The recent expansion of Typha domingensis (Typha) into areas of the Everglades previously dominated by Cladium jamaicense (Cladium) communities has led to competing hypotheses about the importance of nutrient concentration vs. hydroperiod in controlling the distribution of these species. In this study, experimental mixtures of Typha domingensis, Cladium jamaicense, and Eleocharis interstincta (Eleocharis), a member of the Cladium community, were subjected to two levels of nutrient concentration and three contrasting hydroperiods to determine how these variables might affect Typha's ability to displace the Cladium community. Mixtures of the three species were established in outdoor tanks containing soil from the northern Everglades region where the experiment was conducted. Nutrient treatments consisted of nutrient additions to adjust ambient water concentrations to either 50 μg/L phosphorus (P) or 100 μg/L P plus nitrogen (N). The three hydroperiods were achieved by maintaining water depths within ranges observed in the northern Everglades. Maximum water depths of 15, 30, and 60 cm were established throughout the wet season (May‐November) followed by lowering to 5 cm during the dry season. Over a 2‐yr period, biomass was monitored nondestructively and aboveground material was harvested at the end of the experiment. Analysis of the biomass changes over time showed that differences between the species developed by the end of the first growing season. Typha and Eleocharis had initial growth rates substantially higher than those observed for Cladium. Typha's growth in mixtures responded positively to both elevated nutrients (by as much as 45%) as well as to increased water depth (by as much as 60%), while Cladium and Eleocharis did not increase in response to these variables. Tissue P concentrations were found to be higher for Typha and Eleocharis than for Cladium under nearly all conditions. Net accumulation of P in Typha shoots was 2‐3 times greater than in the other species. The enhancement of Typha by elevated nutrients and increased flooding is associated with a syndrome of life history characteristics that includes rapid growth rates, high tissue concentrations of P, tall leaves, and a greater response to contrasting environmental conditions. Cladium, in contrast, showed a slow growth rate, low tissue concentrations of P, a greater capacity to resist invasion by Typha in shallow waters, and less of a growth response to contrasting environmental conditions, traits that would seem to be well suited to the nutrient‐poor, hydrologically unstable conditions natural to the Everglades. Results from this study suggest that attempts to limit the spread of Typha should consider hydrologic restoration as well as reduction in surface water nutrients.
1. Secondary production was estimated for Plecoptera, Odonata and Megaloptera (mostly large predators) occurring on the snag habitat of a subtropical blackwater river in the southeastern U.S.A. Coastal Plain for 2 years. Production estimates and gut analyses were used in estimating species‐specific ingestion to construct a quantitative food web of the predator portion of the invertebrate assemblage. Neither basal resources (e.g. detritus) nor predaceous vertebrates (e.g. fishes) were considered in this analysis. A discharge‐specific model of snag‐habitat availability was used to convert values per m2 of snag surface to values per m2 of river bed. 2. These three orders included the major large predators on the snag habitat, as well as two detritivorous stoneflies. The major predators were the hellgrammite (Corydaluscornutus), five perlid stoneflies (Paragnetinakansensis, Perlestaplacida, Neoperlaclymene, Acroneuriaevoluta and Acroneuriaabnormis) and two dragonflies (Neurocorduliamolesta and Boyeriavinosa). The detritivores were Pteronarcysdorsata and Taeniopteryxlita. 3. Total predator production was high, but varied from only 7.1 to 7.4 g dry mass (DM) m−2 y−1 of snag surface (2.4–2.7 g DM m−2 y−1 of river bed) over two years. Corydalus was the largest predator and had the highest production (2.8–3.1 g DM m−2 of snag surface). The most productive stoneflies were Perlesta (0.7–1.0 g DM m−2 of snag surface) and Paragnetina (1.0–1.3 g DM m−2 of snag surface). The most productive dragonfly was Neurocordulia (0.7–1.9 g DM m−2 of snag surface). Production of the non‐predaceous stoneflies was 1.0–2.3 g DM m−2 of snag surface. Production values per m2 of river bed were 2–3.5 times lower than the values per m2 snag surface. 4. Measurement of ingestion fluxes within the predator portion of the food web showed that predaceous invertebrates were primarily supported by chironomid and mayfly prey. However, the greatest consumption of chironomids and mayflies was by omnivorous hydropsychid caddisflies, which had a considerably higher production than the larger predators. There was a hierarchy of feeding with Corydalus as top predator consuming all other groups, followed in order by dragonflies, stoneflies and hydropsychids. Although the feeding hierarchy suggested the presence of four predatory trophic levels within the invertebrate assemblage, calculations of trophic position indicated there were less than two. With primary consumers (e.g. midges) having a trophic position of 2, Corydalus had a trophic position of only 3.5. 5. A relatively high fraction of invertebrate production was consumed by predaceous invertebrates, ranging from 9 to >100% for various primary consumer groups, with total consumption representing 52% of total production. Because these estimates do not include vertebrate consumption or emergence, it means that a high fraction of larval mortality is due to predation.
