Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from the synthesis to mapped tidal wetlands, applying models fit using empirical data and applied using soil, vegetation and salinity maps, and relying on independently generated soil carbon maps. Soil carbon stocks were far lower on average and varied less spatially and with depth than stocks calculated from available soils maps. Further, variation in carbon density was not well-predicted based on climate, salinity, vegetation, or soil classes. Instead, the assembled dataset showed that carbon density across the conterminous united states (CONUS) was normally distributed, with a predictable range of observations. We identified the simplest strategy, applying mean carbon density (27.0 kgC m<sup>-3</sup>), as the best performing strategy, and conservatively estimated that the top meter of CONUS tidal wetland soil contains 0.72 petagrams C. This strategy could provide standardization in CONUS tidal carbon accounting until such a time as modeling and mapping advancements can quantitatively improve accuracy and precision. This data release includes the soil carbon data currently considered public by the data submittors. Additional detail can be found in the publication. Holmquist JR et al. (2018). Accuracy and Precision of Tidal Wetlands Soil Carbon Mapping in the Conterminous United States. Scientific Reports. DOI:10.1038/s41598-018-26948-7. Funding Sources: NASA Carbon Monitoring System [NNH14AY67I], National Science Foundation [DEB-1655622], Smithsonian Institution, USGS Landcarbon Program.
| Start date | End date |
|---|---|
| 1990 | 2017 |
| Rank name | Value |
|---|---|
| Species | Agrostis spp. |
| Species | Alternanthera philoxeroides |
| Species | Amaranthus cannabinus |
| Species | Ambrosia trifida |
| Species | Arrow arum |
| Species | Athyrium filix-femina |
| Species | Avicennia germinans |
| Species | Baccharis halimifolia |
| Species | Batis maritima |
| Species | Bidens laevis |
| Species | Bolboschoenus maritimus |
| Species | Carex lyngbyei |
| Species | Cornus sericea |
| Species | Cuscuta salina |
| Species | Distichlis spicata |
| Species | Echinochloa spp. |
| Species | Eleocharis palustris |
| Species | Eleocharis spp. |
| Species | Frankenia salina |
| Species | Gaultheria shallon |
| Species | Grindelia stricta |
| Species | Hibiscus spp. |
| Species | Impatiens capensis |
| Species | Iva frutescens |
| Species | Jaumea carnosa |
| Species | Juncus balticus |
| Species | Juncus roemerianus |
| Species | Lonicera involucrata |
| Species | Ludwigia spp. |
| Species | Lysichiton americanus |
| Species | Myrica gale |
| Species | Nuphar advena |
| Species | Nyssa aquatica |
| Species | Oenanthe sarmentosa |
| Species | Panicum hemitomon |
| Species | Paspalum vaginatum |
| Species | Peltandra virginica |
| Species | Phalaris arundinacea |
| Species | Phragmites australis |
| Species | Picea sitchensis |
| Species | Polygonum arifolium |
| Species | Polygonum punctatum |
| Species | Polygonum sagittatum |
| Species | Polygonum spp. |
| Species | Rhizophora mangle |
| Species | Rosa californica |
| Species | Rosa nutkana |
| Species | Rosa pisocarpa |
| Species | Rubus spectabilis |
| Species | Rubus ursinus |
| Species | Sagittaria latifolia |
| Species | Salix lasiolepis |
| Species | Sagittaria lancifolia |
| Species | Salicornia pacifica |
| Species | Salicornia virginica |
| Species | Scirpus acutus |
| Species | Scirpus americanus |
| Species | Schoenoplectus californicus |
| Species | Schoenoplectus tabernaemontani |
| Species | Spartina alterniflora |
| Species | Spartina cynosuroides |
| Species | Spiraea douglasii |
| Species | Spartina foliosa |
| Species | Spartina patens |
| Species | Spartina spp. |
| Species | Taxodium distichum |
| Species | Triglochin maritima |
| Species | Trapa natis |
| Species | Typa angustifolia |
| Species | Typa domingensis |
| Species | Typha latifolia |
| Species | Typha spp. |
| Species | Zizania aquatica |
| Species | Zizaniopsis milaceae |
| 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. | |
