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).