DOI: 10.5061/dryad.ghx3ffbvz
title: Data for: Development of a learning community focused on sea-level rise and coastal habitat change

description: Rapid habitat changes are occuring in salt marshes located in the
 Northeastern United States, including expansion of ponded areas on the
 marsh platform, die off of coastal forests, and subsequent colonization of
 'ghost forests' by marsh vegetation. This work focuses on two
 main areas: (1) environmental conditions along the marsh forest border
 undergoing rapid transitions; and (2) environmental conditions and plant
 stress on marsh platforms with extensive and expanding ponding. 
 To better understand drivers of environmental change in marsh-forest
 borders undergoing rapid transitions, we measured shallow groundwater
 levels,  soil salinity, and forest health and structure along the
 salt marsh-upland border at three sites (in NJ, NY, MA) with varying
 slopes using installation of shallow groundwater wells, drone imagery and
 associated image processing, and geophysical methods. To better understand
 drivers of environmental change on the marsh platform, we again focused on
 three sites (in NJ, NY, MA) where we used piezometers to understand
 vertical gradients in marsh groundwater levels, and measured
 photosynthesis and plant biomass and used drone imagery to map plant
 stress indices. While we anticipate that this data will be published in
 journal articles of the next 2 years, we archive collected data to
 facilitate data sharing, as required by NSF.
description: We collected biological and environmental data to provide
 perspective on rapid habitat change occurring at the salt marsh-forest
 ecotone and on salt marsh platforms converting to open water in the
 Northeastern United States, and to test hypotheses about drivers of
 habitat change. <strong>Marsh-Forest
 Ecotone</strong> In studying the
 marsh forest border, we chose to work at three locations where the
 marsh-forest ecotone is undergoing rapid habitat transitions: the Tuckahoe
 Wildlife Management Area, Egg Harbor Township, NJ (39° 19.506'N;  74°
 39.014'W), Pine Neck Preserve, Quogue, NY (40° 50.440'N;  72°
 33.785'W), and around Sage Lot Pond, Waquoit Bay National Estuarine
 Research Reserve, Mashpee, MA (41° 33.438'N; 70° 30.227'W). We
 hypothesized that we would see steeper environmental gradients in New
 England than along the coastal plain. In addition, we hoped that these
 data sets would provide perspective on salt water intrusion vs. root zone
 flooding as important drivers of maritime forest dieback.
 <em>Drone</em> <em>Imagery </em>- UAV
 surveys were conducted at the three focus sites during leaf-on and
 leaf-off conditions using a DJI Phantom 4 Pro (DJI, Shenzhen, CHN) flown
 at X m altitude at 3.5 m s<sup>−1</sup> to record images with
 80% overlap and a resolution of 3 cm pixel<sup>−1</sup>. At
 the Tuckahoe Wildlife Management Area, these occurred on 12 September 2022
 and  30 January 2023.  At Pine Neck Preserve, these occurred on 3 April
 2021 and  10 August 2022. At  Sage Lot Pond, these occurred on   27 March
 2021 and 11 August 2021. Orthomosaics (5 cm px<sup>−1</sup>)
 were produced from UAV images following a standard photogrammetry workflow
 in Metashape (Agisoft, St. Petersburg, Russia).
