Een stabiele grens: Caltha palastris L. in Friesland

Round about 1930 it was presumed that the imminent closure of the ‘Zuiderzee’ with the resultant change from salt to fresh water might well affect the boundaries of Caltha palustris in the coastal area of the province Friesland. It was thought that inside the dikes Caltha would invade the regions that had previously been too saline for its growth. As many localities as possible were carefully mapped. Now, forty years after the first investigation was carried out the boundary of the area covered by Caltha appears practically unchanged. Very different, on the other hand, is the situation outside the dikes where many new localities have been found on the newly claimed land.