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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Evaluation of pH Dependent Prototype Feral Pig Toxicants

Lawrence, Grant S. 03 May 2017 (has links)
<p> Feral pigs (<i>Sus scrofa</i>) are one of the most ecologically harmful species in North America and are expanding across the U.S. at alarming rates. Feral pigs are an extremely prolific, destructive species and native ecosystems will continue to suffer unless resource managers intervene to reduce the damages caused by feral pigs. In 2015, in cooperation with the Texas Parks and Wildlife Department&ndash;Kerr Wildlife Management Area, I investigated the efficacy of several novel feral pig control prototype products (i.e., toxic baits) to: 1) compare lethality and length of intoxication times between 13 microencapsulated sodium nitrite (MESN) formulations in pseudo gavage dosed captive feral pigs; 2) evaluate residual sodium nitrite levels and potential risks of vomited MESN bait on non-target species; and 3) assess the lethality of 5 unique sodium nitrite formulations in group pen feeding trials. Pseudo gavage trials resulted in 4 MESN formulations achieving a 100% lethality rate with delayed emergence of intoxication symptoms compared to previous literature. Unexpectedly, gastric coatings delayed the onset of intoxication to the same degree as enteric coatings. Vomit appeared to be positively correlated with the delivery of a lethal dose of MESN paste bait as 55/56 pigs (98.21%) vomited and died. Residual sodium nitrite in vomited bait was 90% less than the sodium nitrite concentrations in the delivered paste matrix. Despite this reduction, vomited bait could serve as a potential threat to non-target and secondary consumers, although the degradation time, residual persistence, and probability of non-target vomit consumption remains unknown. Group pen trials, testing 5 unique sodium nitrite formulations, resulted in ?80.95% overall lethality, with the greatest individual formulation lethality equaling 96.77%. Results from these studies will be beneficial in determining a MESN feral swine toxicant formulation for registration with the United States Environmental Protection Agency in the future.</p>
82

Fishing and farming at Lake Chad : a livelihood analysis

Sarch, Marie-Therese January 1999 (has links)
No description available.
83

An organizational perspective on U.S. wildland firefighting operations| Opening the black box

Vigneaux, Gregory J. 23 December 2016 (has links)
<p> The U.S. federal wildland fire management system continues to experience rises in the number of acres burned annually and increases in management expenditures surrounded by firefighter death and injury. Despite a wealth of relevant academic research regarding wildland firefighting operations, a prominent nexus of these dynamics, there is little research regarding the response organization used to facilitate these operations on the fireground. Owing to a lack of research, wildland firefighting operations have remained a black box, meaning something with unknown internal workings, between the top of the response organization and the environment. From the perspective of systems thinking, the absence of a complete understanding of wildland firefighting operations prevents the dynamics of the larger domestic federal wildland fire management system from being holistically understood. In response to this gap in knowledge, this thesis explores wildland firefighting operations from an organizational perspective through a secondary analysis of qualitative data.</p>
84

