Dataset title: Field survey and long-term measurements of biological, geomorphic, and hydrologic properties across ecosystem states in a non-tidal, salinizing peat marsh in Everglades National Park, Florida, USA, June 2018 - ongoing Dataset ID: doi:10.6073/pasta/777be7c8b1847094b25cbdab90e4f0a7 Dataset Creator Name: Dr. Lukas Lamb-Wotton Position: Graduate Student Organization: Florida International University Address: 11200 SW 8th St Miami, FL 33199 Email: llamb009@fiu.edu Name: Dr. Tiffany Troxler Position: Associate Professor Organization: Florida International University Email: troxlert@fiu.edu Metadata Provider Organization: Florida Coastal Everglades LTER Address: Florida International University 11200 SW 8th Street, OE 148 Miami, FL 33199 USA Phone: 305-348-6054 Email: fcelter@fiu.edu URL: https://fcelter.fiu.edu Dataset Abstract This dataset package details a field survey and long-term measurements of biological, geomorphic, and hydrologic properties across ecosystem states found within a salinizing, non-tidal peat marsh in the coastal Everglades. There are four datasets included: FCE1250_Lamb_AltStableState_HydroGeo includes point measurements of soil surface elevation, bedrock elevation, soil depth, water depth, and porewater salinity across ecosystem states: emergent marsh (sawgrass dominated), submerged marsh (submerged aquatic vegetation), and unvegetated open water. The survey was conducted between November 2019 to January 2020. FCE1250_Lamb_AltStableState_Bio contains plot-scale (1 m^2) biological measurements from emergent marsh (sawgrass). Biological measurements (total sawgrass, average individual sawgrass biomass, and total sawgrass aboveground biomass), are inherently plot-level but geomorphic and hydrologic measurements were averaged (n = 3) for each plot. Standard deviations are provided. FCE1250_Lamb_AltStableState_Bio_LongTerm contains biological plot-scale (1 m^2) measurements at a bi-monthly timestep from Nov 2019 - July 2022 from a subset of plots (n = 9) included in the FCE_1250_Lamb_AltStableState_Bio dataset. Each bi-monthly measurement is the average value across all 9 nine plots. Standard deviations are also included. FCE_1250_Lamb_AltStableState_SETMH contains long-term measurements of soil surface elevation change and vertical accretion from surface elevation change and marker horizon plots from June 2018 - May 2023. Average and standard errors across all plots are included as well as measurements from each plot. Also included is the cumulative number of dry days based on the average soil surface elevation for all plots. Data collection for all datasets is complete, except for FCE_1250_Lamb_AltStableState_SETMH. SET-MH measurements are still ongoing. Geographic Coverage Bounding Coordinates Geographic description: The dataset is from a 9 ha coastal, non-tidal peat marsh in the coastal Everglades (25°13’13.17” N, 80°50’36.96” W). This marsh is dominated by sawgrass (Cladium jamaicense), interspersed by the submerged aquatic macrophyte, muskgrass (Chara spp.), unvegetated open water, and to a lesser extent, buttonwood (Conocarpus erectus) and red mangrove (Rhizophora mangle scrub; tree heights < 1.5 m). Soils are histosols (peat) with > 85% organic matter ranging 1.0 - 2.0 m in depth. West bounding coordinate: -80.84725 East bounding coordinate: -80.84336 North bounding coordinate: 25.222762 South bounding coordinate: 25.220243 Temporal Coverage Start Date: 2018-06-14 End Date: 2023-05-17 Data Table Entity Name: FCE1250_Lamb_AltStableState_HydroGeo Entity Description: This data table contains single point measurements of hydrologic and geomorphic variables that were taken from November 2019 to January 2020 in a non-tidal, salinizing peat marsh in the coastal Everglades. Measurements were taken across the 3 ecosystem states found within the peat marsh: emergent marsh (sawgrass dominated), submerged marsh (submerged aquatic vegetation), and unvegetated open water. Hydrologic measurements include surface water depth and porewater salinity (soil depth = 15 cm), while geomorphic measurements include soil surface elevation (rel. North American Vertical Datum of 1988), and soil depth to bedrock. Elevation was measured using real-time