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(1 - 15 of 15)
- Title
- THE ROLE OF THE FERAL PIG (SUS SCROFA) AS A DISTURBANCE AGENT AND SEED DISPERSER IN CENTRAL FLORIDA'S NATURAL LANDS.
- Creator
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Brescacin, Camille, Jenkins, David, University of Central Florida
- Abstract / Description
-
Feral pigs (Sus scrofa) are considered to be among the world's worst invasive species due to their successful invasion and ecological and economic impact to native and agricultural plants and animals around the world. Feral pigs are significant disturbance agents that destroy plant communities, change soil characteristics, alter nutrient cycling, and create open sites for colonization of both native and non-native plant species through their foraging behavior called rooting. In contrast to...
Show moreFeral pigs (Sus scrofa) are considered to be among the world's worst invasive species due to their successful invasion and ecological and economic impact to native and agricultural plants and animals around the world. Feral pigs are significant disturbance agents that destroy plant communities, change soil characteristics, alter nutrient cycling, and create open sites for colonization of both native and non-native plant species through their foraging behavior called rooting. In contrast to native animal disturbances, rooting is a striking feature in the landscape that varies in space, seasonal timing, frequency (number of times rooted), and intensity (depth of rooting). During this study, feral pigs rooted 7.7% of the search area, which increased to 12% when abandoned patches (baseline patches that were not rooted during this study) were included. Overall, feral pigs rooted and re-rooted habitats along roads and trails significantly more than wetlands. Rooting also varied temporally with the most rooting occurring during July-November, which also corresponds to the peak in rooting intensity. Implications to land managers include avoiding the installation of roads and trails near wet to mesic habitats or other habitats that contain species of concern in order to conserve habitat quality and recreational value. Despite less rooting activity, feral pigs still pose a significant threat to wetlands as evidenced by the large amount of abandoned patches documented. In order to conserve natural areas, effective management and development of efficient control methods is needed to keep feral pig populations in check. As a large opportunistic omnivore, feral pigs have the potential to be important vectors for endozoochorus seed dispersal of a variety of plant species. Feral pigs can travel long distances and have a gut retention time up to 49 hours, therefore seeds can be deposited throughout the landscape far from the parent plant. Over the course of this study, feral pigs dispersed 50 plant species from a wide range of ecological and morphological characteristics, though the majority were native, small seeded, wetland species. For most plant species, location of deposition matched their habitat preference and suggests a high probability of survival. Feral pigs disperse mainly wetland plant species, which has important implications for wetland conservation. However, feral pigs also deposited unwanted species into wetlands and predated the seeds of important wetland canopy tree species.
Show less - Date Issued
- 2010
- Identifier
- CFE0003468, ucf:48934
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003468
- Title
- THE EFFECTS OF EXPOSURE TO FEMINIST IDEOLOGY ON WOMEN'S BODY IMAGE.
- Creator
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Peterson, Rachel, Dunn, Stacey, University of Central Florida
- Abstract / Description
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Body image disturbance has become an increasing problem among women (Cash & Henry, 1995). Thus researchers have begun to focus on methods of prevention and intervention. Programs utilizing psychoeducation and Festinger's cognitive dissonance theory, for example, have been found to reduce body image dissatisfaction and related symptomatology. The information provided and potential impact are limited, however, because the interventions do not offer women an adaptive method of interpreting the...
Show moreBody image disturbance has become an increasing problem among women (Cash & Henry, 1995). Thus researchers have begun to focus on methods of prevention and intervention. Programs utilizing psychoeducation and Festinger's cognitive dissonance theory, for example, have been found to reduce body image dissatisfaction and related symptomatology. The information provided and potential impact are limited, however, because the interventions do not offer women an adaptive method of interpreting the many appearance-related messages they experience. This study sought to determine if exposure to feminist theory of body image may act as a buffer – a filter through which cultural messages about thinness and beauty are challenged. This feminist schema may provide an alternative interpretation of cultural messages, thereby increasing body image satisfaction. Participants were exposed to one of three interventions (feminist, psychoeducational, control). Exposure to the feminist condition resulted in increased physical appearance satisfaction and likelihood to self-identify as a feminist when compared with the control group. While findings were not extensive, they are nonetheless promising due to the brevity of the intervention.
Show less - Date Issued
- 2005
- Identifier
- CFE0000467, ucf:46374
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000467
- Title
- Disturbance-Based Management and Plant Species Change in Massachusetts Sandplain Heathlands over the Past Two Decades.
