Wetland soil formation in the rapidly subsiding Mississippi River Deltaic Plain: Mineral and organic matter relationships

Nyman, John A.; DeLaune, Ronald D.; Patrick, W. H.

doi:10.1016/0272-7714(90)90028-p

Cited by 184 publications

(106 citation statements)

References 18 publications

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“…Some of the difference may have resulted from differences in porosity. As mentioned, soil porosity decreases from these fresh to brackish to saline marshes (Nyman et al 1990), which probably allowed more contact between fresh marsh soil and the atmosphere. But other factors must also have been important, otherwise there would have been a gradient of decreasing Eh from fresh to brackish to saline cores.…”

Section: Discussionmentioning

confidence: 85%

“…The significant interaction between marsh type and watertable depth ruled out the possibility that differences among marsh types were related to different hydrological conditions among them. Soil porosity in these fresh marsh soils (96%) is greater than that in the brackish (9 1%) and saline (88%) marsh soils (Nyman et al 1990) and may partially account for differences in CO2 emission rates. The greater soil porosity in fresh marsh probably allows more contact between soil organic matter and the atmosphere, thus promoting more aerobic respiration than in brackish and saline soils.…”

Section: Discussionmentioning

confidence: 90%

“…C cycling may also be important in wetland stability. Oxidation of organic matter to CO2 may contribute significantly to the erosion of peat (Stewart and Wheatley 1990), and in coastal marshes, the amount of soil organic matter required for marsh soil formation increases as submergence rates increase (Nyman et al 1990). Much of the organic matter required for march soil formation is needed to com-I Formerly the Laboratory for Wetland Soils and Sediments.…”

mentioning

confidence: 99%

“…pensate for the decomposition of soil organic matter and the resulting emission of CO2 and CH, (Nyman et al 1990).…”

mentioning

confidence: 99%

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CO²emission and soil Eh responses to different hydrological conditions in fresh, brackish, and saline marsh soils

Nyman

DeLaune

1991

Limnology & Oceanography

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The effects of various water-table depths during continuous and simulated tidal drainage on CO, emissions and soil Eh were examined in intact fresh, brackish, and saline marsh soil cores. CO, emissions did not differ between continuous and tidal drainage. CO, emissions were greatest in fresh cores and least in brackish cores at all water-table depths tested. Eh was higher in brackish cores and lower in fresh and saline cores at all water-table depths tested. Eh increased with decreasing water-table depth and increased more during continuous drainage than during tidal drainage. These results exclude the possibility that reported differences in field measurements of CO, emission among fresh, brackish, and saline marsh soils relate to different hydrological conditions in the marsh types; they also mdicate that fundamental differences in decomposition processes and soil Eh exist among these marsh types. Although not tested, differences were attributed to the different species of emergent vegetation occupying the different marsh types and which arc the sources of soil organic matter.

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Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 90%

mentioning

confidence: 99%

“…pensate for the decomposition of soil organic matter and the resulting emission of CO2 and CH, (Nyman et al 1990).…”

mentioning

confidence: 99%

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CO²emission and soil Eh responses to different hydrological conditions in fresh, brackish, and saline marsh soils

Nyman

DeLaune

1991

Limnology & Oceanography

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“…Marsh vegetation can trap sediment, reduce erosion, increase OM contributions to below-and above-ground biomass, and add nitrogen and carbon to the system (Goman et al 2008;Morris et al 2002;Pethick 2001;Temmerman et al 2004). Species composition, structure, and density of vegetation will influence sediment deposition and rooting pore spaces (Nyman et al 1990(Nyman et al , 2006. OM accumulation and biomass has been shown to be important components in maintaining marsh elevation (Goodman et al 2007;Reed 2002;Culberson et al 2004;Callaway et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Importance of Biogeomorphic and Spatial Properties in Assessing a Tidal Salt Marsh Vulnerability to Sea-level Rise

