Carbon accumulation rates are highest at young and expanding salt marsh edges

Miller, Carson B.; Rodriguez, Antonio B.; Bost, Molly C.; McKee, Brent A.; McTigue, Nathan D.

doi:10.1038/s43247-022-00501-x

Cited by 20 publications

(4 citation statements)

References 59 publications

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“…Coarser, denser inorganic sediment is mainly deposited near the marsh edge, while the inner marsh receives a higher proportion of finer sediments, as supported by the observed grain size distribution along the transect (Fig. 4c), and less dense organic material (Leonard et al, 2002;Miller et al, 2022). In addi-tion to the already larger proportion of organic material settling in the inner marsh, the supply of finer inorganic sediment (Fig.…”

Section: Discussionmentioning

confidence: 54%

Spatial patterns of organic matter content in the surface soil of the salt marshes of the Venice Lagoon (Italy)

Puppin,

Tognin,

Ghinassi

et al. 2024

Biogeosciences

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Abstract. Salt marshes are crucial eco-geomorphic features of tidal environments as they provide important ecological functions and deliver a wide range of ecosystem services. Being controlled by the interplay between hydrodynamics, geomorphology, and vegetation, the contribution of both organic matter (OM) and inorganic sediments drives salt marsh vertical accretion. This allows marshes to keep pace with relative sea level rise and likewise capture and store carbon, making them valuable allies in climate mitigation strategies. Thus, soil organic matter (SOM), i.e. the organic component of the soil, plays a key role within salt marsh environments, directly contributing to soil formation and supporting carbon storage. This study aims at inspecting spatial patterns of OM in surface salt marsh soils (top 20 cm), providing further insights into the physical and biological factors driving OM dynamics that affect salt marsh survival and carbon sink potential. Our results reveal two scales of variations in SOM content in marsh environments. At the marsh scale, OM variability is influenced by the interplay between surface elevation and changes in sediment supply linked with the distance from the marsh edge. At the system scale, OM content distribution is dominated by the gradient generated by marine and fluvial influence. The observed variations in SOM are explained by the combination of inorganic and organic input, preservation conditions, and sediment grain size. Our results highlight the importance of marshes as carbon sink environments, further emphasising that environmental conditions within a tidal system may generate strongly variable and site-specific carbon accumulation patterns, enhancing blue carbon assessment complexity.

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Section: Discussionmentioning

confidence: 54%

Spatial patterns of organic matter content in the surface soil of the salt marshes of the Venice Lagoon (Italy)

Puppin,

Tognin,

Ghinassi

et al. 2024

Biogeosciences

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“…capacity and through their greater potential for protection of C by means of organic-mineral interaction and micro-or macroaggregates (Kelleway et al, 2016). Furthermore, the enriched OM content of inner marsh may also be explained by the different sources of material available for salt marsh accretion across the platform (Miller et al, 2022). Due to the preferential deposition of the denser inorganic fraction of suspended sediments within tidal flow during the initial phase of inundation, inorganic sediment is mainly deposited near the marsh edge, whereas the inner marsh is supplied with more organic material due to, the transport and deposition of less dense organic particles, in addition to in situ decaying vegetation (Leonard et al, 2002;Miller et al, 2022).…”

Section: Organic Content Variabilitymentioning

confidence: 99%

“…Furthermore, the enriched OM content of inner marsh may also be explained by the different sources of material available for salt marsh accretion across the platform (Miller et al, 2022). Due to the preferential deposition of the denser inorganic fraction of suspended sediments within tidal flow during the initial phase of inundation, inorganic sediment is mainly deposited near the marsh edge, whereas the inner marsh is supplied with more organic material due to, the transport and deposition of less dense organic particles, in addition to in situ decaying vegetation (Leonard et al, 2002;Miller et al, 2022). Organic supply includes allochthonous particulate OM and organic debris and wrack deposited during storms (Miller et al, 2022), and autochthonous plant litter collected and moved above the marsh platform (Leonard et al, 2002).…”

Section: Organic Content Variabilitymentioning

confidence: 99%

Spatial patterns of Organic Matter content in the surface soil of the salt marshes of the Venice Lagoon (Italy)

