Evaluating Wetland Restoration Success in ...

In Denmark, wetland restoration has been successfully used as a tool to mitigate nitrogen and phosphorus losses from agricultural lands. However, no certain guidelines have been set regarding biodiversity in the restored areas. The aim of the work was to evaluate restoration success in 10 wetland restoration projects in Kratholm catchment (on Fyn island, where many project have been implemented), focusing on vegetation, plant communities, as well as nitrogen and phosphorus stock in aboveground biomass and nutrient leaching. During the field work, 172 vegetation plots were described, and 50 aboveground biomass samples collected. Species richness in the vegetation plots was low, however species diversity tends to increase with an increase of wetland age. Species preferring half-light conditions, humidity and moderate nutrient rich to nutrient rich soils are dominant in the restored areas. Nitrogen and phosphorus stocks in the dry aboveground biomass were high, however for plant communities that are storing high amount of nitrogen and phosphorus, leaching rates were also high. Nitrogen and phosphorus stock and leaching rates tend to decrease with an increase of wetland age. To increase the nutrient removal and species richness, periodical mowing with biomass removal from the restored areas as well as grazing is suggested. The outcome of the restoration projects regarding the vegetation can be improved, therefore more certain goals should be set for further projects along with the development of management and monitoring plans.