861 resultados para Unvegetated Habitat


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This document summarizes the activities that were accomplished in 2008, the sixth year of the research project “Effect of hydrologic restoration on the habitat of the Cape Sable seaside sparrow”, a collaborative effort among the US Army Corps of Engineers, Everglades National Park, Florida International University, and the US Geological Survey (Florida Integrated Science Center). The major activities in 2008 included field work, data analysis, and presentations. Jay Sah presented the results of 6th year field work at the Cape Sable seaside sparrow (CSSS) Fire Meeting 2008, held on December 2-3 at the Krome Center, Homestead, Florida. In the same meeting, Mike Ross presented results from a related USFWS-funded project on encroachment pattern of woody plants in Cape Sable seaside sparrow habitat.

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In the fall of 2005, U.S. Fish and Wildlife Services (USFWS) contracted with Florida International University (FIU) to study the physical and biological drivers underlying the distribution of woody plant species in the marl prairie habitat of the Cape Sable Seaside Sparrow (CSSS). This report presents what we have learned about woody plant encroachment based on studies carried out during the period 2006-2008. The freshwater marl prairie habitat currently occupied by the Cape Sable seaside sparrow (CSSS; Ammodramus maritimus mirabilis) is a dynamic mosaic comprised of species-rich grassland communities and tree islands of various sizes, densities and compositions. Landscape heterogeneity and the scale of vegetative components across the marl prairie is primarily determined by hydrologic conditions, biological factors (e.g. dispersal and growth morphology), and disturbances such as fire. The woody component of the marl prairie landscape is subject to expansion through multiple positive feedback mechanisms, which may be initiated by recent land use change (e.g. drainage). Because sparrows are known to avoid areas where the woody component is too extensive, a better understanding of invasion dynamics is needed to ensure proper management.

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This document summarizes the activities that were accomplished in FY 2009 on the research project “Cape Sable seaside sparrow habitat – Vegetation Monitoring”, a collaborative effort among the US Army Corps of Engineers, Florida International University, and the US Geological Survey. The major activities in 2009 included field work, data analysis and presentations. The results of 2009 field work were presented at the 4th International Congress of Fire Ecology and Management, Savannah, GA from November 30 to Dec 5, 2009 and at the Cape Sable seaside sparrow (CSSS) Fire Meeting, held at the Krome Center, Homestead, FL on December 8, 2009. Field sampling was conducted between March 23 and June 3, 2009, during which we resurveyed 234 sites: 191 Census sites, 3 sites on Transect B, 7 sites on Transect D, and 33 sites on Transect F. The number of sites sampled in 2009 was higher than in any previous year, primarily because a large number of sites burned in Mustang Corner fire and three other wild fires in 2008 were included in 2009 sampling. At all sites surveyed in 2009, we recorded structural and compositional vegetation parameters following the methods used in previous years (2003-2008) and tagged shrubs and trees (woody plants > 1 m) present in the 5 x 60 m plots. In addition, for the first time, we measured height of sawgrass (Cladium jamaicense) stubble in the compositional plots at the sites that were burned in 2008. Field data were entered by field crews, and were thoroughly checked by Jay Sah (Co-PI) to ensure that the data were complete, correct, and compliant with sampling methodologies. The data are stored under a project folder on a shared network drive maintained by the Southeast Environmental Research Center (SERC) at FIU. The shared network drive is backed up daily.

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For the last two decades, the Cape Sable seaside sparrow (CSSS), a federally endangered species, has been a pivot point for water management operations in the Everglades, primarily because a decline in sparrow population in the early 1990s was attributed in part to managementinduced alterations in hydrologic regimes. With a goal of understanding the response of landscape-level processes to hydrological restoration and its interaction with fire, a study intended to monitor vegetation structure and composition throughout the marl prairie landscape has been conducted since 2003 with funding from U.S. Army Corps of Engineers (USACE). In the first three years (2003-2005), vegetation structure and composition was characterized in relation to the existing hydrologic regime and fire history. During 2006-2010, vegetation was resampled to assess vegetation change within the sparrow habitat. This document summarizes the vegetation change pattern observed between the two sampling periods in sub-population A, C, E and F, emphasizing the work accomplished in FY 2010.