Cattle ranching on the western Great Plains| A study of adaptive decision-making

Wilmer, Hailey 04 January 2017 (has links)
<p> Ranching social-ecological systems (SESs) in the semi-arid, western Great Plains persist under highly variable inter- and intra-annual weather conditions and globally influenced markets. Ranch spatial scales and manager decision-making processes have traditionally been excluded from conventional grazing experiments, leading to considerable debate between scientists and land mangers about grazing strategies to achieve both beef production and biodiversity conservation outcomes on rangelands. In this dissertation I use collaborative, interdisciplinary methodologies to link rangeland and grazing management decision-making processes and learning with ecological outcomes in the semi-arid rangeland social-ecological systems (SESs) of Wyoming and Colorado. </p><p> Chapter 2 analyzes relationships between ranchers and rangeland ecosystems, inspired by the rise of adaptive management discourses in the natural resource management literature and informed by post-colonial and feminist scholarship. Rancher decision-making processes during and after drought can be understood through an ethic of care, as ranchers try to reduce social and ecological vulnerability through adaptation, learning, and respect over long-term (generations-long) time frames. Chapter 3 follows a participatory grazing research project, the Collaborative Adaptive Rangeland Management (CARM) experiment, for four years (2012-2016). I track the social learning processes of a group of 11 stakeholders representing 3 groups: ranchers, conservation NGOs, and public agencies. These stakeholders manage 10 experimental pastures in the shortgrass steppe with comparison to the traditional grazing management practice. These pastures are managed to maintain or improve a viable cattle operation, grassland bird diversity, and rangeland vegetation structure, composition, and cover. Decisions by the stakeholder group about grazing and prescribed burning illustrate the complex role of existing management knowledge in social learning and the outcomes of participatory rangeland research. </p><p> In Chapter 4, I use repeated interviews and ecological monitoring on 17 family-owned and operated ranches in eastern Colorado and eastern Wyoming to categorize different grazing management strategies and compare plant species composition outcomes across those different strategies, accounting for environmental factors. After accounting for environmental influences, using non-metric multidimensional scaling and linear mixed models, I found a reduction of perennial cool-season grasses on ranches in higher grazing stocking rates and on cow-calf/yearling operations compared to cow-calf operations, but no significant differences in plant species composition on ranches with different grazing rotation strategies or different planning styles (tacit vs. explicit planners). I classified ranches into adaptive cycle trajectories to interpret ranch decision-making in terms of ranch SES-scale resilience. In Chapter 5, I review critical social literature to reflect on my positionality as a researcher, as well as the importance of consent and respect in social-ecological research. </p><p> Findings in this dissertation provide useful information for understanding the adaptation of ranch-scale rangeland SESs. Future research or outreach projects seeking to engage with rancher stakeholders may be improved by considering complex decision-making processes, caring practices, and the stewardship ethic of ranchers. Future efforts to bring multiple public-lands stakeholder groups with different management perspectives together for adaptive management will be improved if they consider the important role of stakeholder practices and experiences with rangeland management in social learning, and commit to building trust and knowledge through engagement that extends beyond the typical 3-5 year window for grazing research projects. My investigation of ranch-SES adaptive processes illustrates diverse decision-making strategies on different ranches. More research is needed on stocking rate decision-making, including around the social and political contexts of stocking rate decisions. This work suggests that a resilience lens can contribute to existing theory on ranch adaptive decision-making. Outreach and education efforts are likely to be more successful if they consider that one size does not fit all for ranch grazing management strategies.</p>
85

Scientists, Uncertainty and Nature, An Analysis of the Development, Implementation and Unintended Consequences of the Northwest Forest Plan

Miller, Gilbert David 06 April 2019 (has links)
<p> The conflict in the Pacific Northwest between competing visions of how federal forests should be managed resulted in a political stalemate in the early 1990s. The Northwest Forest Plan (NWFP) was initiated to resolve the demands for maintaining ecosystem processes and biological diversity with the social and economic needs for timber harvest. The foundation for the plan rested with the development of ecosystem management. The intent of this research is to explore the events which led up to the adoption of the NWFP, how it was implemented by the US Forest Service and Bureau of Land Management and the subsequent reactions to and consequences of the plan. </p><p> The primary research consisted of thirty-eight semi-structured interviews with individuals responsible for the development of the initial plan, those tasked with implementing the plan and current federal agency personnel from the land management agencies and regulatory agencies. With the use of thematic analysis, key meanings were captured as expressed by the interviewees. The data was analyzed using institutional theory, capturing the organizational relations within the organizational field of the land management agencies. </p><p> Research findings suggest that the NWFP was unsuccessful in meeting the goal of addressing the social and economic issues as well as the goals for ecosystem management. This dissertation explores the organizational practices and cultural meanings that led to the final instantiation of the plan. It seeks to shed light on the reasons why these goals were not met and how future forest plans can move beyond the current stalemate between conservation and preservation.</p><p>
86

