Herbaceous zones in a Carolina bay in Maryland (Delmarva Bay) were monitored annually during 1987-97 by fixed-point photography and by sampling peak percent cover of each species in permanent plots during years of sufficient drawdown. The peripheral Panicum hemitomon zone of 1987 became dominated in 5 years by Acer rubrum (red maple) and Liquidambar styraciflua (sweet gum) with mean peak percent cover increasing from 22% to 88%. Live P. hemitomon cover decreased from 80% to 1%, and Rhexia virginica disappeared from sampling plots. Since the P. hemitomon population did not expand or migrate toward the center of the bay, this zone could be replaced by forest.Another peripheral zone, dominated in 1987 by Rhynchospora charalocephala, also was overtaken by red maple and sweet gum; Rhexia virginica all but disappeared from the zone; and this zone likewise could become forested. The central zone was dominated throughout the study by Scleria reticularis, R. virginica, Lachnanthes caroliniana, and Panicum verrucosum. Although the relative cover of central zone species changed from year to year, a significant trend in absolute percent cover did not occur over the 11-year period. However, in ecotone plots of the central zone and the P. hemitomon zone, R. virginica decreased significantly while red maple and sweet gum increased significantly, thus indicating that afforestation of peripheral communities is already affecting the central zone. Woody plant establishment is probably related to very low rainfall during the winters of 1984-85 and 1985-86 and summers of 1986 and 1987. Once established, subsequent flooding conditions were insufficient to kill saplings and small trees. Studies are needed to understand the potential contribution of farm irrigation wells, regional drainage ditches, and a contiguous pine plantation to bay afforestation. In addition, knowledge of the historic role of Amerindian fires in the Delmarva Bay ecosystem could be helpful in better understanding natural vegetation dynamics. Published by Southern Appalachian Botanical Society. Abstract reproduced by permission.