I. Data Set Descriptors A. Title: Steven C. Pennings. 2026. GCE-LTER Altamaha River Plant Community Monitoring Survey in October 2025. Georgia Coastal Ecosystems LTER Data Catalog (data set PLT-GCEM-2511c; /data/PLT-GCEM-2511c) B. Accession Number: PLT-GCEM-2511c C. Description 1. Originator(s): Name: Steven C. Pennings Address: Department of Biology and Biochemistry University of Houston Houston, Texas 77204-5513 Country: USA Email: scpennin@central.uh.edu 2. Abstract: A quadrat survey was conducted in October 2025 to measure the species and size distribution of plants at 3 sampling sites on the creekbank of the Altamaha River. The sites were chosen to capture the transition from Spartina alterniflora to Spartina cynosuroides (site SCSA) and the transition from Spartina cynosuroides to Zizaniopsis miliacea (sites ZSC1 and ZSC2). The quadrats were established as permanent plots in October 2012 by placing PVC stakes along the creekbank at each site. Plots were evenly spaced, but were not randomly located because the goal was to start with mixtures of vegetation in most of the plots, and vegetation was distributed in patches along the creekbanks. Therefore, these plots provide useful measures of vegetation change, but are not a random sample of the vegetation at the site. Plots will be replaced each year as necessary to replace any lost to disturbance. The plots were visually surveyed and the species, shoot height, and flowering status was recorded individually for each shoot over 10 cm in height present in each plot. Observations from plots exhibiting signs of disturbance were noted in a separate data set. This survey will be repeated annually to assess changes in plant distribution and biomass in relation to environmental changes documented by other GCE LTER monitoring efforts. 3. Study Type: Monitoring 4. Study Themes: Population Ecology 5. LTER Core Areas: Population Studies 6. Georeferences: none 7. Submission Date: Jan 28, 2026 D. Keywords: aboveground biomass, Acrididae, Acrididea, Acridoidea, Angiospermae, Animalia, Arthropoda, Bilateria, biomass, Bolboschoenus robustus, Caelifera, Cladium jamaicense, Cladium mariscus, Cyperaceae, Cyrtacanthacridinae, Ecdysozoa, Embryophyta, flowering, GCE, Georgia, Georgia Coastal Ecosystems, Hexapoda, Insecta, Juncaceae, Juncus roemerianus, Lilianae, LTER, Magnoliopsida, marshes, monitoring, Neoptera, Orthoptera, permanent plots, plant biomass, plant communities, plant cover, plant ecology, plant growth, Plant Monitoring, Plantae, Poaceae, Poales, Polyneoptera, Population Studies, Protostomia, Pterygota, Sapelo Island, Schistocerca obscura, Schoenoplectus americanus, Schoenoplectus pungens, Schoenoplectus tabernaemontani, Scirpus americanus, Scirpus olneyi, Scirpus robustus, Scirpus validus, shoot height, Spartina alterniflora, Spartina cynosuroides, Spermatophytina, Streptophyta, Tracheophyta, Typha angustifolia, Typhaceae, USA, Viridaeplantae, Viridiplantae, Zizaniopsis miliacea II. Research Origin Descriptors A. Overall Project Description 1. Project Title: Georgia Coastal Ecosystems LTER - V 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: Jul 01, 2025 to Jun 30, 2031 4. Objectives: The GCE-V project has 5 objectives. Obj. 1 Characterize spatial and temporal patterns in mean and variability of drivers and responses. This will be done by measuring external drivers (e.g., sea level), marsh and estuarine conditions, the wetland biophysical template, and modeling. Obj. 2 Evaluate linkages between external drivers and ecological responses, and determine whether assessing the variability of abiotic drivers improves explanatory power for predicting ecological responses. This will be done by analyzing long-term data and conducting field campaigns in areas with different salinity standard deviations and time-varying inundation, and complementary mechanistic experiments exploring effects of driver variability (e.g., salinity). Obj. 3 Assess disturbances and their effects on patterns of variability in ecological responses. This will be done by tracking response and recovery to natural disturbances in the field and in ongoing experimental manipulations. Obj. 4 Evaluate how ecological properties change across abiotic gradients, and determine whether variability increases near habitat transitions. This will be done using remote sensing, sampling across gradients of salinity and inundation, and establishing new long-term monitoring sites in forested areas to track upland marsh migration. Obj. 5 Determine the mechanisms by which coastal wetlands respond to changing drivers and assess whether variability informs this understanding. This will be done by conducting univariate and multivariate analyses relating key ecosystem variables (e.g., net ecosystem exchange, plant biomass) to drivers (salinity, inundation, temperature), using remote sensing to investigate spatial and temporal patterns in the mean and variability of marsh productivity and their relationship to variability in climate drivers, and synthesizing results to describe net daytime production and above- and below-ground C stocks and how they might change in response to future conditions. 