Assessments of the anthropogenic threats to savanna ecosystems are primarily focussed on land use change, bush encroachment, and biological invasions. There is, however, very little understanding as to the threats from atmospheric pollution. South Africa is the major emitter of CO2 on the African content while the Mpumalanga region bordering the Kruger National Park (KNP) is among the leading regions for nitrous oxide pollution in the world. It is not only increasing atmospheric pollution, but rainfall intensity is also predicted to increase for southern Africa. As savannas are nutrient limited, an increase in nitrogen deposition will have major consequences for vegetation structure and this can only be exacerbated by increased rainfall amounts. Current research suggests that these predicted increases in water and nutrients will result in increasing grass biomass and decreasing herbaceous species richness. The effects of global change drivers on savanna vegetation are also likely to propagate through to multiple trophic levels, with changes in vegetation structure cascading down to invertebrate assemblages. As invertebrates are ubiquitous, form the bulk of metazoan species diversity and biomass on earth, and play a pivotal role in many ecosystems, I discuss in the introductory chapter of this thesis why the influence of global change on these assemblages should not be ignored. In my first data chapter, Chapter 2, I examine the effect that increases in available nutrients and water may have on vegetation structure, and how this may cascade down to grasshopper and ant assemblages. I do this using a fully factorial experiment in KNP with nutrient and water additions where I assessed both herbaceous (forb and grass) and insect (ant and grasshopper) assemblages five years after resource additions began. My results show that there was a substantial increase in grass biomass while plant and insect species richness declined with water addition alone and that a combination of nutrients and water resulted in the greatest increases in grass biomass and concomitant decreases in plant and insect species richness. The effects of nutrient and water additions on the insect community assembly was primarily driven by a decrease in grasshopper species and ant abundance respectively. An analysis of ant functional traits showed that the rare ant species mediated the impact of the resource additions on the ant assemblage. Fire is inherent to savanna systems with profound effects on vegetation structure. There has, however, been relatively little research on the effects of fire on savanna invertebrate fauna. In Chapter 3 I look at the effect that fire may have on the vegetation and insect community assembly at my study site between five and eight months after the site had been burned. These results show an increase in grass biomass and decrease in plant and insect species richness with a combination of nutrients and water. My results also show that grasshopper biomass, abundance, and species richness decreased as herbaceous biomass decreased. While ant species richness decreased, ant abundance increased post-fire, primarily related to an increase in patches of bare ground. With global change, drought frequency is also expected to increase. The insect and grass assemblages, both on and off Macrotermes mounds, at two sites in the southern section of KNP had been sampled in a separate study in 2012. In Chapter 4 I describe a study where I resampled these mounds during the peak of the most severe drought in 30 years. The two sites differed in drought severity, one where the drought severity was very high and the other where severity was much lower. The objective was to determine the effects that drought may have on the grass and associated insect assemblages both on and off termite mounds. My results show that at the high severity site grass cover and biomass and grasshopper abundance decreased both on and off mounds. The overall reduction in habitat structure resulted in an increase in both ant abundance and species richness but the mound and matrix ant assemblages diverged during drought. Where the drought was less severe there was an increase in large mammal herbivores as animals moved out of the more affected areas. This increase in mammal herbivory was more evident on rather than off mounds resulting in grass biomass being lower on rather than off mounds. The cascading effect saw grasshopper abundance decrease on and increase off mounds. The mound and matrix ant assemblages did not respond to the comparatively smaller change in habitat structure. Finally, in the synthesis chapter I discuss my results in the broader context of how global change drivers such as increased nitrogen deposition may cascade down from plant to insect community assembly. At present there is very little understanding of the amounts of nitrogen being deposited in KNP or the effect that this may have. The results of my study would suggest that this increase in nitrogen deposition will have major consequences for vegetation structure and that this will cascade down to the insect assemblage. In mitigating for this, it is therefore essential that management in KNP adapt a monitoring protocol for nitrogen deposition, especially when considering that where N deposition is really high fire may not volatilise everything to allow the system to reset itself back to its original state. It is not only nitrogen deposition, but drought frequency is also likely to increase. In mitigation for this there should also be monitoring programmes to consider the effects of drought as animals may move from areas of high drought severity to areas where severity is lower. Such movement will increase grazing pressure on both low and high nutrient environments with cascading effects on vegetation structure and insect assemblages.

