Patterns and processes in natural wetland vegetation in the Dutch fluvial area: a palaeoecological study

Palynological study of deposits in the residual channel and flood basin of a former Rhine distributary reveals the species composition and development of natural wetland vegetation prior to major human interference. Flood-basin vegetation resembled a Typho-Phragmitetum thelypteridetosum vegetation during river activity. After this, vegetation succession shows a terrestrialization pattern, although duration of terrestrialization phases suggests continuous rising water levels in the flood basin. Grazing of wetland mammals is suggested by a sample probably representing a fossil excrement. During minor river activity reed marshes were present along the margins of the active channel, with Typha angustifolia and Sparganium in the deeper parts. After river activity ended a Bidentetea-vegetation originated on the lower clayey parts of the natural levees, succeeded by an extension of reed marshes. There are traces of fire, which temporarily disturbed the vegetation. Vegetation succession ended with the development of alder carr.