- The Southeast Saline Everglades revisited: 50 years of coastal vegetation change - 101 Journal of Vegetation Science 11: 101-112, 2000 © IAVS; Opulus Press Uppsala. Printed in Sweden Abstract. We examined the vegetation of the Southeast Saline Everglades (SESE), where water management and sea level rise have been important ecological forces during the last 50 years. Marshes within the SESE were arranged in well-defined compositional zones parallel to the coast, with mangrove-domi- nated shrub communities near the coast giving way to graminoid- mangrove mixtures, and then Cladium marsh. The compositional gradient was accompanied by an interiorward decrease in total aboveground biomass, and increases in leaf area index and periphyton biomass. Since the mid-1940s, the boundary of the mixed graminoid-mangrove and Cladium communities shifted inland by 3.3 km. The interior boundary of a low-productivity zone appearing white on both black-and-white and CIR photos moved inland by 1.5 km on average. A smaller shift in this ‘white zone’ was observed in an area receiving fresh water overflow through gaps in one of the SESE canals, while greater change occurred in areas cut off from upstream water sources by roads or levees. These large-scale vegetation dynamics are appar- ently the combined result of sea level rise - ca. 10 cm since 1940 - and water management practices in the SESE. Keywords: Biomass; Cladium jamaicense; Correspondence Analy- sis; Eleocharis cellulosa; Leaf Area Index; Periphyton; Rhizo- phora mangle; Salinity index; Sea level rise; Water management. Nomenclature: Long & Lakela (1971). Abbreviation: SESE = Southeast Saline Everglades. Introduction Coastal wetlands reflect a dynamic hydrologic bal- ance between the marine and upstream or upslope terres- trial ecosystems which bound them on all sides. In these transitional settings, ecological responses which arise principally as a result of changes in the marine system may be modified by physiography, management, or land use patterns in the terrestrial environment, or vice versa. One example of these interactions is found in the response of mangrove ecosystems to sea level rise, which varies in rate or even direction in different physical settings or under alternative water management scenarios (Meeder et al. 1993). At a landscape scale, the anticipated response of coastal wetlands to change in sea level is even more The Southeast Saline Everglades revisited: 50 years of coastal vegetation change Ross, M.S. 1* , Meeder, J.F. 1 , Sah, J.P. 1 , Ruiz, P.L. 1 & Telesnicki, G.J. 2 1 Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA; 2 Duke University Phytotron Department of Botany, Box 90340, Science Drive, Durham, NC 27708, USA; * Corresponding author; Fax +1 305 348 4096; E-mail rossm@fiu.edu complex, especially if the dramatic vegetation zonation typical of many coastal wetlands is incorporated. Nearly 50 years ago, Dr. Frank Egler described the vegetation of the area south and east of the Atlantic Coastal Ridge in southernmost peninsular Florida, noting a conspicuous coastal zonation within the area he called the ‘Southeast Saline Everglades’ (Egler 1952). Egler’s description was based on 1938 and 1940 aerial photo- graphs, and on field work undertaken 1940-1948. He described the vegetation pattern in the coastal Everglades at the time as ‘fossil’, responding slowly to a rapidly changing environment that included a rising sea level, a decline in the level of the surface freshwater aquifer, a reduction in fire frequency, and a range of anthropogenic modifications to natural drainage patterns. Egler docu- mented several examples of local vegetation change over the period of his study, including the invasion of the halophytic Rhizophora mangle into freshwater wetlands far from the coast. At the same time, he anticipated a continued interiorward shift in the vegetation gradient. Egler’s work preceded the connection of the South Dade Conveyance system to the sea via the C-111 canal. Completed in the late 1960s, this project allowed more effective drainage of the agricultural and urban lands abutting the Southeast Saline Everglades (SESE). In conjunction with roads and agricultural ditches, opera- tion of the canal system altered fresh water delivery to SESE wetlands, starving some areas of water while augmenting the supply to others. Five decades after Egler’s ecological studies, we re- examined the vegetation of the SESE. Our objectives were (1) to describe current vegetation patterns of the area in relation to known environmental or geographic variables, and (2) to document and interpret changes in the coastal wetland vegetation since our predecessor’s studies. We hypothesized that changes in SESE marshes would reflect salinization effects associated with sea level rise, and that these effects would be more severe in areas cut off from upstream water sources by canals or roads. Documentation of temporal change in SESE veg- etation was derived from two sources: floristic surveys and aerial photo interpretation.