Long-term restoration assessment of historic tallgrass prairie at Spirit Mound: Changes in vegetation composition 12 years post-restoration

Background/Question/Methods

Spirit Mound is a tallgrass prairie near Vermillion, South Dakota with great historical value because it is one of the few locations that was clearly described by Lewis and Clark in their voyage across the country in 1804. Beginning in 1868, Spirit Mound was converted to agricultural uses, primarily row-crop agriculture, until 2001 when prairie was restored across Spirit Mound. Plant community composition and aboveground biomass production were assessed shortly after the restoration in 2003 and 2004, and we will reassess the site this summer to evaluate long-term changes in aboveground biomass production, plant diversity, and non-native species abundance among different, distinct areas across Spirit Mound. We will sample thirteen previously established100-meter transects across the site and will harvest aboveground biomass using a stratified random sampling method throughout the growing season.

Results/Conclusions

In 2003 and 2004 combined, 132 species were observed and identified, 61% of which were tallgrass prairie species native to the area. Biomass did not significantly differ between 2003 and 2004. Overall, non-prairie plant abundance decreased from 2003 to 2004. There was no significant difference in plant species richness between the two years. However, there were strong differences across different areas of the site (high beta diversity); the greatest percentage of explainable variation was due to differences among sites (79%). This is likely related to the different land-use histories at the site including cropland, feedlot and grazing.  We expect continued changes in plant community composition as the restoration has matured, including increased abundance of warm-season grasses and decreased abundance of non-native species.  We expect beta diversity at the site to remain high due to the legacy effects of the previous land-use histories at the site. Quantifying the long-term change in plant community composition and biomass production at this historic prairie will be used not only to inform management at the site, but also to inform visitors to the site about the ecology of tallgrass prairies and their changes following restoration.