Virginia Institute of Marine Science
Increasing rates of sea-level rise and wave actionthreaten coastal populations. Defense of shorelinesby protection and restoration of wetlands has beeninvoked as a win-win strategy for humans and na-ture, yet evidence from field experiments supportingthe wetland protection function is uncommon, as isthe understanding of its context dependency. Herewe provide evidence from field manipulationsshowing that the loss of wetland vegetation, regard-less of disturbance size, increases the rate oferosion on wave-stressed shorelines. Vegetationremoval (simulated disturbance) along the edge ofsalt marshes reveals that loss of wetland plants ele-vates the rate of lateral erosion and that extensiveroot systems, rather than aboveground biomass,are primarily responsible for protection againstedge erosion in marshes. Meta-analysis furthershows that disturbances that generate plant die-off on salt marsh edges generally hasten edgeerosion in coastal marshes and that the erosion pro-tection function of wetlands relates more to lateralthan vertical edge-erosional processes and ispositively correlated with the amount of below-ground plant biomass lost. Collectively, our findingssubstantiate a coastal protection paradigm thatincorporates preservation of shoreline vegetation,illuminate key context dependencies in this theory,and highlight local disturbances (e.g., oil spills)that kill wetland plants as agents that can acceleratecoastal erosion.
Silliman, Brian R.; He, Qiang; Angelini, Christine; Smith, Carter S.; Kirwan, Matthew L.; and et al, Field Experiments and Meta-analysis Reveal Wetland Vegetation as a Crucial Element in the Coastal Protection Paradigm (2019). Current Biology, 29, 1800-1806.