Revegetation of littoral zones in snowmaking reservoirs: field assessment of aquatic plant establishment and biodiversity responses

Alpine freshwater ecosystems are biodiversity hotspots providing key ecosystem services but face threats from climate change and human activities. Snowmaking reservoirs have rapidly expanded in alpine regions in response to declining snow cover and growing winter tourism. The banks of the artificial waterbodies are often mineral, steep, and poorly vegetated, and can act as ecological traps. This study experimentally assessed the feasibility of littoral revegetation using coir macrophyte rolls as a Nature-based Solution in a high-elevation snowmaking reservoir in the French Alps, and whether such revegetation can initiate successional trajectories comparable with the regional species pool. Four native plant species were introduced and monitored over two years. Helophytes showed high survival (>97%), clonal expansion, and flowering, while hydrophytes initially grew but their longer-term persistence appears difficult under the specific management regime of the reservoir. Additional species colonized the rolls spontaneously, signalling the onset of secondary succession. Nearby waterbodies hosted 29 macrophyte species, indicating potential for gradual natural recolonization. We will also present preliminary results on amphibians, aquatic invertebrates, odonates, and zooplankton to provide a broader assessment of biodiversity responses. Overall, our findings indicate that coir rolls can establish functional littoral zones in snowmaking reservoirs, and targeted ecological design can help reconcile operational needs with alpine biodiversity conservation.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Benjamin Gerfand, Université Savoie Mont Blanc (gerfand.benjamin@gmail.com)

Authors:

Benjamin Gerfand, Univ. Savoie Mont Blanc, INRAE, CARRTEL, Thonon-les-Bains, France  (gerfand.benjamin@gmail.com)

Stéphanie Gaucherand, Université Grenoble Alpes, INRAE, LESSEM, 38000, Grenoble, France  (stephanie.gaucherand@inrae.fr)

Pierre Berteloot, INRAE, Aix Marseille Univ., RECOVER, Aix-en-Provence, France  (pierre.berteloot@inrae.fr)

Samuel Westrelin, INRAE, Aix Marseille Univ., RECOVER, Aix-en-Provence, France  (samuel.westrelin@inrae.fr)

Léo Tixier, ADS–Domaine de Montagne Les Arcs/Peisey-Vallandry/Villaroger, Bourg-Saint-Maurice, France  (leo.tixier@compagniedesalpes.fr)

André Evette, Université Grenoble Alpes, INRAE, LESSEM, 38000, Grenoble, France  (andre.evette@inrae.fr)

Florent Arthaud, Pôle R&D ECLA, France  (florent.arthaud@univ-savoie.fr)