Variations of aquatic bryophyte assemblages in the Rhine Rift related to water quality. 1. The Alsatian Rhine floodplain

A survey of the relationships between aquatic bryophyte assemblages and wat er trophic level was performed in the Rhine alluvial floodplain in Alsace ( France). Ten strictly aquatic bryophyte species showed mostly monotonic rel ationships with N-NH4+, P-PO43- and water temperature. They segregated alon g the first axis of a principal components analysis whose site scores were significantly correlated with the logarithms of the means of [N-NH4+] and w ith the standard deviation of temperature at p < 0.0001, with the logarithm of the means of [P-PO43-] and with the means of [N-NO3-] at p < 0.001, and with the standard deviation of [P-PO43-] at p < 0.05. Chiloscyphus pallesc ens, Pellia endiviifolia and Amblystegium tenax showed an oligotrophic stat us in Alsace as opposed to Amblystegium fluviatile, Cinclidotus danubicus, C. riparius and Fissidens crassipes. Amblystegium riparium, Fontinalis anti pyretica and Rhynchostegium riparioides exhibited a very broad trophic rang e but occurred more often in eutrophic streams. The trophic ranges of these species in Alsace are compared with those found in other areas and the dif ferences are discussed.