Static chamber fluxes of carbon dioxide and methane from Phragmites wetlands and supporting data collected across a salinity gradient on Cape Cod, Massachusetts

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Frequently anticipated questions:

What does this data set describe?

Title:
Static chamber fluxes of carbon dioxide and methane from Phragmites wetlands and supporting data collected across a salinity gradient on Cape Cod, Massachusetts
Abstract:
Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted vast areas of coastal wetlands to tidal exchange. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here we present measurements of net ecosystem exchange of carbon dioxide (CO2) and methane, along with ancillary meteorological data, collected from coastal wetlands across Cape Cod to evaluate the effect of hydrological management and salinity on carbon exchange in coastal wetlands.
Supplemental_Information:
For more information, see the following field activity: https://cmgds.marine.usgs.gov/fan_info.php?fan=2020-019-FA
  1. How might this data set be cited?
    Sanders-DeMott, Rebecca, Eagle, Meagan, Kroeger, Kevin, Brooks, T. Wallace, Jennifer A. O'Keefe Suttles, Nick, Sydney, and Mann, Adrian, 20220427, Static chamber fluxes of carbon dioxide and methane from Phragmites wetlands and supporting data collected across a salinity gradient on Cape Cod, Massachusetts: data release DOI:10.5066/P9RRL3T0, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Sanders-DeMott, Rebecca, Eagle, Meagan, Kroeger, Kevin, Wang, Faming, Brooks, T. Wallace, Jennifer A. O'Keefe Suttles, Nick, Sydney, Mann, Adrian, and Tang, Jianwu, 2022, Carbon dioxide and methane fluxes with supporting environmental data from coastal wetlands across Cape Cod, Massachusetts (ver 2.0, June 2022): data release DOI:10.5066/P9RRL3T0, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Sanders-DeMott, R., Eagle, M.J., Kroeger, K.D., Wang, F., Brooks, T.W., O'Keefe Suttles, J.A., Nick, S.K., Mann, A.G., and Tang, J., 2022, Carbon dioxide and methane fluxes with supporting environmental data from coastal wetlands across Cape Cod, Massachusetts (ver 2.0, June 2022): U.S. Geological Survey data release, https://doi.org/10.5066/P9RRL3T0.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.5070
    East_Bounding_Coordinate: -70.0550
    North_Bounding_Coordinate: 41.9380
    South_Bounding_Coordinate: 41.5520
    Description_of_Geographic_Extent: Cape Cod, MA
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/62588267d34e21f82770a1a1?name=phragmites_chamber.jpg (JPEG)
    Browse graphic is a photograph of a chamber sampling platform in a Phragmites wetland at Sage Lot Pond, Waquoit, MA.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 15-Jul-2020
    Ending_Date: 15-Nov-2020
    Currentness_Reference:
    Ground condition. These dates bracket the period of monthly sampling when the measurements were made.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: tabular digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference:
      Geographic Names Information System (GNIS) placenames are included as keywords to give the general location of core collections. The entity contains attributes with specific latitude and longitude of each core collection; several attributes are also included to describe the core collection location (nearest body of water and vegetation type). Refer to the entity and attribute definitions for "site_name", "veg_type", "site_name", "status", and "sampling_location_name" for details.
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (120)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 1.0E-5. Longitudes are given to the nearest 1.0E-5. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    chamber_fluxes.csv
    Comma Separated Value (CSV) file containing data on methane and carbon dioxide fluxes. This dataset has 120 records. (Source: Producer Defined)
    date
    Date the measurement was collected in the format yyyy-mm-dd. (Source: Producer Defined) Numeric value representing the date
    start_datetime
    Date and time that the chamber incubation was started in local standard time (UTC - 05:00) in the format yyyy-mm-dd hh:mm:ss. (Source: Producer Defined) Numeric value representing the date and time.
    end_datetime
    Date and time that the chamber incubation was ended in local standard time (UTC - 05:00) in the format yyyy-mm-dd hh:mm:ss. (Source: Producer Defined) Numeric value representing the date and time.
    site_name
    Site name of sampling location (Source: Producer Defined)
    ValueDefinition
    Sage Lot PondA site located within the Waquoit Bay National Estuarine Research Reserve in Waquoit, MA.
    Herring RiverA site located within the Cape Cod National Seashore in Wellfleet, MA.
    status
    Hydrological management status of the sampling location (Source: Producer Defined)
    ValueDefinition
    UnrestrictedIndicates that the sampling location experiences natural, unrestricted tidal exchange.
