Abstract Introduction > Marl Prairie Habitat & Community Everglades Hydrologic History Methods Results Discussion Conclusions Acknowledgements References Figures & Tables PDF

Within the ~6,000 km² of wetlands comprising the greater Everglades ecosystem lies a mosaic of vegetation types, including tree-islands, mangrove forests, cypress swamps, marl prairies, sawgrass marshes, and sloughs (Fig. 1a) (Davis, 1943; Loveless, 1959; Davis and others, 1994). Marl prairie landscapes occupy ~1,990 km² of higher-elevation sites within this mosaic (Fig. 1b), consisting of a mixture of wet prairie, sawgrass, tree islands, and tropical hammock communities (Olmstead and Loope, 1984). Marl prairies have the shortest hydroperiods of the Everglades (2-9 months) (Lodge, 2005); under present conditions, many sites east of Shark River Slough are dry for an average of 9 months per year (Van Lent and others, 1993; Fennema and others, 1994). The short hydroperiods and shallow water depths that characterize marl prairies result in accumulation of a calcitic mud substrate (Fig. 2) rather than a peat substrate, and periphyton assemblages are dominated by calcite-encrusting, filamentous cyanobacteria such as Scytonema and Schizothrix (Browder and others, 1994; Davis and others, 2005). Marl prairies have high plant diversity, with approximately 100 different species (Lodge 2005). Of those, approximately half are grasses and sedges (Porter, 1967), and the dominant species depends on hydroperiod: sites with 1-2 month hydroperiods are dominated by Schizachyrium rhizomatum (Florida little bluestem), those with 3-5 month hydroperiods are dominated by Muhlenbergia (muhly grass), and those with 6-8 month hydroperiods are dominated by Cladium (sawgrass) (Olmstead and Loope, 1984; Davis and others, 2005). The combination of low-stature herbaceous ground cover and extended dry periods has fostered development of specialized faunal assemblages that are closely tied to the habitat, including the Cape Sable Seaside Sparrow, macroinvertebrates, herpetofauna, and wading birds.

Figure 2. a) Sediment core collected from solution hole in marl prairie habitat. Note marl layer at top of core. b) Photograph of periphyton and marl sediment that makes up surface sediments in Everglades marl prairies. [larger image]