Global map of soil carbon in tidal marshes

Tidal marshes are a threatened coastal ecosystem valued for their capacity as a carbon sink. Given that effective action on climate change includes the protection, enhancement and restoration of natural carbon sinks, it is crucial to accurately quantify and map the current soil carbon stocks in this ecosystem. We aim to produce the first globally consistent map of soil carbon storage in tidal marshes.

A globally distributed soil carbon core dataset was compiled by a systematic literature review (n = 2,127 locations), supplemented by data from the Coastal Carbon Research Coordination Network database (n = 1,798 locations). We then developed a list of global landscape-level environmental drivers that are important in determining variation in soil carbon, including vegetation indices, elevation, flow accumulation, water occurrence, tidal amplitude, and other climatic variables. 

Using the carbon cores as training data and the environmental driver data as covariate layers, we are developing a machine learning model to map global marsh carbon stocks and their uncertainties at 0-30 and 30-100 cm depths, at a high resolution, and applying these to a new globally consistent tidal marsh extent map. The model and the global map will be easily updatable when new information (i.e. additional soil cores) becomes available. This map will be valuable to support conservation efforts, compliment blue carbon studies, and Nationally Determined Contributions.