Tallgrass prairie is among the world’s most endangered ecosystems, with <1% remaining from pre-European settlement in North America. In an effort to conserve Minnesota’s natural landscapes, restoration of 160 acres of land in the northwestern MN is underway through a joint project with MSU-Moorhead, MN DNR, and consultation with TNC. One project goal includes long-term monitoring of several taxa (microbial, plants, and small mammals) with expectation that species diversity will increase as a result of restoration.
The study area includes two regions currently under restoration: a former monoculture golf course (appx. 50 years; low plant & mammal diversity); and an abandoned field that had been previously exploited for agriculture (unmanaged >20 years; moderate plant & mammal diversity). We also included three reference sites: a remnant prairie and two prairie sites restored >20 years ago (dry and mesic). This study was designed to monitor the the soil microbiome across all sites by assessing changes in taxonomic and functional diversity that occur throughout the restoration process.
Taxonomic diversity was estimated by 16S rRNA gene sequencing for samples collected in June/July (39) and September (36). Functional diversity was estimated from community level physiological profiling (CLPP), and soil chemical analyses were performed for summer collections.
Taxonomic diversity differed among sites in the summer and fall (F3,35=7.6, P=0.0005 and F3,32=6.12, P=0.002, respectively), with the golf course (GC) and restored mesic prairie (TNC4) having the highest diversity in summer and the dry restored prairie (TNC7) having the highest diversity in fall. The CLPP revealed functional diversity differences among sites (F3,33=7.61, P=0.0005), TNC7 having lowest diversity and GC and TNC4 with highest diversity. The soil chemical tests showed TNC7 differed consistently from the other sites in several ways, including having the lowest cation exchange capacity (F4,32=6.88, P=0.0024) and organic matter (F4,32=3.92, P=0.0227).
In conclusion, each sites’ range in taxonomic and functional diversity appears not to be defined by human activity as much as by its nutrient levels and seasonal variation. Interestingly, the decades of GC management for grass monoculture did not result in consistently low taxonomic or functional diversity of microbes compared to restored and remnant sites. Future assessments of each site must use the chemical composition of the soil, baseline bacterial diversity, and restoration status to monitor biological response to land management.