The Virginia Coast Reserve Long-Term Ecological Research project focused  barrier island, salt marsh, watershed and lagoon systems located on the Atlantic Coast of the Delmarva Peninsula (Figure 1).  We investigated whether ecosystem dynamics and pattern on the landscape are controlled by the interaction between the vertical positions of the land, sea, and groundwater surfaces, and the movements of organisms and materials across the landscape.  The project monitored the processes, such as plant growth, movement of nutrients and organisms, organic matter dynamics, population growth and disturbance, which will determine the future landscape of the Virginia Coast Reserve.

    In 2007, a large-scale seagrass experiment was initiated, with the planting of seagrass in a 509-acre set-aside area in Hog Island Bay, which had been unoccupied by seagrass since the 1930s. We documented the recovery of key ecosystem functions related to primary productivity, carbon and nitrogen sequestration, increased water column clarity, and bottom stabilization with the growth of seagrass, with full recovery expected in a decade.  The showed that the positive feedback of seagrass on water clarity is sufficient to induce bistable dynamics between bare and seagrass-vegetated states.

     Our long-term record of salt-marsh elevation indicates that some of the mainland marshes are accumulating new material at a rate sufficient to keep up with existing rates of sea-level rise (Fig. 2), but that bay marshes are more vulnerable to submergence, which has adverse effects on waterbirds.  Additionally, disturbance promotes fragmentation and pond formation, which in turn causes dynamic changes in salt-marsh food webs.

    On the barrier islands, we showed that controls on plant community distribution can be explained by two key environmental parameters: distance from the shoreline (beach face) and elevation above sea level  (Fig 3). These two parameters integrate a number of important physical and biotic variables. For example, distance from the shoreline affects exposure to sea spray, burial by windblown sand, and vulnerability to storm-related disturbance (i.e., overwash) and, as a result, the extent to which ecological succession can take place. Elevation above sea level determines disturbance vulnerability, and influences groundwater and nutrient availability. The presence of plants feeds back to influence elevation by trapping and accumulating sand, or by maintaining low elevations. These relationships can be used to assess changes in species distribution with variations in island geomorphology and with climate change scenarios of accelerating sea-level rise and altered storm frequencies.  Over the last 30 years, we have observed a dramatic increase in shrub thickets by >400% as shrubs encroach onto grasslands (Fig. 4).

     Additionally, we used our observations to develop several quantitative models. A model of the seagrass ecosystem was used to explore the role of depth, water clarity and temperature on seagrass. Results from this model can be used to predict areas where seagrass reestablishment might occur in future scenarios of climate and land-use change.  We also developed a model that describes the strong coupling between the evolution of marshes and tidal flats. Marsh edge erosion and sediment transport influence the dynamics of these alternative states. Our decadal scale (1957 – 2009) and detailed short-term measurements show that erosion rates vary more than an order of magnitude (0.1 m to 1.5 m per year). We showed that wave attack at the marsh boundary increases with tidal elevation until the marsh is submerged and then rapidly decreases. Wave energy at the marsh boundary produces a wide array of marsh edge morphologies (wave-cut gullies, terrace...

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