kinematic surveys with a Trimble R8. Object Name: FCE1250_Lamb_AltStableState_HydroGeo.csv Data Format Number of Header Lines: 1 Attribute Orientation: column Field Delimiter: , Number of Records: Attributes Attribute Name: trnsct Attribute Label: trnsct Attribute Definition: Transect plot location Storage Type: string Measurement Scale: t1= transect 1 t2= transect 2 t3= transect 3 Missing Value Code: Attribute Name: ptNme Attribute Label: ptNme Attribute Definition: Point name Storage Type: string Measurement Scale: text Missing Value Code: Attribute Name: vegCls Attribute Label: vegCls Attribute Definition: Vegetation type or ecosystem state Storage Type: string Measurement Scale: aS= submerged aquatic vegetation gMCl= sawgrass wtr= open water Missing Value Code: Attribute Name: date Attribute Label: date Attribute Definition: Date of survey Storage Type: dateTime Measurement Scale: Missing Value Code: Attribute Name: Y_NAD83 Attribute Label: Y_NAD83 Attribute Definition: Y coordinate (North American Datum of 1983) Storage Type: float Measurement Scale: Units: meter Number Type: real Missing Value Code: Attribute Name: X_NAD83 Attribute Label: X_NAD83 Attribute Definition: X coordinate of point Storage Type: float Measurement Scale: Units: meter Number Type: real Missing Value Code: Attribute Name: elev_m_NAVD88 Attribute Label: elev_m_NAVD88 Attribute Definition: Elevation of survey point (North American Vertical Datum of 1988) Storage Type: float Measurement Scale: Units: meter Number Type: real Missing Value Code: Attribute Name: soilDepth_m Attribute Label: soilDepth_m Attribute Definition: Soil depth of survey point Storage Type: float Measurement Scale: Units: meter Number Type: real Missing Value Code: Attribute Name: bedrock_m_NAVD88 Attribute Label: bedrock_m_NAVD88 Attribute Definition: Elevation of bedrock (North American Vertical Datum of 1988) Storage Type: float Measurement Scale: Units: meter Number Type: real Missing Value Code: Attribute Name: h2oDepth_cm Attribute Label: h2oDepth_cm Attribute Definition: Water depth of survey point Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: pwSal_ppt Attribute Label: pwSal_ppt Attribute Definition: Porewater salinity (soil depth = 15 cm) Storage Type: float Measurement Scale: Units: partsPerThousand Number Type: real Missing Value Code: Data Table Entity Name: FCE1250_Lamb_AltStableState_Bio Entity Description: This data table contains plot-scale (1 m^2) measurements of biologic, hydrologic, and geomorphic variables that were taken from November 2019 to January 2020 within Cladium jamaicense (sawgrass) dominated plots in a non-tidal, salinizing peat marsh in the coastal Everglades. Biologic measurements include total number of sawgrass per plot, average individual sawgrass aboveground biomass, and total aboveground sawgrass biomass. Methods for biomass estimates are described in Childers et al. (2006). Hydrologic measurements include water depth and porewater salinity (soil depth = 15 cm), while geomorphic measurements include soil surface elevation (rel. North American Vertical Datum of 1988), and soil depth to bedrock. For each hydrologic and geomorphic measurement, three measurements were taken across each plot, then averaged. Standard deviation for all measurements are included in a separate column. Object Name: FCE1250_Lamb_AltStableState_Bio.csv Data Format Number of Header Lines: 1 Attribute Orientation: column Field Delimiter: , Number of Records: Attributes Attribute Name: date Attribute Label: date Attribute Definition: Date of measurement Storage Type: dateTime Measurement Scale: Missing Value Code: Attribute Name: trnsct Attribute Label: trnsct Attribute Definition: Transect Storage Type: string Measurement Scale: t1= transect 1 t2= transect 2 t3= transect 3 Missing Value Code: Attribute Name: plot Attribute Label: plot Attribute Definition: Biomass plot Storage Type: string Measurement Scale: text Missing Value Code: Attribute Name: Y_NAD83 Attribute Label: Y_NAD83 Attribute Definition: Y coordinate (North American Datum of 1983) Storage Type: float Measurement Scale: Units: meter Number Type: integer Missing Value Code: Attribute Name: X_NAD83 Attribute Label: X_NAD83 Attribute