De invloed van het Zoutgehalte op de verspreiding van verschillende Halophyten

A study of the halophytes along the coast of the island of Overflakkee showed that there is a marked difference between the vegetation on the salt marshes of the North coast and those of the South. Aster Tripolium, Glaux maritima, Plantago maritima, Puccinellia spec., Spergularia media, Triglochin maritima are to be found in the marshes along both the North and South coasts. Obione portulacoides, Statice Limonium and Suaeda maritima on the other hand are only met with on the South coast. The causes of this difference probably are the following: the North coast is watered by the „Haringvliet” which may be considered to form one of the mouths of the Rhine, perhaps even its main mouth; hence the sodiumchloride content of the water varies between much lower limits than that of the „Volkerak”, „Krammer” and „Grevelingen”, the estuaries South of the island (the figures on map IX give the total content of salts in gr. pro L.). This conclusion is corroborated by a study of the spread of halophytes along the former „Zuiderzee”, as well as by some waterculture experiments in the laboratory for plant physiology of the University of Amsterdam. Obione portulacoides, Suaeda maritima and Statice Limonium are real halophytes able to sustain the struggle for existence only in an environment with a high salt content; Aster Tripolium, Glaux, Plantago maritima etc. are semi-halophytes able to sustain this struggle also in a environment which differs much less from a normal one. Salicornia herbacea occupies an intermediate position. A sociological and ecological study will be necessary however to elucidate this matter entirely.