I. Data Set Descriptors A. Title: Christopher B. Craft. 2024. Photosynthetic available radiation (PAR) measurements from the GCE-LTER Seawater Addition Long-Term Experiment (SALTEx) Project. Georgia Coastal Ecosystems LTER Data Catalog (data set PLT-GCED-2404a; /data/PLT-GCED-2404a) B. Accession Number: PLT-GCED-2404a C. Description 1. Originator(s): Name: Christopher B. Craft Address: Indiana University - School of Public and Environmental Affairs Room 408. MSB II. Bloomington, Indiana 47405 Country: USA Email: ccraft@indiana.edu 2. Abstract: SALTEx (Seawater Addition Long-Term Experiment) is a field experiment designed to simulate saltwater intrusion in a tidal freshwater wetland to predict how chronic (Press) and acute (Pulse) salinization will affect this and other tidal freshwater ecosystems. The SALTEx experiment was initiated in 2012 and consists of 31 field plots, each 2.5 m on a side. There are three treatments (Press, Pulse, and Fresh) and two types of controls (with and without sides), each consisting of six replicates. The Press treatment plots receive regular (4 times each week) additions of a mixture of seawater and fresh river water. Pulse plots receive the same mixture of seawater and river water during September and October, which is historically a time of low flow in the river when natural saltwater intrusion occurs. The Fresh treatment plots receive regular additions of fresh river water. Treatment water is added during low tide to facilitate its infiltration into the soil, and all plots are inundated by astronomical tides at high tide. Light availability was measured using photosynthetically active radiation (PAR) both above and below the plant canopy. 3. Study Type: Directed Study 4. Study Themes: Plant Ecology 5. LTER Core Areas: Other Site Research 6. Georeferences: none 7. Submission Date: Apr 30, 2024 D. Keywords: GCE, Georgia, Georgia Coastal Ecosystems, irradiance, LTER, percent cover, plants, press, pulse, salinity, SALTEx, Sapelo Island, 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: SALTEx -- SALTEx Research Site, Champney Island, Georgia, USA Coordinates: SALTEx -- NW: 081 28 01.91 W, 31 20 23.40 N NE: 081 27 58.28 W, 31 20 23.40 N SE: 081 27 58.28 W, 31 20 20.23 N SW: 081 28 01.91 W, 31 20 20.23 N b. Physiographic Region: SALTEx -- unspecified c. Landform Components: SALTEx -- unspecified d. Hydrographic Characteristics: SALTEx -- unspecified e. Topographic Attributes: SALTEx -- unspecified f. Geology, Lithology and Soils: SALTEx -- unspecified g. Vegetation Communities: SALTEx -- Zizaniopsis, Spartina cynosuroides 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: SALTEx was initiated in 2012 (measurements began in 2014) and consists of 31 field plots , each 2.5 m on a side. There are three treatments (Press, Pulse, and Fresh) and two types of controls (with and without sides), each consisting of six replicates. The replicates are blocked by elevation in statistical analyses. The Press treatment plots receive regular (4 times each week) additions of a mixture of seawater and fresh river water. Pulse plots receive the same mixture of seawater and river water during September and October, which is historically a time of low flow in the river when saltwater intrusion naturally occurs. The Fresh treatment plots receive regular additions of fresh river water. b. Permanent Plots: none c. Data Collection Duration and Frequency: Light availability was measured using photosynthetically active radiation (PAR). Initial measurements in March 2014 served as a baseline for pre-treatment. Four to five measurements per growing season were made during dosing while 1-2 were made during recovery. Beginning of Observations: Mar 26, 2014 End of Observations: Aug 01, 2022 3. Research Methods a. Field and Laboratory Methods: Light Measurement -- Light availability was measured using photosynthetically active radiation (PAR). A SunScan Canopy Analysis System was used to collect PAR values above plant canopy and 10 cm above the soil surface. The proportion of light penetrating the canopy was then calculated. Initial measurements in March 2014 served as a baseline for pre-treatment. Four to five measurements per growing season were made during dosing while 1-2 were made during recovery. Analysis focused on comparing summer months (June and July), when aboveground biomass reaches its seasonal peak, except for 2017 when light was measured only in October. b. Protocols: none c. Instrumentation: SunScan Canopy Analysis System Manufacturer: Delta-T Devices (Model: SS1-UM-1.05) Parameter: PAR intensity (Accuracy: 10%, Readability: 0.3 mmol/m^2/s, Range: 0-2500 mmol/m^2/s) d. Taxonomy and Systematics: not applicable e. Speclies List: f. Permit History: not applicable 4. Project Personnel a. Personnel: Christopher B. Craft b. Affiliations: Indiana University at Bloomington, Bloomington, Indiana III. Data Set Status and Accessibility A. Status 1. Latest Update: 25-Jul-2024 2. Latest Archive Date: 25-Jul-2024 3. Latest Metadata Update: 25-Jul-2024 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: Apr 30, 2024, Public: Apr 30, 2026 b. Citation: Data provided by the Georgia Coastal Ecosystems Long Term Ecological Research Project, supported by funds from NSF OCE 1832178 (data set PLT-GCED-2404a) 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-GCED-2404a_1_0.CSV 2. Size: 369 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: 7. Authentication Procedures: 8. Calculations: Light_penetration: PAR_below/PAR_above Light_lost: 1-Light_penetration 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-GCED-2404a.txt (369 records) Data processing history: 25-Jul-2024: new GCE Data Structure 1.1 created ('newstruct') 25-Jul-2024: 369 rows imported from ASCII data file 'PLT-GCED-2404a.txt' ('imp_ascii') 25-Jul-2024: 10 metadata fields in file header parsed ('parse_header') 25-Jul-2024: data structure validated ('gce_valid') 25-Jul-2024: Q/C flagging criteria applied, 'flags' field updated ('dataflag') 25-Jul-2024: automatically assigned study date metadata descriptors based on the range of date values in date/time columns (add_studydates) 25-Jul-2024: updated 1 metadata fields in the Dataset section(s) ('addmeta') 25-Jul-2024: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 25-Jul-2024: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 25-Jul-2024: updated 6 metadata fields in the Data section(s) ('addmeta') 25-Jul-2024: updated 15 metadata fields in the Status, Data sections to reflect attribute metadata ('updatecols') 25-Jul-2024: parsed and formatted metadata ('listmeta') B. Variable Information 1. Variable Name: column 1. Year column 2. Month column 3. Treatment column 4. Replicate column 5. PAR_above column 6. PAR_below column 7. Light_penetration column 8. Light_lost 2. Variable Definition: column 1. Year measurement was taken column 2. Month measurement was taken column 3. Sample treatment column 4. Replicate of the treatment plot column 5. Photosynthetically active radiation measured above the canopy column 6. Photosynthetically active radiation measured below the canopy column 7. Percentatge of light that penetrated the canopy column 8. Percentage of light lost to canopy 3. Units of Measurement: column 1. YYYY column 2. MM column 3. none column 4. none column 5. umol/m^2/s column 6. umol/m^2/s column 7. % column 8. % 4. Data Type a. Storage Type: column 1. integer column 2. integer column 3. string column 4. integer column 5. floating-point column 6. floating-point column 7. floating-point column 8. floating-point b. Variable Codes: c. Numeric Range: column 1. 2014 to 2022 column 2. 3 to 10 column 3. (none) column 4. 1 to 9 column 5. 168.1 to 8161.1 column 6. 12.9 to 1994 column 7. 0.036782 to 1.2474 column 8. -0.24741 to 0.96322 d. Missing Value Code: 5. Data Format a. Column Type: column 1. numerical column 2. numerical column 3. text column 4. numerical column 5. numerical column 6. numerical column 7. numerical column 8. numerical b. Number of Columns: 8 c. Decimal Places: column 1. 0 column 2. 0 column 3. 0 column 4. 0 column 5. 1 column 6. 1 column 7. 3 column 8. 3 6. Logical Variable Type: column 1. datetime (discrete) column 2. datetime (discrete) column 3. nominal (none) column 4. nominal (discrete) column 5. data (continuous) column 6. data (continuous) column 7. calculation (continuous) column 8. calculation (continuous) 7. Flagging Criteria: column 1. x<2014="Q";x>2022="Q" column 2. x<1="I";x>12="I";x<3="Q";x>10="Q" column 3. none column 4. none column 5. none column 6. none column 7. none column 8. 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