| publication_type | Code indicating the type of publication the study originates from. | dissertation = Source was a Ph.D. dissertation. government report = Source was a government report. peer reviewed publication = Source was a peer reviewed publication. private sector report = Source was a private sector report. publically available dataset = Source was a publically available dataset. thesis = Source was a master's thesis. |
| n | Number of cores per study. | number |
| coring_method | Code indicating what type of device was used to collect soil depth profiles. | gouge auger = A half cylinder coring device in which the coring section is open, not sealed off by a fin. hargas corer = A large diameter (>10 cm) coring device consisting of a tube, piston, and a cutting head. mcauley corer = A half cylinder coring device with the coring section sealed off by a fin attached to a rotating pivot point. mccaffrey peat cutter = U-shaped blade that extracts a core by cutting down through peat. none specified = No coring device was specified. other shallow corer = Any other type of coring device typically taking cores shallower than 30 centimeters. piston corer = A device that extrudes core into tube upward with a plunger. push core = Any number of coring types involving driving a tube into the sediment to recover a core. pvc and hammer = PVC pipe was driven into the sediment with a hammer to recover a core. russian corer = A half cylinder coring device with the coring section sealed off by a fin attached to a rotating pivot point. vibracore = A technique involving collecting a core by sinking a continuous pipe into sediment attaching a source of vibration, then recovering using a winch and pulley. |
| roots_flag | Any notable comments on how the authors either included or excluded live roots from carbon assesments. | roots and rhizomes included = Roots and rhizomes were included in dry bulk density and or organic matter and carbon measurements. roots seperated using floation = Roots and rhizomes were separated from soil using floatation before dry bulk density and or organic matter and carbon measurements. |
| compaction_flag | Any notable comments on how the authors qualified or quantified compaction of the core. | < 10-20% = Compaction was less than 10 to 20% of the core depth. corer limits compaction = Authors specified that the coring device's design minimized compaction. no obvious compaction = Authors observed no obvious compaction. |
| dry_bulk_density_temperature | Temperature at which samples were dried to measure dry bulk density. | celsius |
| dry_bulk_density_time | Time over which samples were dried to measure dry bulk density. | hour |
| dry_bulk_density_flag | Any notable comments on how the authors quantified dry bulk density. | air dried to constant mass = Methodology specified that samples were air dried to a constant mass. duplicate measurements = Methodology specified that the reported values are the averages of duplicated measurements. estimated from loss on ignition and particle densities of mineral and organic solids = Bulk density was not measured, but was modeled from loss on ignition and assumptions about the particle densities of organic and inorganic matter. freeze dried = Bulk density was measured on freeze dried samples. no details = No additional details regarding bulk density methodology were provided. removed non structural water = Bulk density methodology did not specify drying temperature or length, only that non-strucural water was removed. time approximate = Bulk density time recorded herin is an approximate estimate. time not specified = Bulk density time was not specified. 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 |
| loss_on_ignition_flag | Any notable comments on how the authors estimated organic matter fraction using loss on ignition. | duplicate measurements = Methodology specified that the reported values are the averages of duplicated measurements. ground and sieved = Methodology specified that the samples were ground and seived before loss on ignition. no details = No additional details regarding loss on ignition methodology were provided. time not specified = No additional details regarding loss on ignition duration were provided. |
| 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. modeled = Fraction carbon was modeled as opposed to measured. |
