The effects of some natural ecological factors (timing of floods, groundwater level) and of human influence on floristic composition and vegetation structure of ecotones were analysed. Vegetation transects across the plant community and its transitional zone in the Morava river floodplain was established. The research has shown a relation between the ecotone characteristics and the steepness of ecological gradients. Higher species number was found only in some ecotones. High frequency of neophytes was typical for the human-affected ecotones. The edge effect between the grassland and wetland communities was manifested by high density of Iris sibirica in studied ecotones. A close positive relationship between the water level fluctuations in habitat and the spatial and temporal dynamics of vegetation in ecotones between oxbow and its bank was found.