The Influence of Sulphide on the Distribution of Higher Plants in Salt Marshes

(1) Soluble sulphide in surface (0-5 cm) salt marsh sediments was detectable only on the lower marsh, salt pans and creek beds. On the lower-marsh only Salicornia europaea amongst the vascular plant species present was rooted in sulphide-containing sediments. (2) No significant correlation was observed between soluble sulphide concentration and redox potential in soil samples from the lower-marsh. (3) When eight salt marshes from around the coast of Britain were compared, six had a detectable sulphide concentration in the lower-marsh sediments. Divisixe information analysis of the vegetation data from these sites indicated that in all cases the most significant association was between Salicornia europaea and otherwise bare ground. In two marshes where no soluble sulphide could be measured, S. europaea was associated with other plant species rather than bare ground. (4) Monthly observations of plant cover and sulphide concentration in sixteen permanent quadrats on the lower marsh revealed a significant positive correlation between the cover of Salicornia europaea and soil sulphide. In contrast, Puccinellia maritima showed a significant negative correlation with sulphide concentration. (5) In liquid media, the growth of Atriplex patula, Festuca rubra and Puccinellia maritima, was significantly inhibited by sulphide whereas there was no marked effect on that of Salicornia europaea. (6) The results suggest that S. europaea is relatively tolerant of sulphide and is able to establish on areas of the lower marsh from which other species are excluded by the presence of sulphide.