Definition: X coordinate (North American Datum of 1983) Storage Type: float Measurement Scale: Units: meter Number Type: integer Missing Value Code: Attribute Name: totPlnt Attribute Label: totPlnt Attribute Definition: Total count of sawgrass within plot Storage Type: float Measurement Scale: Units: numberPerMeterSquared Number Type: integer Missing Value Code: Attribute Name: aveIndBio Attribute Label: aveIndBio Attribute Definition: Average individual sawgrass plant biomass Storage Type: float Measurement Scale: Units: gram Number Type: real Missing Value Code: Attribute Name: totEstBio Attribute Label: totEstBio Attribute Definition: Total estimated aboveground sawgrass biomass Storage Type: float Measurement Scale: Units: gramPerMeterSquared Number Type: real Missing Value Code: Attribute Name: Elevation_m_NAVD88 Attribute Label: Elevation_m_NAVD88 Attribute Definition: Average plot soil surface elevation (rel. North American Vertical Datum of 1988) Storage Type: float Measurement Scale: Units: meter Number Type: real Missing Value Code: -9999 (No elevation measurement taken) Attribute Name: elev_SD Attribute Label: elev_SD Attribute Definition: Plot soil surface elevation standard deviation (rel. North American Vertical Datum of 1988) Storage Type: float Measurement Scale: Units: meter Number Type: real Missing Value Code: -9999 (No measurement taken) Attribute Name: soilDepth_cm Attribute Label: soilDepth_cm Attribute Definition: Average plot soil depth to bedrock Storage Type: float Measurement Scale: Units: centimeter Number Type: integer Missing Value Code: Attribute Name: soilDepth_SD Attribute Label: soilDepth_SD Attribute Definition: Plot soil depth to bedrock standard deviation Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (Only 1 measurement taken) Attribute Name: wtrDpth_cm Attribute Label: wtrDpth_cm Attribute Definition: Average plot water depth Storage Type: float Measurement Scale: Units: centimeter Number Type: integer Missing Value Code: Attribute Name: wtrDpth_SD Attribute Label: wtrDpth_SD Attribute Definition: Plot water depth standard deviation Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (Only 1 measurement taken) Attribute Name: pwSalt_ppt Attribute Label: pwSalt_ppt Attribute Definition: Average plot porewater salinity (soil depth = 15 cm) Storage Type: float Measurement Scale: Units: partsPerThousand Number Type: real Missing Value Code: Attribute Name: pwSalt_SD Attribute Label: pwSalt_SD Attribute Definition: Plot porewater salinity (soil depth = 15 cm) standard deviation Storage Type: float Measurement Scale: Units: partsPerThousand Number Type: real Missing Value Code: -9999 (Only 1 measurement taken) Data Table Entity Name: FCE1250_Lamb_AltStableSate_Bio_LongTerm Entity Description: Dataset details bi-monthly plot measurements of sawgrass aboveground biomass, water depth, porewater and surface water salinity that were taken from November 2019 to July 2022. Rainfall and dry days are also included. Measurements other than rainfall and dry days are the average and standard deviation of nine plots across the study area. Object Name: FCE1250_Lamb_AltStableSate_Bio_LongTerm.csv Data Format Number of Header Lines: 1 Attribute Orientation: column Field Delimiter: , Number of Records: Attributes Attribute Name: date Attribute Label: date Attribute Definition: date Storage Type: dateTime Measurement Scale: Missing Value Code: Attribute Name: site Attribute Label: site Attribute Definition: Site name Storage Type: string Measurement Scale: BW= Brackish water Missing Value Code: Attribute Name: aveIndBio Attribute Label: aveIndBio Attribute Definition: Average biomass of individual sawgrass plant Storage Type: float Measurement Scale: Units: gramPerMeterSquared Number Type: real Missing Value Code: Attribute Name: totPlnt Attribute Label: totPlnt Attribute Definition: Total count of sawgrass per meter squared Storage Type: float Measurement Scale: Units: numberPerMeterSquared Number Type: real Missing Value Code: Attribute Name: totEstBio Attribute Label: totEstBio Attribute Definition: Total estimated aboveground sawgrass live biomass per meter squared Storage Type: float Measurement Scale: Units: gramPerMeterSquared