scholarly journals How strong are salt marshes? Geotechnical properties of coastal wetland soils

Author(s):  
Helen Brooks ◽  
Iris Moeller ◽  
Tom Spencer ◽  
Katherine Royse ◽  
Simon Price ◽  
...  
2019 ◽  
Vol 16 (2) ◽  
pp. 425-436 ◽  
Author(s):  
Hilary Ford ◽  
Angus Garbutt ◽  
Mollie Duggan-Edwards ◽  
Jordi F. Pagès ◽  
Rachel Harvey ◽  
...  

Abstract. Carbon stored in coastal wetland ecosystems is of global relevance to climate regulation. Broadscale inventories of this “blue” carbon store are currently lacking and labour intensive. Sampling 23 salt marshes in the United Kingdom, we developed a Saltmarsh Carbon Stock Predictor (SCSP) with the capacity to predict up to 44 % of spatial variation in surface soil organic carbon (SOC) stock (0–10 cm) from simple observations of plant community and soil type. Classification of soils into two types (sandy or not-sandy) explained 32 % of variation in SOC stock. Plant community type (five vegetation classes) explained 37 % of variation. Combined information on soil and plant community types explained 44 % of variation in SOC stock. GIS maps of surface SOC stock were produced for all salt marshes in Wales (∼4000 ha), using existing soil maps and governmental vegetation data and demonstrating the application of the SCSP for large-scale predictions of blue carbon stores and the use of plant community traits for predicting ecosystem services.


2021 ◽  
Vol 4 (1) ◽  
pp. 168-192
Author(s):  
Judith S. Weis ◽  
Elizabeth Burke Watson ◽  
Beth Ravit ◽  
Charles Harman ◽  
Metthea Yepsen

Salt marshes are key coastal ecosystems that provide habitats for wildlife, including invertebrates, fishes, and birds. They provide ecosystem services such as protection from storm surges and waves, attenuation of flooding, sequestration of pollutants (e.g., blue carbon), and nutrient removal. They are currently under great threat from sea level rise (SLR). We collected information about trends in the horizontal extent (acreage) of New Jersey salt marshes and recent elevation changes compared with the current local rate of SLR in New Jersey, which is between 5 and 6 mm year−1. We found pervasive, although variable, rates of marsh loss that resulted from both anthropogenic disturbance as well as edge erosion and interior ponding expected from SLR. Elevation trends suggest that the current rates of SLR exceed most marsh elevation gains, although some Phragmites-dominated marshes keep pace with SLR. Four potential remedies to address current coastal trends of marsh loss were described in the context of New Jersey’s regulatory and management environment: protection of marsh inland migration pathways, altered management of Phragmites, thin layer sediment placement, and living shoreline installations. Proactive steps are necessary if coastal wetland ecosystems are to be maintained over the next few decades.


2021 ◽  
Author(s):  
Jeremy Lundholm ◽  
Tasha R.M. Rabinowitz ◽  
Lyndsay Greene ◽  
Alisha D. Glogowski ◽  
Tony Bowron ◽  
...  

Abstract Salt marshes are a type of coastal wetland that are affected by dynamic coastal processes. Ice blocks and wrack (mats of plant debris) regularly float onto northern marshes and become stranded, affecting vegetation and soil accretion. There is little research regarding the capacity of ice and wrack to transport viable plant propagules onto marshes where they can colonize, which may be particularly important at barren new salt marsh restoration sites. Contributions of sediment by ice may also be important at restoration sites to raise the marsh platform to elevations appropriate for plant colonization. We collected ice (n = 27) and wrack (n = 18) samples at marshes in the Bay of Fundy, ran germination trials with the contents, and measured the quantity of sediment in the ice. We found viable propagules from halophytic and non-halophytic species in wrack, and viable propagules of Sporobolus pumilus in ice. Additionally, we found sediment densities between 0.01 and 4.75 g·cm−3 in ice blocks that translated to 26.61 – 21,483.59 kg of total sediment per block, representing a large source of sediment. We found that the number of germinating propagules could not be predicted by wrack size, and that pH, sediment density, sediment weight in ice blocks were variable across the marsh surface, while ice salinity was negatively correlated with elevation and distance from creek. Our results indicate that ice and wrack represent a potential source for vegetation colonization at salt marsh sites and highlights their contributions to facilitating vegetation colonization through building marsh soils.


Geoderma ◽  
2019 ◽  
Vol 337 ◽  
pp. 1267-1277 ◽  
Author(s):  
Havalend E. Steinmuller ◽  
Kyle M. Dittmer ◽  
John R. White ◽  
Lisa G. Chambers

Author(s):  
Helen Brooks ◽  
Iris Möller ◽  
Tom Spencer ◽  
Kate Royse ◽  
Simon James Price

Salt marshes and, to a lesser extent, tidal flats, attenuate incoming hydrodynamic energy, thus reducing flood and erosion risk in the coastal hinterland. However, marshes are declining both globally and regionally (the Northwest European region). Salt marsh resistance to incoming hydrodynamic forcing depends on marsh biological, geochemical and geotechnical properties. However, there currently exists no systematic study of marsh geotechnical properties and how these may impact both marsh edge and marsh surface erosion processes (e.g. surface removal, cliff undercutting, gravitational slumping). This has led to poor parameterization of marsh evolution models. Here, we present a systematic study of salt marsh and tidal flat geotechnical properties (shear strength, bulk density, compressibility, plasticity and particle size) at Tillingham, Essex, UK.


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