Estimates of global carbon stocks in coastal wetlands reveal that these
are some of the most efficient carbon-sequestering environments in the
world, which has prompted a renewed interest in conservation and
restoration programs as an opportunity for greenhouse gas abatement.
Accumulation of carbon in coastal wetlands is linked to diverse factors
such as the type of vegetation, geomorphic setting, and sediment supply.
Feedbacks between these factors and the tidal flow conditions drive the
dynamics of carbon accumulation rates. Climate change-induced sea-level
rise has been shown to increase the vulnerability to submergence of
saltmarsh and mangroves in coastal wetlands, even if accommodation and
landward colonization are possible. These potential losses of wetland
vegetation combined with the reduced productivity of newly colonized
areas will directly affect the capacity of the wetlands to sequester
carbon from sediments and root growth. Here, we implement an
eco-geomorphic model to simulate vegetation dynamics, soil carbon
accumulation, and changes in soil carbon stock for a restored
mangrove-saltmarsh wetland experiencing accelerated sea-level rise. We
evaluate model outcomes for existing conditions and two different
management scenarios aimed at mitigating sea-level rise effects and
conserve wetland vegetation. Even though some management measures can
result in partial conservation of wetland vegetation, they do not
necessarily result in the best option for soil carbon capture. Our
results suggest that accelerated sea-level can trigger accelerated
wetland colonization resulting in wetland areas with limited
opportunities for soil carbon capture from sediment and root
mineralization, an issue that has not been considered in previous
studies.