The vegetation of the dunes near Oostvoorne (The Netherlands) with a vegetation map ¹)

The vegetation is described of a young, dynamical and periodically built up dune area. Some geomorphological and environmental data are given. 5 zones are described. Manifold animal and human influences are discussed in the light of information theory as applied by Chr. G. van Leeuwen. It is stated that the area has an exceptional variability and consequently a high number of species, ca 400. Structural description is emphasised. 10 formations were distinguished. A key to the formations and major vegetation types is presented. Two new descriptional terms are introduced: shroud layer and carpeting layer. Arguments are mentioned for a considerable freedom in choosing method and symbols in vegetation mapping. A survey of current vegetation mapping methods is given. The method followed here is introduced: it concerns a superposition of local species combinations (classified in the Braun-Blanquet system as far as possible) upon a physiognomic-structural division, the latter being interpreted from an air photograph. Remarks on typification and classification are made. The continuum point of view is emphasised. The cline-concept (Huxley) is applied. Three types of syncline are mentioned: toposyncline, ecosyncline and chronosyncline. The single-plot analysis method (Braun-Blanquet) was followed. It is argued why no multiple plot analysis method could be employed. 56 Communities and variants are described; a scheme of their relationships is added. Per Community or variant a list of characteristic (constant, dominant and faithful) species is given, as well as a list of differential species towards related communities.