Can assisted migration alleviate dispersal limitation in restored riparian fens?
Annette Baattrup‐Pedersen, Paraskevi Manolaki, Dagmar Kappe Andersen, Lars Jørgen Amstrup, Tenna RiisAbstract
Introduction
Natural flooding maintains hydrological connectivity and facilitates dispersal in riparian habitats, yet restoration of fen‐meadow vegetation often remains constrained by dispersal limitation and unsuitable environmental conditions. Flood‐transported sediments may contain few target species, further limiting recovery.
Objectives
We examined how flooding‐associated sediment deposition affects plant community composition and whether assisted migration can improve the conservation status of protected fens within a Natura 2000 site.
Methods
We conducted a six‐year field experiment in three rich fens, simulating prolonged flooding followed by sediment deposition (WS) and sediment deposition with seed addition of five target species (WSS). Vegetation was monitored in 14 post‐treatment surveys to assess community change and target‐species establishment.
Results
Sediment‐dispersed species were predominantly ruderal or competitive taxa, shifting vegetation initially toward ruderals and subsequently toward competitors, with stronger persistent effects in low‐productive fens. Some sediment‐introduced species became dominant and outcompeted less competitive species. Establishment of seeded target species was limited, with only one persisting at the end of the experiment.
Conclusions
Flooding with sediment deposition can cause persistent shifts in riparian fen vegetation and promote homogenization rather than recovery of rich‐fen communities. Assisted migration had limited long‐term effects and did not substantially redirect community trajectories toward characteristic rich‐fen vegetation.