SEEDS AND SEEDLINGS OF THE HAMILTON MARSHES, A DELAWARE RIVER TIDAL FRESH-WATER WETLAND

Seed bank studies, conducted over a 15 year Period in a tidal freshwater wetland, yielded 115+ species germinating in the greenhouse from soil samples taken from a variety of habitats in a tidal freshwater wetland. Species diversity was greater in sites near the tidal channel (18+/-2 per 20 x 20 cm sample) than from the high marsh (6.6+/-0.7). Densities ranged from 1620 in the stream channel to 51,750 m-2 in a shrub forest site. Only 30 species occurred in the field as seedlings. Study of the depth distribution of germinable seeds and spring depletion due to germination documented three seed bank strategies. Seed dispersal, tolerance to anaerobic soil conditions, and germination requirements, coupled with seedling tolerances, vary with species and help explain vegetation distribution patterns. Superimposed on these are year to year fluctuations in seed bank, seedling populations, and vegetation composition. Hydrological regime influences many factors that have an impact on life history stages.