Soil Health Assessment of the Sanborn Field Long-term Experimental Study

Norkaew, Saranya 16 April 2019 (has links)
<p> Soil health assessment uses a combination of potential indicators affecting soil processes to comprehensively monitor soil change, caused by cropping systems and soil management. The objectives of the study were to assess the effects of selected cropping systems, soil management and landscape slope positions on the soil health characteristics of the Sanborn Field long-term experimental study in Columbia, Missouri, United States. Soil samples were collected on each of four dates over two years (8<sup>th</sup> May 2014, 4<sup>th</sup> September 2014, 1<sup>st</sup> April 2016, and 18<sup> th</sup> August 2016) from selected plots to address each objective, and these time samples were used as replications. Soil physical, chemical, and biological characteristics were analyzed in the laboratory for these samples to assess soil health using the Cornell Comprehensive Assessment of Soil Health (CASH) method. To assess soil health in this study, soil health scoring was determined used R-studio version 1.1.149 to relate the interaction of cropping systems, soil management, and slope positions. Most soil resources on Sanborn Field are a poorly-drained claypan soil classified as a Mexico silt loam (fine, smectitic, mesic Vertic Epiaqualf). In addition, soil samples collected from Tucker Prairie was used as a proxy for the original state of Sanborn Field soils. The first study was conducted to evaluate the effects of long-term cropping systems on soil health properties. The results from the characterization indicated that continuous timothy (<i>Phleum pretense</i> L.) and warm season grass treatments were classified with very high soil health scores, and the lowest score was found for continuous corn (<i>Zea mays</i> L.). In addition, results showed strong positive linear associations between soil organic carbon, total nitrogen, potentially mineralizable nitrogen, active carbon, microbial biomass, and water stable aggregates; while a strong negative linear correlation existed between each of these properties and bulk density. The second study was conducted to evaluate the effects of long-term annual applications of no fertilizer, full fertilizer, and manure on soil health measurements of selected cropping systems. Different cropping systems, including continuous corn, continuous wheat (<i>Triticum aestivum</i> L.), corn-wheat-red clover (<i>Trifolium pretense</i> L.) rotation, and corn-soybean (<i>Glycine max</i> L.)-wheat rotation treatments were used in this study. Results showed that annual dairy cow (<i>Bos Taurus </i>) manure applications had the greatest effect on all soil health indicators and had the largest overall soil health score compared to full fertility and no fertilizer treatments. Moreover, continuous wheat with manure application presented the best combination of effects on soil properties with the largest score for most soil health indicators and an overall health score of 82 out of 100 classified as very high which is the best. The last study evaluated the effects of landscape slope positions on soil health properties of the long-term experiment. Results showed that the summit position had the highest overall soil health score while the lowest score was found on the shoulder position. However, there were no significant differences along the transect slope for water-stable aggregates and bulk density. There were significant differences along the transect for the biological properties such as soil organic carbon, active carbon, potentially mineralizable nitrogen, and microbial biomass. Results of this study illustrate the effect of selected variables on soil health and provide the recent addition of using biological characteristics to account for soil health properties. It is important to remember that this study of the long-term Sanborn Field experiment is just for a small-sized plot area. Future studies of soil management effects on soil health need to account for their own field conditions and their own unique environment.</p><p>
87

Evaluating Methods to Describe Dietary Patterns of Lake Michigan Salmonids

Benjamin S. Leonhardt (5930720) 18 December 2018 (has links)
<div>Documenting trophic relationships in aquatic ecosystems can facilitate understanding of not only system processes, but also the potential responses of food webs to stressors. Often, trophic studies assume consistent behavior and trophic roles among individuals in a population, but intraspecific diet variation, such as individual specialization, can play a critical role in food web complexity and can promote ecosystem resilience. In Lake Michigan, the introduction of invasive species (e.g., zebra mussel, Dreissena polymorpha; quagga mussel, Dreissena bugensis; round goby, Neogobius melanostomus) and reduced nutrient loading has resulted in changes in nutrient dynamics, system productivity, and community composition over the past two decades. As a result, abundances of many forage fish have declined, including alewife (Alosa pseudoharengus) which have historically supported the five dominant salmonid species of Lake Michigan (brown trout, Salmo trutta; Chinook salmon, Oncorhynchus tshawytscha; Coho salmon, Oncorhynchus kisutch; lake trout, Salvelinus namaycush; rainbow trout, Oncorhynchus mykiss). With these ecosystem changes, there is uncertainty as to the extent of how different species of salmonids will transition to alternative prey items (e.g., round goby). Common methods for examining diet patterns and trophic linkages include stomach content analysis, stable isotope ratios (e.g., δ13C and δ15N), and fatty acid composition, but these methods vary in temporal resolution and have differential biases. Furthermore, elucidating agreement of these trophic indicators and whether or not agreement is consistent across species can improve their use in future food web studies. The first research chapter of this thesis investigated the diet complexity of Lake Michigan salmonids by evaluating stomach content composition, diversity, and potential specialized consumption of different alewife lengths. Stomach contents revealed that Chinook salmon almost exclusively consumed alewife and had a lower diet diversity compared to the other four species, which consumed round goby (brown trout and lake trout), aquatic invertebrates (Coho salmon), and terrestrial invertebrates (rainbow trout) in addition to alewife. Although there were clear spatio-temporal and size-related feeding patterns for each species, much of the variation in diet composition and diet diversity was present at the individual-level. Additionally, salmonid species appeared to consume the entire size range of alewife that were available to them and individually specialized on alewife lengths. Due to their reliance on alewife, it is likely that Chinook salmon may be more negatively impacted than other salmonid species if alewife abundance continue to decline in Lake Michigan. The second research chapter assessed the agreement of multiple trophic indicators. Although we found agreement among trophic indicators across the five salmonid species using linear and logistic models, particularly between stomach contents, δ13C, and fatty acid 16:1n-7, there was significant variation in relationships across species, potentially due to variation among salmonids in specific prey items consumed (e.g., alewife and round goby) and species-specific regulation of fatty acids. Additionally, δ15N estimated from stomach contents using linear mixing models were typically greater relative to observed δ15N, which may suggest small alewife were underrepresented in stomachs of 2016 angler-caught salmonids. Lastly, stomach contents underestimated benthic resource use by rainbow trout, which may be related to biases associated with fish collection methods and stomach content analysis. Overall, the results of trophic indicator comparisons indicate that caution should be taken when generalizing trophic relationships across species and to consider biases associated with trophic indicators, especially when relying on a single diet metric.</div>
88