 <em>Salinity - </em>We used a Geonics Model EM38-MK2
 Conductivity Meter (Geonics Ltd, Mississauga, Ontario, Canada) in
 horizontal mode, held 0.75 m over the marsh surface to record soil
 conductivity readings.  The readings were the result of an induced current
 generated by the instrument, and measures were made using the 1m setting
 to record measures 0.75 m, ie., at the soil surface
 (https://geonics.com/pdfs/downloads/catalogue.pdf). At each location
 occupied, the apparent electrical conductivity readings
 (EC<sub>a </sub>values) were recorded, in milliSeimans
 meter<sup>−1</sup> (mS m<sup>−1</sup>), and the
 location of the measured point was recorded using a Garmin 64sx handheld
 GPS (accuracy of ca. 3m). We occupied 175-200 points at each of the three
 sites, with grid spacings on the order 10-20m. Measures were made at
 Waquoit Bay, MA on 7 June 2021, at Pine Neck Preserve on 19 May 2021, and
 at Tuckahoe Wildlife Mangement area on 21 July 2021. At each site, we also
 collected ca. 15-20 soil samples  for salinity calibration, to convert
 apparent electrical conductivity readings
 (EC<sub>a </sub>values) to soil salinity. Surface soil
 salinity was measured  on 5:1 slurries made of 5 parts water to one part
 dry sediment using a YSI pro30 conductivity and salinity meter. Soil
 salinity was not back corrected to the original water contact, as the
 average water:dry soil ratio was 5.13. EC<sub>a</sub> data
 were converted to soil salinity values using empirical calibration curves
 constructed from a least-squares regression of EC<sub>a</sub>
 values against soil salinities, forced through the origin. Regressions
 were <em>y</em>=0.0915<em>x</em> for Waquoit Bay
 (<em>r<sup>2</sup></em>=0.78),
 <em>y</em>=0.1765x for Pine Neck Preserve
 (<em>r<sup>2</sup></em>=0.90), and
 <em>y</em>=0.08<em>x</em> for Tuckahoe
 (<em>r<sup>2</sup></em>=0.80),  where
 <em>y</em> is soil salinity, and <em>x</em> is
 EC<sub>a</sub>. Following field sampling and laboratory
 analyses, shapefiles were created in ArcGIS version 10.3 (ESRI, Redlands,
 CA) by creating a text file which included latitude, longitude, and
 estimated soil salinity. We used the kriging function in ArcGIS Spatial
 Analyst using a 1-m pixel size using default values of ordinary kriging
 using a spherical variogram model and a search radius setting of 12 to
 create marsh-specific salinity contour maps.
 <em>Water levels</em> - At each of three sites, we
 installed 10 wells (screened at 0.5 - 1.0 meters of depth) across the
 marsh-forest ecotone for a total of 30 wells. The wells at each site were
 arranged in two transects, with the well at the lower-most elevation sunk
 into the marsh, the well at the highest elevation in intact forest, and
 the other three wells tranversing the marsh-forest ecotone. The wells were
 constructed of SDR 21 PVC pipe of a nominal diameter of 3.175 cm
 (1.25"), within inner diameter of 3.82 cm  and an outer diameter of
 4.22 cm.  To allow for water exchange, holes were drilled in PVC, PVC
 chips were removed with a file, and the outside of the piezometer was
 covered in well sock. An soil auger was used to bore a hole for the
 piezometer, which was subsequently filled with coarse sand following the
 insertion of the piezometer. Above the screened depth, the augered hole
 was backfilled with marsh peat, and near the surface  cement were used to
 seal the piezometer and to prevent the area around the well from acting as
 a macropore or or preferential flow pathway.
 <strong>Marsh
 Platform</strong> In studying the
 marsh platform, we chose to work at three locations where the marsh
 platform has large and expanded ponded areas and is undergoing rapid
 habitat transitions: the Tuckahoe Wildlife Management Area, Corbin City,
 NJ (39° 17.440'N; 74° 39.378'W), Bass Creek, Mashomack Preserve,
 Shelter Island, NY (41° 2.925'N;  72° 17.245'W), and  Sage Lot
 Pond, Waquoit Bay National Estuarine Research Reserve, Mashpee, MA (41°
 33.222'N; 70° 30.692'W). We hypothesized that locations that
 were similar in elevation but that had different groundwater hydrologic
 regimes would display contrasts in vegetation stress and biomass. To
 address these hypotheses, we established well nests at four locations in
 three marshes (a total number of 12 well nests and 24 individual wells),
 where we monitored vertical hydrologic gradients for one year, measured
 photosynthesis and greenhouse gas exchange during two summer growing
 seasons, collected aboveground biomass, and collected multispectral drone
 imagery during peak biomass (e.g., July or August).
