Salt marshes and coastal defence

One of the most in intriguing-looking projects currently hosted on the Garden's Research Plots involves a line of six ply and polythene domes! These are part of a Marie Curie funded research collaboration between Dr Ruth Reef, Dr Iris Moller and Dr Tom Spencer from the Cambridge Coastal Research Unit (CCRU) at the Department of Geography.

In these domes they are growing salt marsh plants in order to investigate how global change is affecting the energy dissipation properties of salt marsh vegetation so to better understand the role salt marshes play in coastal defence and how this role might change under future climate scenarios. Coastal salt marshes protect our coastlines by dissipating wave energy and reducing erosion.
Salt marshes comprise a diversity of specialised plants that grow in the inter-tidal zone and thrive in this extreme environment. In the UK, salt marshes are widely distributed along sheltered coastlines and can be made up of more than 40 plant species.

The domes on the Research Plots are open-top elevated CO (carbon dioxide) growth chambers which house sections of salt marsh collected in Essex. There are six domes in total, three receive CO2 enriched air (from the cylinders in the wooden cages) at concentrations predicted to be experienced by salt marshes here in the UK by the end of the century and three receive ambient atmospheric conditions.

The team have also included a nutrient enrichment treatment to some of the salt marsh blocks to investigate the impact the rise in nutrients in coastal waters will have on salt marsh plants now and into the future. CO2 concentrations can have significant effects on plant growth and morphology as well as on plant species diversity. In this experiment, they are measuring different facets of salt marsh responses to the change in growing conditions such as growth, morphology and physiology as well as changes to root production and thus soil volume.

The CCRU is a global leader in the monitoring and modelling of wave energy dissipation by coastal vegetation and the findings from this study will contribute to the effective management of UK coasts into the future.

Dr Ruth Reef