Number Type: real Missing Value Code: Attribute Name: wtrDpth Attribute Label: wtr Attribute Definition: Water depth in centimeters Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: pwSal Attribute Label: pwSal Attribute Definition: Porewater salinity in parts per thousand Storage Type: float Measurement Scale: Units: partsPerThousand Number Type: real Missing Value Code: Attribute Name: swSal Attribute Label: swSal Attribute Definition: Surface water salinity Storage Type: float Measurement Scale: Units: partsPerThousand Number Type: real Missing Value Code: Attribute Name: SD_aveIndBio Attribute Label: SD_Ind Attribute Definition: Standard deviation of average individual sawgrass biomass Storage Type: float Measurement Scale: Units: gramPerMeterSquared Number Type: real Missing Value Code: Attribute Name: SD_totPlnt Attribute Label: SD_plnt Attribute Definition: Standard deviation of average total sawgrass plants Storage Type: float Measurement Scale: Units: numberPerMeterSquared Number Type: real Missing Value Code: Attribute Name: SD_totEstBio Attribute Label: SD_bio Attribute Definition: Standard deviation of total estimated aboveground sawgrass biomass Storage Type: float Measurement Scale: Units: gramPerMeterSquared Number Type: real Missing Value Code: Attribute Name: wtrDpth_SD Attribute Label: wtr_SD Attribute Definition: Standard deviation of water depth Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: pwSal_SD Attribute Label: pwSal_SD Attribute Definition: Standard deviation of porewater salinity Storage Type: float Measurement Scale: Units: partsPerThousand Number Type: real Missing Value Code: Attribute Name: swSal_SD Attribute Label: swSal_SD Attribute Definition: Standard deviation of surface water salinity Storage Type: float Measurement Scale: Units: partsPerThousand Number Type: real Missing Value Code: Attribute Name: daysDry Attribute Label: daysDry Attribute Definition: Number of dry days where soil surface is exposed (water depth < 0 cm) between each bi-monthly measurement. Storage Type: float Measurement Scale: Units: days Number Type: integer Missing Value Code: Attribute Name: rainfall_bimon Attribute Label: rainfall_bimon Attribute Definition: Total rainfall between each bi-monthly measurement Storage Type: float Measurement Scale: Units: millimeter Number Type: real Missing Value Code: Attribute Name: daysDry_Upper Attribute Label: daysDry_Upper Attribute Definition: Upper bound of dry days after accounting for standard error of soil surface elevation (2 cm) Storage Type: float Measurement Scale: Units: days Number Type: integer Missing Value Code: Attribute Name: daysDry_Lower Attribute Label: daysDry_Lower Attribute Definition: Lower bound of dry days after accounting for standard error of soil surface elevation (2 cm). Storage Type: float Measurement Scale: Units: days Number Type: integer Missing Value Code: Data Table Entity Name: FCE1250_Lamb_AltStableState_SETMH Entity Description: Dataset includes long-term measurements of soil elevation change, vertical accretion, and cumulative dry days that were taken from June 2018 to May 2023. Geomorphic measurements are from surface elevation table and marker horizons. Object Name: FCE1250_Lamb_AltStableState_SETMH.csv Data Format Number of Header Lines: 1 Attribute Orientation: column Field Delimiter: , Number of Records: Attributes Attribute Name: date Attribute Label: date Attribute Definition: Date Storage Type: dateTime Measurement Scale: Missing Value Code: Attribute Name: SITENAME Attribute Label: SITENAME Attribute Definition: Site name Storage Type: string Measurement Scale: BW= Brackish water Missing Value Code: Attribute Name: years Attribute Label: years Attribute Definition: Years since baseline measurement Storage Type: float Measurement Scale: Units: years Number Type: real Missing Value Code: Attribute Name: SET_all_ave Attribute Label: SET_all_ave Attribute Definition: Mean soil surface elevation change across all plots Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: SET_all_se Attribute Label: SET_all_se Attribute Definition: Standard error of soil elevation change measurements across all plots Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: set1_ave Attribute Label: set1_ave Attribute Definition: Mean soil surface elevation change for SET plot 1 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: set1_se Attribute Label: set1_se Attribute Definition: Standard error of soil surface elevation change for SET plot 1 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: set2_ave Attribute Label: set2_ave Attribute Definition: Mean soil surface elevation change for SET plot 2 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: set2_se Attribute Label: set2_se Attribute Definition: Standard error of soil surface elevation change for SET plot 2 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: set3_ave Attribute Label: set3_ave Attribute Definition: Mean of soil surface elevation change for SET plot 3 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: set3_se Attribute Label: set3_se Attribute Definition: Standard error of soil surface elevation change for SET plot 3 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: MH_all_ave Attribute Label: MH_all_ave Attribute Definition: Mean vertical accretion across all marker horizon plots Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: MH_all_se Attribute Label: MH_all_se Attribute Definition: Standard error of vertical accretion across all marker horizon plots Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: mh880_ave Attribute Label: mh880_ave Attribute Definition: Mean vertical accretion for marker horizon plot 880 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: Attribute Name: mh880_se Attribute Label: mh880_se Attribute Definition: Standard error of vertical accretion across marker horizon plot 880 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: mh881_ave Attribute Label: mh881_ave Attribute Definition: Mean of vertical accretion for marker horizon plot 881 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: mh881_se Attribute Label: mh881_se Attribute Definition: Standard error of vertical accretion for marker horizon plot 881 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: mh64_ave Attribute Label: mh64_ave Attribute Definition: Mean vertical accretion for marker horizon plot 64 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: mh64_se Attribute Label: mh64_se Attribute Definition: Standard error of vertical accretion for marker horizon plot 64 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: mh63_ave Attribute Label: mh63_ave Attribute Definition: Mean vertical accretion for marker horizon plot 63 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: mh63_se Attribute Label: mh63_se Attribute Definition: Standard error of vertical accretion for marker horizon plot 63 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: mh61_ave Attribute Label: mh61_ave Attribute Definition: Mean vertical accretion for marker horizon plot 61 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: mh61_se Attribute Label: mh61_se Attribute Definition: Standard error of vertical accretion for marker horizon plot 61 Storage Type: float Measurement Scale: Units: centimeter Number Type: real Missing Value Code: -9999 (No data collected) Attribute Name: dryDays_All Attribute Label: dryDays_All Attribute Definition: Cumulative number of dry days where soil surface is exposed (water depth < 0 cm) Storage Type: float Measurement Scale: Units: days Number Type: real Missing Value Code: Attribute Name: dryDays_all_Upper Attribute Label: dryDays_all_Upper Attribute Definition: Upper bound of dry days after accounting for standard error of soil surface elevation across plots. Storage Type: float Measurement Scale: Units: days Number Type: real Missing Value Code: Attribute Name: dryDays_all_Lower Attribute Label: dryDays_all_Lower Attribute Definition: Lower bound of dry days after accounting for standard error of soil surface elevation across plots Storage Type: float Measurement Scale: Units: days Number Type: real Missing Value Code: Methods Method Step Description For FCE_1250_AltStableState_HydroGeo: A field survey was conducted to characterize hydrogeomorphic variability across the study site, initiated in November 2019 and completed in January 2020. The survey was conducted along three, 300 m transects, spaced 