Does vegetation prevent wave erosion of salt marsh edges?

This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves.

[1]  Heidi Nepf,et al.  Vertical secondary flows in submersed plant‐like arrays , 1999 .

[2]  M. K. Sørensen,et al.  The Asian Tsunami: A Protective Role for Coastal Vegetation , 2005, Science.

[3]  Carrie V. Kappel,et al.  Coastal Ecosystem-Based Management with Nonlinear Ecological Functions and Values , 2008, Science.

[4]  J. Benoit,et al.  The National Academies Report on Mitigating Shore Erosion along Sheltered Coasts , 2007 .

[5]  Luca Carniello,et al.  Critical bifurcation of shallow microtidal landforms in tidal flats and salt marshes. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[6]  S. Temmerman,et al.  Vegetation causes channel erosion in a tidal landscape , 2007 .

[7]  R. Feagin.  Vegetation's Role in Coastal Protection , 2008, Science.

[8]  E. Houwing.  Morphodynamic development of intertidal mudflats: consequences for the extension of the pioneer zone , 2000 .

[9]  Urs Neumeier,et al.  The influence of vegetation on turbulence and flow velocities in European salt‐marshes , 2006 .

[10]  Peter M. J. Herman,et al.  Density-dependent linkage of scale-dependent feedbacks: a flume study on the intertidal macrophyte Spartina anglica , 2009 .

[11]  M. Weinstein,et al.  Concepts and Controversies in Tidal Marsh Ecology , 2000, Springer Netherlands.

[12]  A. Baird,et al.  Natural Barriers to Natural Disasters , 2007 .

[13]  M. Luther,et al.  Flow hydrodynamics in tidal marsh canopies , 1995 .

[14]  Johan van de Koppel,et al.  Self‐Organization and Vegetation Collapse in Salt Marsh Ecosystems , 2004, The American Naturalist.

[15]  C. C. Watson,et al.  Restoration of the Mississippi Delta: Lessons from Hurricanes Katrina and Rita , 2007, Science.

[16]  R. Thomas,et al.  Causes of Salt Marsh Erosion in Galveston Bay, Texas , 2009 .

[17]  A. C. Redfield,et al.  THE AGE OF SALT MARSH PEAT AND ITS RELATION TO RECENT CHANGES IN SEA LEVEL AT BARNSTABLE, MASSACHUSETTS. , 1962, Proceedings of the National Academy of Sciences of the United States of America.

[18]  M. Bertness,et al.  Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated sea-level rise , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[19]  Kenneth Pye,et al.  Flow Structure in and above the Various Heights of a Saltmarsh Canopy: A Laboratory Flume Study , 1995 .

[20]  Iris Möller,et al.  Wave Transformation Over Salt Marshes: A Field and Numerical Modelling Study from North Norfolk, England , 1999 .

[21]  S. Fearnley.  The Soil Physical and Chemical Properties of Restored and Natural Back-Barrier Salt Marsh on Isles Dernieres, Louisiana , 2008 .

[22]  K. McKee,et al.  Hurricane Mitch: effects on mangrove soil characteristics and root contributions to soil stabilization , 2003 .

[23]  M. Kirwan,et al.  A coupled geomorphic and ecological model of tidal marsh evolution , 2007, Proceedings of the National Academy of Sciences.

[24]  Iris Möller,et al.  Wave dissipation over macro-tidal saltmarshes: Effects of marsh edge typology and vegetation change , 2002, Journal of Coastal Research.

[25]  K. Kathiresan,et al.  Coastal mangrove forests mitigated tsunami , 2005 .

[26]  R. Delaune,et al.  Erosion rather than plant dieback as the mechanism of marsh loss in an estuarine marsh , 1994 .

[27]  Iris Möller,et al.  Quantifying saltmarsh vegetation and its effect on wave height dissipation: Results from a UK East coast saltmarsh , 2006 .

[28]  P. Hensel,et al.  High-Precision Measurements of Wetland Sediment Elevation: II. The Rod Surface Elevation Table , 2002 .

[29]  Andrea Rinaldo,et al.  Biologically‐controlled multiple equilibria of tidal landforms and the fate of the Venice lagoon , 2007 .

[30]  C. Hopkinson,et al.  RELATIONSHIP OF ORGANIC CARBON AND MINERAL CONTENT TO BULK DENSITY IN LOUISIANA MARSH SOILS , 1984 .

[31]  G. van der Velde,et al.  Interactions between waves, bank erosion and emergent vegetation: An experimental study in a wave tank , 1996 .

[32]  Weiguo Zhang,et al.  Spatial and temporal variations in sediment grain size in tidal wetlands, Yangtze Delta: On the role of physical and biotic controls , 2008 .

[33]  C. S. Milan,et al.  Organic and Inorganic Contributions to Vertical Accretion in Salt Marsh Sediments , 2002 .

[34]  Bruno Chatenoux,et al.  Impacts from the 2004 Indian Ocean Tsunami: analysing the potential protecting role of environmental features , 2007 .

[35]  R. S. Bhalla.  Do bio-shields affect tsunami inundation? , 2007 .

[36]  C. Watson,et al.  Sedimentation–erosion dynamics of abandoned reclamations: the role of waves and tides , 2000 .