5. Abstract: The Georgia Coastal Ecosystems (GCE) Long Term Ecological Research (LTER) program, which was established in 2000 to understand estuaries (places where salt water from the ocean mixes with fresh water from the land) and their adjacent coastal wetlands (i.e., marshes and tidal forests) and how they respond to long-term change. The GCE LTER researchers evaluate how environmental conditions (e.g., sea level, temperature, storms and hurricanes) and human activities (e.g., land use) affect the properties of estuaries (e.g., salinity, flooding patterns), and how that in turn affects wetlands and their ability to provide food and refuge for fish, shellfish and birds, to protect the shoreline from storms, to help to keep the water clean, and to store carbon, all of which have significant implications for the US economy. Many of the changes that are occurring are affecting not just average conditions, but also their fluctuations and extremes (e.g., variability). For example, not only has the average high tide level increased over the past decade, but the number of extreme flooding events has also increased, both of which have the potential to lead to wetland loss through drowning. During this award, the research team will conduct studies to systematically evaluate 1) whether we can improve our predictions of ecological responses by considering variability in environmental conditions, and 2) the use of variability as an early indicator of underlying environmental stress. The findings from this research will be important for predicting the long-term survival of coastal wetlands in a time of global change. In addition to research, the GCE program works with teachers and students, coastal managers, citizen scientists, and the general public to enhance scientific literacy and improve our understanding of coastal ecosystems. 6. Funding Source: NSF OCE 2425396 B. Sub-project Description 1. Site Description a. Geographic Location: SCSA -- SCSA Altamaha Plant Transition Site, Georgia, USA ZSC1 -- ZSC1 Altamaha Plant Transition Site, Georgia, USA ZSC2 -- ZSC2 Altamaha Plant Transition Site, Georgia, USA Coordinates: SCSA -- NW: 081 22 34.61 W, 31 19 25.64 N NE: 081 22 16.54 W, 31 19 25.64 N SE: 081 22 16.54 W, 31 19 20.07 N SW: 081 22 34.61 W, 31 19 20.07 N ZSC1 -- NW: 081 27 11.04 W, 31 19 47.07 N NE: 081 26 54.01 W, 31 19 47.07 N SE: 081 26 54.01 W, 31 19 37.01 N SW: 081 27 11.04 W, 31 19 37.01 N ZSC2 -- NW: 081 27 18.91 W, 31 20 31.29 N NE: 081 27 05.14 W, 31 20 31.29 N SE: 081 27 05.14 W, 31 20 19.92 N SW: 081 27 18.91 W, 31 20 19.92 N b. Physiographic Region: SCSA -- Lower coastal plain ZSC1 -- Lower coastal plain ZSC2 -- Lower coastal plain c. Landform Components: SCSA -- Estuarine tidal marsh ZSC1 -- Estuarine tidal marsh ZSC2 -- Estuarine tidal marsh d. Hydrographic Characteristics: SCSA -- Site borders the Altamaha River, and is subject to 2-3m semi-diurnal tides ZSC1 -- Site borders the Altamaha River, and is subject to 2-3m semi-diurnal tides ZSC2 -- Site borders the Champney River, and is subject to 2-3m semi-diurnal tides e. Topographic Attributes: SCSA -- Flat, with elevations ranging from 0-3m above mean low tide ZSC1 -- Flat, with elevations ranging from 0-3m above mean low tide ZSC2 -- Flat, with elevations ranging from 0-3m above mean low tide f. Geology, Lithology and Soils: SCSA -- unspecified ZSC1 -- unspecified ZSC2 -- unspecified g. Vegetation Communities: SCSA -- Spartina alterniflora and Spartina cynosuroides ZSC1 -- Spartina cynosuroides and Zizaniopsis miliacea ZSC2 -- Spartina cynosuroides and Zizaniopsis miliacea h. History of Land Use and Disturbance: SCSA -- Oct 14, 2013: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. The following plots were disturbed by wrack: C1. The following plots are located on creek bank areas that are collapsing: C1, C4. Oct 17, 2014: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. The following plots are on creekbank areas that are collapsing: C4, C7. The following plots were lost and replaced: C1 (replaced with C11). Oct 22, 2015: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. The following plots are on creekbank areas that are collapsing: C5. The following plots were lost due to creekbank erosion (terminal slump) and replaced: C11, C4, C7, C8 (replaced with C21, C14, C17, C18 resp). ZSC1 -- Oct 14, 2013: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. No disturbance was observed, and no plots were replaced. Oct 17, 2014: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. No disturbance was observed, and no plots were lost and replaced. Oct 22, 2015: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. No disturbance was observed, and no plots were lost and replaced. ZSC2 -- Oct 14, 2013: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. No disturbance was observed, and no plots were replaced. Oct 17, 2014: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. The following plots were disturbed by wrack: C3 (no plants). No plots were lost and replaced. Oct 22, 2015: Plots were examined for signs of disturbance by wrack inundation, animal activity, and creek bank erosion. The following creekbank plots are on creekbank areas that are collapsing (slump): C3. Not plots were lost and none were replaced. 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: A quadrat survey was conducted in October 2025 to measure the species and size distribution of plants in the permanent plots at 3 GCE LTER sampling sites along the Altamaha River. Sites were chosen to represent transition zones in major plant species along the estuary. b. Permanent Plots: Permanent plots were established in the creek bank zone at each sampling site in October, 2012. Eight plots were evenly spaced along vegetated patches at each site and marked with PVC stakes. c. Data Collection Duration and Frequency: Species and size distribution of plants of three sites along the Altamaha River were measured in 8 evenly space plots in the creekbank zone at each site. Plots were chosen to provide useful measures of vegetation change, but are not a random sample of the vegetation at the site. Beginning of Observations: Oct 18, 2025 End of Observations: Oct 18, 2025 3. Research Methods a. Field and Laboratory Methods: Method 1: Quadrat sampling -- Quadrats were placed within the creekbank zone at each site (eight plots per site) to create permanent plots in October 2012. The quadrats were marked using PVC stakes and measured 0.5m by 0.5m, as indicated in the "Quadrat_Area" data column. Method 2: Plant measurement -- The taxon, shoot height, and flowering status was recorded for each live shoot > 10cm in height present in each quadrat. Method 3: Biomass Calculation -- Plant biomass was calculated for predominant flowering plants based on the allometric relationships between plant height, flowering status and biomass calculated by site, zone and species using the formula: ln(Biomass) = constant + htslope*ln(Plant_Height) + flslope*ln(Flowering_Status). b. Protocols: Method 1: none Method 2: none Method 3: none c. Instrumentation: Method 1: none Method 2: PVC ruler, Parameter: length Method 3: none d. Taxonomy and Systematics: Method 1: not applicable Method 2: not applicable Method 3: not applicable e. Speclies List: f. Permit History: Method 1: not applicable Method 2: not applicable Method 3: not applicable 4. Project Personnel a. Personnel: Steven C. Pennings b. Affiliations: University of Houston, Houston, Texas III. Data Set Status and Accessibility A. Status 1. Latest Update: 30-Jan-2026 2. Latest Archive Date: 30-Jan-2026 3. Latest Metadata Update: 30-Jan-2026 4. Data Verification Status: Reviewed by IM 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: Jan 28, 2026, Public: Jan 28, 2027 b. Citation: Data provided by the Georgia Coastal Ecosystems Long Term Ecological Research Project, supported by funds from NSF OCE 2425396 (data set PLT-GCEM-2511c) 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-GCEM-2511c_1_0.CSV 2. Size: 221 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: E = location estimated based on GPS coordinates of prior or replacement plot(s) 7. Authentication Procedures: 8. Calculations: Plant_Biomass(g) = e^(constant + htslope*ln(Shoot_Height(cm)) + flslope*(Flowering_Status)), based on the following parameter estimates for constant, htslope and flslope from curve fits of allometry data by plot, marsh zone and species, respectively: Site 1, Zone 1, Species_Code A1, Year 2002: -6.83, 1.806, 0.354; Site 1, Zone 2, Species_Code A3, Year 2002: -7.873, 1.731, 0; Site 1, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 1, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 1, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 1, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 1, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 1, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 2, Zone 1, Species_Code A1, Year 