Abstract
* Background and Aims - Plants need different survival strategies in habitats differing in hydrological regimes.
This probably has consequences for vegetation development when former floodplain areas that are currently confronted
with soil flooding only, will be reconnected to the highly dynamical river bed. Such changes in river management
are increasingly important, especially at locations where increased water retention can prevent flooding
events in developed areas. It is therefore crucial to determine the responses of plant species from relatively lowdynamic
wetlands to complete submergence, and to compare these with those of species from river forelands, in
order to find out what the effects of such landscape-scale changes on vegetation would be.
* Methods - To compare the species’ tolerance to complete submergence and their acclimation patterns, a greenhouse
experiment was designed with a selection of 19 species from two contrasting sites: permanently wet
meadows in a former river foreland, and frequently submerged grasslands in a current river foreland. The
plants were treated with short (3 weeks) and long (6 weeks) periods of complete submergence, to evaluate if
survival, morphological responses, and changes in biomass differed between species of the two habitat.
* Key Results - All tested species inhabiting river forelands were classified as tolerant to complete submergence,
whereas species from wet meadows showed either relatively intolerant, intermediate or tolerant responses.
Species from floodplains showed in all treatments stronger shoot elongation, as well as higher production of
biomass of leaves, stems, fine roots and taproots, compared with meadow species.
* Conclusions - There is a strong need for the creation of temporary water retention basins during high levels of
river discharge. However, based on the data presented, it is concluded that such reconnection of former wetlands
(currently serving as meadows) to the main river bed will strongly influence plant species composition and
abundance.
