Riparian zones: where biochemistry meets biodiversity in management practice

Riparian zones are well known for their inherent ecological properties related to biogeochemical cycles, biodiversity, and catchment management. The international MAB/UNESCO programme which was running between 1988 and 1998 was related to the land/water ecotones, mainly riparian zones. This article, inspired by this programme seeks to highlight the role of riparian processes on biogeochemical cycles and biodiversity under different climatic conditions. Their role is investigated by focusing on: i) the lateral ecotone between land and water systems, ii) their longitudinal corridor structure and, iii) the dry-wet cycles. This information is then used to suggest the value of riparian zones in landscape management. We emphasize the key roles of the ecotonal structure, longitudinal connectivity and timing of the occurrence of wet-dry cycles for riparian zones to process nitrate fluxes and to maintain high levels of biodiversity at the landscape scale. In the context of the worldwide transformations of flow regimes, the deterioration of water quality and loss of biodiversity, restoring riparian zones is both a key objective and a formidable challenge that implies envisioning the consequences of management actions on the long term, considering entire river basins, and paying attention to other environmental, regional and global changes.