Wel en wee van pionierplanten in de Voornse duinen

The distribution areas of some pioneer plants in the Voorne dunes in the past (1962) and recently (1980) were compared. Those of the dune slack plants amongst them such as Epipactis palustris. and Pyrola rotundifolia decreased during that period, but the ruderal species Cynoglossum officinale became more abundant. The decline of the dune slack plants was brought about by increasing density of the vegetation. This succession is favoured by an offshore harbour area which reduces the salt transport from the sea by wind action. The occurrence of ruderals is promoted by several human activities.