Learning and change in rural regions: understanding influences on sense of place.

Measham, Thomas George, Tom.Measham@csiro.au January 2004 (has links)
This thesis is about how people develop attachments to places, and what this means for natural resource management. The concept of ‘sense of place’ is generating strong interest in the domain of natural resource management. In particular, the concept offers considerable potential as a way of integrating social, ecological and economic dimensions of environment. This makes the concept highly relevant to an emerging agenda from a range of disciplines and management approaches concerned with the links between social systems and natural systems at local and regional scales (Berkes and Folke 1998; Cheng Kruger and Daniels 2003; Plumwood 2002).¶ Recent interest in place has led to a research agenda for exploring how this concept can play a greater role in resource management (Cantrill and Senecah 2001). Central to this research agenda are questions of how attachments to places are influenced and how sense of place changes over time. In response to the emerging role of sense of place in natural resource management and the research agenda for exploring this concept, this thesis is concerned with three questions: what are the key influences on sense of place?; what is the relationship between sense of place and activities in practice?; and how do people learn about places and respond to change? To explore these questions, the thesis presents findings from interviews with 40 participants in case studies of the Atherton Tablelands and Woodstock, north Queensland. The research employed a purposeful sampling design with the aim of capturing as many different senses of place as possible within the limits of this study. Participants represented a broad range of land uses, ethnic backgrounds, ages and durations of time in the place of the interview. The data from these interviews were analysed using qualitative methods drawing on grounded theory (Charmanz 2000) and influenced by adaptive theory (Layder 1998). The research included a focus on honouring human experience (Braud and Anderson 1998), and also recognising the importance of prior research on how people develop a sense of place (Piaget 1971; Relph 1976).¶ The analysis showed how sense of place was influenced strongly by childhood experiences, both for people who grew up in the case study locations and for people who grew up elsewhere. Other strong influences on place involved living in a similar environment overseas, seeking profit and having a sense of self focussed on agricultural production. Of particular interest is that for many participants who moved to the case study locations, their sense of the Atherton Tablelands or Woodstock was well developed prior to arriving there. This implies that influencing people’s sense of place once they have arrived in a new place will be difficult. Attempts to influence people’s sense of place before they arrive, or soon after arrival, are more likely to be successful. ¶ The ways that sense of place related to practice are presented as a series of overlapping themes. These include the practice of admiring one’s place from the comfort of home, making the land produce, and engaging with a place through activities such as hunting, camping and fishing. Participants also described the practice of caring for place, such as looking after traditional country and restoring the family farm. ¶ The ways participants learned about their places focussed on their childhood experiences, learning from elders, the role of comparisons between places, and the importance of continuity of experience. Participants described very few ways of learning about their place during adulthood. One of these was seeing places under different conditions, such as during a rat plague or after a bushfire. Another was through involvement in community events such as festivals.¶ In discussing the implications of these findings for natural resource management and policy, the thesis highlights how for several participants the key influences on sense of place were tied to non-economic values. Furthermore, this thesis shows that for many people identity and place were strongly linked and this adds to research that explains why farmers may not behave in economically ‘rational’ ways (Botterill 2001a). The thesis also discusses the links between sense of place and post-productivist values in considering transitions in regional Australia identified by Holmes (2002). The findings of this thesis emphasise the potential role for environmental education during childhood to encourage learning about places. The thesis also discusses the implications of how people learn about their places during adulthood, arguing that further support for festivals and community events can play a significant role in exploring the links between social and ecological systems.¶ In conclusion, the thesis argues that the concept of place continues to offer considerable potential for understanding change in regional Australia, and in particular a grass roots shift towards post-productivist values. This role can be developed by further supporting environmental education in childhood and community events such as festivals which help us to learn about the links between ourselves and our environments.
89

