Macrophyte Species Changes in the Everglades: Examination along a Eutrophication Gradient
1999
Vaithiyanathan, P. | Richardson, C. J.
Macrophyte species distribution in the marsh and slough areas of the northern Everglades were examined along a surface water and soil P gradient to characterize the effects of nutrient enrichment on the macrophyte community changes in the Everglades ecosystem. Macrophyte species distribution and frequency examined at 51 sites located in the Water Conservation Area (WCA-2A) revealed distinct trends in species changes with P enrichment. Marshes in the unenriched and enriched areas were dominated by Cladium jamaicense and Typha domingensis, respectively. Open water areas were characterized by Eleocharis sp., Utricularia sp., Chara zeylanica, and Nymphaea odorata in the unenriched areas and by floating plants and Polygonum sp. in the enriched areas. We compared the macrophyte species distribution with the soil P contour map of WCA-2A and derived six major categories of P enrichment (labeled 0–5) that may be used to adequately describe macrophyte species distribution in the WCA-2A. Soil and surface water P values that correspond to the different P-enrichment categories and the number of macrophyte species in each category have been estimated. Examination of the relative abundance of the macrophyte species in the six P-enrichment categories showed a decline in characteristic slough macrophyte species with P enrichment. Increase in P status of the system was also accompanied by the advent and gradual establishment of macrophytes such as Mikania scandens, Sarcostemma clausum, Polygonum sp., Acrostichum danaeifolium, and a variety of floating plants. Characteristic slough macrophyte species such as Utricularia purpurea, Eleocharis elongata, and Eleocharis cellulosa serve as indicators of the unenriched P conditions.
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