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The effect of a small vegetation dieback event on salt marsh sediment transport
Author(s) -
Coleman Daniel J.,
Kirwan Matthew L.
Publication year - 2018
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.4547
Subject(s) - salt marsh , marsh , hydrology (agriculture) , erosion , vegetation (pathology) , geology , sediment , estuary , dominance (genetics) , environmental science , sediment transport , accretion (finance) , geomorphology , wetland , ecology , oceanography , geotechnical engineering , medicine , biochemistry , chemistry , physics , pathology , gene , astrophysics , biology
Vegetation is a critical component of the ecogeomorphic feedbacks that allow a salt marsh to build soil and accrete vertically. Vegetation dieback can therefore have detrimental effects on marsh stability, especially under conditions of rising sea levels. Here, we report a variety of sediment transport measurements associated with an unexpected, natural dieback in a rapidly prograding marsh in the Altamaha River Estuary, Georgia. We find that vegetation mortality led to a significant loss in elevation at the dieback site as evidenced by measurements of vertical accretion, erosion, and surface topography compared to vegetated reference areas. Below‐ground vegetation mortality led to reduced soil shear strength. The dieback site displayed an erosional, concave‐up topographic profile, in contrast to the reference sites. At the location directly impacted by the dieback, there was a reduction in flood dominance of suspended sediment concentration. Our work illustrates how a vegetation disturbance can at least temporarily reverse the local trajectory of a prograding marsh and produce complex patterns of sediment transport. © 2018 John Wiley & Sons, Ltd.