The Southeast Saline Everglades revisited: 50 years of coastal vegetation change

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-dominated 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 apparently the combined result of sea level rise - ca. 10 cm since 1940 - and water management practices in the SESE.