Wadden Sea carbon stock dynamics during thirty years of summer polder restoration

Salt marshes along the Wadden Sea coast are often shaped by anthropogenic alterations to their hydrology and sedimentation. To investigate the effects of hydrological restoration through summer dike openings on soil carbon storage capacities, soil samples were collected from four study sites along the Lower Saxony Wadden Sea coast, Germany. Each site featured restored areas, i.e., former summer polders reconnected to tidal exchange, and reference salt marshes adjacent to the polders. The polders varied in restoration age, i.e., 0 (control, not restored), 8, 14, and 28 years, forming a chronosequence for temporal analysis, while the reference salt marshes remained unchanged. Soil samples were taken along transects that represented different marsh zones, including pioneer, lower salt marsh, and upper salt marsh. The soil samples covered soil layers down to a depth of 100 cm and were collected in five sections of 20 cm using an Edelman corer. Total carbon, organic carbon, and inorganic carbon were analyzed using CN-elementary analysis and calcimeter methods. This dataset provides valuable insights into the potential of hydrological restoration measures to enhance soil carbon sequestration in salt marshes.