    ImpoundedIndicates that at this sampling location water is retained but tidal exchange is limited or excluded by infrastructure such as dikes, roads, or culverts.
    veg_type
    Dominant vegetation at sampling location (Source: Producer Defined)
    ValueDefinition
    Phragmites wetlandSampling location is a wetland dominated by Phragmites australis
    sampling_location_name
    Sampling location name indicating both the hydrological management and salinity status relative to the geographical site as referenced in the related publication (Sanders-DeMott and others, 2022) (Source: Producer Defined)
    ValueDefinition
    Unrestricted-HighSampling location that experiences natural, unrestricted tidal exchange and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    Unrestricted-LowSampling location that experiences natural, unrestricted tidal exchange and is the low salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    Impounded-HighSampling location that experiences tidal exchange that is limited or excluded and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    Impounded-LowSampling location that experiences tidal exchange that is limited or excluded and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    chamber_rep
    Identifier of the chamber replicate at each sampling location (Source: Producer Defined)
    Range of values
    Minimum:1
    Maximum:3
    latitude
    Latitude decimal degrees north, NAD83 (Source: Producer Defined)
    Range of values
    Minimum:41.55772
    Maximum:41.93785
    Units:decimal degrees
    longitude
    Longitude decimal degrees west, NAD83. The negative value indicates a location in the western hemisphere. (Source: Producer Defined)
    Range of values
    Minimum:-70.50438
    Maximum:-70.05468
    Units:decimal degrees
    elevation
    Elevation relative to NAVD88 datum in meters. (Source: Producer Defined)
    Range of values
    Minimum:0.06
    Maximum:0.48
    Units:meters
    chamber_transparency
    Indicator of whether chamber incubation was conducted with transparent chamber to allow light exposure or opaque chamber to block out light. (Source: Producer Defined)
    ValueDefinition
    opaqueChamber incubation conducted with an opaque cover to block out sunlight and assess fluxes in the dark.
    transparentChamber incubation conducted with a transparent chamber to allow sunlight and assess fluxes in the light.
    CH4_flux
    Flux of methane calculated from the slope of CH4 concentration change in nanomoles of CH4 per square meter per second (nmol CH4 m-2 sec-1). Positive values indicate a flux of methane out of the ecosystem into the atmosphere and negative values indicate a flux out of the atmosphere into the ecosystem. (Source: Producer Defined)
    Range of values
    Minimum:0.49
    Maximum:376.59
    Units:nmol CH4 m-2 sec-1
    CH4_flux_ebullition
    Flux of methane calculated in nanomoles of CH4 per square meter per second (nmol CH4 m-2 sec-1) when ebullition was suspected. Calculation is based on the difference between initial and final concentration as applicable when ebullition was suspected due to non-linear changes in CH4 concentration during incubation. Positive values indicate a flux of methane out of the ecosystem into the atmosphere and negative values indicate a flux out of the atmosphere into the ecosystem. (Source: Producer Defined)
    ValueDefinition
    empty cellNo ebullition was observed
    Range of values
    Minimum:72.37
    Maximum:826.99
    Units:nmol CH4 m-2 sec-1
    CO2_flux
    Flux of carbon dioxide calculated from the slope of CO2 concentration change in micromoles of CO2 per square meter per second (umol CO2 m-2 sec-1). Positive values indicate a flux of CO2 out of the ecosystem into the atmosphere and negative values indicate a flux out of the atmosphere into the ecosystem. (Source: Producer Defined)
    Range of values
    Minimum:-23.32
    Maximum:18.95
    Units:umol CO2 m-2 sec-1
    soil_moisture
    Soil volumetric water content (VWC) in percent integrated over the top 5 cm of soil. Measured with handheld Meter Group Inc., TEROS-10 just outside each collar after gas sampling. (Source: Producer Defined)
    Range of values
    Minimum:40.3
    Maximum:91.7
    Units:percent
    phragmites_biomass.csv
    Comma Separated Value (CSV) file containing data on phragmites biomass. This dataset has 40 records. (Source: Producer Defined)
    date
    Date the measurement was collected in the format yyyy-mm-dd. (Source: Producer Defined) Numeric value representing the date
    site_name
    Site of the sampling location (Source: Producer Defined)
    ValueDefinition
    Sage Lot PondA site located within the Waquoit Bay National Estuarine Research Reserve in Waquoit, MA.
