Effects of landscape gradients on wetland vegetation communities: information for large-scale restoration

Projects of the scope of the restoration of the Florida Everglades require substantial information regarding ecological mechanisms, and these are often poorly understood. We provide critical base knowledge for Everglades restoration by characterizing the existing vegetation communities of an Everglades remnant, describing how present and historic hydrology affect wetland vegetation community composition, and documenting change from communities described in previous studies. Vegetation biomass samples were collected along transects across Water Conservation Area 3A South (3AS)

Research objectives to support the South Florida Ecosystem Restoration initiative-Water Conservation Areas, Lake Okeechobee, and the East/West waterways

The South Florida Ecosystem encompasses an area of approximately 28,000 km2 comprising at least 11 major physiographic provinces, including the Kissimmee River Valley, Lake Okeechobee, the Immokalee Rise, the Big Cypress, the Everglades, Florida Bay, the Atlantic Coastal Ridge, Biscayne Bay, the Florida Keys, the Florida Reef Tract, and nearshore coastal waters. South Florida is a heterogeneous system of wetlands, uplands, coastal areas, and marine areas, dominated by the watersheds of the Kissimmee River, Lake Okeechobee, and the Everglades. Prior to drainage, wetlands dominated the ecosystem, covering most of central and southern Florida. The landscapes included swamp forests; sawgrass plains; mosaics of sawgrass, tree islands, and ponds; marl-forming prairies dominated by periphyton; wet prairies dominated by Eleocharis and Nymphaea; freshwater marshes; saltwater marshes; cypress strands; and a vast lake-river system draining into Lake Okeechobee. Elevated areas that did not flood supported pine flatwoods, pine rocklands, scrub, tropical hardwood hammocks, and xeric hammocks dominated by oaks. The natural seascapes of South Florida consisted of riverine and fringe mangrove forests; beaches and dunes; seagrass beds; intertidal flats; mud banks; hardbottom communities; coral reefs; and open, inshore shallows. All these habitats were interconnected on an extremely low topographic gradient (2.8 cm/km) with elevations ranging from about 6 m at Lake Okeechobee to below sea level at Florida Bay. The Science SUb-Group (1993) described the defining characteristics of the South Florida Ecosystem and the problems that resulted from hydrologic alterations and other anthropogenic changes. Restoration objectives were proposed for each sub-regionand the region as a whole. The overall goal of the restoration effort is to restore a sustainable South Florida Ecosystem that preserves the valued properties of South Florida's natural systems and supports productive agriculture-, fishery-, and tourist. based economies and a high quality of urban life. Sustainability means high natural productivity, human and ecosystem health, and resiliency to climatic extremes and catastrophic events. It also means accommodation of needs of human systems-flood control, irrigation, and drinking water supply. SCOPE This section addresses the entire ecosystem, cutting across the artificial boundaries of designated subregions, as well as geopolitical and geomorphological boundaries, to present the broader issues of deVeloping an interagency and interdisciplinary ecosystem-based science program to support South Florida restoration. Here we discuss the general premise and the general approach, with brief discussions on monitoring, modeling, and special studies. The latter two topics are covered in greater detail in other sections. (PDF contains 119 pages

Spatial and Temporal Changes in Tree Islands of the Arthur R. Marshall Loxahatchee National Wildlife Refuge in Response to Altered Hydrologies

Loxahatchee can be grouped into three zones according to the patterns of change of tree islands observed from 1950 to 1991. 1 ) the edge of the refuge adjacent to the canals, 2) the eastern interior of the refuge, and 3) the western interior of the refuge. The general trend is for tree islands Along the edge of the refuge to have decreased in size, number, and percent cover, while those on the interior increased in size, nunber, and percent cover. Results from this study illustrate the importance of flow magnitude as well as hydroperiod and depth in stucturing patterns of tree islands within this peat wetland. Restoration of historic hydroperiods and depths without historic flow patterns may not be sufficient to restore or maintain the historic pattern and function of the system. (60 pages

Comparison of cattail (Typha sp.) occurrence on a photo-interpreted map versus a satellite data map

A comparison between a 1985 photo-interpreted vegetation map and a vegetation map made from classified 1987 satellite data of the Loxahatchee National Wildlife Refuge showed that 81% of samples taken in areas occupied by cattail (Typha sp.) on the photo-interpreted map corresponded with cattail on the satellite data map.(5 page document

Effects of Natal Departure and Water Level on Survival of Juvenile Snail Kites (\u3ci\u3eRostrhamus sociabilis\u3c/i\u3e) in Florida

Survival rate from fledging to breeding, or juvenile survival, is an important source of variation in lifetime reproductive success in birds. Therefore, determining the relation-ship between juvenile survival and environmental factors is essential to understanding fitness consequences of reproduction in many populations. With increases in density of individuals and depletion of food resources, quality of most habitats deteriorates during the breeding season. Individuals respond by dispersing in search of food resources. Therefore, to understand the influence of environmental factors on juvenile survival, it is also necessary to know how natal dispersal influences survival of juveniles. We examined effects of various environmental factors and natal dispersal behavior on juvenile survival of endangered Snail Kites (Rostrhamus sociabilis) in central and southern Florida, using a generalized estimating equations (GEEs) approach and model selection criteria. Our results suggested yearly effects and an influence of age and monthly minimum hydrologic levels on juvenile Snail Kite survival. Yearly variation in juvenile survival has been reported by other studies, and other reproductive components of Snail Kites also exhibit such variation. Age differences in juvenile survival have also been seen in other species during the juvenile period. Our results demonstrate a positive relationship between water levels and juvenile survival. We suggest that this is not a direct linear relationship, such that higher water means higher juvenile survival. The juvenile period is concurrent with onset of the wet season in the ecosystem we studied, and rainfall increases as juveniles age. For management purposes, we believe that inferences suggesting increasing water levels during the fledging period will increase juvenile survival may have short-term benefits but lead to long-term declines in prey abundance and possibly wetland vegetation structure