2002: -6.325, 1.869, 0; Site 2, Zone 2, Species_Code A1, Year 2002: -8.458, 2.366, -0.455; Site 2, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 2, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 2, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 2, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 2, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 2, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 3, Zone 1, Species_Code A1, Year 2002: -5.669, 1.672, 0; Site 3, Zone 2, Species_Code A1, Year 2002: -7.261, 2.062, -0.36; Site 3, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 3, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 3, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 3, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 3, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 3, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 4, Zone 1, Species_Code A1, Year 2002: -6.583, 1.87, 0; Site 4, Zone 2, Species_Code A1, Year 2002: -6.231, 1.71, 0; Site 4, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 4, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 4, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 4, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 4, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 4, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 5, Zone 1, Species_Code A1, Year 2002: -6.944, 1.938, 0.205; Site 5, Zone 2, Species_Code A1, Year 2002: -7.738, 2.066, 0; Site 5, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 5, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 5, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 5, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 5, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 5, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 6, Zone 1, Species_Code A1, Year 2002: -6.095, 1.76, 0.212; Site 6, Zone 2, Species_Code A1, Year 2002: -6.934, 1.973, 0; Site 6, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 6, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 6, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 6, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 6, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 6, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 7, Zone 1, Species_Code A4, Year 2002: -15.021, 3.521, 0; Site 7, Zone 2, Species_Code A4, Year 2002: -17.192, 3.953, 0; Site 7, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 7, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 7, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 7, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 7, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 7, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 8, Zone 1, Species_Code A1, Year 2002: -5.455, 1.604, 0.224; Site 8, Zone 2, Species_Code A1, Year 2002: -5.366, 1.591, 0; Site 8, Zone 1, Species_Code A2, Year 2002: -11.954, 2.804, 0.405; Site 8, Zone 2, Species_Code A3, Year 2002: -6.527, 1.507, 0; Site 8, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 8, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 8, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 8, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 8, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 8, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 9, Zone 1, Species_Code A1, Year 2002: -5.455, 1.604, 0.224; Site 9, Zone 2, Species_Code A1, Year 2002: -5.366, 1.591, 0; Site 9, Zone 3, Species_Code A3, Year 2002: -6.527, 1.507, 0; Site 9, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 9, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 9, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 9, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 9, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 9, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 10, Zone 1, Species_Code A1, Year 2002: -6.011, 1.719, 0; Site 10, Zone 2, Species_Code A1, Year 2002: -7.311, 1.988, 0; Site 10, Zone 3, Species_Code A1, Year 2002: -7.311, 1.988, 0; Site 10, Zone 2, Species_Code A2, Year 2002: -11.954, 2.804, 0.405; Site 10, Zone 2, Species_Code A3, Year 2008: -6.078, 1.44, 0; Site 10, Zone 3, Species_Code A3, Year 2008: -6.078, 1.44, 0; Site 10, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 10, Zone 2, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site 10, Zone 1, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 10, Zone 2, Species_Code A6, Year 2007: -9.458, 2.153, 0; Site 10, Zone 1, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site 10, Zone 2, Species_Code A7, Year 2007: -14.315, 3.397, 0.347; Site NaN, Zone 1, Species_Code A1, Year 2002: -5.455, 1.604, 0.224; Site NaN, Zone 