- Creator
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Martin, Kirsten, VonHolle, Mary, Quintana-Ascencio, Pedro, Weishampel, John, University of Central Florida
- Abstract / Description
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Massachusetts sandplain heathlands are habitats of conservation concern, harboring many rare plant species and providing habitat for animals that depend on openlands. These heathlands are threatened by human development, shrub encroachment in the absence of disturbance, and potentially increasing soil nutrient levels. Sandplain heathlands are managed with prescribed fire, in order to maintain their open structure and maintain species diversity. In order to assess how past management was...
Show moreMassachusetts sandplain heathlands are habitats of conservation concern, harboring many rare plant species and providing habitat for animals that depend on openlands. These heathlands are threatened by human development, shrub encroachment in the absence of disturbance, and potentially increasing soil nutrient levels. Sandplain heathlands are managed with prescribed fire, in order to maintain their open structure and maintain species diversity. In order to assess how past management was correlated with species change, I used a data set that spanned twenty years from three different heathlands in Massachusetts. I looked for correlations between management and species change. Correlations between species change and prescribed burning were very site, or microsite, specific, indicating that variables such as vegetation type and edaphic characteristics need to be taken into account before management is applied. Prescribed fire was also associated with an increase in ruderal species in one of the sites studied, indicating that there may be undesirable effects of prescribed fire in this system. Species diversity was negatively associated with shrub encroachment, reinforcing the importance of preventing shrubs from encroaching into these heathlands. I also found evidence that burning has not been a successful technique in preventing shrub encroachment in these sites. Lastly, the nitrophilic species Carex pensylvanica increased in all three sites, indicating that future studies should investigate the possibility that sandplain heathlands are currently experiencing nitrogen deposition beyond their critical loads.
Show less - Date Issued
- 2013
- Identifier
- CFE0004886, ucf:49677
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004886
- Title
- Predictors of School Engagement for Females with Emotional and Behavioral Disabilities.
- Creator
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Hardin, Stacey, Dieker, Lisa, Hines, Rebecca, Marino, Matthew, Kea, Cathy, University of Central Florida
- Abstract / Description
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Women in general have been historically overlooked in society and, more recently, in research females with emotional and behavioral disabilities (EBD) have been unnoticed (Rice, Merves, (&) Srsic, 2008). The purpose of the current study is to build a foundation of knowledge and practices for educators and researchers to better support and education this unique population of females. To better understand females with EBD, the researcher imposed a three-phase study, situated in two frameworks(-...
Show moreWomen in general have been historically overlooked in society and, more recently, in research females with emotional and behavioral disabilities (EBD) have been unnoticed (Rice, Merves, (&) Srsic, 2008). The purpose of the current study is to build a foundation of knowledge and practices for educators and researchers to better support and education this unique population of females. To better understand females with EBD, the researcher imposed a three-phase study, situated in two frameworks(-)the Culturally Responsive Theory Framework (Wlodkowski (&) Ginsberg, 1995) and the Participation-Identification Model (Finn, 1989), to look into the predictors of school engagement for females with EBD. In the first phase the researcher utilized quantitative data from the National Longitudinal Transition Study 2 to build three structural equation models (SEM) on the predictors of school engagement for students with EBD. Results and procedures are discussed for each SEM created. During phase two the researcher shifted the focus to females with EBD and interviewed six current females with EBD, ages 14-17. The participants were engaged in separate interviews that allowed the researcher to uncover additional variables necessary for females with EBD to engage in the school setting. The third phase consisted of an intersection of phases one and two to create a newly developed SEM model for females with EBD merging the interviews and the SEM built in phase one. The newly developed SEM is provided for future research, as well as are the provision of recommendations and implications of the results from the study.
Show less - Date Issued
- 2014
- Identifier
- CFE0005348, ucf:50473
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005348
- Title
- Wetland diversity in a disturbance-maintained landscape: Effects of fire and a fire surrogate on aquatic amphibian survival and species depauperateness.
- Creator
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Klaus, Joyce, Noss, Reed, Quintana-Ascencio, Pedro, Jenkins, David, Dr. L. Katherine Kirkman, University of Central Florida
- Abstract / Description
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Disturbance is one of the central concepts explaining how diversity arises and is perpetuated in ecological time. A good model system for testing hypotheses related to disturbance is the longleaf pine ecosystem in the southeastern U.S. because in this ecosystem frequent, low-severity fires acts as a disturbance that maintains a unique vegetation structure and high species richness. Vegetation structure influences animal distributions; in fire-dependent ecosystems many animals rely on open...
