A field experiment on the influence of the postulated global climatic change on coastal marshland soils

Abstract

AbstractA climatic scenario postulates an increase of atmospheric CO2, 55 cm water‐level rise combined with a 30 cm higher tidal amplitude for the North Sea. Further, more frequent and stronger west storms, a 2.5°C mean‐annual‐temperature increase together with 15% more rainfall during winter time are to be expected until 2050 due to recent human impact.The possible consequences of the postulated changes in temperature and flooding dynamics were studied for soil formation as well as for soil‐ecological attributes and processes of two sites at Hedwigenkoog foreshore in N Germany: aHypersali‐tidalic Fluvisol(protothionic, calcaric) (1.5 m asl with >500 annual floods) and aGleyi‐sali‐tidalic Fluvisol(calcaric) under a salt meadow (2.2 m asl with 70 annual floods). Temperature, water, redox, nutrient and gas dynamics were measured at different soil depths for a period of 2 y. The topsoil of theGleyi‐sali‐tidalic Fluvisolwas permanently heated over an area of 14 m2to simulate a temperature rise of 1.5–2.5°C. The results are discussed in relation to two realistic scenarios. If the ground level of theGleyi‐sali‐tidalic Fluvisolis heaved up (due to sedimentation) as intensively as the sea level rises, it may be assumed that the soil unit including vegetation cover in principle will not noticeably change. Then, the temperature increase will intensify the activity of soil organisms, bioturbation, and formation of a crumb structure, however, there will be no further accumulation of soil humus. If there was no sedimentation during the next 50 y, the salt meadow itself together with the upper part of theGleyi‐sali‐tidalic Fluvisolwould be destroyed by erosion, and aHypersali‐tidalic Fluvisolwould be formed similar to the studied one.