    Herring RiverA site located within the Cape Cod National Seashore in Wellfleet, MA.
    status
    Hydrological management status of the sampling location (Source: Producer Defined)
    ValueDefinition
    UnrestrictedIndicates that the sampling location experiences natural, unrestricted tidal exchange.
    ImpoundedIndicates that at this sampling location water is retained but tidal exchange is limited or excluded by infrastructure such as dikes, roads, or culverts
    veg_type
    Dominant vegetation at sampling location (Source: Producer Defined)
    ValueDefinition
    Phragmites WetlandSampling location is dominated by Phragmites australis
    sampling_location_name
    Sampling location name indicating both the hydrological management and salinity status as referenced in the related publication (Sanders-DeMott and others, 2022) (Source: Producer Defined)
    ValueDefinition
    Unrestricted-HighSampling location that experiences natural, unrestricted tidal exchange and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022).
    Unrestricted-LowSampling location that experiences natural, unrestricted tidal exchange and is the low salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022).
    Impounded-HighSampling location that experiences tidal exchange that is limited or excluded and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    Impounded-LowSampling location that experiences tidal exchange that is limited or excluded and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    latitude
    Latitude decimal degrees north, NAD83 of the center point of the survey (Source: Producer Defined)
    Range of values
    Minimum:41.55773
    Maximum:41.93784
    Units:decimal degrees
    longitude
    Longitude decimal degrees west, NAD8 of the center point of the survey. The negative value indicates a location in the western hemisphere. (Source: Producer Defined)
    Range of values
    Minimum:-70.50437
    Maximum:-70.0547
    Units:decimal degrees
    distance
    Horizontal distance in meters of the sampling quadrat from the center point of the sampling location. (Source: Producer Defined)
    Range of values
    Minimum:4
    Maximum:8
    Units:m
    azimuth
    Horizontal angle in degrees from magnetic North of the quadrat from the center point of the sampling location (Source: Producer Defined)
    Range of values
    Minimum:0
    Maximum:288
    Units:degrees
    density
    Density of Phragmites australis culms in measured square meter quadrat, culms per meter squared (culms m-2) (Source: Producer Defined)
    Range of values
    Minimum:12
    Maximum:70
    Units:culms m-2
    height
    Average height of Phragmites australis culms above the sediment surface in centimeters within the measured quadrat (Source: Producer Defined)
    Range of values
    Minimum:150
    Maximum:420
    Units:cm
    diameter
    Average diameter in centimeters (cm) at 50 cm height above the sediment surface of Phragmites australis culms within the measured quadrat (Source: Producer Defined)
    Range of values
    Minimum:0.4
    Maximum:1.2
    Units:cm
    biomass
    Average calculated dry biomass of Phragmites australis within the measured quadrat in kilograms per square meter (kg m-2). (Source: Producer Defined, calculation based on Lu and others, 2016.)
    Range of values
    Minimum:0.1
    Maximum:3.6
    Units:kg m-2
    air_soil_temp.csv
    Comma Separated Value (CSV) file containing data on soil and air temperature. The dataset has 97924 records. (Source: Producer Defined)
    datetime
    Date and time that sensor measurement was logged in local standard time (UTC - 05:00) in the format yyyy-mm-dd hh:mm:ss. (Source: Producer Defined) A numeric value representing date and time.
    site_name
    Site of the sampling location (Source: Producer Defined)
    ValueDefinition
    Sage Lot PondA site located within the Waquoit Bay National Estuarine Research Reserve in Waquoit, MA.
    Herring RiverA site located within the Cape Cod National Seashore in Wellfleet, MA.
    status
    Hydrological management status of the sampling location (Source: Producer Defined)
    ValueDefinition
    UnrestrictedIndicates that the sampling location experiences natural, unrestricted tidal exchange.