 <em>Water levels</em> - At each of 12 locations, we
 installed two piezometers to better understand vertical water movements in
 healthier vs. ponded areas of the salt marsh platform. The piezometers
 were constructed of SDR 21 PVC pipe of a nominal diameter of 3.175 cm
 (1.25"), within inner diameter of 3.82 cm  and an outer diameter of
 4.22 cm. The two piezometers were screened at depths of 0.25-0.50 cm and
 1.0-1.25m below the soil surface. To allow for water exchange, holes were
 drilled in PVC, PVC chips were removed with a file, and the outside of the
 piezometer was covered in well sock. An soil auger was used to bore a hole
 for the piezometer, which was subsequently filled with coarse sand
 following the insertion of the piezometer. Above the screened depth, the
 augered hole was backfilled with marsh peat, and near the surface
 bentonite and cement were used to seal the piezometer and to prevent the
 area around the well from acting as a macropore or or preferential flow
 pathway. <em>Drone</em>
 <em>Imagery </em>- UAV surveys were conducted at the three
 focus sites during leaf-on conditions using a DJI Phantom 4 Pro (DJI,
 Shenzhen, CHN) flown at X m altitude at 3.5 m s<sup>−1</sup>
 to record images with 80% overlap and a resolution of 3 cm
 pixel<sup>−1</sup>. At the Tuckahoe Wildlife Management Area,
 these occurred on 2 September 2022.  At Mashomack Preserve, this occurred
 on 10 August 2022. At Waquoit Bay, this occurred on 21 July 2022.
 Orthomosaics (2 cm px<sup>−1</sup>) were produced from UAV
 images following a standard photogrammetry workflow in Metashape (Agisoft,
 St. Petersburg, Russia). <em>Greenhouse gas
 exchange </em>- Photosynthesis, community respiration, net ecosystem
 exchange, and methane emissions were measured once in the summers for 2021
 and 2022 to provide perspectives on plant stress. An LGR ultraportable
 greenhouse gas analyzer (ABB, San José, CA) was used to measure the
 greenhouse gas concentration of gases circulated through the headspace of
 a 20L chamber attached to 30-cm diameter)(12") PVC collars installed
 in the marsh soil. We conducted twelve at each marsh in each year, three 
 in the proximity (&lt;3m) each well nest. Measurements of net
 ecosystem exchange were collected during three minute incubations in a
 transparent chamber, and respiration was determined by similar incubations
 with the chamber covered with black-out material.  Photosynthesis was
 calculated as the sum of respiration and net ecosystem. The Ideal Gas Law
 (<em>PV</em> = <em>nRT</em>) was used to convert
 linear changes in CO<sub>2</sub> and
 CH<sub>4</sub> concentrations within the chamber during each
 incubation period to fluxes standardized to the surface area of the plant
 pots.  Measures were made at Tuckahoe Wildlife Management Area on 17
 August 2021 and 8 July 2022, at Bass Creek on 13 August 2021 and 29 June
 2022, and at Sage Lot Pond on 11 August 2021 and 20 July 2022.
 <em>Leaf-based photosynthesis measures - </em>At the
 same locations were greenhouse gas exchange measures were conducted, in
 2021, we used a CI-340 handheld photosynthesis system (CID Bioscience,
 Camas, WA, USA) to measure leaf-based photosynthetic uptake and ambient
 fluorescence using the CI-510CF chlorophyll fluorescence module. Measures
 were recorded for three minute incubations. Measures were made at Tuckahoe
 Wildlife Management Area on 17 August 2021, at Bass Creek on 13 August
 2021, and at Sage Lot Pond on 11 August 2021.
