Coastal wetland response to sea level rise: an integrative marsh – mangrove study on soil elevation and soil carbon response
Coastal wetlands, such as mangroves and marshes, are unique ecosystems that are often feared to be lost by sea level rise. However they can adapt to a rising sea level to some extent by raising their elevation via sediment accumulation, and they can mitigate climate change by storing carbon into their soils. Present insights into the feedbacks between sea level rise, sediment and carbon accumulation mainly come from studies on marshes, while much less is known for mangroves. Here we will conduct for the first time an integrated field and modelling study on these feedbacks in both mangroves (in the Sundarbans, Bangladesh) and marshes (in the Scheldt estuary, Belgium & Netherlands). We will test the hypotheses that: (1) the response of mangroves and marshes to sea level rise is governed by similar feedbacks between tidal flooding, sediment and carbon accumulation rates; (2) the specific strength of these feedbacks, hence the adaptability to sea level rise, differs between mangroves and marshes due to intrinsic vegetation differences. This project will generate a unique comprehensive field data set which will feed the development of a common model for both mangroves and marshes to simulate sediment and carbon accumulation rates in response to 21st century sea level rise. Based on the model and on global datasets we will provide a new global assessment of carbon storage and areas of mangroves and marshes at risk of drowning under 21st century sea level rise.