EVOLUTION OF MAJOR PATTERN MODELS AND PROCESSES OF ALLUVIAL FOREST OF THE RHINE IN THE RIFT-VALLEY (FRANCE GERMANY)

In the rift valley (North-East of France/South-West of Germany), the Rhine runs freely for 300 km from South to North. The absence of natural obstacles allows the development of a very regular profile of the river. We have therefore an opportunity to study very gradual modifications of the alluvial forest communities of the fluvial corridor from upstream to downstream, according to the gradual evolution of the ecological factors, related to slope decrease and hydrological modifications. We describe, from Basel to Mainz: 1) modification of dynamic processes in the forest communities such as successional sequences or sylvigenetic mosaïcs of the terminal stages. 2) modification of species richness. 3) reduction of species diversity. 4) simplification of the forest stratification. 5) modification of efficiency of the biogeochemical cycling. 6) ecological vicariances. 7) modification in species behaviour. © 1990 Kluwer Academic Publishers.