Estimating upland areas of hammocks Dr. Merryl Alber University of Georgia

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

malber@uga.edu https://marsci.uga.edu/directory/people/merryl-alber https://orcid.org/0000-0002-9467-4449 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. Merryl Alber University of Georgia

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

malber@uga.edu https://marsci.uga.edu/directory/people/merryl-alber https://orcid.org/0000-0002-9467-4449 Principal investigator 2007-01-01 2009-12-31 Dr. Christine M. Hladik Georgia Southern University

Department of Geology and Geography Georgia Southern University Statesboro Georgia 30460 USA

chladik@georgiasouthern.edu https://www.georgiasouthern.edu/cosm/sees/christine-hladik/ https://orcid.org/0000-0002-0265-6412 Graduate research assistant 2007-01-01 2009-12-31 Caitlin Yeager University of Georgia

Department of Marine Sciences University of Georgia Athens Georgia 30602 USA

cyeager@uga.edu Undergraduate research assistant 2007-01-01 2009-12-31 2026

C. Yeager (BS student, UGA) and M. Alber (UGA) evaluated the differences in the digitized canopy border, obtained from aerial imagery, and ground-truthed observations of the upland border of marsh hammocks evaluated as part of the 2007 survey. They calculated the mean halo width of 54 marsh hammocks ranging in size, from <1 ha to >20 ha, and origin and tested to see whether there was a significant difference in the mean halo widths between hammocks of different origins, and sizes, as well as whether the presence of a creek bank significantly affected halo width. They also looked to see whether the slope of the land within a transect affected halo width. Halo width averaged 5.59 ± 8.81 m, and the halo width of Pleistocene hammocks was significantly different from that of other hammock origins (single factor analysis of variation, p< 0.05). The halo width of size class I hammocks was found to be significantly greater than size classes II, III, and IV (t-tests, p < 0.02). In addition, the halo width at points located along a creek bank were significantly larger than those that were located in the marsh (7.87 ± 4.07 m vs. 4.58 ± 8.29 m, t-test assuming equal variances, p<0.05). Lastly, the slope within the halo ranged from 15.67 to -67.43 with a mean -6.49 ± 8.25. Although there was a general decrease in elevation from the upland order to the canopy line, no consistent trend could be discerned when halo width was plotted against slope for each transect.

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 aerial imagery Georgia halo hammock marsh upland Overall geographic extent of the research project -81.295506 -81.195661 31.546868 31.395295 2007-01-01 2009-12-31

National Science Foundation grant number OCE-0620959

estuary marsh complex Hunt Camp - Barrier island/marsh site on western Sapelo Island. This site is located at the upper reaches of the Duplin River, and is within the Sapelo Island National Estuarine Research Reserve. Existing well fields border small marsh area to northwest, some wells have been installed to south end of hammock where marsh is more extensive and permanent plots are located. Two existing hydrographic sondes and weather stations within this site are operated by SINERR (Hunt Camp dock) and UGAMI (flume dock). -81.295506 -81.258908 31.497026 31.462320 North Sapelo - High salinity marsh/Sapelo Sound site. Few or no small creeks, but one large creek is easily accessed. Further upstream upland drainage is affected by culvert at Reynolds' duck pond. Upland is heavily forested. Hydrographic sonde is deployed adjacent to this site attached to a channel marker (under U.S. Coast Guard permit). A huge mud flat is present at the northern tip of Sapelo Island. -81.233249 -81.195661 31.546868 31.515188 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 Hammock overview. https://gce-lter.marsci.uga.edu/public/resources/projects/hammockOverview.png