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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.
121

Spawning Site Selection and Fry Development of Invasive Lake Trout in Yellowstone Lake, Yellowstone National Park, Wyoming

Simard, Lee 01 January 2017 (has links)
Since their discovery in Yellowstone Lake in 1994, Lake Trout (Salvelinus namaycush) have been the object of an intensive gillnet suppression program due to their predation on native Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri). Managers are also interested in targeting early life stages to augment suppression. A benthic sled was used to sample for Lake Trout eggs at 24 locations, hypothesized to be spawning sites, that encompassed a range of depths, slopes, and substrate composition to determine the location and characteristics of spawning sites in Yellowstone Lake. Lake Trout eggs were collected at seven sites, five of which had not been previously confirmed as spawning sites. Habitat characterization at these sites indicate Lake Trout spawning in Yellowstone Lake is limited to areas with rocky substrate, but is not constrained to areas with interstitial spaces or contour breaks as is seen within the species' native range. Lake Trout fry were captured around Carrington Island, an additional spawning site in Yellowstone Lake, in 2014 and 2015. These fry were significantly larger at each developmental stage, consumed more food beginning at earlier stages, and were captured much later into the summer than fry captured at a spawning site in Lake Champlain. The lack of potential egg and fry predators in Yellowstone Lake could be driving these differences in spawning site selection and fry behavior. This information will allow managers to identify additional spawning locations for suppression and evaluate the impact their efforts might have on the Lake Trout population in Yellowstone Lake.
122

Development of a Karst Tourism Management Index to Assess Tourism-Driven Degradation of Protected Karst Sites

Semler, Keith R 01 July 2019 (has links)
The intent of this research was to create and evaluate a karst tourism management index (KTMI). This index is intended to be a new management tool designed to quantify environmental disturbances caused specifically by tourism activities in karst regions, particularly show caves and springs. In an effort to assess the effectiveness of the index as a management tool in karst terrains, after development, the index was applied to six case study sites. A review of the management policies at each study site was conducted with the use of standard policy critique methods and semistructured interviews with managers at the study sites. After interviews were completed, the newly created index was applied to the study areas with the aid of park land managers. Including land managers in the application process allowed for active land managers to provide more meaningful feedback on potential improvements to the KTMI to ensure the most universally applicable and thoroughly field-tested index tool was created. Upon application and continual refinement of the index to the six study sites, a new data-driven management tool to measure disturbances to karst terrains by tourism was developed. The KTMI consist of an Overall Score category that is broken down into the two main categories of Management and Tourism. The KTMI contains 168 indicators that all need to be scored individually to obtain results, with Management containing 100 of the indicators and Tourism containing the other 68 indicators.
123

Applying Bayesian Belief Network To Understand Public Perception On Green Stormwater Infrastructures In Vermont

REN, Qing 01 January 2018 (has links)
Decisions of adopting best management practices made on residential properties play an important role in reduction of nutrient loading from non-point sources into Lake Champlain and other waterbodies in Vermont. In this study, we use Bayesian belief network (BBN) to analyze a 2015 survey dataset about adoption of six types of green infrastructures (GSIs) in Vermont’s residential areas. Learning BBNs from physical probabilities of the variables provides a visually explicit approach to reveal the message delivered by the dataset. Using both unsupervised and supervised machine learning algorithms, we are able to generate networks that connect the variables of interest and conduct inference to look into the probabilistic associations between the variables. Unsupervised learning reveals the underlying structures of the dataset without presumptions. Supervised learning provides insights for how each factor (e.g. demographics, risk perception, and attribution of responsibilities) influence individuals’ pro-environmental behaviors. We also compare the effectiveness of BBN approach and logistic regression in predicting the pro-environmental behaviors (adoption of GSIs). The results show that influencing factors for current adoption vary by different types of GSI. Risk perception of stormwater issues are associated with adoption of GSIs. Runoff issues are more likely to be considered as the governments’ (town, state, and federal agencies) responsibility, whereas lawn erosion is more likely to be considered as the residents’ own responsibility. When using the same set of variables to predict pro-environmental behaviors (adoption of GSI), BBN approach produces more accurate prediction compared to logistic regression.
124

