Resilcoast

Integrating ecosystem resilience into coastal planning for the persistence of natural flood protection and wetland ecosystem services

Cluster Leader: Dr Martin Skov, Bangor University

The more frequent and costly flood disasters in recent years have fuelled a drive for nature-based flood protection that promises cost savings, wide-scale opportunities for implementation and will boost the delivery of other natural benefits. Thus, there is a critical need to understand how natural protection systems, such as saltmarshes, change over time and are affected by changing climate and other stressors.

Resilcoast addressed the role of saltmarshes in delivering ecosystem services and how this is impacted by the resilience of saltmarshes to environmental change.

Aims:

Resilcoast research addressed the role of saltmarshes in delivering ecosystem services such as coastal protection, recreation, carbon storage, grazing and biodiversity by integrating natural and social-sciences research. These results, combined with stakeholder interviews, were then used by the Cluster to inform coastal governance and management. Resilcoast also examined the resilience of saltmarshes: what are the dynamics shaping patterns of expansion, erosion, and even complete disappearance of vegetation? The Cluster then used this knowledge to predict future patterns of saltmarsh resilience and evaluate their implications for governance, management, and society.

Research activities:

  • Field experiments at saltmarshes throughout Wales to identify the impacts of grazing and environmental processes on marsh erosion and growth.
  • Large-scale disturbance experiments to investigate how expansion/erosion of vegetation depends on interactions between plant density, wave forces and sediment management.
  • A systematic review of 98 publications to investigate global patterns of storm influences on marsh vertical accretion and causes of marsh erosion.
  • Investigation of historical and experimental dynamics of marshes in the context of grazing, sea level rise, and climate change (increased storm frequency) to assess saltmarch resilience.
  • The development of advanced mathematical models to predict future changes to saltmarsh area cover and how such changes will likely affect the natural benefits that humans get from marshes.
  • Coupling these data to research on shoreline management plans (SMPs), to assess the benefits that saltmarshes provide to society, how state-shifts are considered in the current SMPs, and how well SMPs accommodate natural resilience.
  • Using UK-wide questionnaires and Welsh stakeholder interviews to map uses and views of ecosystem services concepts in Welsh legislation.

Key findings:

  • Global and regional patterns of saltmarsh resilience: Saltmarshes experience natural periods of expansion and retreat, but their resilience is threatened by environmental change combined with human impacts. UK patterns of saltmarsh expansion and retreat are explained by north-south gradients in sea level rise and sediment supply. As sediment supply from rivers has experienced global declines due to damming, active management is required to ensure saltmarsh resilience. Extreme coastal storms, however, might provide the amount of sediment that saltmarshes need for their long-term persistence.
  • Mechanisms underpinning marsh resilience:
  • At the marsh-scale, the underlying sediment underpins marsh resilience. Muddier marshes are more resistant to erosion, which enables them to extend further. Sandy marshes are more erosion-prone, but erosion can be significantly mitigated by biological structures (e.g. roots and organic matter).
  • At the creek scale, livestock grazing can reduce saltmarsh erosion by increasing soil compaction.
  • At the patch scale, the mechanisms underpinning vegetation structure and resilience are linked to specific dynamics: in sheltered sites, low densities of plants can thrive whereas in exposed sites, higher densities are required to prevent erosion.
  • Sea level rise will impact more heavily on marshes near the mouth of an estuary, than on those more elevated at the top of the estuary.
  • Implications for society, governance and management: Saltmarshes are intrinsically dynamic; the economic and wellbeing implications of this to society depend on the natural benefit in question. Flood protection by marshes, for example, is viable but spatially and temporally variable, and the most valuable marshes for carbon sequestration will be those that are more stable over time.
  • Ecosystem service concepts in policy, practitioner and public domains:
  • The consideration of ecosystem services and benefits within legislation Welsh national legislation is limited, limiting the potential for these Acts to realise their goals.
  • Welsh coastal management stakeholder views towards ecosystem service concepts is positive, with a feeling that there could be a shift towards greater integration and development of a common language with collective, common goals.
  • The Welsh public show high uncertainty about what saltmarshes are and have limited understanding of the importance of saltmarshes for coastal protection, carbon storage and biodiversity.

Publication highlights:

  • Pagès, J.F., Jenkins, S.R., Bouma, T.J., Sharps, E., Skov, M.W. (2018) Opposing Indirect Effects of Domestic Herbivores on Saltmarsh Erosion. Ecosystems https://doi.org/10.1007/s10021-018-0322-5
  • Boada, J., Arthur, R., Alonso, D., Pagès, J.F., Pessarrodona, A., Oliva, S., Ceccherelli, G., Piazzi, L., Romero, J., and Alcoverro, T. (2017) Immanent conditions determine imminent collapses: nutrient regimes define the resilience of macroalgal communities. Proceedings of the Royal Society B 284: 20162814. http://dx.doi.org/10.1098/rspb.2016.2814
  •  Davidson, K.E., Fowler, M.S., Skov, M.W., Doerr, S., and Griffin, J.N. (2017). Livestock grazing alters multiple ecosystem properties and services in salt marshes: a meta-analysis. Journal of Applied Ecology 54: 1395-1405. http://dx.doi.org/10.1111/1365-2664.12892

The NRN-LCEE produced the following briefing on the policy implications of Multi-Land's research:

Salt marsh resilience and coastal management

The Quotient researchers included:

Bangor University

  • Martin Skov                                 
  • Stuart Jenkins                              
  • Jordi Pages                                  
  • Mollie Duggan-Edwards          

Cardiff University

  • Rhoda Ballinger                                       
  • Emma McKinley                                      
  • Clare Hall

Swansea University

  • John Griffin                                  
  • Mike Fowler                                 
  • Davide de Battisti   

Centre for Ecology & Hydrology, Bangor

  • Angus Garbutt                             

Natural Resources Wales

  • Emmer Litt

Plymouth Marine Laboratory

  • Nicola Beaumont         

University of Southampton

  • Eli Lazarus       

Royal Netherlands Institute for Sea Research (NIOZ)

  • Tjeerd Bouma                              

Please see the ‘NRN-LCEE Final Overview 2013-2019’  for further details of the Cluster’s research.