Regeneration of Floodplain Biotopes on the Upper Rhine – The “Polder Altenheim” Case

Abstract

The floodplain of the Upper Rhine and its biocoenoses have, through different river-regulatory activities over the last 175 years, undergone large scale degradation. At the same time flood protection for the downstream inhabitants has been greatly reduced. For reasons of flood protection, the “Polder Altenheim” in Baden-Württemberg, Germany southwest of Strasbourg, France, with so called retention flooding, was put into operation in 1987. The original floodplain had been diked for the previous 17 years, during which no flooding occurred. Since 1989 “ecological flooding” also is carried out. This has assisted in the regeneration of floodplain biotopes and promoted the floodplain biotic communities and the readaption of the bioceonosis to a regular flooding regime. The creation of new floodplain biotopes of early succession stages, particularly through geomorphodynamic processes, has followed the more than ten flood ocassions and typical biotic communities have colonised these sites. This will be presented together with selected examples of terrestrial and limnical species and communities. The following species and communities will be discussed: kingfisher Alcedo atthis, carabid communities (Coleoptera), the red alga Hildenbrandia rivularis (Rhodophyceae), the freshwater snail Theodoxus fluviatilis (Neritacea) and the freshwater bug Aphelocheirus aestivalis (Hydrocorisae).