Nutrient supply of herbaceous bank vegetations in Dutch coastal dunes; The importance of nutrient mobilization in relation to (artificial) infiltration

The occurrence of competitive tall hemicryptophytes with high nutrient demands in phreatophytic vegetations is generally related to an excessive supply of macronutrients. In unaffected areas of the Dutch coastal dunes these species can be found on locally humic soils. Plant species with an extremely high nutrient demand grow abundantly on the banks of infiltration ponds in dune areas which are artificially infiltrated with highly eutrophic water for public water supply purposes. There they overgrow the rare species of the authentic dune slack vegetations. In this paper it is investigated how the vegetation on banks of dune ponds is connected with the nutrient supply due to both mobilization (mainly mineralization) and infiltration water flow. This study leads to the conclusion that prepurification of infiltration water will suppress the growth of the most competitive species on the banks in infiltrated dune areas. Phosphate stripping seems to be the most effective strategy for this prepurification.