I. Data Set Descriptors A. Title: null. 2023. Spartina alterniflora marsh vegetation data along the Georgia coast used in the Belowground Ecosystem Resiliency Model version 2.0. Georgia Coastal Ecosystems LTER Data Catalog (data set PLT-GCET-2308; /data/PLT-GCET-2308) B. Accession Number: PLT-GCET-2308 C. Description 1. Originator(s): null 2. Abstract: Study plots (1-m2) were established in eight Spartina alterniflora-dominated marshes (7 on Sapelo Island, Georgia, and 1 on Skidaway Island, Georgia). At three sites, plots were sampled once each during May, July, August, September, and October of 2016. At all sites, plots were sampled once each during June, August, and November of 2021, February, May, August, and November of 2022, and February of 2023. One long-term (quarterly 2013 to 2023) GCE LTER sampling site is also included. Nine replicate plots were placed in vegetated marsh along transects that spanned 3 Landsat-8 and -9 pixel footprints, with 3 plots per pixel footprint. In each plot, measurements included plant biomass, plant species, stem density, and height. Aboveground biomass was calculated using allometric relationships between plant height and mass from plant clipping studies. During these surveys, destructive core sampling was also performed in the proximity of the plots (n = 1 per plot) to measure above and below ground biomass. Chlorophyll, foliar N, and Leaf Area Index measurements were taken in the proximity of the plots. This dataset reflects an update to the "PLT-GCED-2106" dataset (doi: 10.6073/pasta/03f4f78c6498aecca34faf4339591129). This project also utilized data from the "PLT-GCEM-1610" dataset doi: 10.6073/pasta/9746c71b35e9f8c544ea12c601c33949). Those data utilized in this project are duplicated here for completeness. 3. Study Type: Graduate Thesis Study 4. Study Themes: Plant Ecology 5. LTER Core Areas: Primary Production 6. Georeferences: geographic coordinates as data columns 7. Submission Date: Aug 22, 2023 D. Keywords: belowground biomass, biomass, chlorophyll, cores, foliar N, GCE, Georgia, Georgia Coastal Ecosystems, leaf area index, LTER, marshes, Plant Monitoring, plants, Primary Production, Sapelo Island, Skidaway Island, Spartina, Spartina alterniflora, stem density, stem height, USA II. Research Origin Descriptors A. Overall Project Description 1. Project Title: Georgia Coastal Ecosystems LTER - IV 2. Principal Investigators: Name: Merryl Alber Address: Dept. of Marine Sciences University of Georgia Athens, Georgia 30602-3636 Country: USA Email: malber@uga.edu 3. Funding Period: Feb 01, 2019 to Jan 31, 2025 4. Objectives: The GCE-LTER project has four goals. 1) Track environmental and human drivers that can cause perturbations in our focal ecosystems. This will be accomplished this through continuing long-term measurements of climate, water chemistry, oceanic exchange, and human activities on the landscape. 2) Describe temporal and spatial variability in physical, chemical, geological and biological characteristics of the study system (coastal wetland complexes) and how they respond to external drivers. This will be accomplished through field monitoring in combination with remote sensing and modeling. 3) Characterize the ecological responses of intertidal marshes to disturbance. This will be accomplished by ongoing monitoring and experimental work to evaluate system responses to major perturbations in three key marsh habitats (changes in inundation and predator exclusion in Spartina-dominated salt marshes; increases in salinity in fresh marshes; changes in runoff in high marshes), by implementing standardized experimental disturbances along salinity and elevation gradients, and by tracking responses to natural disturbances. 4) Evaluate ecosystem properties at the landscape level (habitat distribution, net and gross primary production, C budgets) and assess the cumulative effects of disturbance on these properties. The project will also develop relationships between drivers and response variables, which can be used to predict the effects of future changes. This will be accomplished through a combination of data synthesis, remote sensing and modeling. 