Cityscape connections: National Park Service relevance and resilience in urban areas

Perry, Elizabeth Eleanor 01 January 2018 (has links)
The National Park Service (NPS) strives to embody U.S. democratic ideals, conserving our collective stories and scenery for their intrinsic value and the enjoyment of current and future generations. However, although these places are conserved for all, they are not enjoyed by all. As with other conservation agencies, the NPS finds itself increasingly concerned with building relevance with diverse potential stewards. In cities, where 80% of the U.S. population and 40% of the NPS portfolio is based, there is a prime opportunity to build relevance with large, diverse, and proximate audiences. Recognizing this opportunity, the NPS initiated its Urban Agenda as a centerpiece of its 2016 centennial. The Urban Agenda seeks to connect people with proximate NPS parks and programs, primarily by using collaborations as pathways to relevance. In doing so, the agency may become a more resilient and value-added component of these larger landscapes. However, connections between relevance, resilience, and collaborations, especially at the organizational level, have rarely been addressed. This dissertation: 1) identifies perspectives on NPS relevance in the urban context; 2) examines the diversity of brokers and roles in facilitating relevance across collaborative networks; and 3) assesses areas of intra-NPS relationship-building for enhanced relevance. A multi-site, multi-methods evaluation was conducted. Detroit, Tucson, and Boston, all cities with Urban Agenda investment but representing different proximities to physical NPS parks, were selected as cases. Qualitative in-depth interviews with NPS staff and community partners were paired with quantitative social network analysis. The first phase of research identifies areas of commonality and difference among perceptions about relevance. Qualitative inquiry found that, across cities, NPS staff tended to conceptualize relevance in agency-focused ways while community partners conceptualized it on broader scales, both in audiences and goals. These differences in scale may be complementary, though, with the NPS further enhancing its relevance by recognizing the larger context and embedding its perspectives within this context. The second phase of research quantitatively examines collaborative network composition and potential, especially regarding network and broker diversity. Study results suggest that building the breadth and depth of a network, as well as targeting specific areas of desired growth, are ways to effectively build network resilience and further connections for relevance. The third phase of research examines relationships among parks, programs, and offices of the NPS. Combining qualitative and quantitative methods, this inquiry found that relationships between parks are most numerous and supported by institutional structures. However, connections to and within programs are a desired area for further connection. All relationship-building structures and language must emphasize the utility of internal connections for external relevance. Balancing relationship types while being inclusive of non-park groups may be essential in promoting organizational resilience and relevance. This evaluation contributes to theoretical understanding about and indicators of relevance and resilience. Together, results from these three phases of study can help the NPS understand specific relevance considerations in urban areas, efficiently use their resources to enhance relevance, and continue to strive toward our democratic ideals.
125

Tools for landscape-scale automated acoustic monitoring to characterize wildlife occurrence dynamics

Balantic, Cathleen Michelle 01 January 2019 (has links)
In a world confronting climate change and rapidly shifting land uses, effective methods for monitoring natural resources are critical to support scientifically-informed management decisions. By taking audio recordings of the environment, scientists can acquire presence-absence data to characterize populations of sound-producing wildlife over time and across vast spatial scales. Remote acoustic monitoring presents new challenges, however: monitoring programs are often constrained in the total time they can record, automated detection algorithms typically produce a prohibitive number of detection mistakes, and there is no streamlined framework for moving from raw acoustic data to models of wildlife occurrence dynamics. In partnership with a proof-of-concept field study in the U.S Bureau of Land Management’s Riverside East Solar Energy Zone in southern California, this dissertation introduces a new R software package, AMMonitor, alongside a novel body of work: 1) temporally-adaptive acoustic sampling to maximize the detection probabilities of target species despite recording constraints, 2) values-driven statistical learning tools for template-based automated detection of target species, and 3) methods supporting the construction of dynamic species occurrence models from automated acoustic detection data. Unifying these methods with streamlined data management, the AMMonitor software package supports the tracking of species occurrence, colonization, and extinction patterns through time, introducing the potential to perform adaptive management at landscape scales.
126

