Sapelo Research Application Form
Research Application ID: GCE-158-2026 (submitted: 08/14/2026, status: approved)
Provide a brief title for web display
GCE-V: Variability x Experimental Flooding
Investigator Information
On Island Sponsor: GCE SINERR UGAMI GADNR
| Principal Investigator: | Georgianne Moore | ||
| Home Institution: | Georgia Southern University | ||
| Award Information: | GCE-LTER sub-award to Georgia Southern, NSF, ~$20k | ||
| Mailing Address: | Phone Number: | ||
| E-mail Address: | gmoore@georgiasouthern.edu | ||
| Co-investigators: | Hossain Sammi (Georgia Southern University) | ||
Briefly describe the project goals and methodology
Storm surges and sea-level rise (SLR) cause saltwater intrusion and frequent flooding in coastal forest ecosystems; two drivers or stressors that are primarily responsible for coastal forest retreat and subsequent marsh expansion (Tully et al. 2019; Middleton and David 2022). Along with the reduction or halting of forest regeneration, young trees are typically the first to experience mortality from these stressors (Desantis et al. 2007). The physiological responses of plants to salt stress and flooding may be similar across species; however, the mechanisms they use to handle these stressors are highly species-specific (Domec et al. 2021). Pinus taeda L. (loblolly pine) is a moderately flood-tolerant, mesophytic tree species (Hook 1984), capable of growing on a wide array of soils, such as the lower coastal plain in pure and mixed stands, where water is poorly drained. The coastal forests that loblolly pines naturally occupy experience flooding and occasional saltwater intrusion due to storms and/or high-tide events (Pezeshki 1992). But this species is known to be sensitive to salt exposure. Therefore, considering P. taeda as our study subject, we will manipulate inundation and salinity (external drivers) to examine morphophysiological responses of P. taeda. The primary objective of our saline flooding experiment is to help "understand how changes in both the mean and variability of salinity, inundation, and temperature affect ecological responses". This study directly addresses two research questions outlined in the GCE-V LTER project description: "Q1: What are the linkages between external drivers and ecological responses, and Q2: does assessing the variability of key abiotic drivers improve explanatory power for predicting ecological responses?"
To simulate flooding conditions, first, 1.5 ft deep and 0.5 ft wide trenches will be dug around the base of 15 selected pine trees in a 10 ft × 10 ft square configuration. Next, 2 ft plastic barriers will be placed vertically in each trench to fully enclose each tree. Approximately 6 inches of the plastic barrier will be visible aboveground. Groundwater monitoring wells, soil moisture and EC sensors, soil respiration collars, and automated dendrometer bands will be installed for periodic/continuous monitoring. Each tree group, comprised of 5 trees, will receive one of the three following treatments:
1. Monthly flooding (press): Up to 120 gallons of saltwater per tree per month pumped during the full moon over a 12-month period. Delivery will be rapid enough to temporarily raise the water table below those 5 trees (<1 hr).
2. Annual flooding (pulse): Up to 1440 gallons of saltwater per tree (equivalent to the total amount of water pumped to each tree under monthly flooding treatment) during the September full moon, over 3 or 4 high tide cycles. Delivery will again be rapid, but modulated to keep from overtopping the barriers (n=5 trees)
3. Normal seawater exposure control: No artificial seawater addition and enclosures are perforated to prevent restriction of lateral water movement (n=5 trees).
Where will the project be located?
At the beginning of lighthouse road, east side. 31 23'32.32" N, 81 16'20.84" W
How will you provide GPS coordinates for study sites?
I will provide a spreadsheet containing GPS coordinates for my study sites
What are the expected start and end dates of the project?
Start Date: 09/01/2026 End Date: 06/30/2029
How many people will access the site and at what frequency?
Over a period of 8 - 10 days, broken into three trips, 3 people will dig ditches, install plastic barriers, install sensors, install wells, and wire/power the site with a centralized enclosure, datalogger, batteries, and solar panel. This will be ideally completed during the fall/winter dormant season to minimize tree stress. In early spring, we will begin monitoring tree-physiological responses during a pre-treatment period of 3 months. Access to the site will be 2 days per month with 2 persons. Starting around April 2027, monthly flooding will be conducted by a 2-people group during full moon over 2 days and annual flooding by a group of 3 - 4 people for over 3 - 5 days in September 2027. Post-treatment data will continue to be collected for approx. one year after the flooding experiment ends to monitor tree recovery.
Keywords that describe your project
What equipment will be deployed in the field?
All equipment will be in the vicinity of the trees within the upland (adjacent to salt marsh). We will minimize the amount of equipment visible from the Lighthouse Road. Shallow groundwater wells will be placed inside each enclosure (2" PVC, approx. 40" deep and 8" aboveground). 8-foot metal posts driven 3-feet into the ground will be used to mount enclosures (up to 2) and solar panels (up to 2) at strategic locations near the trees. 10-inch diameter PVC rings (total of 15) will be installed in each enclosure for soil respiration measurements. Some wire from trees to the enclosure(s) containing a datalogger will be placed on the soil surface. Two 300-gallon tanks will be left on site for the duration of the flooding and pipes will connect from those tanks to the 5 trees selected for the monthly flooding. Additional larger tanks (open top fiberglass basins) and more hoses will be used temporarily for the September 2027 pulse event and removed within a week. Those larger tanks will be located nearer to the road because of their size. Additional details about equipment used during different project phases is described below.