100 m apart, with survey points positioned roughly every 30 m and stratified across three ecosystem states: Emergent (EMG), submerged (SUB), and open-water (OW). Percent cover of > 75% of Cladium jamaicense within a 1-m2 plot was used to identify the EMG state. Presence of Chara sp. and absence of C. jamaicense was used to identify the SUB state. The OW state was identified based on the absence of any vegetation. Measurements at each survey point included geomorphic measurements of soil surface elevation and soil depth, and hydrologic measurements of porewater salinity and surface water depth. For EMG and SUB points, soil surface elevation was measured by placing the survey rod on the soil surface. Surface water depth was measured simultaneously via centimeter markings on the survey rod. For OW points, there was generally a thick layer of flocculent, unconsolidated sediment, making the soil surface difficult to discern. To standardize measurements, the survey rod was allowed to gently fall through this flocculent layer until resistance was met. The point at which resistance was met was identified as the soil surface and subsequent measurements of elevation and surface water depth were taken. Soil depth was measured at each point using a stainless-steel soil probe by driving the probe through the soil profile to the bedrock. Porewater salinity was measured at a soil depth of 15 cm using a YSI Model 600 XL (Xylem, Inc., Yellow Springs, OH, USA). References: Gillins, D.T., D. Kerr, and B. Weaver. 2019. Evaluation of the online positioning user service for processing static GPS surveys: OPUS-Projects, OPUS-S, OPUS-Net, and OPUS-RS. Journal of Surveying Engineering 145: 1-14. Method Step Description Methods that pertain to FCE_1250_AltStableState_Bio: To estimate C. jamaicense aboveground (ABG) biomass, we used a non-destructive, phenometric technique developed and validated in the Florida Everglades (Childers et al. 2006). Measurements were initiated in November 2019 and completed in January 2020. Within 1 m2 plots (n = 29), we counted all live individual C. jamaicense culms and randomly selected 1/3 of all individual plants, or a minimum of 15 when the total culm density was less than 45. For this subset, we measured: (1) length of longest leaf, (2) culm diameter at the base, and (3) inflorescence height, if present. Biomass estimates for each individual C. jamaicense plant measured was then estimated using a multiple regression model developed and described in Childers et al. (2006). Total ABG biomass (g m-2) for each plot was then estimated by multiplying culm density per m2 by mean plant biomass (g dw). Soil surface elevation, soil depth, water depth, and porewater salinity were surveyed at three points within each plot to obtain plot-level averages. Methods for these geomorphic and hydrologic methods can be found in the methods description for the FCE_1250_AltStableState_HydroGeo dataset. Methods that pertain to FCE_1250_AltStableState_Bio_LongTerm: ABG biomass, water depth, and porewater salinity measurements were taken across a subset of the EMG aboveground biomass plots, with three plots positioned along each transect, for a total of nine, 1-m2 plots. Six plots were established in November 2019 with an additional three plots established in January 2020. Measurements continued bi-monthly from Nov 2019/Jan 2020 - July 2022. Plot locations were selected to cover the range of soil surface elevation and C. jamaicense aboveground biomass based on the initial field survey. Specific methods for ABG biomass, water depth, and porewater salinity can be found in the methods description for the FCE_1250_AltStableState_HydroGeo and FCE_1250_AltStableState_Bio datasets. For each time point, ABG biomass was averaged across all plots while water depth and porewater salinity were averaged for each plot, then averaged across all plots. Additionally, we estimated dry days water depth was continuously measured in a permanent well at 30-minute intervals and calibrated monthly for the duration of the study using an AquaTroll 200 (In-Situ Inc., Fort Collins, CO). These data were averaged to the daily scale before calculating the number of dry days. To calculate dry days for