Physicochemical Properties of Residuals from Anaerobic Digestion of Dairy Manure and Food Waste: Nutrient Cycling Implications and Opportunities for Edible Mushroom Cultivation

O'Brien, Brendan J. 01 January 2019 (has links)
Organics recycling is increasing in New England as multiple states have enacted laws to divert organic materials, including food scraps and food processing residuals, away from landfills. Anaerobic digesters on dairy farms represent an attractive approach to food waste recycling because existing infrastructure is in place and co-digestion of dairy manure with food waste can increase renewable biogas production. In addition, anaerobic digestion results in effluents that can be separated into solid and liquid residual materials, or 'digestates'. Screw-press separated solids consist of lignocellulosic biomass resistant to microbial degradation during anaerobic digestion. These separated solids are typically recycled on farms as animal bedding before returning to the digester, whereas remaining liquid digestates are typically spread as fertilizer for nearby feed crops or pasture fields. Within this model, anaerobic digestion is not a nutrient management solution and repeated land application of digestate nutrients can create eutrophication risk over time. Alternative models are needed where digestate materials are converted into valuable products to be sold off-farm, enabling the removal of nutrients to help meet nutrient management goals. In this thesis, I address two research questions related to the pursuit of such alternative models. First, how do physicochemical characteristics of digestate materials vary across full-scale systems in the region, including systems with and without food waste as a substantial proportion of feedstock, and how do these variations affect the potential for conversion of digestates into valuable products (e.g., soil amendments)? Second, can separated digestate solids be used for commercial cultivation of gourmet oyster mushrooms (Pleurotus ostreatus) to produce food for human consumption, providing synchronous nutrient recovery and food production? Results from my first research chapter indicate that increasing food waste inputs (and thus diversification of feedstock recipes) will likely increase the variability of some solid and liquid digestate characteristics and can result in greater contamination with synthetic particles, with implications for nutrient recovery efforts and associated products. My second research chapter shows that screw-press separated digestate solids can offset non-local substrate ingredients to a degree while achieving oyster mushroom yields comparable to commercial recipes. Furthermore, this strategy could divert nutrients away from land adjacent to digesters and directly into safe, nutritious, protein-rich food for humans, while also producing a useful spent mushroom substrate product.
127

Decision Making of Environmental Engineers on Project Selection

Davis, Millicent Amanda 01 January 2016 (has links)
Some environmental engineers do not understand how to perceive profitable opportunities in redeveloping the large number of contaminated brownfield sites in New Jersey. The purpose of this qualitative exploratory case study was to find effective decision-making strategies that help environmental engineers acquire profitable environmental redevelopment projects. The target population consisted of 4 environmental engineers in an environmental organization in Camden County, New Jersey who possessed proven decision-making strategies that helped them acquire profitable environmental redevelopment projects in the past 5 years. The conceptual framework for this study was the multiple criteria decision method (MCDM). Semistructured interviews were conducted with the engineers, and company documents were additional sources of data gathered. Triangulation and member checking were used to ensure the trustworthiness of interpretations. Five themes emerged from the analyses relating to strategies for an MCDM assessment in project management, a go/no-go assessment in project selections, education and training, ethics as an organizational value, and project management. These findings may lead to social change in Camden County, New Jersey community organizations, such as schools, daycare centers, and local businesses, which may benefit from the knowledge and safety recommendations of remediation decision making. Furthermore, these findings may provide opportunities for environment organizations to teach and train stakeholders on environmental processes while providing profitable opportunities to shareholders through sustainable practices.
128