 <em>Biomass - </em>At each location where greenhouse
 gas exchange measures were made, all aboveground biomass in the footprint
 of the (30-cm diameter)(12") PVC collars was harvested. After
 returning from the field, biomass material was rinsed over a 2-mm sieve to
 remove sediment and salt, placed in a pre-dried brown paper bag and dried
 in a drying oven at 60°C to constant weight.
description: # Data for: Development of a learning community focused on sea-level rise
 and coastal habitat change
 [https://doi.org/10.5061/dryad.ghx3ffbvz](https://doi.org/10.5061/dryad.ghx3ffbvz) We have presented data for two areas: (1) the marsh-forest ecotone; (2) the marsh platform. ## Description of the data and file structure *Marsh-forest Ecotone* The follow datafiles are available for this study: 1\. water levels ecotone \_water_levels_metadata.csv ecotone_water_levels_waquoit.csv ecotone_water_levels_pine_neck.csv ecotone_water_levels_tuckahoe.csv ecotone \_water_levels_metadata.csv - This file has locations and metadata for the well data from 30 wells positioned along the marsh-upland ecotone. The fields include Well ID, location, latitude, longitude, installation_day, installation_month, installation_year, inner_diameter, outer_diameter, well_top_elevation, top_of_well_to_soil, soil_elevation, start_day, start_month, start_year, end_day, end_month, and end_year. The field Well ID has names of wells, where P stands for Pine Neck, T stands for Tuckahoe, and WB for Waquoit Bay, the numbers 1-5 reflect wells where the lowest elevation wells are denoted with a 1 and the highest elevation wells are a 5, and E and W are the east and west transects. The field for location has three values: Waquoit, Pine_Neck, or Tuckahoe. The latitude is in decimal degrees N, and longitude is in decimal degree west (negative). Installation_day,  installation_month, and installation_year are the day, month, and year that the wells were installed and instrumented. The fields inner_diamter, and outer_diameter are the inner and outer diameter of the wells, in meters. The field well_top_elevation is the elevation of the top of the well in meters relative to the NAVD88 datum.  The field top_of_well_to_soil is the distance from the top of the well to the soil in meters. The field  soil_elevation is the elevation of the soil surface in meters relative to the NAVD88 datum.   The fields start_day, start_month, and start_year are the beginning of the record, while end_day, end_month, and end_year are end of the water level record. Missing data is filled with -999. ecotone_water_levels_waquoit.csv - This file has water level data collected at the marsh-upland ecotone at Waquoit Bay, MA. The file has the following fields: date, time,WB1E, WB2E, WB3E, WB4E, WB5E, WB1W, WB2W, WB3W, WB4W, WB5W, and WB_creek. The date is the date the water level data was collected in MM/DD/YY format. Time is time in HH:MM:SS, GMT -4:00:00. The remainder of the 11 fields are water level observations for 10 groundwater wells (WB1E, WB2E, WB3E, WB4E, WB5E, WB1W, WB2W, WB3W, WB4W, WB5W), and in the tidal creek (WB_creek), in meters relative to the NAVD88 datum. Missing data is filled with -999. ecotone_water_levels_pine_neck.csv - This file has water level data collected at the marsh-upland ecotone at Pine Neck Preserve, NY. The file has the following fields: date, time, P1E, P2E, P3E, P4E, P5E, P1W, P2W, P3W, P4W, P5W, and PN_creek. The date is the date the water level data was collected in MM/DD/YY format. Time is time in HH:MM:SS, GMT -4:00:00. The remainder of the 11 fields are water level observations for 10 groundwater wells (P1E, P2E, P3E, P4E, P5E, P1W, P2W, P3W, P4W, P5W), and in the tidal creek (PN_creek), in meters relative to the NAVD88 datum. Missing data is filled with -999. ecotone_water_levels_tuckahoe.csv - This file has water level data collected at the marsh-upland ecotone at Tuckahoe, NJ. The file has the following fields: date, time, T1E, T2E, T3E, T4E, T5E, T1W, T2W, T3W, T4W, and T5W. The date is the date the water level data was collected in MM/DD/YY format. Time is time in HH:MM:SS, GMT -4:00:00. The remainder of the 10 fields are water level observations for 10 groundwater wells (T1E, T2E, T3E, T4E, T5E, T1W, T2W, T3W, T4W, and T5W) in meters relative to the NAVD88 datum. Missing data is filled with -999. 