MEPS prepress abstract  -  DOI:

Seedling stability in waterlogged sediments: an experiment with saltmarsh plants

Regine Redelstein*, Gerhard Zotz, Thorsten Balke


ABSTRACT: Saltmarsh seedlings are exposed to extreme soil conditions in combination with mechanical disturbance by waves and tides, especially at the seaward fringe. We tested whether soil waterlogging affects resistance of seedlings against physical disturbance, thereby potentially influencing the distribution of saltmarsh species. A greenhouse experiment was conducted to investigate effects of waterlogging on plant traits, in particular root growth, and tolerance of seedlings against sediment erosion. Three species, each dominating different elevations in NW European salt marshes (Salicornia europaea, Atriplex portulacoides and Elytrigia atherica), were selected for the experiments. Individual seedlings were grown under different waterlogging treatments and finally subjected to an erosion treatment. The depth of erosion at which the seedlings toppled (Ecrit) was determined and related to above- and below-ground morphological traits of the seedlings. Resistance against erosion decreased in all three species from drained to completely waterlogged soil conditions, with the strongest negative impact of waterlogging on the upper marsh species E. atherica. Root length and biomass, shoot biomass and the root:shoot biomass ratio were the most important traits positively affecting Ecrit. The experiment demonstrates that rapid root growth is essential for the stability of seedlings, which is presumably of great importance for their successful establishment on tidal flats where sediment erosion may be a limiting factor. Root growth, in turn, is affected by a species-specific response to waterlogging. Our study suggests that this species-specific effect of waterlogging on seedling stability contributes to species sorting along the inundation gradient of coastal ecosystems.