Plant studies Dr. Steven C. Pennings University of Houston

Department of Biology and Biochemistry University of Houston Houston Texas 77204-5513 USA

scpennin@central.uh.edu https://uh.edu/nsm/biology-biochemistry/people/profiles/steven-pennings/ https://orcid.org/0000-0003-4757-7125 Georgia Coastal Ecosystems LTER Project

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

gcelter@uga.edu https://gce-lter.marsci.uga.edu/ Dr. Steven C. Pennings University of Houston

Department of Biology and Biochemistry University of Houston Houston Texas 77204-5513 USA

scpennin@central.uh.edu https://uh.edu/nsm/biology-biochemistry/people/profiles/steven-pennings/ https://orcid.org/0000-0003-4757-7125 Principal investigator 2009-01-01 Dr. Adrian B. Burd University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

adrianb@uga.edu http://www.marsci.uga.edu/directory/adrian-burd https://orcid.org/0000-0001-6345-8770 Co-investigator 2009-01-01 Jacob Shalack University of Georgia Marine Institute

University of Georgia Marine Institute Sapelo Island Georgia 31327 USA

shalack@uga.edu Research technician 2009-10-01 Kristen Anstead University of Georgia Marine Institute

University of Georgia Marine Institute Sapelo Island Georgia 31327 USA

kanstead@uga.edu Research technician 2009-01-01 2026

In order to help parameterize the plant model, we are conducting a greenhouse experiment evaluating the sensitivity of three common salt marsh plants, Spartina alterniflora, Juncus roemerianus, and Borrichia frutescens, to varying levels of shade (0 to 80% of light blocked) and salinity (0 to 60 PSU). Monthly measurements of plant size and photosynthetic rate over the course of a single growing season (2009) will help inform the model about how the three plant species respond to competition for light (as simulated by shade cloth) and salinity.

In order to help parameterize the plant model, we are collecting data on high marsh plant communities and associated soils. In 2009 we collected light profiles in stands of Spartina alterniflora, Juncus roemerianus, and Borrichia frutescens, with associated data on plant heights and densities. These data will provide information on how stands of different plant species at different densities affect the light environment for other plants (one mechanism of competition among plants). In 2009 we also collected data on soil porewater content and porewater salinity from stands of the same three plant species. These data will provide information on how the physical environment experienced by each plant species varies over space and time. To determine if plants are in fact rooting in the soils that we are sampling, we collected pre-dawn xylem pressure potential readings on all three species of plants (in theory, pre-dawn XPP readings are in equilibrium with soil water potentials).

Area 3: Responses to Salinity and Inundation (more information) Area 3: Responses to Salinity and Inundation (more information) Question 4: What are the underlying mechanisms by which proximity of marshes to upland habitat drives ecosystem change along lateral gradients in the intertidal zone? (more information)

LTER NSF GCE Borrichia Juncus Spartina greenhouse Overall geographic extent of the research project -81.299522 -81.264378 31.418899 31.371003 2009-01-01 2012-11-01

National Science Foundation grant number OCE-0620959

estuary marsh complex Dean Creek - Doboy Sound/salt marsh site at the southern end of Sapelo Island near Dean Creek and the Sapelo lighthouse. A few small creeks are present, but a large creek (Dean Creek) is easily accessed. Upland is composed of small hammocks and some constructed causeways, with sand dune complexes east of Dean Creek and extending to the beach. Upper end of the watershed is affected by a culvert at Beach Road and heavy student use of marsh immediately adjacent to culvert. A hydrographic sonde is deployed in Doboy Sound near Commodore Island approximately 1.5km from this site. GCE6 is also the focus of Sapelo Island Microbial Observatory research on microbial diversity and genomics (http://simo.marsci.uga.edu) -81.299522 -81.264378 31.394072 31.371003 Marsh Landing - Marsh landing, where the Georgia DNR ferry docks on its route between the mainland (Meridian) and Sapelo Island. -81.297445 -81.294606 31.418899 31.416399 UGA Marine Institute - The University of Georgia Marine Institute is located on the southern end of Sapelo Island, a barrier island off the central Georgia coast. -81.282950 -81.278834 31.398877 31.395295