Succession and fluctuation in the vegetation of a Dutch beach plain

The development of the vegetation of a brackish sand flat with scattered embryo-dunes on one of the West Frisian islands, Schiermonnikoog (The Netherlands), was recorded over a ten-year period. Some persisting trends, as well as pronounced annual fluctuations, were observed. Therophyte populations are especially vulnerable to environmental fluctuation. The behaviour of various species populations is discussed in relation to environmental instability and life-forms. Special attention is paid to the shuttling of populations of short-lived species on the dune slope. The zonation of the latter may vary, which could be ascribed to their reaction on abiotic conditions as affected by specific life-history characteristics, viz. the germination period, the duration of the life-cycle and the mode of reproduction. Some concluding remarks are made about succession and the role species of different life-forms play in this process.