Marsh migration in the coastal critical zone: Drivers and impacts of hydrological, biogeochemical, and ecological change

Ghost forests and abandoned farms are stark indicators of ecological change along world coastlines, caused by sea level rise (SLR). These changes adversely affect terrestrial ecosystems and economies, but expanding coastal marshes resulting from SLR also provide crucial ecosystem services such as carbon sequestration and mediate material fluxes to the ocean. We introduce a US-NSF Critical Zone Network project designed to untangle the hydrological, ecological, geomorphological, and biogeochemical processes that are altering the functioning of the marsh-upland transition in the coastal critical zone. We have instrumented six sites in the mid-Atlantic region of the US, along the coastlines of the Atlantic Ocean, Delaware Bay, and Chesapeake Bay where marshes are rapidly encroaching into forests and farmland. We have installed field sensors to observe the effects of slow hydrologic change (i.e. SLR) and fast episodic events such as high tides and storm surges on water levels, land surface elevation, salinity, redox conditions, and sap flow. We are coupling these measurements to laboratory experiments and analyses, as well as modeling to elucidate drivers and feedbacks in these complex and highly transient critical zone systems.