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 −12 to 41 cm (NAVD88) and supported assorted plant community compositions driven by local environmental conditions. SCAR ranged from 75 to 430 g C·m−2·yr−1, which were comparable in the two youngest and two oldest marshes. Longer‐term CAR ranged from 18 to 99 g C·m−2·yr−1 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.
| Start date | End date |
|---|---|
| 2015-09-18 | 2016-09-01 |
| Rank name | Value |
|---|---|
| Species | Spartina alterniflora |
| Species | Aster tenuifolius |
| Species | Borrichia frutescens |
| Species | Bulboschoenus robustus |
| Species | Distichlis spicata |
| Species | Spartina patens |
| Species | Batis maritima |
| attribute name | definition | format, unit or codes |
|---|---|---|
| study_id | Unique identifier for the study made up of the first author's family name, as well as the second author's or 'et al.' if more than three, then publication year spearated by underscores. See worksCited.bib for more detail. | |
| coring_method | Code indicating what type of device was used to collect soil depth profiles. | polycarbonate tube = polycarbonate tube with a diameter of 6.35 cm and a sharpened bottom edge |
| roots_flag | Code indicating whether live roots were included or excluded from carbon assessments. | roots and rhizomes included = Roots and rhizomes were included in dry bulk density and or organic matter and carbon measurements |
| compaction_flag | Code indicating how the authors qualified or quantified compaction of the core. | corer limits compaction = Authors specified that the coring device's design minimized compaction |
| dry_bulk_density_temperature | Temperature at which samples were dried to measure dry bulk density. This can include either samples that were freeze dried or oven dried. | celsius |
| dry_bulk_density_flag | Any notable codes regarding how the authors quantified dry bulk density. | to constant mass = Bulk density methodology did not specify drying temperature or length, only that samples were dried to a constant mass |
| loss_on_ignition_temperature | Temperature at which samples were combusted to estimate fraction organic matter. | celsius |
| loss_on_ignition_time | Time over which samples were combusted to estimate fraction organic matter. | hour |
| carbon_measured_or_modeled | Code indicating whether fraction carbon was measured or estimated as a function of organic matter. | measured = Fraction carbon was measured as opposed to modeled |
| carbonates_removed | Whether or not carbonates were removed prior to calculating fraction organic carbon. | TRUE = Carbonates were removed before measuring organic carbon. |
| carbonate_removal_method | The method used to remove carbonates prior to measuring fraction carbon. | acid fumigation = Carbonates were removed by fumigating with concentrated acid |
| fraction_carbon_method | Code indicating the method for which fraction carbon was measured or modeled (Note: regression based models are permitted, but the use of the Bemmelen factor [0.58 gOC gOM-1] is discouraged). | EA = Each sample presented was measured using Elemental Analysis |
| fraction_carbon_type | Code indicating whether fraction_carbon refers to organic or total carbon. | organic carbon = Author specified that fraction carbon measurements were of organic carbon |
| attribute name | definition | format, unit or codes |
|---|---|---|
| study_id | Unique identifier for the study made up of the first author's family name, as well as the second author's or 'et al.' if more than three, then publication year spearated by underscores. See worksCited.bib for more detail. | |
| site_id | Site identification code unique to each study. | |
| core_id | Core identification code unique to each site. | |
| core_date | Date of core collection. | YYYY-MM-DD |
| core_latitude | Positional latitude of the core in decimal degree WGS84. | degree |
| core_longitude | Positional longitude of the core in decimal degree WGS84. | degree |
| core_position_method | Code indicating how latitude and longitude were determined. | RTK-GPS = Real-time kinematic global position system (GPS) |
| core_elevation | Surface elevation of the core relative to defined datum. | meter |
| core_elevation_method | Code indicating how elevation was determined | RTK-GPS = Real-time kinematic global position system (GPS) |
| salinity_class | Code based on submitter field observation or measurement indicating average annual salinity (Note: Palustrine and freshwater should only include tidal wetlands, or wetlands that are potentially/formerly tidal but artificially freshened due to artificial tidal restrictions). | saline = 30-50 ppt |
| vegetation_class | Code based on submitter field observations or measurement indicating dominant wetland vegetation type. | emergent = Describes wetlands dominated by persistent emergent vascular plants |