| carbonates_removed | Whether or not carbonates were removed prior to calculating fraction organic carbon. | FALSE = Carbonates were not removed before measuring organic carbon. TRUE = Carbonates were removed before measuring organic carbon. |
| carbonate_removal_method | The method used to remove carbonates prior to measuring fraction carbon. | 1N H3PO4 = I normal phosphoric acid was used to remove carbonates. direct acid treatment = Carbonates were removed using direct application of dilute acid. HCl fumigation = Carbonates were removed by fumigating with concentrated hydrochloric acid. low carbonate soil = Organic carbon fraction were measured without removing carbonates becasuse assuming carbonate content of the soil type was minimal. none specified = Carbonate removal methodology was not specified. |
| fraction_carbon_flag | Any notable comments on how the authors measured fraction carbon. | extrapolated from subset of samples = A regression model fit using a subset of measurements was used to predict fraction carbon as a funciton of fraction organic matter. fumigated to remove microbeal biomass = Authors report removing microbeal biomass with acid fumigation. no details = No additional detals were provided regarding fraction carbon methodologies. replicate samples = Methodology specified that the reported values are the averages of duplicated measurements. |
| 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. | |
| core_id | Author defined unique identifier assiged to a core. | |
| core_latitude | Positional latitude of the core decimal degrees (World Geodetic System 1988 [WGS1988]). | degree |
| core_longitude | Positional longitude of the core decimal degrees (World Geodetic System 1988 [WGS1988]). | degree |
| position_code | Code assigned to rank the quality of latitude and longitude information extracted from the source. | a = Latitude and longitude were likely from a high quality source. a1 = Latitude and longitude from handheld GPS or better. a2 = Latitude and longitude were likely high quality but may refer to a general area rather than individual core location. b = Latitude and longitude represented coarse and general site coordinates. c = Latitude and longitude were extracted from a map figure. c1 = Latitude and longitude were extracted from a relatively high quality map figure. c2 = Latitude and longitude were extracted from a relatively low quality map figure. |
| core_elevation | Elevation of the coring site relative to North American Vertical Datum 1988 (NAVD88). | meter |
| salinity_code | Code indicating broad salinity of the coring site. | Bra = Brackish (0.5 to 30 parts per thousand salinity). Bra Fre = Brackish to Fresh (< 30 parts per thousand salinity). Bra Sal = Brackis to Saline (> 0.5 parts per thousand salinity). Del = Deltaic (Recieves primariy freshwater input from river discharge). Est = Estuarine (5 to 35 parts per thousand salinity). Fre = Freshwater (< 0.5 parts per thousand salinity). Int = Intermediate salinity (Salinity is somewhere between fully fresh and fully saline). Mes = Mesohaline (5 to 18 parts per thousand salinity). Oli = Oligohaline (0.5 to 5 parts per thousand salinity). Pol = Polyhaline (18 to 30 parts per thousand salinity). Riv = Riverine (Salinity is dominated by freswater river discharge). Sal = Saline (30 to 50 parts per thousand salinity). |
| vegetation_code | Code indicating broad vegetation categories at the coring site. | EM = Dominated by emergent non woody vasular plant biomass. FO = Dominated by forested biomass. FO/SS = Dominated by forested to scrub/shrub biomass. |
| inundation_class | Code based on userent indicating how often the coring location is inundated. | High = Core was collected from the high zone of the tidal frame. Hollow = Core was collected from a low elevation hollow zone. Hummock = Core was collected from a high elevation hummock zone. Levee = Core was collected from a high elevation built up edge of a marsh. Low = Core was collected from the low zone of the tidal frame. Mid = Core was collected from the mid zone of the tidal frame. Plain = Core was collected from a low elevation interior of a marsh. River's Edge = Core was collected from a river's edge. |
