In a tidal marsh on the Savannah River (Georgia, USA), rate of plant community change along a salinity gradient was measured using a reciprocal transplant study. Donor sods were moved in all possible combinations from freshwater to brackish sites and from brackish to freshwater sites at four different locations. The reciprocal aspect of the experiment also allowed the determination of how the rate of plant community change is affected by the direction and level of displacement along the salinity gradient. Stem densities of each species were counted in each transplanted plot in June and October for a 30-month period. Plant community structure and composition changed by a significantly measurable amount within 6 to 18 months of a change in salinity. However, the time required for the transplanted sods to resemble their surrounding communities (at the p ≤ 0.05 level) ranged from 6 to more than 30 months, with some transplanted sods never resembling the surrounding plant communities during the study period. If freshwater or oligohaline sods were moved to more saline environments, environmental conditions appeared to have an overriding effect on the vegetation and community change was rapid, occurring in 6–10 months (mean = 9.3 months, SE = 1.9). Shifts from brackish to fresher sites on the salinity gradient delayed community change to about 18 months (mean = 15.3 months, SE = 1.7) and appeared to be controlled by biotic factors such as vegetative expansion and interspecific competition.