Shark River Slough Consists of a Vegetative Mosaic That Includes Extensive Stands of Sawgrass

Effects of Litter Quality on Landscape Scale Vegetation Patterns in Shark River Slough, Florida Everglades

Christopher G. Lewis and Mark W. Clark

University of Florida, Gainesville, FL

Shark River Slough consists of a vegetative mosaic that includes extensive stands of sawgrass (Cladium jamaicense Crantz) interspersed with open water sloughs and wet prairies containing floating leaf macrophytes, emergents, and periphyton. This area includes the topography-defined landscapes such as the ridge and slough communities of central Shark River Slough. The term ridge and slough describes the elevation differences of the peat soil surface and associated communities. Cladium stands cover the higher peat ridges, and the lower elevation sloughs are characterized by openwater and macrophytes (Eleocharis and Nymphaea species).

Due to the hydrogeomorphology of Shark River Slough, water levels do not differ significantly east and west. However, because soil elevation has a significant influence on the hydropattern of any given location, and therefore influences the vegetative community present, it is critical to understand factors that may influence rates of soil accretion.

The vegetative mosaic found in Shark River Slough is thought to be determined by allocthonous (external and typically abiotic) and autocthonous (internal and typically biotic) factors. It has been reported that autocthonous factors, such as primary productivity and biomass, are greater in sawgrass marshes (ridges) than in sloughs. This may result in higher rates of litter and soil accretion in ridge communities relative to sloughs. Organic matter decomposition, also an autocthonous factor, may also affect soil elevation. Because litter quality is an important regulator of organic matter decomposition, many factors related to litter decomposition, such as litter nitrogen content, phosphorus content, C/N ratio, C/P ratio, and lignin/cellulose ratio may indirectly affect soil accretion rates and vegetation pattern.

In this investigation, average litter N content was 0.757% and 0.997% for ridge and slough vegetation respectively. Litter P content was .015% and .024% for ridge and slough vegetation respectively. On average, the data suggest litter N and P content was higher in slough vegetation. Conversely, litter carbon content was higher in ridge vegetation (38.5% sloughs, 44.2% ridge). As a result, higher C/N ratios and C/P ratios were observed in ridge vegetation. This, along with higher lignin content in ridge vegetation (9.8%) versus slough (4.0%), might partially explain the observed elevation differences in the Shark River Slough ecosystem.