5. Abstract: The Georgia Coastal Ecosystems (GCE) Long Term Ecological Research (LTER) program, based at the University of Georgia Marine Institute on Sapelo Island, Georgia, was established in 2000 to study long-term change in coastal ecosystems. Estuaries (places where salt water from the ocean mixes with fresh water from the land) and their adjacent marshes provide food and refuge for fish, shellfish and birds; protect the shoreline from storms; help to keep the water clean; and store carbon. The GCE LTER researchers study marshes and estuaries to understand how these ecosystems function, to track how they change over time, and to predict how they might be affected by future changes in climate and human activities. They accomplish this by tracking the major factors that can cause long-term change in coastal areas (e.g. sea level, rainfall, upstream development), and measuring the effects of these factors on the study site. They also conduct focused studies to assess how key marsh habitats will respond to major changes expected in the future, including large-scale experiments to evaluate the effects of a) increases in the salinity of the water that floods freshwater marshes (mimicking drought and/or sea level rise), b) changes in water runoff from land into the upland marsh border (mimicking drought or upland development), and c) exclusion of larger organisms in the salt marsh (mimicking long-term declines in predators). During this award they will initiate additional studies to systematically evaluate how coastal wetlands respond to disturbances. Disturbances, or disruptions in the environment, are particularly important to understand in the context of long-term background changes such as increasing sea level, and GCE researchers are working to assess the cumulative effects of multiple disturbances on the landscape. The GCE education and outreach program works to share an understanding of coastal ecosystems with teachers and students, coastal managers, citizen scientist and the general public. 6. Funding Source: NSF OCE 1832178 B. Sub-project Description 1. Site Description a. Geographic Location: Sapelo -- Sapelo Island, Sapelo Island, Georgia Coordinates: Sapelo -- NW: 081 18 28.72 W, 31 32 10.93 N NE: 081 10 34.26 W, 31 32 10.93 N SE: 081 10 34.26 W, 31 22 48.54 N SW: 081 18 28.72 W, 31 22 48.54 N b. Physiographic Region: Sapelo -- unspecified c. Landform Components: Sapelo -- Barrier island d. Hydrographic Characteristics: Sapelo -- unspecified e. Topographic Attributes: Sapelo -- unspecified f. Geology, Lithology and Soils: Sapelo -- unspecified g. Vegetation Communities: Sapelo -- Salt marsh vegetation on the island exterior (dominated by Spartina alterniflora), transitioning to marsh meadow and maritime forest on the island interior h. History of Land Use and Disturbance: none recorded i. Climate: Climate summary for Sapelo Island, Georgia, based on NWS data from 1980-2010: Daily-aggregated Values: Mean (sample standard deviation) mean air temperature: 20.09°C (7.28°C) minimum air temperature: 15.02°C (7.96°C) maximum air temperature: 24.82°C (6.98°C) total precipitation: 3.26mm (10.3mm) Yearly-aggregated Daily Values: Mean (sample standard deviation) total precipitation (1980-2010): 1124mm (266mm) 2. Experimental or Sampling Design a. Design Characteristics: We collected field data to estimate Spartina alterniflora aboveground biomass, belowground biomass, Leaf Area Index, foliar N, and chlorophyll concentration. For this, we established 1-m2 study plots in eight Spartina alterniflora-dominated marshes, 7 on Sapelo Island (Deans Creek, Duplin River, Flux Tower B, Folly River, Hunt Camp, North Sapelo, and UGAMI), and 1 on Skidaway Island (Skidaway). Three marshes (Flux Tower B, Skidaway, and UGAMI) were each sampled once each during May, July, August, September, and October of 2016. All eight marshes were each sampled once during June, August, and November 2021, February, May, August, and November 2022, and February 2023. Quarterly sampling in the GCE LTER long term sampling site (Flux Tower A) took place from 2013 to 2023. Nine replicate plots were placed in vegetated areas along transects that spanned 3 Landsat-8 and -9 pixel footprints, with 3 plots per pixel footprint. b. Permanent Plots: Flux Tower A marsh was at the vegetation long-term sampling sites northwest of the eddy covariance carbon flux tower operated by GCE project on Sapelo Island (SI), GA. Flux tower B was~ 620 m southeast of Flux A. UGAMI marsh, adjacent to the UGA Marine Institute on SI, was a formerly impounded marsh that experienced altered hydrological cycles. The Skidaway marsh was on Skidaway Island, GA, in a more urbanized watershed. The Deans Creek marsh was situated in southern SI, near a Juncus roemerianus/Spartina alterniflora marsh transition zone. The Duplin River marsh is located just off the Duplin River, near the Sapelo Island