    ImpoundedIndicates that at this sampling location water is retained but tidal exchange is limited or excluded by infrastructure such as dikes, roads, or culverts
    veg_type
    Dominant vegetation at sampling location (Source: Producer Defined)
    ValueDefinition
    Phragmites WetlandSampling location is a wetland dominated by Phragmites australis
    sampling_location_name
    Sampling location name indicating both the hydrological management and salinity status as referenced in the related publication (Sanders-DeMott and others, 2022) (Source: Producer Defined)
    ValueDefinition
    Unrestricted-LowSampling location that experiences natural, unrestricted tidal exchange and is the low salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    Unrestricted-HighSampling location that experiences natural, unrestricted tidal exchange and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    Impounded-LowSampling location that experiences tidal exchange that is limited or excluded and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    Impounded-HighSampling location that experiences tidal exchange that is limited or excluded and is the high salinity plot of the site pair as referenced in the related publication (Sanders-DeMott and others, 2022)
    latitude
    Latitude decimal degrees north, NAD83 (Source: Producer Defined)
    Range of values
    Minimum:41.55773
    Maximum:41.93784
    Units:decimal degrees
    longitude
    Longitude decimal degrees west, NAD83. The negative value indicates a location in the western hemisphere. (Source: Producer Defined)
    Range of values
    Minimum:-70.5044
    Maximum:-70.0547
    Units:decimal degrees
    air_temp_1m
    Air temperature recorded at 1 meter height above the sediment surface (Source: Producer Defined)
    ValueDefinition
    empty cellNo Data due to instrument malfunction
    Range of values
    Minimum:-10.5
    Maximum:37.9
    Units:degrees Celsius
    soil_temp
    Soil temperature recorded at 10 cm depth below the sediment surface (Source: Producer Defined)
    ValueDefinition
    empty cellNo Data due to instrument malfunction
    Range of values
    Minimum:0.9
    Maximum:27.3
    Units:degrees Celsius
    sensor
    Sensor manufacturer and model (Source: Producer Defined)
    ValueDefinition
    HOBO U23-003 Temp/TempManufacturer and model of sensor used to record both air and soil temperature
    sensor_sn
    Sensor serial number (Source: Producer Defined) Serial number of sensor used to record both air and soil temperature
    slp_met.csv
    Comma Separated Value (CSV) file containing meteorological data. This dataset has 16276 records. (Source: Producer Defined)
    datetime
    Date and time that sensor measurement was logged in local standard time (UTC - 05:00) in the format yyyy-mm-dd hh:mm:ss. (Source: Producer Defined) A numeric value representing date and time.
    site_name
    Site of the sampling location (Source: Producer Defined)
    ValueDefinition
    Sage Lot PondA site located within the Waquoit Bay National Estuarine Research Reserve in Waquoit, MA.
    status
    Hydrological management status of the sampling location (Source: Producer Defined)
    ValueDefinition
    UnrestrictedIndicates that the sampling location experiences natural, unrestricted tidal exchange.
    veg_type
    Dominant vegetation at sampling location (Source: Producer Defined)
    ValueDefinition
    Phragmites WetlandSampling location is a wetland dominated by Phragmites australis
    latitude
    Latitude decimal degrees north, NAD83 (Source: Producer Defined)
    Range of values
    Minimum:41.55773
    Maximum:41.55773
    Units:decimal degrees
    longitude
    Longitude decimal degrees west, NAD83. The negative value indicates a location in the western hemisphere. (Source: Producer Defined)
    Range of values
    Minimum:-70.50443
    Maximum:-70.50443
    Units:decimal degrees
    air_temp_3m
    Air temperature recorded at 3 meters height above the sediment surface with Onset HOBO Temperature/RH Smart Sensor S-THB-M00x (Source: Producer Defined)
    ValueDefinition
    empty cellNo Data due to instrument malfunction.
    Range of values
    Minimum:-6.706
    Maximum:32.098
    Units:degrees Celsius
    RH
    Relative humidity recorded at 3 meters height above the sediment surface with Onset HOBO Temperature/RH Smart Sensor S-THB-M00x (Source: Producer Defined)
    ValueDefinition
    empty cellNo Data due to instrument malfunction.
    Range of values
    Minimum:27.6
    Maximum:100.0
    Units:percent
    PAR
    Incoming photosynthetically active radiation (PAR) in micromoles photons per meter squared per second (umol photons m-2 sec-1) recorded at 3 meters height above the sediment surface with Onset HOBO Photosynthetically Active Radiation Smart Sensor S-LIA-M003 (Source: Producer Defined)
    ValueDefinition
    empty cellNo Data due to instrument malfunction.
