Regeneration and colonization of aquatic plant fragments in relation to the disturbance frequency of their habitats

The regeneration (regrowth into viable plants) and colonization (establishm ent in the sediment) abilities of vegetative fragments of 16 aquatic plant species occurring in habitats with different disturbance frequencies were c ompared through a laboratory experiment. The hypothesis was that plants occ urring in habitats frequently disturbed by floods should have higher regene ration and colonization abilities than plants in rarely disturbed habitats. Four types of fragments were collected from the plants and their regrowth and/or rooting into the sediment were recorded over 10 weeks. Numerous spec ies exhibited a trade-off between their regeneration and colonization abili ties (e.g. Sparganium emersum, Luronium natans), others presented fragments with high abilities in both fields (e.g. Myriophyllum spicatum, Potamogeto n coloratus), and others showed fragments with low abilities in both fields (e.g. Utricularia vulgaris, Potamogeton lucens). The characteristics of tw o species (Potamogeton coloratus, Ceratophyllum demersum) did not fit in ve ry well with the hypothesis, but this could be explained by their competiti ve abilities and ecological amplitude. Most species from habitats rarely di sturbed by floods presented low regeneration and colonization abilities. As predicted, species from habitats with high or intermediate disturbance fre quencies presented at least one of the two tactics, and this could be relat ed to their adaptation strategies in withstanding disturbance events.