Effect of climate fluctuation on long-term vegetation dynamics in Carolina bay wetlands
Carolina bays and similar depression wetlands of the U. S. Southeastern Coastal Plain have hydrologic regimes that are driven primarily by rainfall. Therefore, climate fluctuations such as drought cycles have the potential to shape long-term vegetation dynamics. Models suggest two potential long-term responses to hydrologic fluctuations, either cyclic change maintaining open emergent vegetation, or directional succession toward forest vegetation. In seven Carolina bay wetlands on the Savannah River Site, South Carolina, we assessed hydrologic variation and vegetation response over a 15-year period spanning two drought and reinundation cycles. Changes in pond stage (water depth) were monitored bi-weekly to monthly each year from 1989 to 2003. Vegetation composition was sampled in three years (1989, 1993, and 2003) and analyzed in relation to changes in hydrologic conditions. Multi-year droughts occurred prior to the 1989 and 2003 sampling years, whereas 1993 coincided with a wet period. Wetland plant species generally maintained dominance after both wet and dry conditions, but the abundances of different plant growth forms and species indicator categories shifted over the 15-year period. Decreased hydroperiods and water depths during droughts led to increased cover of grass, upland, and woody species, particularly at the shallower wetland margins. Conversely, reinundation and longer hydroperiods resulted in expansion of aquatic and emergent species and reduced the cover of flood-intolerant woody and upland species. These semi-permanent Upper Coastal Plain bays generally exhibited cyclic vegetation dynamics in response to climate fluctuation, with wet periods favoring dominance by herbaceous species. Large basin morphology and deep ponding, paired with surrounding upland forest dominated by flood-intolerant pines, were features contributing to persistence of herbaceous vegetation. Drought cycles may promote directional succession to forest in bays that are smaller, shallower, or colonized by flood-tolerant hardwoods.
Requesting Print Publications
Publication requests are subject to availability. Fiscal responsibility limits the hardcopies of publications we produce and distribute. Electronic versions of publications may be downloaded, distributed and printed.
Please make any requests at firstname.lastname@example.org.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- Our online publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS webmaster if you notice any errors which make this publication unusable.
- To view this article, download the latest version of Adobe Acrobat Reader.