Climate change and the ecology of the Weser estuary region: assessing the impact of an abrupt change in climate

The objective of the present study is to assess the direct impact of a rapid change in climate on the amphibious and terrestrial ecosystems of the Weser Estuary, northern Germany, for the year 2050, discounting morphological adaptation. The status quo was documented on the basis of land cover classifications called ‘biotope types’. Elevation, soil type, vegetation and land use data were digitised and assembled in a GIS database (ArcInfo/ArcView): 80% of the marsh (400 km2), the forelands (55 km2) and the tidal marshlands (45 km2) are used as farmlands, of which 90% are grasslands and pasture. Only 2% of the area is habitat for reeds and associated species. Estimations of future climate changes are made on the basis of a downscaled regional climate scenario. Primary effects of climate change due to sea level rise and altered hydrology of the area are as follows: the forelands and the Weser Estuary will become more ‘natural’, because reed areas and shallow waters will increase, whereas grasslands will decrease. In the long term this development will have positive effects for birds and fishes. However, in the marshes and plains protected by dikes, hydrological changes will have minor effects on vegetation and species, because future land use and the management of the drainage and irrigation system determines the biocoenoses here.