Biodiversity in constructed wetlands in Southern Sweden - Evaluation of new wetlands within the Tullstorp Stream Restoration Project

Abstract: Scania is a region in southern Sweden that used to be a region of wetlands. Nevertheless, due to human activities wetland loss is an established matter currently, and following from that, changes in biodiversity, water regime and nutrient retention. One purpose of creating new wetlands is to reinstate good status of biodiversity. The study was based on data gathered in July 2011 from 13 newly constructed wetlands within the Tullstorp catchment area. The aim was to study a progress of biodiversity in that area using a new method developed by the County Administrative Board in Jönköping. The study gave clues on how to construct wetlands in order to increase biodiversity. It was found that combination of wetland features may increase its biodiversity, however different components determines bird species richness, invertebrate species richness and the coverage of wetland vegetation. Large wetland surface area has a positive effect on the number of bird species, particularly when there are no predatory fish in the wetland. Increasing the age of wetland tend to have a positive influence on invertebrate species richness. There is no effect of the age of wetland and the number of birds. Predatory fish are likely to affect the species composition of invertebrates rather than taxon richness. In this study, large diving beetles were only present in wetlands without predatory fish whereas snails were more frequent in wetlands with predatory fish. Macrophytes increase in coverage with increasing age of wetland, but not if crayfish are present. Wetlands rated with poor biological status mostly did not get any points for vegetation, birds or invertebrates. In addition, morphometry and maintenance of the newly constructed wetlands included in this study are physical features that need to be improved in order to get higher scores.