Marsh plant succession 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 Hongyu Guo University of Houston

Department of Biology and Biochemistry 369 Science and Research Bldg 2 University of Houston Houston Texas 77204-5001 USA

greatuniverse@hotmail.com Graduate research assistant 2026

Pennings is conducting parallel experiments in GA and AL to examine 1) how rapidly marsh vegetation can recover from disturbance, and 2) the role of competition in secondary succession. In 3 vegetation zones (Spartina alterniflora-meadow border, meadow-Juncus roemerianus border, J. roemerianus zone) at each of 2 marshes in each state, replicate 3 x 3 m plots were cleared using herbicide and clipping and maintained free of vegetation for 2 years. Control plots were marked but unmanipulated. In 2000, individual plots were divided into two or four quadrants, depending on the diversity of the vegetation in each zone, with one quadrant allowed to recover without further manipulation and the other quadrant(s) treated by periodically removing 1 or 2 dominant plant species occurring in each zone. To date, succession has been fastest in plots on the Spartina alterniflora-meadow border, which have already converged on control plot values, and slowest in the J. roemerianus plots, which are still early in the successional trajectory. Removal treatments indicate that competition plays a strong role in mediating the composition of the vegetation in each zone.

Question 2: How do the spatial and temporal patterns of biogeochemical processes, primary production, community dynamics, decomposition, and disturbance vary across the estuarine landscape, and how do they relate to environmental gradients? (more information)

LTER NSF Alabama Georgia GCE Juncus Spartina competition disturbance marsh recovery succession vegetation Overall geographic extent of the research project -81.299522 -81.264378 31.418830 31.371003 2000-01-01

National Science Foundation grant numbers OCE-9982133 and 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 Airport_marsh - Airport_marsh sampling site used by Amy Kunza in 2005 to study plant species richness -81.289670 -81.289670 31.418830 31.418830