| salinity | Measured salinity at core location | perMille |
| short_term_accretion_rate | Short-term accretion rate established using a 1.0 cm white feldspar clay layer within a .5 square meter quadrat next to the core | centimeterPerYear |
| short_term_organic_matter_accretion_rate | Short-term accretion rate established using a 1.0 cm white feldspar clay layer within a .5 square meter quadrat next to the core | gramsPerSquareMeterPerYear |
| short_term_mineral_accumulation_rate | Short-term accumulation rates derived by calculating the product of percent organic, mineral, or C content and bulk density by the short-term accretion rate | gramsPerSquareMeterPerYear |
| short_term_carbon_accumulation_rate | Short-term accumulation rates derived by calculating the product of percent organic, mineral, or C content and bulk density by the short-term accretion rate | gramsPerSquareMeterPerYear |
| longer_term_accretion_rate | Rate of accretion of sediments and soil organic mattter calculated with depth of dredge horizon | centimeterPerYear |
| longer_term_organic_matter_pool | Density of stored long-term organic matter | gramsPerSquareMeter |
| longer_term_organic_matter_accumulation_rate | Natural marsh longer-term C accumulation rates calculated using the equation after Craft et al. (1991) from accretion rates, bulk density, and organic matter values provided in Smith (2012). | gramsPerSquareMeterPerYear |
| longer_term_mineral_pool | Density of stored long-term mineral matter | gramsPerSquareMeter |
| longer_term_mineral_accumulation_rate | Natural marsh longer-term C accumulation rates calculated using the equation after Craft et al. (1991) from accretion rates, bulk density, and organic matter values provided in Smith (2012). | gramsPerSquareMeterPerYear |
| longer_term_carbon_pool | Density of stored long-term carbon | gramsPerSquareMeter |
| longer_term_carbon_accumulation_rate | Determined by multiplying calculated C densities by respective accretion rates | gramsPerSquareMeterPerYear |
| mean_high_water | Average of all high water heights observed | meter |
| mean_low_water | Average of all low water heights observed | meter |
| fraction_time_flooded | Fraction of time coring location is flooded | dimensionless |
| mean_water_depth | Average depth of water at the coring location | meter |
| attribute name | definition | format, unit or codes |
|---|---|---|
| study_id | Unique identifier for the study made up of the first author's family name, as well as the second author's or 'et al.' if more than three, then publication year spearated by underscores. See worksCited.bib for more detail. | |
| site_id | Site identification code unique to each study. | |
| core_id | Core identification code unique to each site. | |
| depth_min | Minimum depth of a sampling increment. | centimeter |
| depth_max | Maximum depth of a sampling increment. | centimeter |
| sample_id | Sample identification unique to the core. This should be used in the case that there are relevant lab specific sample codes, or in the case that there are multiple replicate samples. | |
| dry_bulk_density | Dry mass per unit volume of a soil sample. This does not include ash free bulk density. | gramsPerCubicCentimeter |
| fraction_organic_matter | Mass of organic matter relative to sample dry mass. Ash free bulk density should not be used here but should be expressed as a loss on ignition fraction. | dimensionless |
| fraction_carbon | Mass of carbon relative to sample dry mass. | dimensionless |
| marker_date | The age of any other dated depth horizon such as an artificial marker, pollen horizon, pollution horizon, etc. | nominalYear |
| marker_type | Code indicating the type of marker. | dredge horizon = Layer of dredge sediment used to estimate depth of marsh above the point of marsh creation |
| fraction_nitrogen | Fraction nitrogen relative to dry weight | dimensionless |
| attribute name | definition | format, unit or codes |
|---|---|---|
| study_id | Unique identifier for the study made up of the first author's family name, as well as the second author's or 'et al.' if more than three, then publication year spearated by underscores. See worksCited.bib for more detail. | |
| site_id | Site identification code unique to each study. | |
| core_id | Core identification code unique to each site. | |
| impact_class | Code indicating any major anthropogenic impacts historically and currently affecting the coring location. | tidally restored = Tidal flow has been restored by removing an artificial obstruction |
| unit name | parent SI unit | unit type | description |
|---|---|---|---|
| gramsPerSquareMeterPerYear | massPerArealMassDensityRate | grams per square meter per year | |
| perMille | amountOfSubstanceConcentration | Equivalent to parts per thousand |
This dataset is listed under a Creative Commons BY 4.0 and can be used with attribution. https://creativecommons.org/licenses/by/4.0/