EMG plots, we referenced water depth to NAVD88 and subtracted the difference between the soil surface elevation at the well and the mean soil surface elevation of the EMG state (-0.09 ± 0.05 m rel. NAVD88). To obtain soil surface elevation at the well, we measured the elevation of top of the well using real-time kinematic surveys (0.61 m rel. NAVD88) and subtracted the height of the well above the soil surface (0.76 m). References: Childers, D. L., Iwaniec, D., Rondeau, D., Rubio, G., Verdon, E., & Madden, C. J. (2006). Responses of sawgrass and spikerush to variation in hydrologic drivers and salinity in Southern Everglades marshes. Hydrobiologia, 569(1), 273-292. Method Step Description Methods that pertain to FCE_1250_AltStableState_SETMH: Soil elevation change and vertical accretion were monitored from June 2018 – May 2023 using the rSET-MH approach. Three rSETs were established in May 2017 at the study site within the SUB state following standard methods. The rSETs were installed ~10 meters apart on alternating sides of a permanent, wooden boardwalk at the edge of the study site adjacent to a major road. The boardwalk was built prior to rSET installation and provided direct access to the plots from the road without disturbing rSET plots. Following an 11-month equilibration period, baseline soil elevation measurements were made by attaching the rSET instrument to the benchmark, leveling the rSET, and lowering fiberglass pins (n = 9) to the soil surface at four fixed azimuths per rSET plot, for n = 36 measurements per plot, and 108 measurements total across rSET plots (Fig. 3a). Soil elevation change measurements were made bi-monthly from June 2018 – June 2019, and seasonally from October 2019 – May 2023, except for one additional measurement made in in June 2021. All rSET plots were in locations that were covered by submerged mats of Chara spp that formed during the wet season. We removed any Chara sp. that was deposited on the soil surface during the dry season so that pin height reflected elevation changes solely from the soil profile. We followed this method for all dry season measurements except in March 2021, when measurements were made shortly after a prescribed fire was conducted that impacted the majority of the study site. Ash deposition and a thick mat of Chara sp. made it difficult to remove material without disturbing the soil surface, so pins were lowered on top of the deposited material. We established five MH plots to monitor vertical accretion at locations characterized by the SUB state along the wooden boardwalk adjacent to rSET plots in May 2017. Marker horizons were established by pouring a white feldspar clay onto the soil surface within a circular bucket with the bottom cut out (circumference = 0.25 m; height of MH layer ~ 5 cm). Feldspar was allowed to settle for one month to form an identifiable layer before the bucket was removed. During each soil elevation measurement, MH plots were examined for accreted material. When accretion was observed, a small soil core was extracted and the depth of vertical accretion above the MH was measured in triplicate. When the soil surface was dry, a serrated knife was used to cut out a core. When the soil surface was inundated, liquid nitrogen was used to “cryo-core” the MH plot. Distribution Online distribution: https://pasta.lternet.edu/package/data/eml/knb-lter-fce/1250/2/fa0b611dc70cfdb80c87f9208625281e Intellectual Rights Dataset Keywords water depth Everglades National Park Florida Coastal Everglades LTER FCE LTER alternate stable state aboveground biomass elevation salinity disturbance organic matter Maintenance knb-lter-fce.1250.2: Data and metadata for FCE1250_Lamb_AltStableState_Bio_LongTerm (complete), FCE_1250_Lamb_AltStableState_SETMH (ongoing) datasets added. Dataset Contact Name: Dr Lukas Lamb-Wotton Position: Graduate Student Organization: Florida International University Address: 11200 SW 8th St Miami, FL 33199 United States Phone: 2078918921 Email: llamb009@fiu.edu Position: Information Manager Organization: Florida Coastal Everglades LTER Address: Florida International University 11200 SW 8th Street, OE 148 Miami, FL 33199 USA Email: fcelter@fiu.edu URL: https://fcelter.fiu.edu