The article documents the colonization of sand flats exposed in a new polder by r-selected species of beach plain environments, i.e. Sagina maritima. Juncus bufonius ssp. ambiguus, Centaurium pulchellum, C. littorale and Sagina nodosa var. moniliformis. Species distribution along transects after eight years of succession in the polder and on the beach plain of the island of Schiermonnikoog were compared and related to combinations of the principal environmental factors: salinity, hydrology and % coverage of the vegetation. It is concluded that several hapaxant species of beach plain communities, and especially those belonging to the B2 life form (summer annuals exhibiting innate dormancy) are pre-destined to be successful colonizers of embanked flats, indicating temporary ecological similarity. The more even distribution of the species in the hapaxant life form spectrum of the polder susceptibly indicates the succession towards mesic communities.