Cross site analysis and synthesis of the role of vegetation, sediment supply, sea level rise and storminess on intertidal coastal geomorphology

Summary: Intertidal coastal environments are prone to changes induced by sea level rise, increase in storminess, and anthropogenic disturbances. It is unclear how changes in external drivers may affect the dynamics of low energy coastal environments because there are multiple evidences that their response might be non-linear, with thresholds and discontinuities. Process based modeling of the ecogeomorphic processes underlying the dynamics of these ecosystems is useful not only to predict their changes through time, but also to generate new hypotheses and research questions. The proposed research focuses on development of a cross site applicable model to Plum Island Ecosystems (PIE), Virginia Coast Reserve(VCR) and the Georgia Coastal Ecosystems (GCE) LTER sites in which the morphological co-evolution of the tidal basin and salt marsh is determined by site specific environmental drivers including tides, wind waves, sediment supply and sea level rise (SLR). The model will build on prior work examining feedbacks between salt marsh platform stability organogenic soil formation and sediment supply (Kirwan et al. 2010, Fagherazzi et al. 2006) as well as feedbacks between tidal basin vegetation and sediment resuspension (Carr et al. 2010, 2012a, 2012b). As such this model will directly incorporate feedbacks that exist between vegetation, hydrologic and geomorphic drivers and will synthesize our understanding of how ongoing site specific 1) anthropogenic (sediment supply), 2) pulse (storms) and 3) press (SLR) stressors affect stable states and non-linear transitions of the coupled salt marsh tidal basin system across the three sites. The proposed research directly addresses the need to characterize the “natural templates vulnerability to climate change.” While this research focuses on responses in the natural template (intertidal ecogeomorpholoy), the coupling to anthropogenic influences on sediment supply allows for examining how “human and natural templates interact to affect vulnerability to climate change in coastal systems.”