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Effects of water depth and quality on the growth of various oligotrophic-wetland plants.
Miao, ShiLi*,1, Goassman, Bryan1, 1 South Florida Water Management District, West Palm Beach, FL
ABSTRACT- One of the greatest challenges in ecosystem restoration is to restore native vegetation in disturbed areas, as both biotic and abiotic conditions in these sites have been altered tremendously. In impacted wetlands, commonly soil and water nutrients are elevated and hydrological regimes are changed. Whether native vegetation can be established and restored in such impacted areas is largely species-specific. The objective of the present study was to examine the effects of water depth and the outflow water quality of a Stormwater Treatment Area (STA) on five species (Nymphaea odorata, Eleocharis cellulosa, Eleocharis elongata, Rhynchospora tracyi, and Cladium jamaicense) without the competition of cattail, a dominant species in nutrient-enriched wetlands. These species occur naturally in pristine Everglades wetlands with water total phosphorus (TP) of 10 ug/L and represent three dominant native vegetation types with distinct hydrologic regimes. The experiment was set up in nine outdoor fiberglass tanks with a flow-through system using the outflow water from STA 1-West. This water had an average TP of 25 ug/L. Seedlings of the five species grown in nutrient enriched soil were placed in the tanks at two water depths (20 and 60 cm) for one year. Water depth affected the survivorship of the five species differently. As water depth increased, marsh species experienced the highest mortality, followed by wet prairie, and finally slough. One slough species, Nymphaea odorata, experienced zero mortality at both water depths. For surviving plants, total biomass of all five species increased by a range of 5 to 20 times. The preliminary results suggest that, in the absence of cattail competition, these native plant species can grow under the examined water quality condition. However, hydrologic regimes, such as water depth, are key in the initial establishment and colonization of these plants.
Key words: water quality, water depth, native species, survivorship