Marsh Landing Ferry Terminal. The Folly River marsh is on Buzzard Roost Island, along the Doboy Sound, near Folly River and GCE5. The Hunt Camp marsh was located in western SI along the upper reaches of the Duplin River and GCE10. The North Sapelo marsh was situated on the northern end of SI, near GCE3. All marshes were vegetated areas transected by tidal channels. c. Data Collection Duration and Frequency: Aboveground biomass was estimated allometrically from stem height and counts within permanent 1 m2 plots. Leaf chlorophyll was estimated via a SPAD chlorophyll meter (Spectrum Technologies, Aurora, IL, USA), calibrated against leaf-level chlorophyll extractions (for each different meter used). Foliar N concentration was estimated via a CHN Analyzer at the University of Georgia Stable Isotope Lab and the University of Texas at Austin Marine Science Institute Core Facilities Lab. Leaf Area index was measured via an AccuPAR LP-80 Ceptometer (Meter Environment, Pullman, WA, USA), which measures LAI via canopy light transmittance. For each plot, LAI was calculated from the average of two downwelling (above canopy) and three upwelling (below canopy) radiation measurements. To estimate Belowground biomass, we collected standing root cores (7.62 x 30 cm) near the permanent plots. Cores were centered on a plant stem clump. Clumps averaged 3 stems (range: 1-9 stems). Above and belowground core material was washed on 1-mm mesh, sorted into live and dead vegetation, and oven-dried at 60°C to constant mass. Live BGB material was identified by root turgor, color, and texture. We estimated plot-scale Belowground Biomass by multiplying the stem counts from the permanent vegetation plots by the core live root:shoot ratio, a scaling method that accounts for the stem variation between low-density tall-form plants and high-density short-form plants. Beginning of Observations: May 01, 2013 End of Observations: Feb 28, 2023 3. Research Methods a. Field and Laboratory Methods: Method 1: Aboveground biomass -- Aboveground biomass was estimated allometrically from stem height and counts within permanent 1 m2. This followed the aboveground biomass part of the protocol for the flux tower monthly vegetation sampling. Method 2: Leaf chlorophyll -- Leaf chlorophyll was estimated via a SPAD chlorophyll meter (Spectrum Technologies, Aurora, IL, USA). Three leaves per plot were measured, wiped clean of silt and/or salt crystals with a damp rag, and then measured via the SPAD meter in the field, where the average of the three reasonable measurements were recorded. Reasonable values are from 10 - 50 (zero= no chlorophyll, 10=yellow leaf, 50=lush dark green leaf). Method 3: Foliar N concentration -- To measure foliar N concentration, live leaf material from representative plants was also collected at the time of vegetation surveys from each plot, where three leaves from three different plants were collected at each plot. Upon return to the lab, leaf samples were oven-dried at 80ºC for at least 24 hours and ball-milled to less than 250 μm particle size and ~3 mg of the ground material was then weighed into 5 x 5 mm tin capsules. Total C and N were then measured via Micro-Dumas combustion via CHN Analyzer (Model NA1500, Carlo Erba Strumentazione, Milan, Italy) at the University of Georgia Stable Isotope Laboratory (http://siel.uga.edu/total-nitrogen) and via CN Analyzer (Thermo Delta V Plus IRMS, FLASH EA-Isolink, Conflo IV, Thermo-Fischer, United States) at the University of Texas at Austin Marine Science Institute Core Facilities Laboratory. Both the UGA Stable Isotope Laboratory and the UTMSI Core Facilities Laboratory calibrate their Analyzer by including solid-phase reference materials in the tin capsule stage at the beginning of each run and at fixed intervals thereafter (usually one reference per ten unknowns.) They typically use ultra-high purity acetanilide as their standard material. In addition, the Stable Isotope lab checks each new lot of standard acetanilide before use on real runs by analyzing samples of National Bureau of Standards NBS1572 Citrus Leaves. They also include empty tin-capsule blanks periodically in each batch, and any detectable N or C in these blanks is subtracted from the sample and standard values to give a true zero baseline. Thus, these blanks provide correction for trace C potentially present in the tin capsules and for the small amount of N2 gas introduced as an impurity in the oxygen pulse during sample combustion. The average standard deviation across