2\. Salinity data  salinity_data.csv pine_inter.tif pine_inter.tfw tuck_inter.tif tuck_inter.tfw waq_east.tif waq.east.tfw waq_west.tif waq_west.tfw Waquoit_Points Tuck_Points Pine_Neck_Points salinity_data.csv - This file refers to soil conductivity measured using the Geonics Model EM38-MK2 Conductivity Meter in horizontal mode collected 0.75 m above the marsh surface. This file has X fields: location, point, conductivity, latitude, longitude, measured soil salinity (salinity_m), and calculated soil salinity (salinity_c).  The location field lists one three locations: Pine_Neck, Tuckahoe, and Waquoit. Point is an arbitrary field code, and may range from 0 to 200 at each location. Apparent conductivity (ECa) is reported in milliSeimans meter−1 (mS m−1), measured with the Geonics EM38-MK2. Latitude is in decimal degrees N, and longitude is in decimal degree west (negative). Measured salinity (salinity_m), is the soil salinity measured on a 5:1 moisture to dry soil ratio. Calculated soil salinity (salinity_c) was calculated using the regression of apparent conductivity against measured soil salinity using simple linear regression, calculated empirically for each site. The regression equation for Pine Neck was *y*=m*x*+b: the regression equation for Waquoit Bay was *y*=m*x*+b; the regression location for Tuckahoe was* y*=m*x*+b; where *y *is calculated salinity (salinity_c), and *x *is apparent conductivity (ECa). Missing data is filled with -999. pine_inter.tif - interpolated soil salinity map for Pine Neck Preserve, geotiff file, resolution 1m x 1m, NAD_1983_UTM_Zone18N pine_inter.tfw - world file for pine_inter.tif tuck_inter.tif - interpolated soil salinity map for Tuckahoe Wildlife Management Area, geotiff file, resolution 1m x 1m, NAD_1983_UTM_Zone18N tuck_inter.tfw - world file for tuck_inter.tif waq_east.tif - interpolated soil salinity map for Waquoit Bay, geotiff file, resolution 1m x 1m, NAD_1983_UTM_Zone18N waq.east.tfw - world file for waq_east.tif waq_west.tif - interpolated soil salinity map for Waquoit Bay, geotiff file, resolution 1m x 1m, NAD_1983_UTM_Zone18N waq_west.tfw - world file for waq_west.tif Waquoit_Points - compressed shapefile of points  with seven fields for Waquoit Bay survey location: FID, Shape, lcn, Lat, Long, conductivi, and salinity. FID is an identification number. Shape, which is "point." lcn  is the point code. Lat is the latitude in decimal degrees. Lon is the longitude in decimal degrees.  conductiviti is apparent conductivity (ECa) in milliSeimans meter−1 (mS m−1), and salinity which is soil salinity on a 5:1 water to dry soil ratio. Tuck_Points - compressed shapefile of points  with seven fields for Tuckahoe Wildlife Management Area survey location: FID, Shape, lcn, Lat, Long, conductivi, and salinity. FID is an identification number. Shape, which is "point." lcn  is the point code. Lat is the latitude in decimal degrees. Lon is the longitude in decimal degrees.  conductiviti is apparent conductivity (ECa) in milliSeimans meter−1 (mS m−1), and salinity which is soil salinity on a 5:1 water to dry soil ratio. Pine_Neck_Points - compressed shapefile of points  with seven fields for Pine Neck Preserve survey location: FID, Shape, lcn, Lat, Long, conductivi, and salinity. FID is an identification number. Shape, which is "point." lcn  is the point code. Lat is the latitude in decimal degrees. Lon is the longitude in decimal degrees.  