SILVER, Amber – 2009
The Influence of Vegetation on Sedimentary Processes in a Macrotidal Salt Marsh
Salt marsh systems are ultimately dependant on the accumulation of sediment for survival. Previous research has shown that vegetation plays the dominate role in controlling sediment dynamics within the marsh zone. Within Macro-tidal environment such as the Bay of Fundy where vegetation may only occupy a small portion of the water column, knowledge of salt marsh sediment dynamics is still evolving. The purpose of this research was to investigate the degree of influence that vegetation has in increasing rates of sedimentation within the vegetative canopy.
This research took place on a natural macro-tidal salt marsh in the upper Bay of Fundy. Three 1 m2 plots were established on the study site, one of the mudflat and two in the low marsh vegetation. One vegetated plot was trimmed and maintained throughout the entire study period to represent an area of lower roughens within the vegetative canopy. Each plot contained three rising stage bottles at two different elevations above the bed to measure the suspended sediment concentration, and three co-located sediment traps to measure the amount of sediment deposited over ten individual tidal cycles. Due to an expected decrease in velocity within the vegetated canopy, it was hypothesized that the highest degree of sedimentation would be observed at the sediment traps within the vegetation canopy. Results of this research indicate that while deposited sediment was higher in the vegetated canopy than on the adjacent mudflat as hypothesized, areas of lower roughness within the vegetated canopy had the highest recording values of deposited sediment and the lowest values of suspended sediment. This suggests that the spatial distribution of vegetation may exert a greater role in sedimentation than previous studied.