Process_Based Management of Downy Brome in Salt Desert Shrublands: Assessing Pre- and Post-Rehabilitation Soil and Vegetation Attributes

Hirsch, Merilynn Carol 01 May 2011 (has links)
A number of technical approaches had to be employed within the planner, namely, 1) translating expected reward into a probability of goal satisfaction criterion, 2) monitoring belief states with a Rao-Blackwellized particle, and 3) employing Rao-Blackwellized particles in the McLUG probabilistic conformant planning graph heuristic. POND-Hindsight is an action selection mechanism that evaluates each possible action by generating a number of lookahead samples (up to a xed horizon) that greedily select actions based on their heuristic value and samples the actions' observation; the average goal satisfaction probability of the end horizon belief states is used as the value of each action.
129

Bioeconomic and Biophilic Intersect in Nature Centers - A Case Study of One Nature Center

Price, Carolyn Jeanne 01 December 2010 (has links)
The purposes of this research were 1) to understand what stakeholders in one nature center are "thinking"about the focus of their center and the niche it occupies; 2) to characterize the role of one nature center in its local community; 3) to examine the nature center in terms of established characteristics of a "best" nature center; 4) to compare stakeholder perceptions with perceptions of directors of exemplar nature centers and environmental education organizations; and 5) to characterize visitor and member stakeholder perceptions and motivations in terms of the extrinsic value of ecosystem services, bioeconomics, versus the intrinsic value of nature, biophilia. This research was conducted utilizing case study methodology with mixed method data collection. Ijams Nature Center visitors and members were surveyed concerning the value of nature; structured interviews were administered to Ijams Nature Center employees, nationally recognized nature center and environmental organization directors. Visitors‘ perceptions of nature focused on the natural surroundings of the nature center, providing opportunities to watch wild animals, appreciate nature, and feel at peace. Nature center member perceptions of nature reflected the concepts of stewardship and advocacy fostered by the Center‘s conservation mission, education programs, and preservation activities. Participants shared common thematic concepts for the role of nature centers and the characteristics of a best nature center. A best nature center was characterized as a composite of factors, practices, and perspectives that merge to form a business plan reflective of best practice guidelines. Participants highlighted the unique quality of centers and the passion and vision that guides development and the roles played by nature centers in their local communities, as identified in this study, i.e., education, advocacy, and immediacy. Ijams Nature Center visitors and members valued nature differently in terms of bioeconomics and biophilia, but both groups rated the biophilic value of nature of greater importance, with differing constructs reflective of that value.
130

Atrazine Contamination and Suspended Sediment Transport within Logsdon River, Mammoth Cave, Kentucky

Schenck Brown, Julie Eileen 01 December 2008 (has links)
Understanding the potential for karst aquifer contamination by sediment-sorbed pesticides is important for cave conservation efforts in agricultural landscapes. Flow rate, water quality parameters and suspended sediment concentrations were measured in Logsdon River, a ~10km karst conduit within the Turnhole Spring Groundwater Basin of Mammoth Cave National Park to determine characteristics of storm-period transport of sediment-sorbed atrazine through a conduit-flow karst aquifer. Analysis of two independent precipitation events occurring in the Spring of 2008 from May 2-4 and May 27-29 demonstrated the rapid response of the Logsdon River to precipitation events with detections of atrazine increasing during the initial turbidity peak and decline in spC, indicating that the atrazine arrives with the initial flush of surface waters that enters the conduit. Distinct peaks of atrazine did not coincide with fine grained (silt and clay-sized) sediment peaks and concentrations of atrazine remained elevated on the falling limb of the hydrograph as turbidity declined. In addition, no systematic relation between filtered and unfiltered samples was evident. There was also exceedingly weak correlation between the concentration of atrazine and suspended sediment, suggesting that if atrazine is sorbed to fine sediment particles this sorption involves only the fractions finer than 0.22 μm.

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