The gopher tortoise is a keystone species that creates networks of underground burrows that are home to an additional 350 species, where 60 are vertebrates. Vertebrates have been shown to differ between habitat types and seasonally, but limited information is known about vertebrate associates in our region. This study was one of the first to investigate this in our region of south Florida. This study was designed to investigate factors that may affect the presence of vertebrates at gopher tortoise burrows. Camera data was collected to determine vertebrate presence and if specific vertebrate groups elicit a territorial response from the tortoise, while habitat vegetation surveys and weather data were collected to evaluate seasonality. Statistical analysis showed variation in vertebrate presence both seasonally and by habitat type. Few territorial interactions were observed overall. This study acts as a starting point to increase our understanding of local tortoise populations. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Natural Resources Management is a combination of disciplines all working together to improve management practices, environmental education, and cross-discipline communication. Land managers and conservationist have become a group of people thrust into the public eye and to help the world make sense of the ecological and climatic changes that are taking place. For this reason, Natural Resources Management PhD?s have become a community needed to interface with the public in order to balance environmental and societal needs. This dissertation project took a renaissance approach by examining a wide range of fields. It is said that a Renaissance man is knowledgeable and proficient in a wide range of fields or they are interdisciplinary. The world is in need of a conservation renaissance to reconnect the environment back to societal values, and it is going to need an interdisciplinary approach to do so. To do this each of the three areas: communication, education, and application were explored. Communication was addressed in two parts, first through the completion of a partnered publication with United States Fish and Wildlife Services, which used a framework from education (backward design) to communicate best practices for tallgrass prairie reconstruction in North Dakota. A second document was then completed describing how the backward design model was used to optimize communication. To further connect the importance of education to Natural Resource Management, I partnered with the Minnesota State University Moorhead Regional Science Center and their curriculum based field trips; drawing artifacts were collected and examined using the coding scheme from Human Figure Drawing and cross-racial facial recognition to determine what cues are utilized in novice plant observers. The Natural Resource Management application research was conducted on conservation lands in eastern North and South Dakota comparing the spike seeding method with more traditional seeding methods.

Bibliography: p. 182-190. / The Kaapsehoop Cycad (Encephalartos laevifolius Stapf and Burtt Davy) has the international, national, and provincial status of "endangered" by virtue of a number of factors which threaten it with extinction. It occurs in only three disjunct populations in southern Africa, of which two are very small and have only adult plants. This situation suggested the need for specific action to ensure the conservation of the plant within its natural habitat. This study was initiated in an attempt to respond to this call for action. The aims of the study were set at gaining an understanding of the ecology of the cycad, establishing the exact nature and extent of the factors threatening it with extinction, and presenting management guidelines as to how the plant and its habitat may be managed to ensure their conservation. Chapter One includes a background to the botanical significance of cycads in general, the reasons for the endangered status of E. laevifolius and a list of aims and objectives. The latter are briefly; to develop. an understanding of the ecology of this cycad, determine the nature and extent of the threats which have placed it in the ''endangered" category, and establish means of managing the plants and their habitat so as to mitigate these threats . The methodology followed to achieve the latter is presented in Chapter Two. The results achieved from work carried out by the author are presented In Chapter Three, and they are then discussed in Chapter Four, together with those obtained from other researchers and experts in the field of cycad ecology and management. From this it becomes apparent that the major factor threatening the plants continued existence in nature, is its illegal removal by unscrupulous collectors. The use of fire as a management tool may cause the loss of sexually propagated off-spring if not based on ecological principals. This would be tragic as the percentage of fertile seed being produced at present is extremely low. Besides the latter two abiotic threats, there are two biotic threats which are also .cause for concern. They are the rotting of the female cones and seed by a pathogenic infection, and the destruction of newly growing tissue by the caterpillars of the Leopard Moth. The insights gained from the study are drawn together as conclusions in Chapter Five. Where these indicate specific management measures or directions for further research, recommendations are made. It must be emphasized that although this study has been used for the enhancement of the author's academic qualification, it is vitally important that the recommendations made be seriously reviewed by those responsible for the conservation of this cycad. If this study is simply put on the shelf after it has achieved its academic goal, the possibility of E. laevifolius becoming extinct is very real.

