Applying the seedling-emergence method under waterlogged conditions to detect the seed bank of aquatic plants in submerged sediments

Seed bank studies focused on submerged aquatic plants are generally performed under submerged conditions, using the seedling-emergence method. However, if a study targets at both submerged species and helophytes, submerged conditions are generally not suitable. We tested the emergence of seedlings from sediment samples from a freshwater canal, comparing a waterlogged treatment with a submerged treatment. From the sediment samples 31 species emerged. Eight species germinated in significantly larger numbers from the waterlogged treatment, one being a submerged species and four helophytes. No species germinated better under submerged conditions. The total number of species germinating under waterlogged conditions was significantly higher than under submerged conditions. Germination experiments with Potamogeton species showed no significant differences in germination percentage between a waterlogged and submerged treatment for at least two species. In the study of seed banks of submerged sediments, aimed at both submerged aquatic plants and helophytes, a waterlogged treatment is therefore suitable to detect both groups of plants. (C) 2002 Elsevier Science B.V. All rights reserved.