Increasing rates of sea-level rise and wave action threaten coastal human populations. Defense of shorelines by protection and restoration of wetlands has been invoked as a win-win strategy for humans and nature, yet intense debate has recently emerged over whether wetland vegetation actually suppresses coastal erosion. Here we provide experimental evidence showing the loss of wetland vegetation increases the rate of land loss on wave-stressed shorelines.
Results/Conclusions
Vegetation removal (simulated disturbance) along the edge of salt marshes reveals that loss of wetland plants increases erosion rates and that extensive root systems, not aboveground stems, are primarily responsible for this protective effect. Aboveground stems did suppress erosion, but only at larger patch sizes. Meta-analyses further show that disturbances that generate plant die-off on salt marsh edges generally hasten erosion in coastal marshes and the below ground plant material is key for shoreline stabilization. Collectively, our findings substantiate a coastal protection paradigm that incorporates preservation of shoreline vegetation and highlights disturbances (e.g. oil spills) that kill wetland plants as agents that can accelerate coastal erosion.