conductiviti is apparent conductivity (ECa) in milliSeimans meter−1 (mS m−1), and salinity which is soil salinity on a 5:1 water to dry soil ratio. *Marsh platform* The following files are available: 1\. water levels platform_water_levels_waquoit.csv platform_water_levels_tuck.csv platform_water_levels_mashomack.csv platform \_water_levels_metadata.csv platform \_water_levels_metadata.csv - This file has locations and metadata for the well nests positioned in healthy and fragmenting locations on the marsh platform from 12 well nests. The fields include location, latitude, longitude, plot, condition, well_depth, inner_diameter, outer_diameter, well_top_elevation, top_of_well_to_soil, soil_elevation, installation_day, installation_month, installation_year, screen_top, screen_bottom,  start_day, start_month, start_year, end_day, end_month, and end_year. The field for location has three values: Waquoit, Pine_Neck, or Tuckahoe. The latitude is in decimal degrees N, and longitude is in decimal degree west (negative). Plot has two values: 1 or 2, which refers to location 1 or 2 in each marsh. Each marsh has two locations of well nests (1 or 2), which are widely separated but there is no significant difference between them. The condition field has two potential values - A and B. A refers to good condition, B refers to marsh that is fragmented and surrounded by open water areas. The field well_depth refers to the depth of the well below the soil surface in m (0.5 m or 1.25 m). The fields inner_diameter, and outer_diameter are the inner and outer diameter of the wells, in meters. The field well_top_elevation is the elevation of the top of the well in meters relative to the NAVD88 datum.  The field top_of_well_to_soil is the distance from the top of the well to the soil in meters. The field  soil_elevation is the elevation of the soil surface in meters relative to the NAVD88 datum.    Installation_day,  installation_month, and installation_year are the day, month, and year that the wells were installed and instrumented. The fields screen_top and screen_bottom are the depth of the screened interval below the soil surface, in meters. The fields start_day, start_month, and start_year are the beginning of the record, while end_day, end_month, and end_year are end of the water level record. Missing data is filled with -999. platform_water_levels_waquoit.csv has 10 fields: Date, Time, WB_1A_S, WB_1A_D, WB_1B_S, WB_1B_D, WB_2A_S, WB_2A_D, WB_2B_S, and WB_2B_D.  The date is in the format of MM/DD/YY. The time is in the format of HH:MM:SS. The remainder of the data (WB_1A_S, WB_1A_D, WB_1B_S, WB_1B_D, WB_2A_S, WB_2A_D, WB_2B_S, and WB_2B_D) are water levels in the piezometers in meters relative to the NAVD88 datum. The fields letters are the initials WB, which refers to Waquoit Bay. The second value in the label refers to location 1 or 2 (the location can be found in the metadata file). The third value in the label refers to healthy (A) or unhealthy marsh (B). The last value in the label (S or D) refers to the screening depth of the shallow piezometer, with those screened  at 0-0.5 m of depth is shallow, or S, while those screened at a depth of 1.25-1.5 m of depth is deeper, or D. Missing data is filled with -999. platform_water_levels_tuck.csv has 10 fields: Date, Time, TU_1A_S, TU_1A_D, TU_1B_S, TU_1B_D, TU_2A_S, TU_2A_D, TU_2B_S, and TU_2B_D.  The date is in the format of MM/DD/YY. The time is in the format of HH:MM:SS. The remainder of the data (TU_1A_S, TU_1A_D, TU_1B_S, TU_1B_D, TU_2A_S, TU_2A_D, TU_2B_S, and TU_2B_D) are water levels in the piezometers in meters relative to the NAVD88 datum. The fields letters are the initials TU, which refers to Tuckahoe. The second value in the label refers to location 1 or 2 (the location can be found in the metadata file). The third value in the label refers to healthy (A) or unhealthy marsh (B). The last value in the label (S or D) refers to the screening depth of the shallow piezometer, with those screened  at 0-0.5 m of depth is shallow, or S, while those screened at a depth of 1.25-1.5 m of depth is deeper, or D. Missing data is filled with -999.  platform_water_levels\_ mashomack.csv has 10 fields: Date, Time, MASH_1A_S, MASH \_1A_D, MASH \_1B_S, MASH \_1B_D, MASH \_2A_S, MASH \_2A_D, MASH \_2B_S, and MASH \_2B_D.  The date is in the format of MM/DD/YY. The time is in the format of HH:MM:SS. The remainder of the data (MASH_1A_S, MASH \_1A_D, MASH \_1B_S, MASH \_1B_D, MASH \_2A_S, MASH \_2A_D, MASH \_2B_S, and MASH \_2B_D) are water levels in the piezometers in meters relative to the NAVD88 datum. The fields letters are the initials MASH, which refers to Mashomack. The second value in the label  refer to location 1 or 2 (the location can be found in the metadata file). The third value in the label refers to healthy (A) or unhealthy marsh (B). The last value in the label (S or D) refers to the screening depth of the shallow piezometer, with those screened  at 0-0.5 m of depth is shallow, or S, while those screened at a depth of 1.25-1.5 m of depth is deeper, or D. Missing data is filled with -999. 