Tidal wetlands are known for their capacity to improve water quality by trapping sediment during tidal exchange. They are considered good sediment retention environments, but little is known about the sedimentations’ spatial variability within these wetlands and the role vegetation plays in the process. This research asked questions on the magnitude and dynamics of sediment deposition and its variability across different vegetation cover types in Tivoli North Bay freshwater marsh. Deposition trends were examined by using rubber collection discs (RCD), and compared among graminoid, broadleaf, submerged aquatic and shrub vegetation.

Results/Conclusions

Differences in deposition data were related to different vegetation types, resulting in significantly different patterns within the marsh. Broadleaf and submerged aquatic vegetation showed greater deposition when compared to graminoid and shrub vegetation. Higher deposition is attributed to a greater proximity to the tidal creek, to an increase of water depth when inundated and to the presence of greater plant surface area for sediment adhesion. Higher biomass and stem density present in the graminoid and shrub vegetation, promoting sedimentation by slowing current velocities, did not have a large effect on accretion in the studied marsh plant assemblages. Vegetation characteristics are an important spatial component of sedimentation dynamics and may affect marsh stability and vegetation change.