Saltmarsh sedimentation: Processes & patterns

When considering the importance of saltmarsh dynamics it is important to understand the processes of saltmarsh sedimentation. Many authors have researched the importance of sedimentation on a saltmarsh via direct settling, but very few have analysed the role of vegetation and the implications it may have for sedimentation. Much opposition exists between researchers in establishing whether vegetation truly plays a role within the sedimentation dynamics on a saltmarsh. This thesis will investigate the importance of vegetation in relation to surface sedimentation on a saltmarsh and assess what temporal and spatial patterns exist. Orchardton Marsh on the Solway Firth, Southwest Scotland, is unusual due to its colonisation by Spartina, which is normally confined to areas in Southern England. Three methods were employed to assess the role of sedimentation in relation to (i) direct settling and (ii) on-vegetation settling. Fieldwork was undertaken on a monthly basis over the period of 1 year. The results demonstrate that vegetation within the saltmarsh system has a significant role in both temporal and spatial aspects. On-vegetation deposition was highest in the mature marsh. It was also found that the highest sedimentation amounts were recorded at creek edges. Thus, deposition of sediment is influenced greatly by vegetative and direct settling. Overall, long-term erosion is occurring on parts of Orchardton saltmarsh