Puppin,

Tognin,

Ghinassi

et al. 2023

Preprint

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Abstract. Salt marshes are crucial eco-geomorphic features of tidal environments as they provide numerous important ecological functions and deliver a wide range of ecosystem services that contribute to human well-being. Being controlled by the interplay between hydrodynamics, geomorphology and vegetation, the deposition of both organic matter (OM) and inorganic sediments drives salt-marsh vertical accretion. This allows marshes to keep pace with relative sea-level rise, and likewise capture and store carbon, making them valuable allies in climate mitigation strategies. Thus, Soil Organic Matter (SOM), i.e. the organic component of the soil, plays a key role within salt-marsh environments, directly contributing to soil formation and supporting carbon storage. This study aims at inspecting spatial patterns of OM in surface salt-marsh soils, providing further insights into the physical and biological factors driving OM dynamics, affecting salt-marsh survival and carbon sink potential. Our results reveal two scales of variations in sedimentary OM content in salt-marsh soils. At the marsh scale OM variability is influenced by the interplay between surface elevation and changes in sediment supply linked with the distance from tidal channels. At the system scale, OM content distribution is dominated by the gradient generated by marine and fluvial influence. Variations in inorganic and organic inputs, both autochthonous and allochthonous, sediment grain size, and preservation conditions may explain the observed variations in SOM. Our results highlight marsh importance as carbon sink environments, furthermore emphasizing that environmental conditions within a tidal system may generate strongly variable and site-specific carbon accumulation patterns, enhancing blue carbon assessment complexity.

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“…Part of this variation is explained by regional environmental controls such as average annual air temperature (Chmura et al 2003), geomorphic setting (van Ardenne et al 2018), salinity gradients, inundation frequency (van de Baustian et al 2017;Luo et al 2019), rainfall patterns (Sanders et al 2016;Negandhi et al 2019), soil pH, soil moisture, and the dominant plant species and soils (Bai et al 2016;Ford et al 2019). Soil C accumulation rates also vary based on the age of the marsh and tend to be highest in newly expanding marsh edges (Miller et al 2022). Other logistical factors contributing to variability and heterogeneity in salt marsh blue C estimates include the type of corer used (Smeaton et al 2020) and https://doi.org/10.5194/egusphere-2023-2627 Preprint.…”

Section: Introductionmentioning

confidence: 99%

Factors controlling spatiotemporal variability of soil carbon accumulation and stock estimates in a tidal salt marsh

Fettrow,

Wozniak,

Michael

et al. 2023

Preprint

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Abstract. Tidal salt marshes are important contributors to soil carbon (C) stocks despite their relatively small land surface area. Although it is well understood that salt marshes have soil C burial rates orders of magnitude greater than those of terrestrial ecosystems, there is a wide range in storage rates among spatially distributed marshes. In addition, wide ranges in C storage rates also exist within a single marsh ecosystem. Tidal marshes often contain multiple species of cordgrass due to variations in hydrology and soil biogeochemistry caused by microtopography and distance from tidal creeks, creating distinct subsites. Our overarching objective was to observe how soil C concentration changes across four plant phenophases and across three subsites categorized by unique vegetation, hydrology, and biogeochemistry, while also investigating dominant biogeochemical controls on soil C concentration. We hypothesized that subsite biogeochemistry drives spatial heterogeneity in soil C concentration, and this causes variability in soil C concentration at the marsh scale. In addition, we hypothesized that soil C concentration and porewater biogeochemistry vary temporally across the four plant phenophases (i.e., senescence, dormancy, green-up, maturity), causing further variation in marsh soil C that could lead to uncertainty in soil C estimates. To test these hypotheses, we quantified soil C concentrations in 12 cm sections of soil cores (0–48 cm depth) across time (i.e., phenophase) and space (i.e., subsite), alongside several porewater biogeochemical variables including dissolved organic carbon (DOC), EEMs/ UV-VIS, redox potential, pH, salinity, reduced iron (Fe2+), reduced sulfur (S2-), and total porewater element (Fe, Ca) concentrations in three distinct subsites. Soil C concentration varied significantly (p<0.05) among the three subsites and was significantly greater during plant dormancy. Soil S, porewater sulfide, redox potential, and depth predicted 44 % of the variability in soil C concentration. Our results show that soil C varied spatially across a marsh ecosystem up to 63 % and across plant phenophase by 26 %, causing variability in soil C storage rates and stocks depending on where and when samples are taken. This shows that hydrology, biogeochemistry, and ecological function are major controls on saltmarsh C content. It is, therefore, critical to consider spatial and temporal heterogeneity in soil C concentration when conducting blue C assessments to account for soil carbon variability and uncertainty in C stock estimates.

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Carbon accumulation rates are highest at young and expanding salt marsh edges

Cited by 20 publications

References 59 publications

Spatial patterns of organic matter content in the surface soil of the salt marshes of the Venice Lagoon (Italy)

Spatial patterns of organic matter content in the surface soil of the salt marshes of the Venice Lagoon (Italy)

Spatial patterns of Organic Matter content in the surface soil of the salt marshes of the Venice Lagoon (Italy)

Factors controlling spatiotemporal variability of soil carbon accumulation and stock estimates in a tidal salt marsh

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