Some observations on the transition zone between the xerosere and the halosere on the Boschplaat (Terschelling, The Netherlands) with special attention to Centaurium vulgare Rafn

Three important plant communities were studied on the salt marsh “the B ischplaat” on the Westfriesian island of Terschelling: the Centaurieto-Saginetum moniliformis D., S. et W. 1940, the Sagineto maritimae-Cochlearietum danicae Tx. et G. 1957 and the Juncetum gerardii W. 1906 (Table 1). The boundary lines of these associations are determined by soil moisture, salinity and density of vegetation. Five bare field plots were prepared in the transition zone. The establishment of species was followed during one year. For most species the original pattern was rapidly restored with some exceptions e.g. Centaurium vulgare Rafn (Table 3). Lifecycle and distribution pattern of Centaurium vulgare were more exactly investigated on one field plot (Table 4). Competition, density of adult plants, density of seedlings and soil moisture appeared to de dependent on each other in this sequence.