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 an alysis of 63 releves showed that this community maintains a well defin ed floristic composition in flowing waters; it was divided into 3 subu nits, according to floristic and ecological criteria. Studies of the s uccession after clearing in two Alsatian waters (and numerous releves which have been made over long periods in some other waters) showed th at the community regenerates easily and recovers the typical former fl oristic composition after three to four years ii the water quality rem ains constant or recovers its oligotrophic status. It may have a pione er behaviour. This study confirms its total destruction by even a slig ht eutrophication.