Show moreDisturbance is one of the central concepts explaining how diversity arises and is perpetuated in ecological time. A good model system for testing hypotheses related to disturbance is the longleaf pine ecosystem in the southeastern U.S. because in this ecosystem frequent, low-severity fires acts as a disturbance that maintains a unique vegetation structure and high species richness. Vegetation structure influences animal distributions; in fire-dependent ecosystems many animals rely on open-structured, fire-maintained vegetation but shrubs and trees encroach into fire-dependent ecosystems where fire has been excluded. Prescribed burning and mechanical removal are commonly used as restoration tools to control encroachment. To better assess and compare the restoration potential of these tools, a more thorough understanding of how they change vegetation structure and habitat suitability for animals is necessary.The southeastern U.S. is a diversity hot-spot for amphibians, many of which require ephemeral wetlands embedded in longleaf pine uplands for the aquatic phase of their life cycle. Amphibian diversity has been declining in recent decades and habitat loss/degradation has been cited as one of the leading causes. Although often overlooked in studies of fire ecology, the ephemeral wetlands required by many amphibians are also fire-dependent habitats that have been negatively impacted by lack of fire. To understand how disturbance interacts with wetland vegetation and aquatic-phase amphibians, three disturbance treatments meant to mimic the effects of natural disturbance on vegetation structure were applied randomly to 28 dry ephemeral wetlands in the Lower Coastal Plain of South Carolina, U.S. The treatments consisted of early growing-season prescribed fire, mechanical vegetation removal (a proposed fire surrogate), and a combination of mechanical removal plus fire; some sites were left untreated for reference. Vegetation structure was quantified and amphibian assemblages were monitored before and after treatments. In addition, one species of amphibian was used in a tadpole survival experiment to examine differences in performance among treatments. Other factors that could be affected by treatments and in turn influence amphibians were measured, including water chemistry, wetland depth, quantity and quality of epilithon, and leaf litter composition.Amphibian survival was lowest, and species depauperateness highest in untreated wetlands. Depauperateness of species whose range was restricted to the range of longleaf pine was lowest in sites that had mechanical treatment plus fire. The mechanical plus fire treatment created the most open vegetation structure with lowest leaf litter accumulation, especially of hardwood litter, conditions correlated with high amphibian survival and diversity. When data from this study was combined with data from a previous study of similar nearby wetlands, a pattern emerged in which one suite of species was absent from recently burned sites, while an entirely different suite of species was absent from long-unburned sites. This evidence suggests that disturbance is related to a shift in amphibian assemblage possibly due to changes in vegetation structure and perhaps wetland ecology in general, from an algal-based system maintained by frequent fire to a detrital-based system that develops in the absence of fire.
Show less - Date Issued
- 2013
- Identifier
- CFE0005015, ucf:49994
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005015
- Title
- SPECIES COMPOSITION AND SPATIOTEMPORAL PATTERN OF THE SEED BANK AND VEGETATION IN NATIVE AND DEGRADED FLORIDA ROSEMARY SCRUB.
- Creator
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Navarra, Jennifer, Quintana-Ascencio, Pedro, University of Central Florida
- Abstract / Description
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The soil seed bank plays a dynamic role in the regeneration of plant communities after natural and anthropogenic disturbance. In this thesis, I addressed how disturbances influence the vegetation and seed bank of Florida rosemary scrub. In Chapter One I evaluated changes in species composition and spatiotemporal pattern of the vegetation and seed bank along a gradient of disturbance. During the summers and winters of 2007-2009 percent ground cover and seed bank species composition were...
Show moreThe soil seed bank plays a dynamic role in the regeneration of plant communities after natural and anthropogenic disturbance. In this thesis, I addressed how disturbances influence the vegetation and seed bank of Florida rosemary scrub. In Chapter One I evaluated changes in species composition and spatiotemporal pattern of the vegetation and seed bank along a gradient of disturbance. During the summers and winters of 2007-2009 percent ground cover and seed bank species composition were assessed among replicates of three vegetation types subjected to minimal, moderate, and extreme anthropogenic disturbance (native rosemary scrub, degraded scrub, and agriculturally improved pasture, respectively). These vegetation types shared the same soil and topographic characteristics but differed in disturbance history. I found that species composition and spatial pattern varied with disturbance. In pastures the compositional and structural characteristics of rosemary scrub were lost and only native scrub species able to evade herbivory persisted in this community. Native and degraded scrub differed most from each other in species abundances and spatial pattern. Degraded scrub showed highest abundance of subshrubs and a spike moss species, while rosemary scrub was dominated by shrubs. The seed banks of scrub herbs in degraded scrub had a tendency towards a random spatial distribution that lacked association with aboveground cover. Conversely, rosemary scrub seed banks tended to have an aggregated distribution and were associated with occurrence of conspecific species aboveground, litter, and shrub cover. These results indicated a change in the spatial heterogeneity of the seed banks of scrub herbs in degraded scrub. In Chapter Two I evaluated changes in seed bank density with time-since-fire in native rosemary scrub. Due to large pulses of recruitment immediately after fire and population decline with time-since-fire, I predicted seed density with time-since-fire would follow a unimodal function with low density in early and late years post-fire, and highest density at intermediate time-since-fire. I compared seed density data among sites with different time-since-fire: two sites each of three, six, ten and 24 years time-since-fire and three long-unburned sites (> 24 years). Variability in seed bank composition and density increased with time-since-fire and only recently burned stands were distinctly different from the other time-since-fire age classes. Some species and functional groups did exhibit a quadratic or cubic association to time-since-fire (ruderal herbs, subshrubs, Ceratiola ericoides, Lechea cernua, Paronychia chartacea, Phyllanthus tenellus); however, timing of the peak in seed density varied depending on life span and age of reproductive maturity. Scrub herbs were the most abundant functional group in the seed bank and showed highest density in the first ten years post-fire. This pattern corresponds to the pattern of aboveground species abundance and suggests abundances above- and belowground are closely linked. Understanding the dynamics of the seed bank in both naturally and anthropogenically disturbed communities in Florida rosemary scrub is important for the restoration of scrub habitat and management of existing populations of endangered and threatened scrub species endemic to the Lake Wales Ridge in central Florida.
