BRYOLOGICAL PATTERNS AND STREAMWATER ACIDIFICATION IN THE VOSGES MOUNTAINS (NE FRANCE) - AN ANALYSIS TOOL FOR THE SURVEY OF ACIDIFICATION PROCESSES

The relationships between water chemistry and aquatic bryoflora in the Vosges Mountains (Eastern France) were studied in an attempt to surve y the processes of acidification. 6 chemical variables (pH, Mg2+, Ca-2 +,Ca- K+, NO3-, Al) were used to explain the segregation of the bryoph ytic communities concerning 19 species in 31 study sites, Ca2+, Mg2+ a nd a lesser extend pH and Al are the four variables best explaining th e relationships between the bryophytes and the chemical data. Acidophi lous species as Marsupella emarginata seem to be sensitive to high cat ions concentrations. On the contrary neutrophilous species as Rhynchos tegium riparioides may be more sensitive to the toxicity of protons or Al than to lacks of cations. The combinations of bryophytes are used to reconstitute the chemical variables and the precision of the modell ing is assessed. (C) 1998 Elsevier Science Ltd.