1, Species_Code A2, Year 2002: -11.954, 2.804, 0.405; Site NaN, Zone 1, Species_Code A2, Year 2002: -11.954, 2.804, 0.405; Site NaN, Zone 1, Species_Code A2, Year 2002: -11.954, 2.804, 0.405; Site NaN, Zone 1, Species_Code A4, Year 2002: -15.021, 3.521, 0; Site NaN, Zone 1, Species_Code A4, Year 2002: -15.021, 3.521, 0; Site 1, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 1, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 1, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 1, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 2, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 2, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 2, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 2, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 3, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 3, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 3, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 3, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 4, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 4, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 4, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 4, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 5, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 5, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 5, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 5, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 6, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 6, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 6, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 6, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 7, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 7, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 7, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 7, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 8, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 8, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 8, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 8, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 9, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 9, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 9, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 9, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 10, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 10, Zone 2, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 10, Zone 1, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site 10, Zone 2, Species_Code A13, Year 2019: -6.8858, 1.5862, 0; Site NaN, Zone 1, Species_Code A5, Year 2007: -6.955, 1.495, 0; Site NaN, Zone 1, Species_Code A9, Year 2020: -8.5794, 2.0752, 0; Site 9, Zone 2, Species_Code A3, Year 2002: -6.527, 1.507, 0; Site 8, Zone 2, Species_Code A2, Year 2002: -11.954, 2.804, 0.405. 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: Altamaha_Template2025.xlsx (221 records) Data processing history: 28-Jan-2026: new GCE Data Structure 1.1 created ('newstruct') 28-Jan-2026: data imported from Excel data file 'Altamaha_Template2025.xlsx' (221 records) 28-Jan-2026: copied/reordered columns Year, Month, Day, Site, Zone, Plot, Quadrat_Area, Species_Code, Shoot_Height and Flowering_Status ('copycols') 28-Jan-2026: replaced values of 'Z SC 1' in column(s) Site with 'ZSC1', performing a full case-sensitive match ('string_replace') 28-Jan-2026: 84 values in 'Site' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Site, 'flags' field updated ('dataflag') 28-Jan-2026: replaced values of 'Z SC 2' in column(s) Site with 'ZSC2', performing a full case-sensitive match ('string_replace') 28-Jan-2026: 42 values in 'Site' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Site, 'flags' field updated ('dataflag') 28-Jan-2026: added column 'Location' at position 7 ('addcol') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: 102 values in 'Location' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: 102 values in 'Location' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: 102 values in 'Location' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: 102 values in 'Location' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: 102 values in 'Location' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: 102 values in 'Location' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: 102 values in 'Location' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: 102 values in 'Location' were updated with new values ('update_data') 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: 31 values in 'Location' were updated with new values ('update_data'): changed record 10 from 'SCSA_CB32' to 'SCSA_CB22', changed