Two common characteristics of Wisconsin landscapes include once-native prairie that has largely been converted to agriculture and a large number of dammed tributaries. Many of these dams are being removed at an ever growing rate leaving an increasing number of drained basins available for prairie restoration. Moreover, many of these sites also provide a unique setting for community outreach concerning the practice of ecological restoration. The objectives of this study were to examine the effect of seeding density and soil properties on the plant community structure in a recently dewatered basin in southwest Wisconsin, and to use this site for community outreach. In 2005, we seeded the 2.0 ha basin with a prairie mix (60%, 40% grasses) at four different densities (1000, 500, 250 and 125 seed m-2) in a randomized 4-block design. In 2006, we conducted a plant survey by dividing each of the 16 treatment-plots (transects) into five equal sections. Individual forb species were counted, while percentage cover of grasses and cover plants were measured. In each quadrat all the biomass was cut to the ground and separated by species. We hypothesized that higher rates of seeding would result in greater biomass of native to invasive species and that this proportion would increase over time.
Results/Conclusions
Different proportions and biomass of native to non-natives species were found after one growing season.There were no significant differences in the biomass of native species among the four seeding rates. We found 26 species of which 16 were invasive and 10 were native. The biomass of the invasive species was markedly greater, 9,016.4 g (96 %), compared to biomass on native species 345.4 g (4 %) within the basin. However, the native species were more evenly distributed (Shannon evenness index = 0.92 vs. 0.42) relative to the invasives. The canonical correspondence analysis (CCA) arranged the species within environmental gradients described by soil nitrate, seeding rate, bulk density, soil volumetric moisture and pH. The total variance (inertia) in the species data was 4.7%. Most of the variance (12.2%) within the species community was explained by the first axis where seeding rate explained 4% of the variability. Thus, environmental variables clearly influenced the plant community assemblage. We will discuss these results and will compare result with biomass from 2007, their implications on prairie restoration in dewatered sediments, and the use of this experimental site for community outreach and education.
