The response of aquatic macrophytes to restoration management in the Morava river oxbows

Aquatic macrophytes in two remnant meanders of the Morava river after their re-connection with the main channel were studied in 1995-2002. Plant species richness, species diversity and floristic similarity of the restored sites were compared with the reference site. Except for the restoration, i.e. man-induced disturbance, the macrophytes cover, diversity and composition had additionally been affected by the extreme flood (natural disturbance) in 1997, which altered the morphology of re-connected sites. The species abundance decreased in all studied sites. However, already in the second after-flood year, floristic similarity in the reference site (the 16(th) rkm oxbow C) exceeded 80% comparing to the 1(st) year records. The response of the two re-connected oxbows was different. In the 12(th) rkm (oxbow B) only Persicaria amphibia f. natans survived, whereas, in the 19(th) rkm (oxbow A) floristic similarity to the 1(st) year survey stabilised on > 40%. This difference might be explained by the different intensity of a fluvial disturbance.