FUNCTIONAL-ANALYSIS OF THE NEWLY ESTABLISHED PLANTS INDUCED BY NESTING GULLS ON RIOU ARCHIPELAGO (MARSEILLES, FRANCE)

The recent population explosion of Yellow-legged gulls (Larus cachinna ns), nesting on the Riou archipelago, off Marseille (France), has pert urbed the flora and the vegetation of this site. The present study con sists of a functional approach to the newly established plant species through an analysis of some of their vital attributes. Small islets ap pear to be more affected by floristic turnover than larger islands. In some cases, more than 50 % of the current flora was not present 35 ye ars ago. The newly established taxa show special adaptations to the se vere ecological pressure induced by gull colonies and to the character istics of the Mediterranean climate. These plant species are mostly th erophytes or hemicryptophytes and have a ruderal or a stress tolerant strategy. Gulls' contribution to propagule dispersal from the continen t appears to be very slight, dispersal by wind being the prevalent mod e. (C) Elsevier, Paris.