Show less - Date Issued
- 2010
- Identifier
- CFE0003108, ucf:48620
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003108
- Title
- IMPACT OF INCREASED GREEN TURTLE NESTING ON LOGGERHEAD FITNESS.
- Creator
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Carmichael, Amanda R, Mansfield, Kate, University of Central Florida
- Abstract / Description
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Marine turtles exhibit strong fidelity to their nesting beaches, making the conservation of nesting beaches important for ensuring successful sea turtle populations. Conservation of these nesting beaches involves understanding how species interact with the environment and each other, and understanding how environmental change and population growth can affect the suitability of the nesting habitat. The Archie Carr National Wildlife Refuge (ACNWR) is unusual in its high density of sea turtle...
Show moreMarine turtles exhibit strong fidelity to their nesting beaches, making the conservation of nesting beaches important for ensuring successful sea turtle populations. Conservation of these nesting beaches involves understanding how species interact with the environment and each other, and understanding how environmental change and population growth can affect the suitability of the nesting habitat. The Archie Carr National Wildlife Refuge (ACNWR) is unusual in its high density of sea turtle nesting by two species: green (Chelonia mydas) and loggerhead (Caretta caretta) turtles. The ACNWR in Melbourne Beach, Florida was established in 1991 due to the high density of loggerhead nesting, but in the time since it was established there has been a significant increase in green turtle nesting, from fewer than 50 nests in 1982 to over 15,000 in 2017. With such a high density of these two species in one relatively small area (21 kilometers of beach), the two species may compete for space. This is especially true for green turtles, which disturb large amounts of sand during their nesting process; in 2017, we observed 338 loggerhead clutches disturbed by nesting females during nesting surveys, nearly all of which were disturbed by green turtles. Using observed spatial and temporal nesting patterns for both green turtles and loggerheads on the ACNWR, I examined the effects these species may have on each other's nests now and in the future. Additionally, green turtles and loggerheads nest in different densities along the length of the ACNWR, with green turtles more concentrated in the southern portions of the Refuge. Finally, green turtle nesting begins and peaks approximately one month later on the ACNWR than loggerhead nesting. For each of these metrics, there is both considerable overlap and distinct separation between the two species. By using these metrics in a modeling approach, I estimated the probability of nest disturbance by a subsequently nesting female, ranging from 0 to 0.105, and how these probabilities are predicted to change over time with a growing green turtle population. Evaluating the carrying capacity of this beach is important in the context of habitat disturbance, including climate change and an increase in storm frequency, and informing adaptive management strategies for effective conservation.
Show less - Date Issued
- 2018
- Identifier
- CFH2000284, ucf:45878
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000284
- Title
- THE RELATIONSHIP AMONG WELLNESS, SEVERITY OF DISTURBANCE, AND SOCIAL DESIRABILITY OF ENTERING MASTER'S-LEVEL COUNSELING STUDENTS.
- Creator
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Smith, Heather, Robinson III, Edward H. "Mike", University of Central Florida
- Abstract / Description
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A wellness paradigm may hold promise for unifying and strengthening the identity of the counseling profession. The construct of wellness may also hold implications for assessment of entering master's-level counseling students, as a tool for continuous evaluation of students, or for overall program evaluation. In this study, the only counseling-based wellness assessment measure, the Five Factor Wellness Evaluation of Lifestyle, was tested for its relationship to two other constructs:...
