How do geomorphic characteristics affect the source of tree water uptake in restored river floodplains?

Alpine rivers and their floodplains have been highly modified by human activities during the last decades. River restoration projects aim to counteract these negative impacts restore ecosystem services provided riparian habitats. We studied two recently restored river sites in Ahr/Aurino Mareit/Mareta Rivers (Italian Alps) investigate how geomorphic conditions, soil moisture, groundwater level affect source of water used grey alder (Alnus incana (L.) Moench). compared isotopic composition (δ2H) tree sap at different locations (low terraces formed bed incision recent after restoration) with that potential sources, is, groundwater, water, rainfall. The monthly variation rainfall was reflected both shallow deeper as well sap. redistribution precipitation differed between post-restoration floodplain post-incision terraces, leading a relation composition. results show transpiration A. trees growing on is mostly supported stream-fed whereas mainly use precipitation-fed water. These marked, morphology-related differences highlight channel degradation still affects ecohydrological processes fluvial corridors. Nonetheless, large interventions—in terms widening—can enable self-formation new areas characterized stream water-fed ecosystems.