This paper reviews the events leading to the channelization of the Kissimmee River, the physical, hydrologic, and biological effects of channelization, and the restoration movement. Between 1962 and 1971, in order to provide flood control for central and southern Florida, the 166 km‐long meandering Kissimmee River was transformed into a 90 km‐long, 10 meter‐deep, 100 meter‐wide canal. Channelization and transformation of the Kissimmee River system into a series of impoundments resulted in the loss of 12,000–14,000 ha of wetland habitat, eliminated historic water level fluctuations, and greatly modified flow characteristics. As a result, the biological communities of the river and floodplain system (vegetation, invertebrate, fish, wading bird, and waterfowl) were severely damaged. Following completion of the canal, the U.S. Geological Survey released a report documenting the environmental concerns associated with channelization of the river. This action led to the 1971 Governor's Conference on Water Management in South Florida that produced a consensus to request that steps be taken to restore the fish and wildlife resources and habitat of the Kissimmee basin. In 1976, the Florida Legislature passed the Kissimmee River Restoration Act. As a result, three major restoration and planning studies (first federal feasibility study [1978–1985], the Pool B Demonstration Project [1984–1990], and the second federal feasibility study [1990‐present] were initiated (1) to evaluate measures and provide recommendations for restoring flood‐plain wetlands and improving water quality within the Kissimmee basin, (2) to assess the feasibility of the recommended dechannelization plan, and (3) to evaluate implementation of the dechannelization plan. The recommended plan calls for the backfilling of over 35 km of C‐38, recarving of 14 km of river channel, and removal of two water‐control structures and associated levees. Restoration of the Kissimmee River ecosystem will result in the reestablishment of 104 km2 of river‐floodplain ecosystem, including 70 km of river channel and 11,000 ha of wetland habitat, which is expected to benefit over 320 species of fish and wildlife.
Abstract:We evaluated effects of rooting by feral hogs (Sus scrofa) on total emergent vegetation cover, vegetation species richness, and diversity of plant-defined microhabitat types in an impounded floodplain marsh in central Florida. Data were collected in 6 split-plots (rooted and control) over 10 post-rooting, monthly sampling periods. Hog rooting led to reduced plant cover in broadleaf marsh habitats and to significantly higher microhabitat diversity and species richness. Although feral hogs can have detrimental effects on native biota and community structure, our data suggest that hog rooting is a disturbance that can enhance plant species richness and associated microhabitat diversity in wetland habitats.
Over the past decade, restoration of the Kissimmee River in central Florida has received considerable attention from local, state, national, and international media. In terms of areal extent, project cost, and ecological evaluation it is one of the largest and most comprehensive river restoration projects in the world. The goal of reestablishing ecological integrity involves restoring the physical attributes and the hydrologic processes that were lost after channelization of the river in the 1960s. The project is expected to restore over 80 km 2 of floodplain wetlands and reestablish over 70 km of river channel. Restoration construction began in 1999; to date, three construction phases have been completed, with the final phase of construction slated for completion in 2019. Restoration evaluation is widely viewed as a critical component of any restoration project. Equally important is the dissemination of information gained from restoration evaluation programs. This introductory article presents a brief overview of project history and outlines the approach and logic of the Kissimmee River Restoration Evaluation Program. The following papers present the results of ecological studies conducted before and after completion of the first phase of restoration construction. This first phase reestablished flow through 23 km of reconnected river channels and seasonally inundated a large portion (approximately 2,900 ha) of the floodplain within the Phase I project area. Although these studies present interim responses prior to full hydrologic restoration, results suggest that the ecosystem is responding largely as predicted by performance measures developed prior to restoration construction.Additional Supporting Information may be found in the online version of this article:Appendix S1. Impacts of channelization and altered hydrology to physical, chemical, and biological attributes of the Kissimmee River and floodplain ecosystem.Appendix S2. The restoration initiative. Appendix S3. Timeline of legislation, planning studies, and other significant events related to the Kissimmee River Restoration Project.Appendix S4. Photographs of the Phase I restoration area.
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