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Angadenia berteroi is a tropical perennial subshrub of the pine rocklands with large yellow flowers that set very few fruits. My dissertation seeks to elucidate the factors that affect the reproductive fitness of Angadenia berteroi a native species of the south Florida pine rocklands. I provide novel information on the pollination biology of this native species. I also assess the effects of herbivory on growth and the reproductive success of A. berteroi. Finally, I elucidate how habitat fragmentation and quality are correlated with reproductive fitness of this native perennial plant. Using a novel experimental approach, I determined the most effective pollinator group. I used nylon fishing line of widths corresponding to proboscis diameter of the major groups of visitors to examine pollen removal and deposition. In the field, I estimated visitation frequency and efficacy of each pollinator type. Using potted plants, I exposed flowers to single visit from different types of pollinators to measure fruit set. I performed artificial defoliation with scissors on plants growing in the greenhouse to assess the effects of defoliation before flowering as well as during flowering. Additionally, I used structural equation modelling (SEM) to elucidate how A. berteroi reproductive fitness was affected by habitat fragmentation and quality. My experiments provide evidence that Angadenia berteroi is specialized for bee pollination; though butterflies, skippers and others also visit its flowers, A. berteroi is exclusively pollinated by two native bees of the South Florida pine rocklands . This research also demonstrated that herbivory by the oleander moth may have direct and indirect effects on Angadenia berteroi growth and reproductive success. The SEM results suggested that habitat quality (litter depth and subcanopy cover) may favor reproduction in native species of the South Florida pine rocklands that are properly maintained by periodic fires and exotic control. Insights from this threatened and charismatic species may provide impetus to properly manage remaining pine rocklands in South Florida for this and other endemic understory species.

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Rodents are often involved at several stages of trophic dynamics. Consequently they often play crucial roles in the structure and function of many complex ecological systems. This study sought to address the lack of baseline data concerning rodents in tropical areas, and south Florida in particular. Live trapping took place in the four major habitat types of the Long Pine Key area of Everglades National Park over the course of one year. I compared population structures and abundance of murid rodents in the four habitat types, and tested multiple weather variables for their effectiveness as predictors of rodent abundance. I found the Long Pine Key area to be depauperate in terms of species diversity. Each of the four species of rodent encountered favored a particular habitat type. The density of the understory vegetation and the avoidance of avian predators in particular appear to be the most important factors in the distribution and abundance of rodents in the Long Pine Key area of Everglades National Park.

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In aquatic systems refuge habitats increase resistance to drying events and are necessary for maintaining populations in disturbed environments. However, reduced water availability and altered flow regimes threaten the existence and function of these habitats. To test refuge function I conducted a capture-mark-recapture (CMR) study, integrating citizen science angler sampling into fisheries-independent methods. The objectives of this study were twofold: 1) To determine the contribution of citizen science anglers to improving CMR research, and 2.) to quantify apparent survival of Florida Largemouth Bass, Micropterus salmoides floridanus, in a coastal refuge habitat across multiple years of drying severity. The inclusion of angler sampling was determined to be an effective and feasible method for increasing capture probability. Apparent survival of Florida Bass varied among hydrologic periods with lowest survival when marshes functionally dried (< 10 cm). Overall mortality from drying events increased with the duration of marsh drying upstream.

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There are several abiotic factors reported in the literature as regulators of the distribution of fish species in marine environments. Among them stand out structural complexity of habitat, benthic composition, depth and distance from the coast are usually reported as positive influencers in the diversity of difentes species, including reef fish. These are dominant elements in reef systems and considered high ecological and socioeconomic importance. Understanding how the above factors influence the distribution and habitat use of reef fish communities are important for their management and conservation. Thus, this study aims to evaluate the influence of these variables on the community of reef fishes along an environmental gradient of depth and distance from shore base in sandstone reefs in the coast of state of Rio Grande do Norte, Brazil. These variables are also used for creating a simple predictive model reef fish biomass for the environment studied. Data collection was performed through visual surveys in situ, and recorded environmental data (structural complexity of habitat, type of coverage of the substrate, benthic invertebrates) and ecological (wealth, abundance and reef fish size classes). As a complement, information on the diet were raised through literature and the biomass was estimated from the length-weight relationship of each species. Overall, the reefs showed a low coverage by corals and the Shallow reefs, Intermediate I and II dominated by algae and the Funds by algae and sponges. The complexity has increased along the gradient and positively influenced the species richness and abundance. Both attributes influenced in the structure of the reef fish community, increasing the richness, abundance and biomass of fish as well as differentiating the trophic structure of the community along the depth gradient and distance from the coast. Distribution and use of habitat by recifas fish was associated with food availability. The predictor model identified depth, roughness and coverage for foliose algae, calcareous algae and soft corals as the most significant variables influencing in the biomass of reef fish. In short, the description and understanding of these patterns are important steps to elucidate the ecological processes. In this sense, our approach provides a new understanding of the structure of the reef fish community of Rio Grande do Norte, allowing understand a part of a whole and assist future monitoring actions, evaluation, management and conservation of these and other reefs of Brazil.

