Stability of organic carbon accumulating in Spartina alterniflora-dominated salt marshes of the Mid-Atlantic U.S.

Unger, Viktoria; Elsey‐Quirk, Tracy; Sommerfield, Christopher K.; Velinsky, David J.

doi:10.1016/j.ecss.2016.10.001

Cited by 46 publications

(46 citation statements)

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“…Higher contributions of allochthonous C and greater preservation of plant-derived C likely influenced greater soil C accumulation in fluvial versus marine geomorphic settings (Saintilan et al, 2013;Kelleway et al, 2016). Similarly, along the Atlantic coast of the US, soil C accumulation and accretion rates were greater in marshes of a coastal plain estuary than in marshes of a coastal lagoon (Unger et al, 2016). In these systems, the C accumulation rate was strongly and positively related to the rate of mineral sedimentation.…”

Section: Introductionmentioning

confidence: 98%

“…Another mechanism potentially causing the depletion of δ 13 C signatures relative to local plant tissue is a greater allochthonous C input consisting of organic matter sorbed onto mineral particles, estuarine phytoplankton, microphytobenthos, and nonlocal macrophytes (Middelburg et al, 1997). Though labile soil C may be derived from algal sources, it is also possible that the environmental conditions in mineral-rich marshes stimulate in situ plant productivity and inputs of labile plant C. Mineral sedimentation, for example, tends to be positively related to C accumulation (Chmura et al, 2003;Unger et al, 2016) and also creates favorable conditions for plant growth (DeLaune et al, 1990;Mendelssohn and Kuhn, 2003). Specifically, mineral sediment input can increase marsh elevation, supply a physical substrate for root growth, supply inorganic nutrients, raise the redox potential, and promote the precipitation of sulfide with iron and manganese to form nontoxic compounds (DeLaune et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Geomorphic influences on the contribution of vegetation to soil C accumulation and accretion in <i>Spartina alterniflora</i> marshes

Elsey‐Quirk

Unger

2018

Biogeosciences

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Abstract. Salt marshes are important hotspots of long-term belowground carbon (C) storage, where plant biomass and allochthonous C can be preserved in the soil for thousands of years. However, C accumulation rates, as well as the sources of C, may differ depending on environmental conditions influencing plant productivity, allochthonous C deposition, and C preservation. For this study, we examined the relationship between belowground root growth, turnover, decay, above- and belowground biomass, and previously reported longer-term rates of total, labile, and refractory organic C accumulation and accretion in Spartina alterniflora-dominated marshes across two mid-Atlantic, US estuaries. Tidal range, long-term rates of mineral sedimentation, C accumulation, and accretion were higher and salinities were lower in marshes of the coastal plain estuary (Delaware Bay) than in the coastal lagoon (Barnegat Bay). We expected that the conditions promoting high rates of C accumulation would also promote high plant productivity and greater biomass. We further tested the influence of environmental conditions on belowground growth (roots + rhizomes), decomposition, and biomass of S. alterniflora. The relationship between plant biomass and C accumulation rate differed between estuaries. In the sediment-limited coastal lagoon, rates of total, labile, and refractory organic C accumulation were directly and positively related to above- and belowground biomass. Here, less flooding and a higher mineral sedimentation rate promoted greater above- and belowground biomass and, in turn, higher soil C accumulation and accretion rates. In the coastal plain estuary, the C accumulation rate was related only to aboveground biomass, which was positively related to the rate of labile C accumulation. Soil profiles indicated that live root and rhizome biomass was positively associated with labile C density for most marshes, yet high labile C densities below the live root zone and in marshes with high mineral sedimentation rates and low biomass signify the potential contribution of allochthonous C and the preservation of labile C. Overall, our findings illustrate the importance of sediment supply to marshes both for promoting positive plant-C accumulation-accretion feedbacks in geomorphic settings where mineral sediment is limiting and for promoting allochthonous inputs and preservation of labile C leading to high C accumulation and accretion rates in geomorphic settings where sediment supply is abundant.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Geomorphic influences on the contribution of vegetation to soil C accumulation and accretion in <i>Spartina alterniflora</i> marshes

Elsey‐Quirk

Unger

2018

Biogeosciences

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“…Newly created dredge sediment marshes exhibit Bridgham et al (2006) Table 2. In natural marshes, longer-term CAR is facilitated by mineral sedimentation through the settling and trapping of allochthonous materials (Mudd et al 2004) and physical or biochemical stabilization of the C pool (Six et al 2002, Unger et al 2016). highly variable abiotic conditions while substrates dewater, stabilize, and become colonized by plants, but there is a paucity of information regarding temporal and spatial drivers of blue C accumulation in created marshes.…”