    Range of values
    Minimum:1.2
    Maximum:2178.7
    Units:umol photons m-2 sec-1
  8. What biological taxa does this data set concern?
    Taxonomy:
    Keywords/Taxon:
    Taxonomic_Keyword_Thesaurus: None
    Taxonomic_Keywords: Phragmites australis
    Taxonomic_Classification:
    Taxon_Rank_Name: Kingdom
    Taxon_Rank_Value: Plantae
    Taxonomic_Classification:
    Taxon_Rank_Name: Subkingdom
    Taxon_Rank_Value: Viridiplantae
    Taxonomic_Classification:
    Taxon_Rank_Name: Infrakingdom
    Taxon_Rank_Value: Streptophyta
    Taxonomic_Classification:
    Taxon_Rank_Name: Superdivision
    Taxon_Rank_Value: Embryophyta
    Taxonomic_Classification:
    Taxon_Rank_Name: Division
    Taxon_Rank_Value: Tracheophyta
    Taxonomic_Classification:
    Taxon_Rank_Name: Subdivision
    Taxon_Rank_Value: Spermatophytina
    Taxonomic_Classification:
    Taxon_Rank_Name: Class
    Taxon_Rank_Value: Magnoliopsida
    Taxonomic_Classification:
    Taxon_Rank_Name: Superorder
    Taxon_Rank_Value: Lilianae
    Taxonomic_Classification:
    Taxon_Rank_Name: Order
    Taxon_Rank_Value: Poales
    Taxonomic_Classification:
    Taxon_Rank_Name: Family
    Taxon_Rank_Value: Poaceae
    Taxonomic_Classification:
    Taxon_Rank_Name: Genus
    Taxon_Rank_Value: Phragmites
    Taxonomic_Classification:
    Taxon_Rank_Name: Species
    Taxon_Rank_Value: Phragmites australis
    Applicable_Common_Name: TSN: 41072

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Rebecca Sanders-DeMott
    • Meagan Eagle
    • Kevin Kroeger
    • T. Wallace Brooks
    • Jennifer A. O'Keefe Suttles
    • Sydney Nick
    • Adrian Mann
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Rebecca Sanders-Demott
    U.S. Geological Survey, NORTHEAST REGION
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2255 (voice)
    rsanders-demott@usgs.gov

Why was the data set created?

Measurements of carbon dioxide and methane fluxes from static chambers were collected to assess carbon exchange at four coastal Phragmites wetland sites across a salinity gradient (4 to 25 psu) in impounded and natural, tidally unrestricted Phragmites wetlands at the Herring River in Wellfleet, MA, USA and at Sage Lot Pond in Waquoit, MA from July through November 2020. Environmental and biologic metrics that could inform carbon exchange, including biomass, air and soil temperature, relative humidity, and photosynthetically active radiation were also collected to support data interpretation. This dataset can help evaluate the effect of salinity on carbon dioxide and methane exchange in coastal wetlands. Data were collected to inform predictive models of carbon fluxes across coastal wetlands of varying salinity and to facilitate National Park Service restoration planning and future blue carbon project assessments.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 15-Nov-2020 (process 1 of 7)
    Four sampling locations were established across a salinity gradient for static chamber sampling. Two sampling locations were established at a site with natural, unrestricted tidal exchange at Sage Lot Pond in a high (Unrestricted-High; mean 2020 salinity of ~25) and low (Unrestricted-Low; mean 2020 salinity of ~12) salinity location relative to the site and two were established at the impounded Herring River in a high (Impounded-High; mean 2020 salinity of ~9) and low (Impounded-Low; mean 2020 salinity of ~4) salinity location relative to the site. Each sampling location was equipped with three replicate collars for static chamber measurements and one pair of air/soil temperature sensors. In addition, data from a 3m tall mast at Sage Lot Pond equipped with sensors to measure relative humidity, temperature, and photosynthetically active radiation (PAR) are included.
    To facilitate static chamber CH4 and CO2 flux measurements, round PVC collars (55 cm inner diameter, 24 cm height, 3 replicates per sampling location (n = 4)) were inserted into the sediment surrounding intact vegetation to a depth of at least 10 cm more than four weeks prior to initial sampling. On each sample collection date, we used a modular system of clear, round acrylic chambers to enclose the vegetation and sediment surface for flux measurement. Chamber sections were 55 cm diameter and 0.91 m tall. Depending on the height of the vegetation at the sampling location we used either two (unrestricted sites at Sage Lot Pond) or three (impounded sites at Herring River) stacked chambers for a total chamber height of 1.83 or 2.74 m and empty chamber volume of 0.43 or 0.64 m3. The topmost chamber always had a transparent lid permanently affixed with silicone caulking and a vent tube to allow for pressure equilibration. Two battery-powered fans (10 cm in diameter) were attached to the inside of the chamber to homogenize air and temperature sensors (HOBO TidbiT v2, Onset Computer Corporation) were mounted to the inside of the top and bottom chambers to record chamber air temperature. All samples were collected during mid-day hours between 10:00-14:00 local standard time. Chamber air was considered equilibrated based on visual inspection of the stability of a linear concentration change in the gases of interest, this was typically less than 60 seconds.
