Open Access

Barbara Stammel, Julia Stäps, André Schwab, Kathrin Kiehl

• Riverbanks are very dynamic habitats for riparian vegetation strongly influenced byfluvial and geomorphic processes. This habitat type was severely reduced in the pastby river straightening and bank stabilisation. Restoration and establishment of newfloodplain streams promote this habitat, but a directed succession to later stages wasobserved many times. Our study aimed to analyse whether the often observeddirected succession of the streambank vegetation after restoration implementationcould be reversed by a natural flood along a newly created floodplain stream. Weinvestigated the effects of a natural flood in 2013 and different prerestorationconditions on species development in the riparian zone. Vegetation was studiedalong 12 transects in four different sections from 2011 to 2014. Species composi-tion differed strongly between the sections. Species richness was lowest in a newlydug steep section with high morphological dynamics and highest on wider flatstreambanks. Changes during the years reflecting different hydrological eventsvaried between sections. The high natural flood in 2013 reduced the cover of theherb layer and increased bare ground, which led in most sections to a loss of non-target species. Total target species richness did not change due to the natural flood,while target species showed a high turnover rate. In the following year, however,the flood‐induced development of species composition, in general, was reversed.Natural floods changed abiotic and biotic conditions along the streambank, but theydid not accelerate ecological restoration towards predefined target ecosystems.However, they were necessary to preserve the needed dynamic vegetation changesand species turnover to hinder the succession to later stages dominated by a fewspecies. Our study shows that riparian vegetation near the streambank can bemonitored most effectively in cross‐profile transects, both in the long‐term andevent‐related.