SEED BANK DYNAMICS IN A SOUTHEASTERN RIVERINE SWAMP

Seed banks were examined in a Taxodium distichum L.-Nyssa aquatica L. (cypress-tupelo) swamp forest and an adjacent bottomland hardwood forest on the floodplain of the Savannah River in South Carolina. Thirty 0.01 m² soil cores were collected in each community at each of three sampling times: before seed fall, after seed fall, and after an early spring river level rise had inundated both communities. Germination and sieving techniques were used to enumerate seeds in each sample. Woody seed banks of the two communities were dissimilar in species composition with both underrepresenting the species composition of the standing vegetation. In contrast, herbaceous seed banks of both communities were similar in species composition with greater species diversity in the seed banks than in the standing vegetation. Both the herbaceous and woody seed banks of the hardwood community changed significantly in seed densities across the three collection dates. Densities increased from September to December, after seed fall for many species, but decreased in April after the early spring water level rise. Seed densities did not change significantly in the cypress-tupelo community across the three collections. Hydrologic regime appears to have a major influence on seed bank composition and dynamics in southeastern riverine swamps.