Characterization of vegetated and ponded wetlands with implications towards coastal wetland marsh collapse

Catena
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Abstract

Coastal wetlands provide numerous ecosystem services; yet these ecosystems are increasingly vulnerable to climate change stressors, especially excessive flooding from sea-level rise and storm events. This study highlights the important contribution of vegetation belowground biomass to marsh stability and identifies loss of vegetation as a critical driver of marsh collapse. We investigated the shear strength of salt marshes and unvegetated interior ponds using a modified cone penetrometer along a chronosequence of wetland marsh collapse (0 to 21 + years following pond formation) to characterize changes in the structural integrity of the marsh soil. Following conversion from vegetated marsh to open water pond, the surficial soils experienced a dramatic loss in shear strength resulting from the loss of vegetation and compaction of soil pore space. The Cone Penetrometer Testing (CPT) data indicate that higher shear strength in the surficial layers of the vegetated marsh sites were never recovered, up to 21 + years following marsh collapse. Coupled with significant elevation loss from marsh collapse, additional sea-level rise, deep subsidence, and reduced sedimentation may contribute to conditions that can exceed critical flooding thresholds, making recovery from marsh collapse difficult or impossible. Therefore, characterizing mechanisms and thresholds of marsh collapse are critical for identifying those coastal marshes that are vulnerable to collapse before conversion from vegetated marsh to open water occurs.

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Publication type Article
Publication Subtype Journal Article
Title Characterization of vegetated and ponded wetlands with implications towards coastal wetland marsh collapse
Series title Catena
DOI 10.1016/j.catena.2022.106547
Volume 218
Year Published 2022
Language English
Publisher Elsevier
Contributing office(s) Wetland and Aquatic Research Center
Description 106547, 9 p.
Country United States
State Louisiana
City Port Sulphur
Other Geospatial Gulf of Mexico, Mississippi River Deltaic Plain
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