Study sites and environmental conditions
In 2021, we monitored, across three seasons (Spring: March-April; Summer: June-July and Autumn: November-December), 20 sites located in the Albarine river catchment in France (Datry 2012, Gauthier et al. 2020). Although under an oceanic climate, the Albarine is subject to natural flow intermittence due to a permeable karstic bedrock and porous alluvial sediments that induce drying events (lasting from weeks to months) in headwaters and in the main-channel (Fig. S1). The Albarine has a total network length of 150 kilometers of which at least 37% are known to be intermittent (Fig. S1). The riparian zone is dominated by deciduous trees such as ash (Fraxinus excelsior ) and hazel (Corylus avellana ), although coniferous trees (e.g. Picea abies ) can dominate in the upper parts of the river. The 20 sampling sites were selected based on a-priori knowledge of their flow regime in order to represent a gradient of flow intermittence and equal distribution of perennial and intermittent reaches among headwaters and the mainstem (Fig. S1).