replicate samples in the analysis from the UGA lab was 0.04% (N = 18) and from the UT lab was 0.02% (N = 52). Method 4: Leaf Area index -- Leaf Area index was measured via an AccuPAR LP-80 Ceptometer (Meter Environment, Pullman, WA, USA), which measures LAI via canopy light transmittance. For each plot, LAI was calculated from the average of two downwelling (above canopy) and three upwelling (below canopy) radiation measurements. Method 5: Belowground biomass -- To estimate Belowground biomass, we collected standing root cores (7.62 x 30 cm) near the permanent plots. Cores were centered on a plant stem clump. Clumps averaged 3 stems (range: 1-9 stems). Above and belowground core material was washed on 1-mm mesh, sorted into live and dead vegetation, and oven-dried at 60°C to constant mass. Live belowground biomass material was identified by root turgor, color, and texture. We estimated plot-scale Belowground Biomass by multiplying the stem counts from the permanent vegetation plots by the core live root:shoot ratio, a scaling method that accounts for the stem variation between low-density tall-form plants and high-density short-form plants. Method 6: Photographs -- During each sampling period from 2021 to 2023 at Deans Creek, Duplin River, Flux Tower B, Folly River, Hunt Camp, North Sapelo, and Skidaway (all sites except Flux Tower A), a photograph was taken at each plot. A personal cellphone was held at nadir at chest height to capture a photograph. Time of day and level of sunlight was not controlled for. b. Protocols: Method 1: none Method 2: none Method 3: none Method 4: none Method 5: Flux Tower Monthly Vegetation Monitoring Protocol Organization: Georgia Coastal Ecosystems LTER Description: Flux Tower Monthly Vegetation Monitoring Protocol. URL: http://gce-lter.marsci.uga.edu/public/app/resource_details.asp?id=774 Author: Steven C. Pennings (email: scpennin@central.uh.edu) Method 6: none c. Instrumentation: Method 1: none Method 2: SPAD chlorophyll meter (Spectrum Technologies, Aurora, IL, USA) Method 3: Micro-Dumas combustion via CHN Analyzer (Model NA1500, Carlo Erba Strumentazione, Milan, Italy) and CN Analyzer (Thermo Delta V Plus IRMS, FLASH EA-Isolink, Conflo IV, Thermo-Fischer, United States) Method 4: AccuPAR LP-80 Ceptometer (Meter Environment, Pullman, WA, USA) Method 5: none Method 6: Google Pixel 3 d. Taxonomy and Systematics: Method 1: not applicable Method 2: not applicable Method 3: not applicable Method 4: not applicable Method 5: not applicable Method 6: not applicable e. Speclies List: f. Permit History: Method 1: not applicable Method 2: not applicable Method 3: not applicable Method 4: not applicable Method 5: not applicable Method 6: not applicable 4. Project Personnel a. Personnel: 1: Kyle Runion 2: Jessica L. O'Connell 3: Merryl Alber 4: Deepak Mishra 5: Kristin Byrd b. Affiliations: 1: University of Texas at Austin 2: Colorado State University, Fort Collins, CO 3: University of Georgia, Athens, Georgia 4: University of Georgia, Athens, Georgia 5: United States Geological Survey III. Data Set Status and Accessibility A. Status 1. Latest Update: 12-Oct-2023 2. Latest Archive Date: 12-Oct-2023 3. Latest Metadata Update: 12-Oct-2023 4. Data Verification Status: New Submission B. Accessibility 1. Storage Location and Medium: Stored at GCE-LTER Data Management Office Dept. of Marine Sciences Univ. of Georgia Athens, GA 30602-3636 USA on media: electronic data download (WWW) or compact disk 2. Contact Person: Name: Adam Sapp Address: Department of Marine Sciences University of Georgia Athens, Georgia 30602 Country: USA Email: asapp@uga.edu 3. Copyright Restrictions: not copyrighted 4. Restrictions: This information is licensed under a Creative Commons Attribution 4.0 International License (see: https://creativecommons.org/licenses/by/4.0/). The consumer of these data ("Data User" herein) has an ethical obligation to cite it appropriately in any publication that results from its use. The Data User should realize that these data may be actively used by others for ongoing research and that coordination may be necessary to prevent duplicate publication. The Data User is urged to contact the authors of these data if any questions about methodology or results occur. Where appropriate, the Data User is encouraged to consider collaboration or co-authorship with the authors. The Data User should realize that misinterpretation of data may occur if used out of context of the original study. While substantial efforts are made to ensure the accuracy