Show moreA wellness paradigm may hold promise for unifying and strengthening the identity of the counseling profession. The construct of wellness may also hold implications for assessment of entering master's-level counseling students, as a tool for continuous evaluation of students, or for overall program evaluation. In this study, the only counseling-based wellness assessment measure, the Five Factor Wellness Evaluation of Lifestyle, was tested for its relationship to two other constructs: psychological disturbance and social desirability. In order to test the research hypotheses, a total of nine programs (in five states) and 204 entering master's-level counseling students completed instrumentation packets comprised of the Five-Factor Wellness Evaluation of Lifestyle, the Marlowe-Crowne Social Desirability Scale, and the Outcome Questionnaire – 45.2. The results of the analyses indicated statically significant relationships in 52 out of 55 correlations between the instruments' total scores and subscale scores. The first null hypothesis was rejected in favor of the alternative hypothesis; there was a statistically significant negative relationship between level of psychological disturbance and level of wellness. The results of the study failed to reject null hypothesis two; the relationship between wellness and social desirability was found to have no statistical significance after removing the influence of psychological disturbance. Null hypothesis three was rejected in favor of the alternative hypothesis; there was a statistically significant negative relationship between level of psychological disturbance and social desirability. Number and percent of participants exceeding psychological disturbance cutoff scores was examined. Measures of central tendency and the effects of demographic variables for each of the instruments were presented. Exploratory data analysis revealed that the first-order wellness factor, second-order wellness factors, and social desirability mean scores of those scoring above the cutoff for Severity of Disturbance, difficulty in Interpersonal Relations, Symptom Distress, and Difficulty in Social Roles were lower than those scoring below each cutoff score. Results of the study were summarized, factors to consider in the interpretation of the results were discussed, and implications for counselor education and future research were provided.
Show less - Date Issued
- 2006
- Identifier
- CFE0001032, ucf:46827
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001032
- Title
- THE EFFECTS OF URBANIZATION ON THE STRUCTURE, QUALITY, AND DIVERSITY OF CYPRESS PLANT COMMUNITIES IN CENTRAL FLORIDA.
- Creator
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Knickerbocker, Courtney, Quigley, Martin, University of Central Florida
- Abstract / Description
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The integrity of wetland ecosystems is largely determined by hydrological functionality, degree of connectivity to like ecosystems, and permeability to external influence. Land use changes in upland areas adjacent to wetland ecosystems may influence hydrology and connectivity while introducing novel biotic and abiotic materials. There is an increasing trend toward the use of remote assessment techniques to determine the degree of impact of external influences on adjacent wetlands. Remote...
Show moreThe integrity of wetland ecosystems is largely determined by hydrological functionality, degree of connectivity to like ecosystems, and permeability to external influence. Land use changes in upland areas adjacent to wetland ecosystems may influence hydrology and connectivity while introducing novel biotic and abiotic materials. There is an increasing trend toward the use of remote assessment techniques to determine the degree of impact of external influences on adjacent wetlands. Remote assessment and predictive capabilities are provided by indices such as the Landscape Development Intensity Index (LDI) (Brown and Vivas 2005) which may be beneficial in determining site condition, and which have the added benefit of providing a quantitative gradient of human impact. This study assessed the predictive ability of the LDI in cypress ecosystems, by testing its correlations with plant community metrics including an index of floral quality calculated using coefficients of conservatism (CC)(Cohen et al. 2004), plant species diversity, and fluctuation in community composition assessed by changes in the wetland status and native status of component plant species. LDI was also compared against an independent measure of disturbance which was used to construct an a priori disturbance gradient. Overall, diversity measures showed little correlation with any of the disturbance indices, while CC scores were significantly correlated. Models were constructed in an attempt to explain each of the variables of plant community response to development in the surrounding landscape. The length of time since the development of the land adjacent to the cypress domes was a predictor of plant community response only when included in models with other variables. LDI was the strongest predictor in all models except where increases in land use associated with hydrological changes helped predict or better predicted proportions of exotic and upland species.
Show less - Date Issued
- 2009
- Identifier
- CFE0002576, ucf:48280
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002576
- Title
- CHARACTERIZING THE VERTICAL STRUCTURE AND STRUCTURAL DIVERSITY OF FLORIDA OAK SCRUB VEGETATION USING DISCRETE-RETURN LIDAR.