Walk-behind trencher and plastic barriers
A walk-behind trencher (Ditch Witch 1020) will be used to dig trenches around the base of 15 selected trees. 2-ft- vertical plastic barriers, 0.5 ft extending above ground, will be placed inside the trenches and back-filled to confine the flood water within the root zone of each tree for at least 30 minutes, or until it drains naturally. After trenching, the trencher will be moved from the site, but the barriers will be in their place until the conclusion of the study.
Tree marking
Aluminum tags will be fastened with a stainless-steel nail to mark the trees that will end up in the experimental study. The locations of all the preliminarily selected trees are provided in the CSV file. Plastic and/or metal dendrometer bands will be attached to each study tree to monitor DBH. Dendrometer bands will be secured and monitored regularly to prevent girdling. Trees will remain tagged until the conclusion of the experiment.
Dataloggers, sap-flow sensors, soil moisture sensors, logger boxes, solar panels, batteries, and enclosures
Two Campbell Scientific weather-resistant fiberglass-reinforced polyester enclosures equipped with Cambell Scientific data logger will be installed in these locations: 31o23'34.98"N, 81o16'20.00"W and 31o23'29.68"N, 81o16'22.37"W. Two sap-flow sensors (comprised of 2 hypodermic needles, copper, and constantan wire), each covered with Reflectix aluminum and polyethylene protective insulation, will be installed on a subset of large-sized trees to measure their sap flow. To measure the root-zone soil moisture of each tree, 3 - 9 SOLYX 14 soil moisture sensors will be placed 12 inches below the soil surface. 3 automated dendrometer bands will be installed to take continuous measurements of DBH. To power the data loggers and sensors, 2 solar panels of approximate dimensions of 23.25" × 19.75" will be installed. 2 steel T-posts of 8 feet in length will be buried 3 feet into the ground, and the remaining length will be above the ground to mount each logger box and panel. Solar panels will be placed to ensure maximum exposure to the sun, while minimizing the distance from the enclosure and being located out of view from the lighthouse road to the extent possible. The Campbell Scientific enclosure or logger box (14" × 12") will protect the data loggers and battery from bad weather and will stay connected to the sensors and solar panel through 8 - 12-gauge PVC exteriors wires. This whole setup is fully removable and will be taken down once we reach the conclusion of our study.
Groundwater monitoring wells
Up to 10 shallow groundwater monitoring wells (~ 4 ft deep) equipped with Solinst level loggers will be strategically installed inside and outside tree enclosures to continuously monitor the groundwater table. Each logger will stay suspended by a Kevlar rope inside of a 6 ft long and 2-inch diameter PVC pipe. The wells and loggers will be removed from the site after the conclusion of the study.
Large water containers and dually truck
Saltwater for the monthly and annual flooding treatment will be sourced from the wet lab at the UGAMI. Two 300-gallon tanks will be filled and carried to the site on the flatbed of a F350 dually. The truck will remain on the roadside only long enough to empty water into two additional holding tanks located closer to the trees. Using a manifold, the water from the holding tanks will be supplied to the base of the 5 designated trees for approximately 30 minutes (timed to high tide, delivery rate optimized to raise water table under the tree temporarily by ~5 cm). To ensure a constant and similar water flow across trees, a pressure regulator equipped with a lightweight composite electromagnetic flow meter (EFM) model M10 will be used.
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Will plants or animals be collected as part of this study?
Yes. Plant parts, such as leaves, stems, and roots, will be collected from each selected loblolly pine. At the duration of the experiment, we will harvest the smaller trees and take tree cores of the larger trees to look at tree rings and analyze aboveground biomass, tissue salt accumulation, and other variables.
What are the likely impacts of the project on the site?
The saltwater treatment may be lethal to some trees. While excavating the soil, a few nearby smaller trees will be trimmed or removed. Soil disturbance from trenching and from removal of the plastic barriers will be mitigated by back filling and levelling the soil to the extent possible.
Will the project design include boardwalks? If not, explain why not.
How long will impacts persist after the research is concluded?
Minimal long-term impacts on soil, vegetation, and ecosystem structures is expected. Trenches will be back filled after removal of plastic barriers. All PVC wells will be removed at the conclusion of the study.
Files attached to this application
GCE-158-2026_Documents_PermitRequest_Lighthouse_ExpFlooding.docx (MS Word file, 5281.58 kb, submitted 08/14/2026)
GCE-158-2026_GPS_Lighthouse_tree_locations.xlsx (MS Excel file, 11.5 kb, submitted 08/14/2026)