Section: Introductionmentioning

confidence: 99%

“…highly variable abiotic conditions while substrates dewater, stabilize, and become colonized by plants, but there is a paucity of information regarding temporal and spatial drivers of blue C accumulation in created marshes. In natural marshes, longer-term CAR is facilitated by mineral sedimentation through the settling and trapping of allochthonous materials (Mudd et al 2004) and physical or biochemical stabilization of the C pool (Six et al 2002, Unger et al 2016. Vegetation communities with higher stem densities therefore may increase sedimentation rates by reducing flow velocity and increasing sediment trapping, subsequently increasing CAR (Mudd et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Factors influencing blue carbon accumulation across a 32‐year chronosequence of created coastal marshes

2019

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Saline coastal marshes are blue carbon ecosystems with relatively high soil carbon (C) stocks and high rates of soil C accumulation. Loss of saline wetlands due to relative sea-level rise, land-use change, and hydrologic alterations liberates previously stored C and reduces the capacity for future C sequestration. Widespread wetland loss has prompted marsh restoration and creation projects around the world; however, little is known about the timescale and capacity for created marshes to function as blue C sinks and the role of environmental conditions in mediating soil C accumulation in restoration sites. Using a chronosequence of five created saline marshes ranging in age from 5 to 32 yr and two adjacent natural reference marshes in southwest Louisiana, USA, short-and longer-term C accumulation rates (SCAR and LCAR, respectively) were determined using feldspar marker horizons and peat depth in cores at six locations in each marsh. Created marshes ranged in elevation from À12 to 41 cm (NAVD88) and supported assorted plant community compositions driven by local environmental conditions. SCAR ranged from 75 to 430 g CÁm À2 Áyr À1 , which were comparable in the two youngest and two oldest marshes. Longer-term CAR ranged from 18 to 99 g CÁm À2 Áyr À1 but did not significantly differ among marshes of different ages.Our findings indicate that LCAR in these created marshes were influenced by site-specific environmental conditions (i.e., stem density and mineral sediment) rather than marsh age. Results suggest that conditions appropriate for the establishment of vegetation with high stem densities, such as Distichlis spicata and Spartina patens, may facilitate higher LCAR in created marshes, which may be useful for restoration project planning and mitigation of climate change.

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“…Some causes of observed variations of accumulation could be different levels of sediment availability at different sites, productivity, and health of the marshes. The higher rates of carbon sequestration in Delaware Bay may be a result of higher productivity, higher suspended sediment availability, and/or a larger tide range [16]. Primary productivity of marshes is a large contribution to the source of carbon that is stored in marsh sediments, as well as allochthonous sediments from other sources.…”

Section: Spatial Resultsmentioning

confidence: 99%

Carbon Sequestration Rate Estimates in Delaware Bay and Barnegat Bay Tidal Wetlands Using Interpolation Mapping

Champlin

Velinsky

Tucker

et al. 2020

Data

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Quantifying carbon sequestration by tidal wetlands is important for the management of carbon stocks as part of climate change mitigation. This data publication includes a spatial analysis of carbon accumulation rates in Barnegat and Delaware Bay tidal wetlands. One method calculated long-term organic carbon accumulation rates from radioisotope-dated (Cs-137) sediment cores. The second method measured organic carbon density of sediment accumulated above feldspar marker beds. Carbon accumulation rates generated by these two methods were interpolated across emergent wetland areas, using kriging, with uncertainty estimated by leave-one-out cross validation. This spatial analysis revealed greater carbon sequestration within Delaware, compared to Barnegat Bay. Sequestration rates were found to be more variable within Delaware Bay, and rates were greatest in the tidal freshwater area of the upper bay. Dataset: Supplemental Data

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Stability of organic carbon accumulating in Spartina alterniflora-dominated salt marshes of the Mid-Atlantic U.S.

Cited by 46 publications

References 53 publications

Geomorphic influences on the contribution of vegetation to soil C accumulation and accretion in <i>Spartina alterniflora</i> marshes

Geomorphic influences on the contribution of vegetation to soil C accumulation and accretion in <i>Spartina alterniflora</i> marshes

Factors influencing blue carbon accumulation across a 32‐year chronosequence of created coastal marshes

Carbon Sequestration Rate Estimates in Delaware Bay and Barnegat Bay Tidal Wetlands Using Interpolation Mapping

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Stability of organic carbon accumulating in Spartina alterniflora-dominated salt marshes of the Mid-Atlantic U.S.

Cited by 46 publications

References 53 publications

Geomorphic influences on the contribution of vegetation to soil C accumulation and accretion in &lt;i&gt;Spartina alterniflora&lt;/i&gt; marshes

Geomorphic influences on the contribution of vegetation to soil C accumulation and accretion in &lt;i&gt;Spartina alterniflora&lt;/i&gt; marshes

Factors influencing blue carbon accumulation across a 32‐year chronosequence of created coastal marshes

Carbon Sequestration Rate Estimates in Delaware Bay and Barnegat Bay Tidal Wetlands Using Interpolation Mapping

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Geomorphic influences on the contribution of vegetation to soil C accumulation and accretion in <i>Spartina alterniflora</i> marshes

Geomorphic influences on the contribution of vegetation to soil C accumulation and accretion in <i>Spartina alterniflora</i> marshes