record 11 from 'SCSA_CB32' to 'SCSA_CB22', changed record 12 from 'SCSA_CB32' to 'SCSA_CB22', changed record 13 from 'SCSA_CB32' to 'SCSA_CB22', changed record 14 from 'SCSA_CB32' to 'SCSA_CB22', changed record 15 from 'SCSA_CB32' to 'SCSA_CB22', changed record 16 from 'SCSA_CB32' to 'SCSA_CB22', changed record 17 from 'SCSA_CB43' to 'SCSA_CB33', changed record 18 from 'SCSA_CB43' to 'SCSA_CB33', changed record 19 from 'SCSA_CB43' to 'SCSA_CB33', changed record 20 from 'SCSA_CB43' to 'SCSA_CB33', changed record 21 from 'SCSA_CB43' to 'SCSA_CB33', changed record 22 from 'SCSA_CB43' to 'SCSA_CB33', changed record 23 from 'SCSA_CB43' to 'SCSA_CB33', changed record 24 from 'SCSA_CB43' to 'SCSA_CB33', changed record 25 from 'SCSA_CB43' to 'SCSA_CB33', changed record 26 from 'SCSA_CB43' to 'SCSA_CB33', changed record 27 from 'SCSA_CB43' to 'SCSA_CB33', changed record 28 from 'SCSA_CB43' to 'SCSA_CB33', changed record 29 from 'SCSA_CB43' to 'SCSA_CB33', changed record 30 from 'SCSA_CB43' to 'SCSA_CB33', changed record 31 from 'SCSA_CB43' to 'SCSA_CB33', changed record 32 from 'SCSA_CB43' to 'SCSA_CB33', changed record 194 from 'ZSC2_CB13' to 'ZSC2_CB3', changed record 195 from 'ZSC2_CB13' to 'ZSC2_CB3', changed record 196 from 'ZSC2_CB13' to 'ZSC2_CB3', changed record 197 from 'ZSC2_CB13' to 'ZSC2_CB3', changed record 198 from 'ZSC2_CB13' to 'ZSC2_CB3', changed record 199 from 'ZSC2_CB13' to 'ZSC2_CB3', changed record 200 from 'ZSC2_CB13' to 'ZSC2_CB3', changed record 201 from 'ZSC2_CB13' to 'ZSC2_CB3' 28-Jan-2026: Q/C flagging criteria applied for column(s) Location, 'flags' field updated ('dataflag') 28-Jan-2026: added Longitude and Latitude columns by matching values in the Location column to entries in the GCE geographic database ('add_stationcoords') 28-Jan-2026: added column 'Location_Notes' at position 8 ('addcol') 28-Jan-2026: updated 1 metadata fields in the Data section(s) ('addmeta') 28-Jan-2026: manually added 'E' flags to 102 records in column(s) Location, Latitude and Longitude ('addflags') 28-Jan-2026: locked Q/C flag criteria for columns Location, Longitude and Latitude to prevent automatic evaluation ('flag_locks') 28-Jan-2026: updated 1 metadata fields in the Data section(s) ('addmeta') 28-Jan-2026: added geographic metadata based on matching values in columns Site and Location to site and transect names registered in 'geo_polygons.mat' and location and station names registered in 'geo_locations.mat' ('add_sitemetadata') 28-Jan-2026: updated 8 metadata fields in the Site section(s) ('addmeta') 29-Jan-2026: updated 1 metadata fields in the Dataset section(s) ('addmeta') 29-Jan-2026: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 29-Jan-2026: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 30-Jan-2026: Added a calculated plant biomass column using curve fit coefficents from allometric analyses relating plant height to mass determined for each Site, Zone and Species ('plant_biomass') 30-Jan-2026: Q/C flagging criteria applied for column(s) Plant_Biomass, 'flags' field updated ('dataflag') 30-Jan-2026: updated 1 metadata fields in the Dataset section(s) ('addmeta') 30-Jan-2026: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 30-Jan-2026: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 30-Jan-2026: flags for columns Location, Longitude and Latitude converted to data columns, flag codes updated in metadata ('flags2cols') 30-Jan-2026: updated 6 metadata fields in the Data section(s) ('addmeta') 30-Jan-2026: updated 15 metadata fields in the Status, Data sections to reflect attribute metadata ('updatecols') 30-Jan-2026: parsed and formatted metadata ('listmeta') B. Variable Information 1. Variable Name: column 1. Year column 2. Month column 3. Day column 4. Site column 5. Zone column 6. Plot column 7. Location column 8. Flag_Location column 9. Location_Notes column 10. Longitude column 11. Flag_Longitude column 12. Latitude column 13. Flag_Latitude column 14. Quadrat_Area column 15. Species_Code column 16. Shoot_Height column 17. Flowering_Status column 18. Plant_Biomass 2. Variable Definition: column 1. Year of observation column 2. Month of observation column 3. Day of observation column 4. GCE LTER sampling site column 5. Nominal marsh zone column 6. Permanent plot number column 7. Geographic location code in the GCE Metadata Database for the sampling plot column 8. QA/QC flags for Geographic location code in the GCE Metadata Database for the sampling plot (flagging criteria, where "x" is Location: manual) column 9. Notes on location assignments and geographic accuracy column 10. Geographic longitude in decimal degrees column 11. QA/QC flags for Geographic longitude in decimal degrees (flagging