River birds as indicators of change in riverine ecosystems

Call, Erynn 17 June 2015 (has links)
<p> River-associated birds may be valuable indicators of environmental change in riverine ecosystems because they are predators of fishes and therefore often top predators in the aquatic food web. To evaluate the likely scope of one form of change - river restoration through dam removal and the expected return of abundant diadromous fish prey - we: 1) developed an appropriate river bird survey protocol; 2) documented the relative importance of sea-run fish in the diet of four river bird species, bald eagle (<i>Haliaeetus leucocephalus</i>), osprey (<i>Pandion haliaetus</i>), belted kingfisher (<i>Megaceryle alcyon</i>), and tree swallow (<i> Tachycineta bicolor</i>); 3) documented nest distribution and brood size of osprey; and 4) investigated the relationships between river bird abundance and various habitat parameters. We expect these measures will reflect changes to the river system post-dam removal as diadromous fish populations recover, proliferate, and integrate into the food web. Based on species accumulation curves and first-order Jacknifes, we concluded that biweekly or triweekly I5 minute surveys are sufficient to meet our objectives. Within the Penobscot River, stable isotope analysis of river bird diets indicated that marine nutrients are consumed by bald eagle, osprey, and belted kingfishers that reside below the lowermost dam, but not tree swallows. Despite greater connectivity for and abundance of spawning diadromous fishes (particularly river herring), in the Kennebec and Sebasticook Rivers as compare to the Penobscot River, osprey brood size was not significantly larger. We suspect other factors such as competition with bald eagles may be limiting the benefit of large river herring runs to nesting osprey. Finally, an ordination of 26 river bird species and 5 single-species (invertivore - spotted sandpiper, piscivore - osprey; piscivore - bald eagle; insectivore - tree Swallow; and omnivore - American black duck) generalized linear models, I revealed associations between estimated species abundance and water flow, water level, distance from the river mouth (river kilometer), site position in relation to a dam (e.g. above, below, or not at a dam), and adjacent land cover composition.</p>
90

The Smokey Generation| A Wildland Fire Oral History and Digital Storytelling Project

Hannah, Bethany E. 19 June 2015 (has links)
<p> This contextual essay provides a full description of The Smokey Generation, an applied thesis project designed around creating an interactive website that collects and presents oral histories and digital stories of current and past wildland firefighters, with an initial focus on hotshots (i.e., specific teams of wildland firefighters notable for their high level of training and experience). The framework of the website is intentionally designed to influence the public perception of wildland fire to better support and align with its necessary ecological role. For this project, I analyzed stories collected during 36 interviews of current and past hotshots, using literary analysis techniques to determine the following: What tropes and schemes do hotshots most commonly use when describing fire in the environment and what meanings and values are revealed through those figures of speech? In addition to identifying tropes and schemes used in the collected stories, I compared the meanings and values put forward by those figures of speech with how the firefighters view the role of fire in the environment. My analysis revealed a disconnect, showing casual use of antagonistic figures of speech to describe wildland fires and firefighting actions; this, despite the interviewees&rsquo; actual beliefs about the role of fire in the environment, which indicate an understanding and appreciation of wildland fire, particularly the importance of using fire to restore healthy ecosystems, and a desire to be able to better use fire as a land management tool. To conclude, I discuss how I approached framing and presenting those findings on the website in order to develop a richer, more meaningful conversation around wildland fire through the use of digital storytelling and oral history. The project website can be found at: http://thesmokeygeneration.com. </p>

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