- Creator
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Angelo, James, Weishampel, John, University of Central Florida
- Abstract / Description
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Vertical structure, the top-to-bottom arrangement of aboveground vegetation, is an important component of forest and shrubland ecosystems. For many decades, ecologists have used foliage height profiles and other measures of vertical structure to identify discrete stages in post-disturbance succession and to quantify the heterogeneity of vegetation. Such studies have, however, required resource-intensive field surveys and have been limited to relatively small spatial extents (e.g.,
Show moreVertical structure, the top-to-bottom arrangement of aboveground vegetation, is an important component of forest and shrubland ecosystems. For many decades, ecologists have used foliage height profiles and other measures of vertical structure to identify discrete stages in post-disturbance succession and to quantify the heterogeneity of vegetation. Such studies have, however, required resource-intensive field surveys and have been limited to relatively small spatial extents (e.g., <15 ha). Light detection and ranging (lidar) is an active remote sensing technology with enormous potential to characterize the three-dimensional structure of vegetation over broad spatial scales. In this study, discrete-return lidar data were used to create vertical profiles for over 500 vegetation patches on approximately 1000 ha of an oak scrub landscape in the Kennedy Space Center/Merritt Island National Wildlife Refuge area on the east-central coast of Florida. Nonparametric multivariate analysis of variance (NPMANOVA) tests detected significant differences among the profiles belonging to the four predominant land use/land cover (LULC) types in the study area. For the dominant LULC category (Herbaceous upland non-forested), pairwise NPMANOVA comparisons indicated that there were significant differences between vertical profiles for some of the distinct time since fire (TSF) values. Measures of vertical structural diversity (VSD) were calculated from the vertical profiles and then null, linear, and quadratic models relating VSD to TSF were compared via an Akaike information criterion (AIC) model selection procedure. As predicted by the Intermediate Disturbance Hypothesis, the quadratic model was the best model for the Herbaceous upland non-forested LULC category, but it explained less than 3% of the total variation in VSD. When fire frequency was considered in conjunction with TSF for this LULC category, however, the model that was quadratic in both predictor variables was the best model among the candidates and explained over 6% of the total variation in VSD. These results support the Extended Keystone Hypothesis, which predicts that disturbance generates discrete structural patterns across landscapes, and the Intermediate Disturbance Hypothesis, since the VSD of the predominant LULC category was maximized at intermediate levels of fire disturbance (i.e., intermediate values of TSF and/or fire frequency). In addition to demonstrating the ability of discrete-return lidar to characterize the vertical structure of vegetation at the landscape scale, this research has potential management implications. Using the techniques developed in this study, practitioners can compare the vertical structure of managed ecosystems to reference natural systems to evaluate the efficacy of managed disturbance regimes.
Show less - Date Issued
- 2010
- Identifier
- CFE0003254, ucf:48520
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003254
- Title
- Population dynamics and environmental factors influencing herbs in intact and degraded Florida Rosemary scrub.
- Creator
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Stephens, Elizabeth, Quintana-Ascencio, Pedro, VonHolle, Mary, Fauth, John, Levey, Douglas, University of Central Florida
- Abstract / Description
-
Species have complex and contextual relationships with their environment; both the relative contributions of life-history stages to population growth and the effect of environmental factors on each stage can be different among co-existing species. Timing and extent of reproduction, survival, and mortality determine population growth, species distributions, and assemblage patterns. I evaluate the role of habitat (intact, degraded) and microsite (shrub, leaf litter, bare sand) on population...
Show moreSpecies have complex and contextual relationships with their environment; both the relative contributions of life-history stages to population growth and the effect of environmental factors on each stage can be different among co-existing species. Timing and extent of reproduction, survival, and mortality determine population growth, species distributions, and assemblage patterns. I evaluate the role of habitat (intact, degraded) and microsite (shrub, leaf litter, bare sand) on population dynamics of Florida scrub herbs. Isolated overgrown shrubs and extensive bare sand areas in degraded scrub were expected to decrease seed predation, reduce competition of herbs with shrubs, and provide larger habitat for recruitment. I provide evidence that habitat and microsite variation influenced demography of five endemic and two common native species through effects on seed removal, emergence, and establishment. Habitat and species affected seed removal: endemic species with large seeds were removed in higher frequency in degraded habitat, likely by vertebrates, while species with small seeds were removed in higher frequency in intact habitat, by invertebrates. There was no evidence of differences in individual seed production between habitats for the two common species, C. fasciculata and B. angustifolia. Invertebrates were primarily responsible for seed removal of both species, although peak season of removal and microsite varied with species. Removal of seeds, emergence, and establishment increased with seed density. Matrix modeling indicated that population growth of C. fasciculata was greater in degraded habitat and greatest in litter microsites, and population growth of B. angustifolia was similar between habitats and greatest in bare sand. Contrasting responses among species to environmental factors in intact and degraded scrub indicated that natural disturbances are not ecologically equivalent to anthropogenic disturbances. Idiosyncratic species dynamics in common environments suggest that understanding relationships between life-history traits and environmental conditions will be required to facilitate restoration.
