Composition et structure de la ripisylve dans les casiers Girardons du vieux Rhône

The Rhône River was heavily channelized in the 19th century for navigation and dammed in many places since the 1950 ’s , with major reductions in peak f lows and channel mobility. W e conducted extensive forest inventories and sampled f ine sediment depth in regulated reaches within the r iparian zone of the old Rhône , and compared pre- versus post- dam forest development and linked patterns of f loodplain development. The pre- versus post- dam surfaces at each site had distinct geomorphic and f loristic characteristics. There was very lit t le post – dam recruitment of poplar and willow, which are pioneer species that rely on dynamic geomorphic conditions. Post- dam f loodplains supported vigorous recruitment by Acer negundo ( box elder), which is non- native and invasive in Europe.