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This report describes a long-term study to monitor and evaluate the ecosystem recovery of seven wetland restorations in south central Minnesota. The study looks at the impact of planting on wetland restoration success in inland wetlands and develops a methodology to assess wetland restoration success. The study focused on the following question: To what extent can revegetation stimulate overall biological recovery in isolated restoration sites? Researchers used aspects of ecosystem function and structure to characterize recovery rates in planted and unplanted restored sites relative to one another and to reference wetlands, as well as indices of biotic integrity for plants, invertebrates, birds, and amphibians in addition to other indicators of ecosystem structure, such as soil organic matter and water chemistry. Researchers developed field protocols, created biotic indices, and established baseline monitoring on each site including an as-built topographic survey, installation of groundwater and surface water stations, characterization of soils, vegetation, and vertebrates. A long-term monitoring system is now in place that will allow for the assessment of ecosystem recovery of seven restored wetlands relative to four reference wetlands.

This report presents the results of a four-year study on techniques for revegetation of native sedges in created basins. Although often the dominant genus in shallow wetlands, sedges (Carex spp.) do not readily recolonize after restoration or creation of the water table. It is unlikely that sedges will naturally establish in created wetlands. The results of seed germination studies on five Carex species suggest the highest germination rates in fresh seeds - with one exception. Wet/cold storage also can prolong seed viability for at least two-and-a-half years. Dry storage is not recommended for wetland sedge seeds. Short-term wet/cold treatment after prolonged dry storage does not improve germination rates. Sensitive to deep water, rising water levels, and competition during the establishment year, seedlings grew well across a wide range of water depths in subsequent growing seasons. Both species outcompeted annual weeds within two to three growing seasons, but not Phalaris arundinacea (reed canary grass). The study recommends weed control during the establishment year to prevent the invasion of P. arundinacea. Wetland soil promotes seedling growth relative to other soils, but does not affect germination rates. Because of the potential for the introduction of undesirable weeds, the study does not recommend the use of donor wetland soil. Instead, study results suggest the potential for the use of organic top-dressings.

Phalaris arundinacea (reed canary grass), a fast-growing, rhizomatous perennial grass, is a major concern for wetland restorations in the northern US because establishment by P. arundinacea often precludes colonization by sedge meadow vegetation in restored prairie pothole wetlands. This research developed a predictive understanding of P. arundinacea (a perennial grass) dominance in prairie pothole wetland restorations and investigated potential control techniques. A large-scale field experiment demonstrated that the most effective way to control P. arundinacea is a combination of later season herbicide applications to maximize rhizome mortality, and burning to reduce the P. arundinacea seed bank density. In a mesocosm experiment, P. arundinacea growth, but not recruitment from seed, was suppressed by the presence of native species established from seed, suggesting that P. arundinacea control will likely be necessary during native species establishment. In a uniform planting study, P. arundinacea exhibited rapid rates of growth which may contribute to its aggressive nature. Controlling P. arundinacea in the most efficient way is crucial to the establishment of native vegetation in wetland restorations. Reduction of P. arundinacea is a long-term process and one that is complicated by potential reinvasion of cleared sites, so control efforts must be as effective as possible. Moreover, P. arundinacea is still widely cultivated as a forage crop and planted as a conservation species, and these populations may serve as sources of continuing propagule pressure, further complicating localized eradication efforts.

Phalaris arundinacea invades sedge meadow restorations, forming persistent monotypes that prevent community establishment. Eradicating Phalaris, however, leaves restored ecosystems prone to reinvasion. In order to restore desired plant communities, methods to control Phalaris are needed. To determine if reducing light by sowing cover crops and reducing nitrogen by incorporating soil-sawdust amendments would prevent Phalaris invasions, a study was conducted under conditions similar to a restored wetland in two experimental basins with controlled hydrology. Seeds of a 10-species target community and Phalaris were sown in plots with high diversity, low diversity, or no cover crops in soils with or without sawdust amendments. Nitrogen, light, tissue C:N ratios, firstyear seedling emergence, establishment, and growth, and second-year above ground biomass were measured. Only high diversity cover crops reduced light and sawdust reduced nitrogen for about 9 weeks. Similar trends in firstyear seedling data and second-year biomass data suggested Phalaris control efforts should focus on establishing perennial communities rather than implementing separate resource-limiting strategies. Sowing high diversity cover crops resulted in Phalaris-dominated communities, making cover crops an ineffective Phalaris control strategy. Using sawdust amendments did not reduce Phalaris invasion much beyond what the target community did but resulted in a community similar to those of natural sedge meadows by increasing the abundance of seeded species from the Cyperaceae family and colonization of non-seeded wetland species. The target community apparently reduced Phalaris invasion by reducing both light and nitrogen. Regardless, no treatment fully prevented invasion, making follow-up Phalaris control necessary to ensure community recovery.