    Field data required to calculate fluxes (i.e., chamber head space, chamber deployment time) were recorded on field datasheets and later entered into electronic spreadsheets. Concentrations of CH4 and CO2 during 3-7 minutes incubations were measured and recorded using a portable optical feedback-cavity enhanced absorption spectrometer (LI-7810 CH4/CO2/H2O Trace Gas Analyzer, LI-COR, Inc.) sampling at 1 Hz. Chamber flux incubations were conducted both in the light with transparent chambers to quantify net ecosystem exchange, and in the dark with opaque covering of the chambers to quantify ecosystem respiration in the absence of photosynthesis.
    We used a sliding regression (“rollRegres” package in R, Christoffersen, 2019) to identify the 150-second window during the incubation where a simple linear regression of CH4 or CO2 concentration by time had a maximum R2. We verified that all linear models used to calculate flux had a significant slope (p less than 0.001) and an RMSE ≤ 1 ppm for CO2 and ≤ 10 ppb for CH4. One measurement did not have a slope significantly different than 0, and that flux was therefore set to 0.
    We also assessed each incubation for non-linear changes in CH4 concentration over time as a signal of potential ebullition. When potential ebullition was observed, in addition to applying the sliding regression described above, we estimated CH4 concentration change based on the initial and final concentration of CH4 gas (VCS, 2015).
    The rate of concentration change of CO2 and CH4 (slope or the difference between final and initial when ebullition was suspected) was converted to an area-based flux using the Ideal Gas Law and the volume and footprint of the chamber, along with measured chamber air temperature (pooled across the two temperature sensors). Calculations were executed with the “conc_to_flux” function in the R package “ecoflux” (Shannon, 2018).
    This process step and all subsequent process steps (unless otherwise noted) were performed by the same person, Rebecca Sanders-Demott.
    Christoffersen, B., 2019, rollRegres: Fast Rolling and Expanding Window Linear Regression. R package version 0.1.3. https://CRAN.R-project.org/package=rollRegres
    Shannon, J., 2018, ecoFlux: Functions for ecological flux studies including sap flux and soil/stem C efflux (0.3.1). https://rdrr.io/github/jpshanno/ecoflux/
    Verified Carbon Standard (VCS), 2015, Approved VCS Methodology VM 0033: Methodology for Tidal Wetland and Seagrass Restoration. Version 1.0, 20 November 2015, Sectoral Scope 14. Developed by Verra with Restore America’s Estuaries and Silvestrum. 1–115. https://verra.org/wp-content/uploads/2018/03/VM0033-Tidal-Wetland-and-Seagrass-Restoration-v1.0.pdf Person who carried out this activity:
    Rebecca Sanders-Demott
    U.S. Geological Survey, NORTHEAST REGION
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2255 (voice)
    rsanders-demott@usgs.gov
    Date: 15-Nov-2020 (process 2 of 7)
    Soil volumetric water content (VWC) integrated over the top 5 cm was measured (Meter Group Inc., TEROS-10) just outside each collar after gas sampling. Values were recorded by hand on a field data sheet and later entered into an electronic spreadsheet.
    Date: 15-Sep-2020 (process 3 of 7)
    A survey of live Phragmites culm density, along with mean height and diameter was conducted in early September 2020 prior to senescence. We established five evenly spaced 1 m2 quadrats around both a 4 m and 8 m radius circle centered on the center point of the sampling location between the chambers using a meter tape and a compass (n = 10 per quadrats per site). From the center point of the chambers, we used a compass to determine the direction of 0, 72, 144, 216, and 288 degrees offset from North (azimuth) and then used a meter tape to measure out 4 m or 8 m along each of those compass readings. We placed a flag at the 4 or 8 m mark and then used a 1 square meter pvc square to delineate the border of the quadrat. Within each quadrat we counted live stems, measured the height of culms with a meter tape, and measured the diameter of culms at 50cm height with a calliper. Measurements were recorded on a field data sheet and later entered into an electronic spreadsheet and mean values for height and diameter were calculated for each quadrat. Dry biomass was calculated using both height and diameter according to a Phragmites-specific allometric equation (Lu and others, 2016).
