Volin, John C.

The impact of five years of rewatering on a desiccated forested wetland within the Everglades Big Cypress Swamp was investigated. It was found that rewatering generally resulted in a shift in species composition along a hydrological gradient. This was particularly evident in the seedling and herbaceous layer of the cypress domes, the most hydric community studied, where obligate and facultative wetland species had their highest species richness. Overall there were no detectable differences in the number of non-indigenous species in rewatered compared to reference sites. Results from this short-term study showed that rewatering may potentially reverse the trend of increasing coverage by non-obligate wetland plants that have established in the past century as a result of regional desiccation.

To improve water quality as part of a large restoration effort, constructed herbaceous wetlands will be used as filters of high nutrient water. In this study, I tested whether mixed forested wetlands could also be used as nutrient filters. I examined water quality parameters within a forested slough isolated from direct anthropogenic disturbance and within an impounded forest wetland receiving direct agricultural effluent. Among the water quality parameters, TP and K concentrations in the forested slough were particular low. Although all nutrients, except TKN, were higher in the impounded wetland, nutrient concentrations within the wetland were lower at interior sites as compared to inflow water. Based on the use of chloride as a conservative tracer, this reduction resulted predominantly from biological and chemical processes, while physical processes played a minimal role. This study established that mixed forested wetlands can significantly reduce high nutrient levels in surface water.

Lygodium microphyllum and L. japonicum are two non-indigenous invasive climbing ferns which are currently spreading through Florida. The reproductive biology of both species was examined to determine if their reproductive strategy partially explains this spread. Gametophytes of both species were grown in vitro as isolates and pairs to examine reproductive strategies. L. microphyllum appeared to be capable of both outcrossing and selfing, while in L. japonicum intragametophytic selfing appeared to be the primary mode of sexual reproduction. Outcrossing in L. microphyllum appeared to be the result of an antheridiogen system that affected sexual expression of neighboring gametophytes and subsequent sporophyte production. Seventy-eight percent of L. microphyllum isolates produced sporophytes while over ninety percent of the L. japonicum isolates produced sporophytes. The high selfing rates achieved by both species likely facilitated their spread through Florida, while the outcrossing ability of L. microphyllum may increase its adaptability and invasive potential.

Everglades restoration includes construction of six Stormwater Treatment Areas (STAs) totaling over 16,000 hectares. These filter marshes are designed to remove excess phosphorus from agricultural runoff and urban wastewater before it reaches the Everglades. Optimizing flow through these wetlands may be important in increasing the efficiency of nutrient removal and achieving lower outflow phosphorus concentrations. We measured periphyton growth and phosphorus uptake in two sets of replicated mesocosms in post-STA treatment water. Flow rates for the study were 1.0 cm s^-1 and 0.11 cm s^-1. Unique mesocosm design allowed for simultaneous control of loading rate, retention time and surface area, leaving flow rate as the single variable between treatments. Periphyton biomass accrual was 25% greater in the faster treatment. Measurements of dissolved oxygen were positively correlated with biomass accrual and there was no significant difference in the export of biomass between treatments.

The need for biological monitoring is increasing in importance as conservation programs are established for natural areas. The primary purpose of this study was to gain basic information on butterfly assemblages that would be useful in developing the use of butterflies as bioindicators. I examined the diversity and seasonal abundance of adult butterflies in seven locations comprising seven habitat types in the Big Cypress Seminole Indian Reservation in southern Florida; two wet meadows, two pine flatwoods, two ecotones, and a disturbed roadside were studied. One ecotone occurred between a wet meadow and a dry hammock, the other between a pine flatwoods and a wet prairie marsh community. Forty-three butterfly species were found during the one-year study. Several butterfly species were found to be potential indicators in most of the habitats studied. Overall, butterfly diversity did not differ significantly among habitats or between seasons, although seasonal differences in abundance were apparent.

Water management in the Everglades has been a challenge for managing agencies for quite some time. Presently, restoration efforts are underway to reestablish natural hydrological patterns such as flow, depth, and hydroperiod. Tree island health is of particular concern because of its importance to the functional integrity of the greater Everglades ecosystem. This study was designed to determine the effects of different hydrological patterns and elevations on native woody vegetation on tree islands. The study site was the Everglades Wildlife Management Area (EWMA) in the north central Everglades. The study site was broken up into two hydrological zones: dry zone and moderately wet zone. It was found that both hydrology and relative elevation were important predictors of woody species diversity and density. Average hydroperiod and ponding depth were the best sole predictors explaining up to 50% of the woody vegetation variability found within the tail and fringe community as well as the whole tree island.