The effects of flood defences on riparian vegetation species richness and abundance

It is widely recognised that flood disturbance has important consequences for the biodiversity of riparian zones and that inundation allows nutrients and organic matter to be exchanged and recycled between aquatic and terrestrial ecosystems. Previous research has focused on the impacts of dams on riparian biodiversity, with little consideration given to the impacts of flood defences. The current study investigated the extent to which the presence and age of flood defences controls riparian plant richness and abundance. Sites without flood defences were found to have significantly higher species richness and abundance. In contrast, flood defence age was found to have little impact although turnover was high between sites with old and new defences. Flood management should therefore focus on more sustainable options that work with natural processes where possible, such as washlands.