of data and associated documentation, complete accuracy of data sets cannot be guaranteed. All data are made available "as is." The Data User should be aware, however, that data are updated periodically and it is the responsibility of the Data User to check for new versions of the data. The data authors and the repository where these data were obtained shall not be liable for damages resulting from any use or misinterpretation of the data. a. Release Date: Affiliates: Aug 22, 2023, Public: Aug 22, 2025 b. Citation: Data provided by the Georgia Coastal Ecosystems Long Term Ecological Research Project, supported by funds from NSF OCE 1832178 (data set PLT-GCET-2308) c. Disclaimer: The user assumes all responsibility for errors in judgement based on interpretation of data and analyses presented in this data set. 5. Costs: free electronic data download via WWW, distribution on CD may be subject to nominal processing and handling fee IV. Data Structural Descriptors A. Data Set File 1. File Name: PLT-GCET-2308_leafn_1_0.CSV 2. Size: 957 records 3. File Format: ASCII text (comma-separated value format) 3a. Delimiters: single comma 4. Header Information: 5 lines of ASCII text 5. Alphanumeric Attributes: 6. Quality Control Flag Codes: Q = questionable value, I = invalid value, E = estimated value 7. Authentication Procedures: 8. Calculations: CN_Ratio: Percent_C/Percent_N 9. Processing History: Software version: GCE Data Toolbox Version 3.9.10 (23-May-2022) Data structure version: GCE Data Structure 1.1 (29-Mar-2001) Original data file processed: PLT-GCET-2308_leafn.txt (957 records) Data processing history: 12-Oct-2023: new GCE Data Structure 1.1 created ('newstruct') 12-Oct-2023: 957 rows imported from ASCII data file 'PLT-GCET-2308_leafn.txt' ('imp_ascii') 12-Oct-2023: 13 metadata fields in file header parsed ('parse_header') 12-Oct-2023: data structure validated ('gce_valid') 12-Oct-2023: automatically assigned study date metadata descriptors based on the range of date values in date/time columns (add_studydates) 12-Oct-2023: updated 1 metadata fields in the Dataset section(s) ('addmeta') 12-Oct-2023: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 12-Oct-2023: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 12-Oct-2023: updated 6 metadata fields in the Data section(s) ('addmeta') 12-Oct-2023: updated 15 metadata fields in the Status, Data sections to reflect attribute metadata ('updatecols') 12-Oct-2023: parsed and formatted metadata ('listmeta') B. Variable Information 1. Variable Name: column 1. Date column 2. Site column 3. Plot column 4. Percent_N column 5. Percent_C column 6. CN_Ratio 2. Variable Definition: column 1. Sampling date column 2. Site code column 3. Plot column 4. Percent of leaf sample that is Nitrogen column 5. Percent of leaf sample that is Carbon column 6. Percent Carbon to percent Nitrogen ratio 3. Units of Measurement: column 1. YYYY-MM-DD column 2. none column 3. none column 4. percent column 5. percent column 6. none 4. Data Type a. Storage Type: column 1. string column 2. string column 3. string column 4. floating-point column 5. floating-point column 6. floating-point b. Variable Codes: Site: deans = Deans Creek, dupli = Duplin River, fluxa = Flux Tower A, fluxb = Flux Tower B, folly = Folly River, huntc = Hunt Camp, north = North Sapelo, skida = Skidaway Island, ugami = UGAMI Marsh c. Numeric Range: column 1. (none) column 2. (none) column 3. (none) column 4. 0.05 to 2.5 column 5. 29.24 to 54 column 6. 16.4 to 857.4 d. Missing Value Code: 5. Data Format a. Column Type: column 1. text column 2. text column 3. text column 4. numerical column 5. numerical column 6. numerical b. Number of Columns: 6 c. Decimal Places: column 1. 0 column 2. 0 column 3. 0 column 4. 2 column 5. 2 column 6. 2 6. Logical Variable Type: column 1. datetime (none) column 2. coded value (none) column 3. nominal (none) column 4. data (continuous) column 5. data (continuous) column 6. calculation (continuous) 7. Flagging Criteria: column 1. none column 2. none column 3. none column 4. none column 5. none column 6. none C. Data Anomalies: V. Supplemental Descriptors A. Data Acquisition 1. Data Forms: 2. Form Location: 3. Data Entry Validation: B. Quality Assurance/Quality Control Procedures: C. Supplemental Materials: D. Computer Programs: E. Archival Practices: F. Publications: not specified G. History of Data Set Usage 1. Data Request History: not specified 2. Data Set Update History: none 3. Review History: none 4. Questions and Comments from Users: none