Show less - Date Issued
- 2013
- Identifier
- CFE0004754, ucf:49791
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004754
- Title
- Effects of mechanical habitat disturbance on the diversity and network structure of plant-bee interaction networks in Central Florida.
- Creator
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Carman, Karlie, Hinkle, Ross, Jenkins, David, King, Joshua, University of Central Florida
- Abstract / Description
-
Ecological interactions within a community shape the structure of ecosystems and influence ecosystem function. Plant-pollinator interactions exist as mutualistic exchange networks that may collapse as habitat loss occurs, thereby threatening the overall health of an ecosystem. Understanding the impacts of human-mediated habitat disturbance on ecological interactions is therefore crucial for conservation efforts. Archbold Biological Station (ABS) in Venus, Florida contains over 2000 hectares...
Show moreEcological interactions within a community shape the structure of ecosystems and influence ecosystem function. Plant-pollinator interactions exist as mutualistic exchange networks that may collapse as habitat loss occurs, thereby threatening the overall health of an ecosystem. Understanding the impacts of human-mediated habitat disturbance on ecological interactions is therefore crucial for conservation efforts. Archbold Biological Station (ABS) in Venus, Florida contains over 2000 hectares of protected Florida scrub habitat nested within a human-dominated environment that is threatened by anthropogenic habitat disturbance. In past studies, over 113 bee species and 157 associated host plants, many endemic to the Lake Wales Ridge, have been found on ABS property, providing an understanding of this system's plant-bee network. Using those data as a baseline, this study investigated the effects of varying levels of mechanical habitat disturbance intensity on the diversity and network structure of plant-bee interaction networks. Flowering plant abundance, richness, diversity, and composition as well as bee abundance and composition were significantly different across mechanical habitat disturbance levels. Interactions between bees and flowering plants also differed with varying disturbance intensity. From these results, it is clear that plants, bees and interactions between them are impacted by mechanical habitat disturbance in this system. This project informs management efforts not only for natural systems with the threat of alteration, but also for agricultural systems, many of which heavily rely on flower visitation by bee pollinators. This research also contributes to the growing field of interaction ecology by increasing understanding of habitat alteration effects on a valuable ecological interaction and ultimately ecosystem function.
Show less - Date Issued
- 2014
- Identifier
- CFE0005311, ucf:50505
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005311
- Title
- LANDCOVER CHANGE AND POPULATION DYNAMICS OF FLORIDA SCRUB-JAYS AND FLORIDA GRASSHOPPER SPARROWS.
- Creator
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Breininger, David, Noss, Reed, University of Central Florida
- Abstract / Description
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I confronted empirical habitat data (1994-2004) and population data (1988-2005) with ecological theory on habitat dynamics, recruitment, survival, and dispersal to develop predictive relationships between landcover variation and population dynamics. I focus on Florida Scrub-Jays, although one chapter presents a model for the potential influence of habitat restoration on viability of the Florida Grasshopper Sparrow. Both species are unique to Florida landscapes that are dominated by shrubs and...
Show moreI confronted empirical habitat data (1994-2004) and population data (1988-2005) with ecological theory on habitat dynamics, recruitment, survival, and dispersal to develop predictive relationships between landcover variation and population dynamics. I focus on Florida Scrub-Jays, although one chapter presents a model for the potential influence of habitat restoration on viability of the Florida Grasshopper Sparrow. Both species are unique to Florida landscapes that are dominated by shrubs and grasses and maintained by frequent fires. Both species are declining, even in protected areas, despite their protected status. I mapped habitat for both species using grid polygon cells to quantify population potential and habitat quality. A grid cell was the average territory size and the landcover unit in which habitat-specific recruitment and survival occurred. I measured habitat-specific recruitment and survival of Florida Scrub-Jays from 1988-2008. Data analyses included multistate analysis, which was developed for capture-recapture data but is useful for analyzing many ecological processes, such as habitat change. I relied on publications by other investigators for empirical Florida Grasshopper Sparrow data. The amount of potential habitat was greatly underestimated by landcover mapping not specific to Florida Scrub-Jays. Overlaying east central Florida with grid polygons was an efficient method to map potential habitat and monitor habitat quality directly related to recruitment, survival, and management needs. Most habitats for both species were degraded by anthropogenic reductions in fire frequency. Degradation occurred across large areas. Florida Scrub-Jay recruitment and survival were most influenced by shrub height states. Multistate modeling of shrub heights showed that state transitions were influenced by vegetation composition, edges, and habitat management. Measured population declines of 4% per year corroborated habitat-specific modeling predictions. Habitat quality improved over the study period but not enough to recover precariously small populations. The degree of landcover fragmentation influenced mean Florida Scrub-Jay dispersal distances but not the number of occupied territories between natal and breeding territories. There was little exchange between populations, which were usually further apart than mean dispersal distances. Florida Scrub-Jays bred or delayed breeding depending on age, sex, and breeding opportunities. I show an urgent need also for Florida Grasshopper Sparrow habitat restoration given that the endangered bird has declined to only two sizeable populations and there is a high likelihood for continued large decline. A major effect of habitat fragmentation identified in this dissertation that should apply to many organisms in disturbance prone systems is that fragmentation disrupts natural processes, reducing habitat quality across large areas. Humans have managed wildland fire for > 40,000 years, so it should be possible to manage habitat for many endangered species that make Florida's biodiversity unique. This dissertation provides methods to quantify landscape units into potential source and sink territories and provides a basis for applying adaptive management to reach population and conservation goals.
