Effects of Seed Treatments, Delayed Planting and Groundwater Levels on the Restoration of Sedge Meadows

Abstract

Using a complete factorial, randomized block design, the effects of seed density (430 or 860 seeds/m2), seed stratification (stratified, non-stratified), split planting (complete seed mix planted in spring vs. non-aggressive species in spring and aggressive species in fall), and distance to groundwater (−5 or − 30 cm) were studied in a mesocosm complex in central Iowa. All 16 treatment combinations were replicated 5 times for a total of 80 mesocosms. The seed mix sown contained 25 species. At the end of the study, groundwater levels had the greatest effect on species richness, total shoot density, and total biomass. Seed stratification, seed density and delayed planting all had a significant impact on species richness and total shoot density. Delaying the planting of aggressive species significantly increased total shoot densities and biomass of non-aggressive species. Of the 20 species actually found in the mesocosms, 12 had higher shoot densities in the delayed planting, 11 in the high groundwater, 7 in the stratified seed, and 3 in the high seed density treatment. Overall, groundwater level and delayed planting of aggressive species had the largest impact on species diversity and shoot density.