Les forêts littorales en milieu dunaire : l'exemple de la Réserve Biologique Domaniale de Merlimont (Pas-de-Calais)

Abstract

Forests on coastal dunes : the example of the National Biological Reserve of Merlimont (Pas-de-Calais). The authors emphasize the special nature of the birchwood in the moist soils of coastal dunes of Merlimont (Pas-de-Calais). The birchwood is the last stage of a successional process which appears on a sequential air photos analysis between 1947 and 1989. A structural complexity of the coastal forest can be well defined only in the inner part of the central depression between the dune ridges. Dynamic processes can be described as dominant in the vegetation landscape as follow : -on the foredune ridge and on the western part of the inter-dune flat area, a linear succession of marram grass and shrubs, -on the eastern part of the inter-dune flat area and on the hollows of the reardune ridge, a cyclic fluctuation in small clearings and borders of the birchwood (inner and outer dynamics), -in the transition area a nuclear colonization with patches of wind-bowed trees.