Establishment of Native Sedge Vegetation in Created Wetlands

Abstract

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.