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Mediterranean regions are characterized by a large intra‐annual and inter‐annual variability in rainfall and associated hydrological regime patterns. Predictions of changes in climate indicate that mean precipitation and annual temperature will both increase, with a concentration of precipitation and the existence of extended and harsher drought periods with profound implications for river ecosystems. Our aim in this study was to predict the response of Mediterranean riparian vegetation to different climate change scenarios, using a dynamic riparian vegetation model that relates flow regime with riparian vegetation dynamics. In our case study, mapped riparian patches were significantly distinct in between, and altitude, height above water table, patch age and stem diameter were the most important of the factors that distinguished succession phases. A floodplain vegetation model was calibrated and achieved a good strength of agreement between simulated and observed maps. Model results with the expected flow regime under the effect of climate change demonstrate that nonwoody sparsely vegetated areas expand outwards and mature succession patches expand inwards, whereas pioneer and young riparian patches decrease in area. Our results suggest that extreme climatic change in Mediterranean rivers will promote the disappearance of the pioneer and young succession stages of riparian woodlands, thus making efforts to conserve these ecosystems a challenging task. Copyright © 2012 John Wiley & Sons, Ltd.

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Patterns of native and exotic species richness and cover were examined together with the composition of species assemblages along a typical Mediterranean river and across its floodplain. Major goals were to characterize species distribution regarding diverse environmental and habitat features, and to explore floodplain landforms relations using plant assemblages and invasion responses as biological indicators of aquatic -terrestrial connectivity. A floristic survey was undertaken during May and early June 1998 in six sites of a southern Iberian basin. Vegetation data were gathered from three transects in three landforms: inundated and frequently flooded banks (FF), infrequently flooded valley floors (IF), and rarely flooded higher floodplains (RF). We used 2Â2 m plots to record each species present and visual estimates of percentage cover of each species. Cover of native and exotic species assemblages were also estimated for each plots, for the transects, and for the landforms. The total number of vascular plant species found was 287 of which only 26 were exotic. Despite the high environmental and geomorphological variability, the hierarchical classification showed that species composition varied across the floodplain, rather than along the river. The IF and RF landforms were the most species-rich, both for native and exotic species group, whereas the cover trends of exotic and native plant species were opposed, with exotics being consistently more abundant in FF, and native cover increasing towards RF landforms. We found positive correlations between native and exotic species richness on the floodplain scale, and on a smaller scale in FF and IF landforms, thus supporting the hypothesis that in aquatic and riparian ecosystems of semi-arid landscapes, species-rich communities are preferentially colonized by exotic species. However, this pattern was not consistently coupled with a high cover of exotic species, and it was not sustained for the dry areas of the RF landforms.