The Cape San Blas Ecological Study

Eglin AFB on Cape San Blas consists of approximately 250 acres located about 180 miles east of the main Eglin reservation. This area lies on the S1. Joseph peninsula, part of a dynamic barrier island chain that extends across the northern Gulf of Mexico. Due to the natural forces that formed Cape San Blas and those that maintain this area, St. Joseph Peninsula has experienced severe land form change over time (see GIS land form change maps). These changes allow for fluctuations in habitat types along Cape San Blas (see GIS land cover change maps)that influence the floral and faunal species using this area. The dynamic environment along Cape San Blasincludes flatwoods, interdunal swale, rosemary scrub, and beachfront. These habitats support a wide array of species, including several threatened and endangered species such as the loggerhead sea turtle (Caretta caretta), PipingPlover (Charadnus melodus), Least Tern (Sterna antillarum), and Bald Eagle (Haliaeetus leucocephalus). Proper management of these species and their habitats require knowledge of their abundance and distribution, and the effects disturbances have on their survival. In addition to threatened and endangered flora and fauna, Cape San Blas also supports tourists and recreationists. Although Gulf County is sparsely populated, with approximately 13,000 inhabitants throughout 578 square miles, summer tourism and heavy recreational use of beaches for fishing, crabbing, and shelling place continued and increasing pressure on the natural resources of these areas (Rupert 1991). Gulf County is also one of the few remaining counties in Florida that permits vehicular traffic on its beaches, including Cape San Blas. In addition to recreational use of these habitats;EAFB also uses the area for military missions. Air Force property on Cape San Blas is primarily used for radar tracking of flying missions over the Gulf of Mexico, although in recent years it has been used for missile launchings and other various military activities. To allow continued military and public use of Air Force property while also protecting the unique flora and fauna of the area,EAFB proposed a characterization of the resources found along Cape San Blas. A complete inventory of the physical features of the area included investigating topography, soil chemistry, hydrology, archeology, and the dynamics of land mass and land cover change over time. Various thematic layers within a geographic information system (GIS) were used to spatially portray georeferenced data. Large scale changes over time were assessed using stereo aerial photography. Vegetation transects, soil samples, elevation transects, an archeological survey, freshwater wells, and a tidal monitor were used to investigate the remaining features. (247 page document

The effects of the Suwannee River Sill on the hydrology and vegetation of Okefenokee Swamp

The Suwannee River sill was constructed following extensive wildfires during 1954-1955, with the intent of protecting the swamp and surrounding uplands from effects of wildfires. During subsequent years, concern was raised that the dam might be adversely affecting the swamp ecology by extending periods of inundation, increasing water depths, and subsequently affecting swamp vegetation. Delineating the effects of the Suwannee River sill on the swamp hydrologic environment and vegetation distributions, in the process of exploring relationships among driving functions and landscape responses, was a purpose of this research.(834 page document

The Semiglades: The Collision of Restoration, Social Values, and the Ecosystem Concept

Abstract Defining success targets in restoration and how social values affect them are two commonly discussed issues in restoration today. We believe that how success is commonly defined-with vague terms such as "healthy ecosystem" or cited as a return to a previous, historic state-needs to be reevaluated. With the increasing number of novel ecosystems, there is an increasing conflict between the ecosystem concept, social values, and restoration. This arises from the fact that ecosystems are defined by the values of the scientists describing them, necessarily constraining the ecosystem to a generally static concept. It is not directly the concept, but how it is perceived through our filter of social values that represses the creativity and innovation needed in restoration today. Within restoration, we feel that the ecosystem concept does a disservice by ignoring the increasing number of novel systems, and that hinders real progress in a time when hesitation can be costly. To best illustrate this, we offer the example of restoration of the Florida Everglades and how it has become a novel system in pattern and process. We suggest renaming the Everglades "The Semiglades" in hopes of opening a dialog to expose social/ecosystem biases and include novel landscapes in management and planning

The Proportion of Snail Kites Attempting to Breed and the Number of Breeding Attempts per Year in Florida

During the breeding season of 1995 we monitored the proportion of adult and subadult Snail Kites (Rostrhamus sociabilis) attempting to breed and the number of breeding attempts using radio telemetry. Our sample consisted of 23 adults (14 females, 9 males) and 9 subadults for which we had data over the entire breeding season. All adults attempted to breed at least once with an observed average of 1.4 (± 0.6 SD) breeding attempts per individual. In contrast, only 3 (33%) of the subadults attempted to breed. Of the adults, 15 (65%) made one breeding attempt, 7 (30%) made two breeding attempts,and 1 (4%) attempted three times. Only one bird (4%) successfully raised two broods. Our data are consistent with previous reports that \u3e1 breeding attempt by Snail Kites in Florida is common during some years, although our estimate for 1995 was lower han previously reported estimates. A combination of our estimation procedures, definitions of a breeding attempt, and annual variability of this parameter probably account for the disparity between our data and previous reports