    Lu, M., Caplan, J.S., Barker, J.D., Langley, J.A., Mozdzer, T.J., Drake, B.G., and Megonigal, J.P., 2016, Allometry data and equations for coastal marsh plants: Ecology, 97(12), 3554. https://doi.org/10.1002/ecy
    Date: 15-Sep-2020 (process 4 of 7)
    Latitude and longitude of each chamber and sensor location, along with elevation of chambers was measured with a Trimble Real-Time Kinematic (RTK) GPS. Accuracy was 2-3 cm according to instrument corrections. Data files were exported from the instrument via a .csv file and appended to the data files of calculated fluxes or sensors via R.
    Date: 15-May-2021 (process 5 of 7)
    At each chamber sampling location, the three replicate collars were paired with one soil temperature sensor (10 cm depth) and one air temperature sensor (1 m height) mounted on a PVC well in June 2020. Air and soil temperature were logged every 15 minutes. Raw data files were downloaded in the field monthly. Ultimately all data was uploaded as .hobo files to the Woods Hole Coastal and Marine Science Center (WHCMSC) network server. Raw data files were converted to CSV files in the software: HOBOware (version 3.7.2.1). Each deployment file was uploaded into R-studio. Data was then checked for completeness by creating a proxy timeseries specific to each collected dataset, timestamp values that were not collected were replaced by blank cell values. Data were plotted to check for any irregularities in sensor functioning. All found irregularities were removed from the final dataset. Data from Sage Lot Pond are included from July 1, 2020 through December 31, 2020 and data from Herring River are included from July 1, 2020 through April 22, 2021.
    Date: 10-Mar-2021 (process 6 of 7)
    At Sage Lot Pond, near the Unrestricted-High sampling location we installed an aluminum mast equipped with sensors to measure above canopy air temperature and relative humidity (Onset HOBO Temperature/RH Smart Sensor S-THB-M00x, Bourne, MA, USA enclosed in a radiation shield) and incoming photosynthetically active radiation (PAR; Onset HOBO Photosynthetically Active Radiation Smart Sensor S-LIA-M003, Bourne, MA, USA). The system was set up to log data every 15 minutes. Raw data files were downloaded in the field monthly. Ultimately all data was uploaded as .hobo files to the Woods Hole Coastal and Marine Science Center (WHCMSC) network server. Raw data files were converted to CSV files in the software: HOBOware (version 3.7.2.1). Each deployment file was uploaded into R-studio. Data were then checked for completeness by creating a proxy timeseries specific to each collected dataset, timestamp values that were not collected were replaced by blank cell values. Data was plotted to check for any irregularities in sensor functioning. All found irregularities were removed from the final data set. Data from Sage Lot Pond are included from July 1, 2020 through December 31, 2020.
    Date: 07-Jun-2021 (process 7 of 7)
    Metadata file was updated to reflect a revision to the larger data release, although data tables described here are unchanged in version 2. Cross references for journal publication and related data release were also added, along with minor corrections of typos and census unit of site locations. The related data release (O'Keefe Suttles and others, 2022) provides time series data from well sensors at each of the sites during the time period of the measurements published here.
    O'Keefe Suttles, J.A., Eagle, M.J., Sanders-DeMott, R., Nick, S.K., Brooks, T.W., Mann, A.G., and Kroeger, K.D., 2022, Continuous water level, salinity, and temperature data from coastal wetland monitoring wells, Cape Cod, Massachusetts: U.S. Geological Survey data release, https://doi.org/10.5066/P9T1KOTW.
  3. What similar or related data should the user be aware of?
    Sanders-DeMott, Rebecca, Eagle, Meagan J., Kroeger, Kevin D., Wang, Faming, Brooks, Thomas W., O'Keefe Suttles, Jennifer A., Nick, Sydney K., Mann, Adrian G., and Tang, Jianwu, 2022, Impoundment increases methane emissions in Phragmites-invaded coastal wetlands: Global Change Biology DOI:10.1111/gcb.16217, Wiley, Hoboken, New Jersey.

