PARENT SESSION
Poster Session #13: Salt Marshes.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Variation in zonation patterns of salt marsh plants among sites.

Buck, Tracy¹, Pennings, Steven^*,1,2, ¹ University of Georgia Marine Institute, Sapelo Island, GA² University of Houston, Houston, TX

ABSTRACT- Salt marsh plants display striking patterns of zonation across elevation that are caused by competition, salinity and flooding. Although overall zonation patterns are consistent across sites within a geographic region, many details may vary. We examined 55 salt marsh sites in coastal Georgia as part of the Georgia Coastal Ecosystems LTER. At each site, we monitored soil salinities monthly for 12 months, noted the shape of the marsh-upland interface, measured tidal distortion (tidal range at each site / tidal range at a reference site), and surveyed the vertical and horizontal ranges of the vegetation zones. Vegetation patterns were correlated with soil salinity. Sites with lower salinities were dominated by Juncus roemerianus. Spartina alterniflora increasingly dominated sites with higher salinities. At sites with the highest soil salinities, a meadow zone consisting of Batis, Distichlis and Salicornia species, and unvegetated areas, was present. These overall patterns were well known; however, the roles of salinity, variation in salinity, upland influence and tidal distortion in creating these patterns were not known. Regression analyses indicated strong relationships between vegetation patterns and soil salinity (as described above) and upland influence (sites with more upland influence had broader ranges of Juncus and narrower ranges of other species). In contrast, variation in the salinity regime (CV of soil salinity over time) and tidal distortion explained very little of the spatial variation in plant community structure.

KEY WORDS: salt marsh, zonation, LTER, wetland