1. Introduction Wetland loss and degradation in Europe have been extreme andare still ongoing. By way of example, at least two-thirds of all shal-low lakes, bogs and wet meadows have been lost in Denmark since1784. The challenge for wetland scientists in Europe is to reversethe loss of wetlands and promote the protection of existing wet-lands and work for restoration of degraded wetlands.The EU Habitats Directive (HD) and the EU Water FrameworkDirective (WFD) are important policy instruments in wetland con-servation. Thus, restoration of wetlands and constructed wetlandshave become increasingly popular as mitigation options in RiverBasin Management Plans under the WFD to reduce nitrogen andphosphorus losses from fields to catchments.An important task for wetland scientists is to enhance our basicand applied understanding of the interlinked hydrological, bio-geochemical and ecological processes in naturally and restoredwetlands. Sound wetland science is not least needed to assist pol-icy makers and planners in the process of wetland conservationand restoration to ensure sustainable solutions for biodiversity andenvironment.This special issue is an outcome of the SWS European ChapterMeeting 17–21st June 2012 at Aarhus University, Aarhus, Denmark,where 120 participants shared their knowledge on wetland science.The meeting had 8 scientific sessions (see Table 1) including sev-eral presentations under the three topics into which the total of 16papers in this special issue are grouped.