    Online Links:

    Jennifer A. O'Keefe Suttles, Eagle, Meagan J., Sanders-DeMott, Rebecca, Nick, Sydney K., Brooks, Thomas W., Mann, Adrian G., and Kroeger, Kevin D., 2022, Continuous Water Level, Salinity, and Temperature Data from Coastal Wetland Monitoring Wells, Cape Cod, Massachusetts: data release DOI:10.5066/P9T1KOTW, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Provides continuous data on water level, salinity, and water temperature concurrent with chamber flux measurements presented in this data release.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The LI-7810 CH4/CO2/H2O Trace Gas Analyzer has a precision of 0.60 parts per billion (ppb) at 2 parts per million (ppm) with 1 second averaging for methane (CH4) and of 3.5 ppm at 400 ppm with 1 second averaging for carbon dioxide (CO2). The instrument calibration was checked using laboratory calibration gases prior to field measurements in spring 2020. All calculated slopes used to calculate fluxes were subject to statistical checks as outlined in Process Step 1. Each sampling location was measured in triplicate for gas fluxes and with ten replicates for biomass assessments to reduce uncertainty. Manufacturer's specifications for the dual channel temperature logger (used in this study for continuous measurement of soil and air (-10 cm and 1 m respectively from land surface; Onset, model type HOBO U23 Pro v2) for accuracy is +/- 0.21 degrees Celsius from 0 degrees Celsius to 50 degrees Celsius; the manufacturer's specification for resolution is 0.02 degrees Celsius at 25 degrees Celsius. Accuracy of the photosynthetically active raditation (PAR) sensor +/- 5 micromoles per meter squared per second and resolution of the PAR sensor is 2.5 micromoles per meter squared per second. Relative humidty (RH) sensor was enclosed within a solar radiation shield and deployed on a mast with other meteorological sensors. Typical accuracy of the RH sensor is +/-2.5 percent and resolution is 0.1 percent RH. No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    Latitude and Longitude were measured for each of the chamber gas sampling collars (3 per sampling location) and the paired soil and air temperature sensors (1 per sampling location) by Trimble Real-Time Kinematic (RTK) GPS at the end of the sampling season. Recorded Horizontal Dilution of Precision (HDOP) was 0.600 or less for all measurements. Average horizontal accuracy of this method is +/- 30 centimeters. No formal positional accuracy tests were conducted.
  3. How accurate are the heights or depths?
    Land surface elevations were measured for each of the chamber gas sampling collars (3 per sampling location) and the paired soil and air temperature sensors (1 per sampling location) by Trimble Real-Time Kinematic (RTK) GPS at the end of the sampling season. Recorded Vertical Dilution of Precision (VDOP) was 0.900 or less for all measurements. Average vertical accuracy of this method is +/- 5 centimeters. No formal positional accuracy tests were conducted.
  4. Where are the gaps in the data? What is missing?
    Gaps in the continuous data record for a given parameter may have been the result of one of several sources: sensor not deployed during that time period, vandalism of an instrument by humans or destruction by chewing animals, removal of an instrument for maintenance, corrupt data file due to malfunctioning instrument. Exclusions of data from the continuous record are coded as blank cells.
  5. How consistent are the relationships among the observations, including topology?
    Each logged parameter set was queried for maximum and minimum values to be sure logged data fell within expected ranges for the environmental conditions.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None. Please see 'Distribution Info' for details.
Use_Constraints None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations.
  1. Who distributes the data set? (Distributor 1 of 1)
    ScienceBase
    U.S. Geological Survey
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The dataset contains four CSV files containing the data (chamber_fluxes.csv; phragmites_biomass.csv; air_soil_temp.csv; slp_met.csv), the browse graphic (phragmites_chamber.jpg), and the FGDC CSDGM metadata in XML format.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    The data release includes 4 comma-delimited text file. The user must have software capable of opening the text file and reading the data formats.

Who wrote the metadata?

Dates:
Last modified: 15-Jun-2022
Metadata author:
Rebecca Sanders-Demott
U.S. Geological Survey, NORTHEAST REGION
384 Woods Hole Road
Woods Hole, MA
US

508-457-2255 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS.
Metadata standard:
FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata (FGDC-STD-001.1-1999)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9RRL3T0/metadata_phragmites_chamber.faq.html>
Generated by mp version 2.9.51 on Mon Jun 27 09:45:05 2022