Sumatran elephant (Elephas maximus sumatranus) continue to decline due to habitat loss, poaching and conflict with humans. Yet, developing effective land conservation strategies for elephants is difficult because there is little information available on their foraging ecology, habitat use, movements and home range behaviors. Using the lead animal technique, 14 free-ranging, tame elephants at the Seblat Elephant Conservation Center (ECC) were observed for 4,496 hours to describe their foraging ecology and diet. The majority of their daily activity was feeding (82.2 ± 5.0%), followed by moving (9.5 ± 4.0 %), resting (6.6 ± 2.1%) and drinking (1.7 ± 0.6%), and individual activity budgets varied among individuals for all activities. At least 273 plant species belonging to 69 plant families were eaten by elephants and five plant families of Moraceae, Arecaceae, Fabaceae, Poaceae, and Euphorbiaceae were most commonly consumed. Elephants browsed more frequently than grazed, especially in the wet season. Levels of crude protein, calcium, phosphorus and gross energy in plants eaten by elephants in Seblat appeared adequate for meeting the nutritional requirements. Home range size of an adult female elephant in the SECC during 2007–2008, was 97.4 km2 for the MCP and 95.0 km2 for the 95% fixed kernel. There were no relationships between average monthly elephant home range sizes or movement distances with rainfall. Distances to rivers and ex-logging roads had little effect on elephant movements, but vegetation productivity, as measured by the Enhanced Vegetation Index, did affect elephant movements. We used resource selection and compositional analysis habitat ranking approaches to describe adult female elephant habitat use in the SECC. The elephant used medium canopy and open canopy forests more than expected; however, during the day closed canopy forests were used more than at night. Locating and capturing wild elephants in tropical rainforest environments are difficult and high-risk tasks. However, using tame elephants improves the search efficiency of finding wild elephants in dense forests and reduces risks to staff and target elephants. Use of experienced veterinarians and standing sedation techniques also greatly reduce the risks of elephant injury while immobilizing elephants.

The Osa Peninsula is one of Costa Rica's most biodiverse areas with more large mammals than anywhere else in the country. During the last two decades, however, mammal species have been subject to illegal hunting pressure of unknown amounts. The goal of this dissertation is to investigate the knowledge and attitudes of villagers and local leaders of Osa Peninsula regarding large mammals and their use, and to compare various estimates of wildlife abundance to assess potential effects of human activities during recent years. From surveys, 58% the 359 interviewees from 15 communities believe that in 1993 there were more wild animals than 2008. Paca is the most poached species, and second in importance is the white-lipped peccary. The main motivation for poaching is for local consumption, but 62% of interviewees strongly disagreed with the notion of poaching being a legitimate activity. Interviews with local leaders indicated that 63% strongly agreed that wildlife persistence is important for the development of the area. They believe that deforestation, poaching, and gold mining are the main activities negatively affecting wildlife species on the Osa Peninsula. During 2001 and 2002 I estimated Relative Abundance Indices (RAI) of nine species of vertebrates from tracks in three sectors differing in human activity: gold mining, farming, and indigenous people's activities. I found that jaguar, puma, white-lipped peccary, tapir, and great curassow had lower RAIs in the mining sector. Other species such as collared peccary, red brocket deer, agouti, and paca were just as common outside the Park as inside. I set up camera trap stations in the core and toward the edge of the CNP during 2003 and in the core of the park in 2008. There were few significant differences in the RAIs of the nine species near vs. far from the park, but abundance some species differed between years, likely a result of an increase in amount of patrolling by park rangers during that time. The results of this study provide insights into perceptions and behaviors of local residents, and into wildlife population changes, that can be used in the conservation of the mammals species in the Osa Peninsula.

No description available.

