A Study of Sediment Accretion Dynamics in Mature and Restored Tidal Freshwater Forested Wetlands in the James River Watershed using Surface Elevation Tables and Marker Horizons

Lopez, Ronaldo.  MS Thesis

Sediment accretion and elevation change in tidal forests, and the corresponding ability of these wetlands to keep pace with sea-level rise (SLR), represent data gaps in our understanding of wetland sustainability. Surface Elevation Tables and marker horizons were installed in three mature tidal forests and a restored tidal marsh, allowing us to measure elevation change, accretion, and subsidence. Additionally, we measured predictor variables to test for their significance in explaining accretion and elevation change rates. Mean accretion at our sites was 11.67 +/- 3.01 mm yr-1 and mean elevation change was -20.22 +/- 8.10 mm yr-1, suggesting subsidence occurring beneath the sites. Processes contributing to accretion and elevation change at our sites may be driven by hydrologic patterns. Comparing our elevation trends with SLR trends suggests that our study sites may not keep pace with SLR. However, we may be observing short-term oscillations that do not indicate true long-term trends.

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