2\. Greenhouse gas data greenhouse_gases.csv greenhouse_gases.csv - The greenhouse gases file reports measures of photosynthesis, respiration, net ecosystem exchange and methane emissions for marsh platform study plots in 2021 and 2022 (12 per marsh; 72 total locations; 144 measures). The file has following fields: location, latitude, longitude, plot, condition, replicate, day, month, and year the measure was collected, starting_time_light, starting_time_30_s_light, ending time_light, starting_time_dark, starting_time_30s_dark, ending time_dark, CO2_light,  CO2_light_r2, CO2_light_n, CO2_dark, CO2_dark_r2, CO2_dark_n, CH4_light, CH4_light_r2, CH4_light_n, CH4_dark, CH4_dark_r2, CH4_dark_n, F_CO2_light, F_CO2_dark, FCH4_light, FCH4_dark, PS, R, CH4_mean, and CH4_mean_h. There are three locations: Waquoit, Mashomack, and Tuckahoe. Latitude is in decimal degrees N, and longitude is in decimal degree west (negative). Plot has two values: 1 or 2, which refers to location 1 or 2 in each marsh. Each marsh has two locations of well nests (1 or 2), which are widely separated but there is no significant difference between them. The condition field has two potential values - A and B. A refers to good condition, B refers to marsh that is fragmented and surrounded by open water areas. Replicate refers to 1, 2, or 3. There are three replicates for each point.  Day refers to the day the measure was collected, month refers to the month the measure was collected, and year refers to the year the measure was collected. The field starting_time_light refers to the time that the measure collected using the transparent chamber was collected. The field  starting_time_30_s_light refers to the time that the measure collected using the transparent chamber was collected plus 30 seconds (we started the analysis 30 seconds in to account for the transit time through tubing). The field ending time_light refers to the ending time of the incubation. The field starting_time_dark refers to the time that the measure collected using the opaque chamber was collected (clear chamber covered with black out cloth). The field  starting_time_30s_dark refers to the time that the measure collected using the opaquechamber was collected plus 30 seconds (we started the analysis 30 seconds in to account for the transit time through tubing). The field ending time_dark refers to the ending time of the incubation. The field  CO2_light refers to the carbon dioxide flux in ppm s-1 for the transparent chamber, where a negative value refers to net uptake and a positive value net emissions. The field   CO2_light_r2 refers to the coefficient of determination for a linear regression model constructed where the independent variable is time, and the dependent variable is carbon dioxide concentration. The field CO2_light_n refers to the number of measures in the aforementioned linear regression model. The field  CO2_dark refers to the carbon dioxide flux in ppm s-1 for the opaque chamber, where a negative value refers to net uptake and a positive value net emissions. The field   CO2_dark_r2, refers to the coefficient of determination for a linear regression model constructed where the independent variable is time, and the dependent variable is carbon dioxide concentration. The field CO2_dark_n refers to the number of measures in the aforementioned linear regression model. The CH4_light light refers to the methane flux in mmol ppm s-1 for the transparent chamber, where a negative value refers to net uptake and a positive value net emissions. The field   CH4_light_r2 refers to the coefficient of determination for a linear regression model constructed where the independent variable is time, and the dependent variable is methane concentration. The field CH4_light_n refers to the number of measures in the aforementioned linear regression model. The field  CH4_dark refers to the methane