Doctor of Philosophy / Department of Biology / Keith B. Gido / Habitat fragmentation and loss threaten global biodiversity, but organism responses to changing habitat availability are mediated by structural properties of their habitats. In particular, organisms inhabiting dendritic landscapes with hierarchically arranged branches of habitat tend to have limited access to some patches even in the absence of fragmentation. Consequently, organisms inhabiting dendritic landscapes such as streams respond strongly to fragmentation. Using a combination of meta-analysis, field observations, and ecological network modeling I show that stream fishes respond to fragmentation in predictable ways. First, I addressed how dams and stream dewatering have created a mosaic of large river fragments throughout the Great Plains. Using a geographic information system and literature accounts of population status (i.e., stable, declining, extirpated) for eight “pelagic-spawning” fishes, I found stream fragment length predicted population status (ANOVA, F2,21 = 30.14, P < 0.01) and explained 71% of reported extirpations. In a second study, I applied a new measure of habitat connectivity (the Dendritic Connectivity Index; DCI) to 12 stream networks in Kansas to test the DCI as a predictor of fish response to fragmentation by road crossings. Results indicated fish communities in stream segments isolated by road crossings had reduced species richness (alpha diversity) and greater dissimilarity (beta diversity) to segments that maintained connectivity with the network, and the DCI predicted patterns in community similarity among networks (n = 12; F1,10 = 19.05, r2 = 0.66, P < 0.01). Finally, I modeled fish distributions in theoretical riverscapes to test for mechanistic linkages between fragmentation and local extirpations. Results suggested the number of small fragments predicted declines in patch occupancy, and the magnitude of change in occupancy varied with dispersal ability (“high” dispersers responded more strongly than “low” dispersers). Taken together, these works show context-dependencies in fish responses to fragmentation, but a unifying theme is that small fragments contribute to attenuated biodiversity. Moreover, the predictable manner in which stream fish react to fragmentation will aid in biodiversity conservation by revealing potential responses to future scenarios regarding changes to habitat connectivity.

Modeling species of conservation concern, such as those that are rare, declining, or have a conservation designation (e.g. endangered or threatened), remains an activity filled with uncertainty. Species that are of conservation concern often are found infrequently, in small sample sizes and spatially fragmented distributions, thereby making accurate enumeration difficult and traditional statistical approaches often invalid. For example, there are numerous debates in the ecological literature regarding methodological choices in conservation-based models, such as how to measure functional traits to account for ecosystem function, the impact of including rare species in biological assessments and whether species-specific dispersal can be measured using distance based functions. This thesis attempts to address issues in methodological choices in conservation-based models in two ways. In the first section of the thesis, the impacts of methodological choices on conservation-based models are examined across a broad selection of available approaches, from: measuring functional diversity; to conducting bio-assessments in community ecology; to assessing dispersal in metapopulation analyses. It is the goal of this section to establish the potential for methodological choices to impact conservation-based models, regardless of the scale, study-system or species involved. In the second section of this thesis, the use of consensus methods is developed as a potential tool for reducing uncertainty with methodological choices in conservation-based models. Two separate applications of consensus methods are highlighted, including how consensus methods can reduce uncertainty from choosing a modeling type or to identify when methodological choices may be a problem.

Reproductive science plays an important role in conservation biology. Quantitative studies of basic reproductive biology in wildlife are critical for the development of successful assisted reproductive technologies. Investigation of the volume regulatory mechanism of spermatozoa could produce options to improve the cryopreservation of spermatozoa and provide a non-hormonal contraceptive option for men, both of which could have significant impacts on global biodiversity preservation. Volume regulation of somatic cells involves the movement of osmolytes through various channels, including potassium channels. The potassium channels involved in volume regulation of human, monkey, and murine spermatozoa were investigated. Flow cytometry was used to gauge the sensitivity of the volume regulatory process of spermatozoa to various potassium channel inhibitors and a simultaneous hypotonic challenge. Channels potentially involved in regulatory volume decrease of spermatozoa varied with species but included voltage-gated (Kv) channels 1.4, 1.5, 1.7, 4.1, 4.2 and 4.3 as well as TWIK1, TWIK2, TASK1, TASK2, TASK3, TREK2 , and minK. The presence of some of these channels was confirmed by western blotting and immunocytochemistry. Changes in the motility patterns of human and monkey spermatozoa in the presence of potassium channel inhibitors during hypotonic stress were also observed, suggesting a relationship between volume regulation and motility. To evaluate potential organic osmolytes involved in, and compare effects of CPAs on, volume regulation, the isotonicity of murine epididymal spermatozoa was measured using a null point method. Spermatozoa were then exposed to high concentrations of various osmolytes and cryoprotective agents in isotonic medium to evaluate which compounds were able to penetrate the sperm plasma membrane. The osmotic responses of spermatozoa from strains of mice known to have spermatozoa of high (B6D2F1) and low (C57BL6) post-thaw fertility were compared during various osmotic challenges in various media. These experiments indicated that spermatozoa from B6D2F1 mice may have better volume regulation capabilities than spermatozoa from C57BL6 mice, suggesting that better post-thaw fertility of murine spermatozoa could be influenced by the volume regulatory process. The knowledge gained from these experiments could contribute to improved sperm handling and preservation techniques and be used to develop non-hormonal male contraceptives based on inhibiting volume regulation.