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The Atlantic Forest in Rio Grande do Norte (RN) is included in Pernambuco biogeographic sub-region and it is composed by Semi-deciduous Forest, deciduous Forest, Mangrove and Restinga. We assessed the conservation status of Atlantic Forest in the RN through remnants mapping using high resolution satellite images and landscape ecology approaches. We evaluated if there is difference between the north and south coastal regions considering their natural a historical land use differences. We also assessed the influence of the small remnants on landscape cover and configuration. The proportion of the original biome area with remnants larger than 3 hectares is 15.60% for the official governmental limit and is 16.60% for the alternative limit (SNE, 2002). This remnants proportion varies between 0.56 and 46.52% in the hydrographic basins. 89.70% of the remnants are smaller than 50 hectares. Only 6.00% of the remnants are greater than 100 hectares, and these remnants are responsible by 65% of remaining area. The patches with smaller area influence all calculated metrics. The south coastal hydrographic basins have higher percentage of coverage of remnants, larger patch densities and fragments with larger areas than north coastal hydrographic basins. The diffuse drainage basins of the southern coastal have the highest percentage of coverage with remnants. 18.28% and 10% of the biome area are protected by reserves, according to the official governmental and alternative limits respectively. The reserves are mainly of sustainable use (IUCN V-VI). Therefore, the Atlantic Forest in Rio Grande do Norte is in critical situation, with low proportion of remaining area and high fragmentation level. It’s indispensable to biome conservation keep all the remaining area, especially the large remnants, and restore areas to increase remnants proportion and to increase landscape connectivity

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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My thesis examines fine-scale habitat use and movement patterns of age 1 Greenland cod (Gadus macrocephalus ogac) tracked using acoustic telemetry. Recent advances in tracking technologies such as GPS and acoustic telemetry have led to increasingly large and detailed datasets that present new opportunities for researchers to address fine-scale ecological questions regarding animal movement and spatial distribution. There is a growing demand for home range models that will not only work with massive quantities of autocorrelated data, but that can also exploit the added detail inherent in these high-resolution datasets. Most published home range studies use radio-telemetry or satellite data from terrestrial mammals or avian species, and most studies that evaluate the relative performance of home range models use simulated data. In Chapter 2, I used actual field-collected data from age-1 Greenland cod tracked with acoustic telemetry to evaluate the accuracy and precision of six home range models: minimum convex polygons, kernel densities with plug-in bandwidth selection and the reference bandwidth, adaptive local convex hulls, Brownian bridges, and dynamic Brownian bridges. I then applied the most appropriate model to two years (2010-2012) of tracking data collected from 82 tagged Greenland cod tracked in Newman Sound, Newfoundland, Canada, to determine diel and seasonal differences in habitat use and movement patterns (Chapter 3). Little is known of juvenile cod ecology, so resolving these relationships will provide valuable insight into activity patterns, habitat use, and predator-prey dynamics, while filling a knowledge gap regarding the use of space by age 1 Greenland cod in a coastal nursery habitat. By doing so, my thesis demonstrates an appropriate technique for modelling the spatial use of fish from acoustic telemetry data that can be applied to high-resolution, high-frequency tracking datasets collected from mobile organisms in any environment.

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Many fish stocks are currently facing collapse or overexploitation as well as warming environments. During the 1950s and 1960s, haddock supported a substantial fishery in southern Newfoundland waters, specifically Northwest Atlantic Fisheries Organization (NAFO) Divisions 3LNO and Subdivision 3Ps, but abundance has been comparatively low over the last several decades and there has been no significant fishery in either 3LNO or 3Ps since the late-1950s. The decline in the fishery for haddock coincided with a decline in scientific research on haddock with the last significant research on haddock in Newfoundland waters conducted in the 1950s-1960s. Other haddock stocks have shown major life history changes since the 1980s, including decreased size-at-age and age/length at maturity. In contrast to this, Newfoundland haddock have not shown a significant change in growth or maturity through time. Based on analysis of habitat associations, haddock abundance is expected to increase with recent warming trends as the available optimum habitat for haddock will increase.