COMPARATIVE ABILITIES OF VEGETATIVE REGENERATION AMONG AQUATIC PLANTSGROWING IN DISTURBED HABITATS

The regeneration (regrowth into viable plants) and colonisation (estab lishment in the sediment) abilities of vegetative fragments of six aqu atic plant species (Elodea canadensis Michaux, Hippuris vulgaris L., L uronium natans (L.) Rafin., Potamogeton pusillus L., Ranunculus tricho phyllus Chair, Sparganium emersum Rehm.) occurring in habitats frequen tly disturbed by floods along the Rhone River (France) were compared t hrough a laboratory experiment. Six types of plant fragments were coll ected from the plants and placed in water over sediment. Their develop ment and/or their rooting into the sediment were recorded over 10 week s. The species exhibited different survival tactics to survive after f ragmentation: (1) fragments from Sparganium and Ranunculus developed r oots and rapidly established into the sediment whereas (2) fragments f rom Luronium, Hippuris and Elodea developed many propagules that could be dispersed but did not establish within the 10 weeks of the experim ent. The fragments of P. pusillus never established nor regenerated. T he results showed a trade-off between regeneration and colonisation re lated to the patterns of recolonisation of cleared patches of the spec ies and their ecological requirements. Maintenance of these species in ecosystems frequently disturbed by floods can partly be explained by their high regeneration abilities, and results are discussed in terms of life-history traits and ecological strategies. (C) 1998 Elsevier Sc ience B.V.