Questions: What is the contribution of the seed bank to restoration of species-rich vegetation in oligotrophic wet dune slacks? Does the restoration management affect the seed bank?
Location: Calcareous coastal dune slacks at the west coast of The Netherlands.
Methods: Species composition of the seed bank and the above-ground vegetation was sampled in dune slacks that had a variable extent of groundwater level rise in combination with either topsoil removal or mowing.
Results: The seed bank had a high potential for restoration of species-rich vegetation: 60 species were found in the seed bank of which 14 were characteristic of oligotrophic, wet dune vegetation. While topsoil removal almost completely removed the seed bank, groundwater level rise did not permanently submerge the seed bank of species of oligotrophic, wet conditions. Changes in abundance in the established vegetation were unrelated to species abundance in the seed bank. Of all new species establishments in the vegetation relevés, 76% occurred where the species was not found in the seed bank. The chance that presence of a species in the seed bank led to establishment the following year was only 11%.
Conclusion: The seed bank was not the dominant source for newly establishing species following the large disturbance that was induced by restoration management. Changes in species abundance after the restoration impact were not related to species abundance in the seed bank, but to ongoing succession and current year dispersal. To attain a high number of new establishments, restoration projects should preferably be planned in the proximity of refuge populations, rather than relying on the seed bank alone.
Nomenclature: van der Meijden (1996).