Thorne

Elliott‐Fisk

Wylie

et al. 2013

Estuaries and Coasts

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We evaluated the biogeomorphic processes of a large (309 ha) tidal salt marsh and examined factors that influence its ability to keep pace with relative sea-level rise (SLR). Detailed elevation data from 1995 and 2008 were compared with digital elevation models (DEMs) to assess marsh surface elevation change during this time. Overall, 37 % (113 ha) of the marsh increased in elevation at a rate that exceeded SLR, whereas 63 % (196 ha) of the area did not keep pace with SLR. Of the total area, 55 % (169 ha) subsided during the study period, but subsidence varied spatially across the marsh surface. To determine which biogeomorphic and spatial factors contributed to measured elevation change, we collected soil cores and determined percent and origin of organic matter (OM), particle size, bulk density (BD), and distance to nearest bay edge, levee, and channel. We then used Akaike Information Criterion (AICc) model selection to assess those variables most important to determine measured elevation change. Soil stable isotope compositions were evaluated to assess the source of the OM. The samples had limited percent OM by weight (<5.5 %), with mean bulk densities of 0.58 g cm -3 , indicating that the soils had high mineral content with a relatively low proportion of pore space. The most parsimonious model with the highest AICc weight (0.53) included distance from bay's edge (i.e., lower intertidal) and distance from levee (i.e., upper intertidal). Close proximity to sediment source was the greatest factor in determining whether an area increased in elevation, whereas areas near landward levees experienced subsidence. Our study indicated that the ability of a marsh to keep pace with SLR varied across the surface, and assessing changes in elevation over time provides an alternative method to long-term accretion monitoring. SLR models that do not consider spatial variability of biogeomorphic and accretion processes may not correctly forecast marsh drowning rates, which may be especially true in modified and urbanized estuaries. In light of SLR, improving our understanding of elevation change in these dynamic marsh systems will play a crucial role in forecasting potential impacts to their sustainability and the survival of these ecosystems.

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Salinity pulses interact with seasonal dry‐down to increase ecosystem carbon loss in marshes of the Florida Everglades

Wilson

Servais

Mazzei

et al. 2018

Ecological Applications

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Coastal wetlands are globally important sinks of organic carbon (C). However, to what extent wetland C cycling will be affected by accelerated sea‐level rise (SLR) and saltwater intrusion is unknown, especially in coastal peat marshes where water flow is highly managed. Our objective was to determine how the ecosystem C balance in coastal peat marshes is influenced by elevated salinity. For two years, we made monthly in situ manipulations of elevated salinity in freshwater (FW) and brackish water (BW) sites within Everglades National Park, Florida, USA. Salinity pulses interacted with marsh‐specific variability in seasonal hydroperiods whereby effects of elevated pulsed salinity on gross ecosystem productivity (GEP), ecosystem respiration (ER), and net ecosystem productivity (NEP) were dependent on marsh inundation level. We found little effect of elevated salinity on C cycling when both marsh sites were inundated, but when water levels receded below the soil surface, the BW marsh shifted from a C sink to a C source. During these exposed periods, we observed an approximately threefold increase in CO2 efflux from the marsh as a result of elevated salinity. Initially, elevated salinity pulses did not affect Cladium jamaicense biomass, but aboveground biomass began to be significantly decreased in the saltwater amended plots after two years of exposure at the BW site. We found a 65% (FW) and 72% (BW) reduction in live root biomass in the soil after two years of exposure to elevated salinity pulses. Regardless of salinity treatment, the FW site was C neutral while the BW site was a strong C source (−334 to −454 g C·m−2·yr−1), particularly during dry‐down events. A loss of live roots coupled with annual net CO2 losses as marshes transition from FW to BW likely contributes to the collapse of peat soils observed in the coastal Everglades. As SLR increases the rate of saltwater intrusion into coastal wetlands globally, understanding how water management influences C gains and losses from these systems is crucial. Under current Everglades’ water management, drought lengthens marsh dry‐down periods, which, coupled with saltwater intrusion, accelerates CO2 loss from the marsh.

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Wetland soil formation in the rapidly subsiding Mississippi River Deltaic Plain: Mineral and organic matter relationships

Cited by 184 publications

References 18 publications

CO²emission and soil Eh responses to different hydrological conditions in fresh, brackish, and saline marsh soils

CO²emission and soil Eh responses to different hydrological conditions in fresh, brackish, and saline marsh soils

Importance of Biogeomorphic and Spatial Properties in Assessing a Tidal Salt Marsh Vulnerability to Sea-level Rise

Salinity pulses interact with seasonal dry‐down to increase ecosystem carbon loss in marshes of the Florida Everglades

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Wetland soil formation in the rapidly subsiding Mississippi River Deltaic Plain: Mineral and organic matter relationships

Cited by 184 publications

References 18 publications

CO2emission and soil Eh responses to different hydrological conditions in fresh, brackish, and saline marsh soils

CO2emission and soil Eh responses to different hydrological conditions in fresh, brackish, and saline marsh soils

Importance of Biogeomorphic and Spatial Properties in Assessing a Tidal Salt Marsh Vulnerability to Sea-level Rise

Salinity pulses interact with seasonal dry‐down to increase ecosystem carbon loss in marshes of the Florida Everglades

Contact Info

Product

Resources

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CO²emission and soil Eh responses to different hydrological conditions in fresh, brackish, and saline marsh soils

CO²emission and soil Eh responses to different hydrological conditions in fresh, brackish, and saline marsh soils