Synsystematic division and syndynamics of the Potamogeton coloratus community in flowing waters of southern central Europe

Phytosociological surveys of the Potamogeton coloratus-community were made in 19 flowing waters of Southern Central Europe (Alsace, south of Germany, Central Switzerland) to study the status of this community; it is characteristic of oligotrophic hard waters and to a large extent independent of morphometry and current velocity. The synsystematic analysis of 63 releves showed that this community maintains a well defined floristic composition in flowing waters; it was divided into 3 subunits, according to floristic and ecological criteria. Studies of the succession after clearing in two Alsatian waters (and numerous releves which have been made over long periods in some other waters) showed that the community regenerates easily and recovers the typical former floristic composition after three to four years ii the water quality remains constant or recovers its oligotrophic status. It may have a pioneer behaviour. This study confirms its total destruction by even a slight eutrophication.