| core_length_flag | Indicated whether or not the coring team believes they recovered a full sediment profile, down to bedrock, or other non-marsh interface. | core depth limited by length of corer = The total depth of the core was limited by the length of the coring device. core depth represents deposit depth = Authors report that the depth of the core represents the depth of the wetland soil deposit. not specified = Authors did not specify whether or not the depth of the core represents the depth of the wetland soil deposit. |
| 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. | |
| core_id | Author defined unique identifier assiged to a core. | |
| depth_min | Minimum depth of a sampling increment. | centimeter |
| depth_max | Maximum depth of a sampling increment. | centimeter |
| dry_bulk_density | Dry mass per unit volume of a soil sample. | gramsPerCubicCentimeter |
| fraction_organic_matter | Mass of organic matter relative to sample dry mass. | dimensionless |
| fraction_carbon | Mass of carbon relative to sample dry mass. | dimensionless |
| fraction_carbon_type | Code assigned to specify the type of measurement fraction_carbon represents. | fraction_organic_carbon = Author specified that fraction carbon measurements were of organic carbon. fraction_total_carbon = Author specified that fraction carbon measurements were of total 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. | |
| core_id | Author defined unique identifier assiged to a core. | |
| species_code | Code associated with a species or a vegetation assembelage. | Mix = Mix of multiple species. Swamp = Louisiana freshwater forested wetlands. UnVeg = Unvegetated. AgSp = Agrostis spp. AlPh = Alternanthera philoxeroides. AmCa = Amaranthus cannabinus. AmTr = Ambrosia trifida. ArAr = Arrow arum. AtFi = Athyrium filix-femina. AvGe = Avicennia germinans. BaHa = Baccharis halimifolia. BaMa = Batis maritima. BiLa = Bidens laevis. BoMa = Bolboschoenus maritimus. CaLy = Carex lyngbyei. CoSe = Cornus sericea. CuSa = Cuscuta salina. DiSp = Distichlis spicata. EcSpp = Echinochloa spp. ElPa = Eleocharis palustris. ElSpp = Eleocharis spp. FrSa = Frankenia salina. GaSh = Gaultheria shallon. GrSt = Grindelia stricta. HiSpp = Hibiscus spp. ImCa = Impatiens capensis. IvFr = Iva frutescens. JaCa = Jaumea carnosa. JuBa = Juncus balticus. JuRo = Juncus roemerianus. LoIn = Lonicera involucrata. LuSpp = Ludwigia spp. LyAm = Lysichiton americanus. MyGa = Myrica gale. NuAd = Nuphar advena. NyAq = Nyssa aquatica. OeSa = Oenanthe sarmentosa. PaHe = Panicum hemitomon. PaVa = Paspalum vaginatum. PeVi = Peltandra virginica. PhAr = Phalaris arundinacea. PhAu = Phragmites australis. PiSi = Picea sitchensis. PoAr = Polygonum arifolium. PoPu = Polygonum punctatum. PoSa = Polygonum sagittatum. PoSpp = Polygonum spp. RiMa = Rhizophora mangle. RoCa = Rosa californica. RoNu = Rosa nutkana. RoPi = Rosa pisocarpa. RuSp = Rubus spectabilis. RuUr = Rubus ursinus. SaLa = Sagittaria latifolia. SaLas = Salix lasiolepis. SaLan = Sagittaria lancifolia. SaPa = Salicornia pacifica. SaVi = Salicornia virginica. ScAc = Scirpus acutus. ScAm = Scirpus americanus. ScCa = Schoenoplectus californicus. ScTa = Schoenoplectus tabernaemontani. SpAl = Spartina alterniflora. SpCy = Spartina cynosuroides. SpDo = Spiraea douglasii. SpFo = Spartina foliosa. SpPa = Spartina patens. SpSpp = Spartina spp. TaDi = Taxodium distichum. TrMa = Triglochin maritima. TrNa = Trapa natis. TyAg = Typa angustifolia. TyDo = Typa domingensis. TyLa = Typha latifolia. TySpp = Typha spp. ZiAq = Zizania aquatica. ZiMi = Zizaniopsis milaceae. |
| 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. | |
| core_id | Author defined unique identifier assiged to a core. | |
| impact_code | Code indicating any major anthropogenic impacts historically and currently affecting the coring location. | Can = Canalled. Dik = Diked. Dit = Ditched. Eut = Eutrophic. Imp = Impounded. Man = Managed. Nat = Natural. Res = Restoring. SalImp = Salt impacted. |
| unit name | parent SI unit | unit type | description |
|---|
This dataset is listed under a Creative Commons BY 4.0 and can be used with attribution. https://creativecommons.org/licenses/by/4.0/. Users should take care to credit both this synthesis effort and all primary sources listed herein.