criteria, where "x" is Longitude: x<-180="I", x>180="I", manual) column 12. Geographic latitude in decimal degrees column 13. QA/QC flags for Geographic latitude in decimal degrees (flagging criteria, where "x" is Latitude: x<-90="I", x>90="I", manual) column 14. Areal measurement of the quadrat frame column 15. Plant species code column 16. Height of the plant shoot above the substrate column 17. Presence or absence of inflorescence column 18. Plant biomass calculated from shoot height and flowering status, based on curve fits of allometric data collected for each site, marsh zone and species 3. Units of Measurement: column 1. YYYY column 2. M column 3. D column 4. none column 5. none column 6. none column 7. none column 8. none column 9. none column 10. degrees column 11. none column 12. degrees column 13. none column 14. m^2 column 15. none column 16. cm column 17. none column 18. g 4. Data Type a. Storage Type: column 1. integer column 2. integer column 3. integer column 4. string column 5. integer column 6. integer column 7. string column 8. string column 9. string column 10. floating-point column 11. string column 12. floating-point column 13. string column 14. floating-point column 15. string column 16. floating-point column 17. integer column 18. floating-point b. Variable Codes: Site: ZSC1 = ZSC1 Altamaha Plant Transition Site, ZSC2 = ZSC2 Altamaha Plant Transition Site, SCSA = SCSA Altamaha Plant Transition Site Flowering_Status: 1 = flowering, 0 = not flowering, missing = not scored Species_Code: A1 = Spartina alterniflora, A2 = Spartina cynosuroides, A3 = Juncus Roemerianus, A4 = Zizaniopsis miliacea, A5 = Scirpus spp., A6 = Panicum spp., A7 = Typha spp., A8 = Unidentified rush, A9 = Schoenoplectus tabernaemontani, A10 = Cladium jamaicense, A11 = Schoenoplectus tabernaemontani Zone: 1 = creek bank zone, 2 = mid-marsh zone, 3 = additional Juncus zone in high marsh, -1 = old creek bank zone prior to plot relocation Flag_Location: E = location estimated based on GPS coordinates of prior or replacement plot(s) Flag_Longitude: E = location estimated based on GPS coordinates of prior or replacement plot(s) Flag_Latitude: E = location estimated based on GPS coordinates of prior or replacement plot(s) c. Numeric Range: column 1. 2025 to 2025 column 2. 10 to 10 column 3. 18 to 18 column 4. (none) column 5. 1 to 1 column 6. 1 to 61 column 7. (none) column 8. (none) column 9. (none) column 10. -81.4551 to -81.3734 column 11. (none) column 12. 31.323 to 31.3413 column 13. (none) column 14. 0.5 to 0.5 column 15. (none) column 16. 30 to 330 column 17. 0 to 1 column 18. 0.70551 to 177.234 d. Missing Value Code: 5. Data Format a. Column Type: column 1. numerical column 2. numerical column 3. numerical column 4. text column 5. numerical column 6. numerical column 7. text column 8. text column 9. text column 10. numerical column 11. text column 12. numerical column 13. text column 14. numerical column 15. text column 16. numerical column 17. numerical column 18. numerical b. Number of Columns: 18 c. Decimal Places: column 1. 0 column 2. 0 column 3. 0 column 4. 0 column 5. 0 column 6. 0 column 7. 0 column 8. 0 column 9. 0 column 10. 6 column 11. 0 column 12. 6 column 13. 0 column 14. 4 column 15. 0 column 16. 0 column 17. 0 column 18. 3 6. Logical Variable Type: column 1. datetime (discrete) column 2. datetime (discrete) column 3. datetime (discrete) column 4. coded value (none) column 5. coded value (discrete) column 6. nominal (discrete) column 7. nominal (none) column 8. coded value (none) column 9. free text (none) column 10. geographic coordinate (continuous) column 11. coded value (none) column 12. geographic coordinate (continuous) column 13. coded value (none) column 14. calculation (continuous) column 15. coded value (none) column 16. data (continuous) column 17. logical (discrete) column 18. calculation (continuous) 7. Flagging Criteria: column 1. none column 2. x<1="I";x>12="I" column 3. x<1="I";x>31="I" column 4. flag_notinlist(x,"ZSC1,ZSC2,SCSA")="Q" column 5. ~inarray([-1,1,2,3])="I" column 6. x<1="I";x>100="Q" column 7. manually-assigned flags column 8. none column 9. none column 10. x<-180="I";x>180="I";manually-assigned flags column 11. none column 12. x<-90="I";x>90="I";manually-assigned flags column 13. none column 14. x<.06="Q";x>.5="Q" column 15. flag_notinlist(x,"A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,A11")="Q" column 16. x<0="I";x>400="Q" column 17. x<0="I";x>1="I";strcmp(col_Species_Code,"JURO")&~isnull(col_Flowering_Status)="Q";inlist (col_Species_Code,"SPAL,SPCY")&~isnull(col_Shoot_Height)&isnull(col_Flowering_Status)="Q " column 18. x<=0="I" 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