Proposal of new syntaxa and series of Grey Willow forests of humid dunes slacks of the North-Atlantic coasts of Europe

This article aims to point out the recent emergence of willows within the dune slacks of the Atlantic coasts following land abandonment. Firstly, a new association present in Brittany is examined: the <i>Epipactido palustris – Salicetum atrocinereae ass. nova hoc loco</i> with a detailed description about its physiognomic, floral, and ecological characteristics. Related dynamico-catenal trajectories that follow the expression of those forests are also described. This survey highlights an original littoral forest formation that could constitute the head of a vegetation series. Elements of reflection are proposed as for the conservation of the dune slacks woodlands and should allow the managers to refine their strategies. Secondly, the existence of a similar association along the coasts of the Channel and the North Sea is reported (<i>Hydrocotylo vulgaris – Salicetum cinereae ass. nova</i>). A new alliance (<i>Carici flaccae – Salicion cinereae all. nova</i>) is proposed in order to regroup these Northwest-European willow forests of the dune slacks and to clarify their synsystematic status.