil microbiomes toward those of native prairie soils. Given the complexity of soil carbon dynamics and the crucial role of mutualist fungi, we applied shotgun metagenomic sequencing and compositional data analysis to explicate the underlying relationships between land use, succession, and restoration management and the broader microbial community diversity and functions. Analysis of beta-diversity revealed agriculture and restoration soils formed taxonomically and functionally distinct microbial communities. In comparison to agriculture soils, restored soils had higher functional diversity and lower relative abundances of greenhouse gas-emitting ammonia oxidizing archaea (AOA). Arbuscular mycorrhizal fungi (AMF), Verrucomicrobia, and genes linked to carbohydrate metabolism were also more abundant in restored soils. Analysis of the samples from the restored soil chronosequence found strong effects of succession age (i.e., years since restoration) and whether the sites had been subject to a prescribed burn on biodiversity and differential abundances of microbes and genes. Comparison of sites burned within the sampling year compared to those burned in the previous year demonstrate microbial patterns similar to key observations made between restoration and agriculture soils: higher alpha diversity, fewer AOA, and greater AMF abundances in soils subjected to recent burn. Over the chronosequence, succession is linked to a more even distribution of taxa marked by increasing abundances of symbiotic ectomycorrizal fungi and greenhouse gas-metabolizing methylotrophic bacteria. Altogether, the patterns we observed in taxonomic and functional diversity support the hypothesis that a combination of restoration, prescribed burn, and maturation will improve tallgrass prairie carbon sequestration and help reduce greenhouse gas emissions.