flux in ppm s-1 for the opaque chamber, where a negative value refers to net uptake and a positive value net emissions. The field CH4_dark_r2, refers to the coefficient of determination for a linear regression model constructed where the independent variable is time, and the dependent variable is methane concentration. The field CH4_dark_n refers to the number of measures in the aforementioned linear regression model. The field F_CO2_light refers to carbon dioxide flux in mmol m-2 s-1 under light conditions where a negative value refers to net uptake and a positive value net emissions. This is also referred to as net ecosystem exchange (NEE). The field F_CO2_dark refers to carbon dioxide flux in mmol m-2 s-1 under dark conditions where a negative value refers to net uptake and a positive value net emissions. This is also referred to as respiration (R). The field FCH4_light refers to methane flux in mmol m-2 s-1 under light conditions where a negative value refers to net uptake and a positive value net emissions. The field FCH4_dark refers to methane flux in mmol m-2 s-1 under dark conditions where a negative value refers to net uptake and a positive value net emissions. The field PS refers to photosynthesis in mmol m-2 s-1 or the difference between respiration and net ecosystem exchange. The field R refers to respiration or the flux under dark conditions. The field CH4_mean is the mean of methane emissions in mmol m-2 s-1 during light and dark conditions. The field CH4_mean_h refers to the mean of methane emissions during light and dark conditions in mmol m-2 hr-1. 3\. Photosynthesis data photosynthesis.csv photosynthesis.csv - The photosynthesis file reports leaf-based photosynthesis. The file has the following fields: location, latitude, longitude, plot, condition, replicate, fluorescence, photosynthesis, year, month, day, h, m, and s. The field has three potential locations: Waquoit, Mashomack, and Tuckahoe. Latitude is in decimal degrees N, and longitude is in decimal degree west (negative). Plot has two values: 1 or 2, which refers to location 1 or 2 in each marsh. Each marsh has two locations of well nests (1 or 2), which are widely separated but there is no significant difference between them. The condition field has two potential values - A and B. A refers to good condition, B refers to marsh that is fragmented and surrounded by open water areas. Replicate refers to 1, 2, or 3. There are three replicates for each point.  Fluorescence refers to ambient fluorescence under natural illumination. Photosynthesis refers to net photosynthesis rate in mmol m-2 s-1. Positive values refer to photosynthetic assimilation.  Date collected includes three fields: year (YY), month (MM), and day (DD). Time collected is in hour (h), minute (m), and second (s). Missing data is filled with -999. 4\. Plant aboveground biomass data biomass.csv biomass.csv - The biomass file reports plant aboveground biomass. The file has the following fields: year, location, latitude, longitude, plot, condition, replicate, date collected, biomass_collected, and  biomass_per_sq_m. The field of year has two values, 2021 or 2022, corresponding to year collected. There are three locations: Waquoit, Mashomack, and Tuckahoe. Latitude is in decimal degrees N, and longitude is in decimal degree west (negative). Plot has two values: 1 or 2, which refers to location 1 or 2 in each marsh. Each marsh has two locations of well nests (1 or 2), which are widely separated but there is no significant difference between them. The condition field has two potential values - A and B. A refers to good condition, B refers to marsh that is fragmented and surrounded by open water areas. Replicate refers to 1, 2, or 3. There are three replicates for each point.  Date collected is day collected in MM/DD/YY format.  Biomass_collected is in grams of dry biomass collected (in a collar of 12" in diameter; 30.48 cm). Biomass_per_sq_m is in units of grams of dry biomass per square meter. ## Changelog Changes June 16, 2025: Fixed incorrect elevations for the groundwater wells at the Tuckahoe site in two files: ecotone_water_levels_metadata.csv and ecotone_water_levels_tuckahoe.csv