Show less - Date Issued
- 2009
- Identifier
- CFE0002537, ucf:47638
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002537
- Title
- INTERNATIONAL SPACE STATION REMOTE SENSING POINTING ANALYSIS.
- Creator
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Jacobson, Craig, Leonessa, Alexander, University of Central Florida
- Abstract / Description
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This paper analyzes the geometric and disturbance aspects of utilizing the International Space Station for remote sensing of earth targets. The proposed instrument is SHORE (Station High-Sensitivity Ocean Research Experiment), a multi-band optical spectrometer with 15 m pixel resolution. The analysis investigates the contribution of the error effects to the quality of data collected by the instrument. The analysis begins with the discussion of the coordinate systems involved and then...
Show moreThis paper analyzes the geometric and disturbance aspects of utilizing the International Space Station for remote sensing of earth targets. The proposed instrument is SHORE (Station High-Sensitivity Ocean Research Experiment), a multi-band optical spectrometer with 15 m pixel resolution. The analysis investigates the contribution of the error effects to the quality of data collected by the instrument. The analysis begins with the discussion of the coordinate systems involved and then conversion from the target coordinate system to the instrument coordinate system. Next the geometry of remote observations from the Space Station is investigated including the effects of the instrument location in Space Station and the effects of the line of sight to the target. The disturbance and error environment on Space Station is discussed covering factors contributing to drift and jitter, accuracy of pointing data and target and instrument accuracies. Finally, there is a brief discussion of image processing to address any post error correction options.
Show less - Date Issued
- 2005
- Identifier
- CFE0000855, ucf:46661
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000855
- Title
- Dynamic Behavior and Performance of Different Types of Multi-Effect Desalination Plants.
- Creator
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Abdelkareem, Mohamed, Chow, Louis, Mansy, Hansen, Das, Tuhin, Duranceau, Steven, University of Central Florida
- Abstract / Description
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Water and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of...
Show moreWater and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of primary energy and electricity consumption compared to other thermal desalination systems. The motivation for this research is to address thermo-economics and dynamic behavior of different MED feed configurations with/without vapor compression (VC). A new formulation for the steady-state models was developed to simulate different MED systems. Adding a thermal vapor compressor (TVC) or mechanical vapor compression (MVC) unit to the MED system is also studied to show the advantage of this type of integration. For MED-TVC systems, results indicate that the parallel cross feed (PCF) configuration has better performance characteristics than other configurations. A similar study of MED-MVC systems indicates that the PCF and forward feed (FF) configurations require less work to achieve equal distillate production. Reducing the steam temperature supplied by the MVC unit leads to an increase in second law efficiency and a decrease in specific power consumption (SPC) and total water price. Following the fact that the MED may be exposed to fluctuations (disturbances) in input parameters during operation. Therefore, there is a requirement to analyze their transient behavior. In the current study, the dynamic model is developed based on solving the basic conservation equations of mass, energy, and salt. In the case of heat source disturbance, MED plants operating in the backward feed (BF) may be exposed to shut down due to flooding in the first effect. For all applied disturbances, the change in the brine level is the slowest compared to the changes in vapor temperature, and brine and vapor flow rates. For MED-TVC, it is recommended to limit the seawater cooling flow rate reduction to under 12% of the steady-state value to avoid dryout in the evaporators. A reduction in the motive steam flow rate and cooling seawater temperature of more than 20% and 35% of steady-state values, respectively, may lead to flooding in evaporators and plant shutdown. Simultaneous combinations of two different disturbances with opposing effects have only a modest effect on plant operation and they can be used to control and mitigate the flooding/drying effects caused by the disturbances. For the MED-MVC, the compressor work reduction could lead to plant shutdown, while a reduction in the seawater temperature will lead to a reduction in plant production and an increase in SPC.
Show less - Date Issued
- 2019
- Identifier
- CFE0007423, ucf:52735
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007423
