Abstract
Coastal marshes, which provide a number of ecosystem services including flood control, nutrient regulation, carbon sequestration, and wildlife habitat, have been experiencing extensive loss due to sea level rise (SLR) in addition to other natural and anthropogenic factors. One way in which coastal marshes can respond to SLR is through landward migration when suitable habitat is available. The objective of this research is to assess whether the landward migration of marshes was occurring at the Grand Bay National Estuarine Research Reserve (GBNERR) in southeastern Mississippi over two ~30-year intervals, 1955-1988 and 1988-2015. More specifically, we aim to identify land cover types with the greatest change over time and those that contributed to the replacement of upland forests and marshes. We applied the Land Change Modeler in TerrSet 2020 to evaluate land cover change based on the National Wetland Inventory (1955 and 1988) and WorldView-2 based classification (2015). We found that (1) forest experienced the greatest net change followed by agricultural land and marsh from 1955-1988 while marsh experienced the largest net change, followed by non-vegetated type and forest from 1988-2015; (2) forest-marsh dynamics were dominated by forest replacing marshes and the replacement rate declined in the second 30-year time window; and (3) upland forests were replaced by marshes in the northern GBNERR from 1988-2015 at low elevations but those losses were largely negated by forest replacement of marshes elsewhere. Prescribed fire used to restore upland pine savannas may slow forest expansion and provide opportunities for marsh transgression. This research is important for the development of a mechanistic model to simulate forest-marsh dynamics and will contribute to more informed ecosystem management at the GBNERR.
