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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.
361

Factors Influencing Annual Survival and Recovery Rates, Primary Feather Molt, and Hatch Chronology of White-winged Doves in Texas

Hall, Jared Daniel 19 May 2018 (has links)
<p> Understanding survival and breeding season length of game birds are important for effective management and conservation. By determining the variables that drive survival and recovery rates for white-winged doves (<i>Zenaida asiatica</i>), I can offer management implications to agencies across their range. There is currently little knowledge about white-winged dove molting and hatching chronology. The objectives of this study were to: 1) investigate annual survival and recovery rates of white-winged doves, 2) determine intrinsic and extrinsic factors influencing them, 3) determine AHY primary feather molt rate and the factors that influence molt rate and initiation, and 4) describe hatch chronology and determine the factors that influence hatching. To understand what influences annual survival and recovery, I examined subpopulation, climate variables, urbanization characteristics, molt, and band type as covariates. I used the Brownie approach in the RMark package of R to compare annual survival and recovery models and generate estimates. I used Underhill and Zucchini models in the Moult package of R to determine AHY primary feather molt rate and the best predictors of molt rate and initiation. I analyzed molt scores of HY doves recorded during annual banding using GLMs in R to determine the factors that influence hatching. I used AIC to select the most parsimonious models for each <i>a priori</i> candidate set. I analyzed 71,675 bands, of which, 3,086 were recovered from 2007 &ndash; 2016. My most supported model influencing survival and recovery was [<i>S</i>(age class x urban intensity) <i>f</i>(age class X MRPP)]. Average AHY primary molt rate across Texas was 13.21 &plusmn; 0.93 days. MRPP subpopulation + Year was the most supported model influencing AHY primary molt rate, AHY molt initiation, and hatch date. Within my sample, 95% of AHY white-winged doves began molting from 7 April to 8 July and completed molt 17 August to 17 November. White-winged doves hatched as early as 6 January and as late as 27 July, with 95% of all hatching occurring between 22 March and 18 June and peaking at 5 May. Urban intensity was an important variable influencing annual survival, which is expected for such an urbanized species. MRPP subpopulations influenced vital rates and should be considered for future harvest management. </p><p>
362

Essays on Land Conversion, Crop Acreage Response, and Land Conservation Benefits| Evidence from the Dakotas

Parvez, Md. Rezwanul 02 February 2018 (has links)
<p> This research is composed of three essays. It highlights the driving factors of land conversion and crop acreage response focusing on North Dakota agriculture and estimates the benefits of conservation land measures at west central South Dakota watershed. The major questions that are addressed here are how and why agricultural producers decide among different land use choices, crop selection, and land conservation measures and how their decision vary over time? The first essay examines the long run land conversion trend interconnected with change in crop, oil, and ethanol prices, climate and renewable fuel policy mandates. Data are obtained from Cropland Data Layer from 1997 to 2015 period of National Agricultural Statistics Service (NASS) at the USDA. The first essay employs a Seemingly Unrelated Tobit Regression approach to better understand the connection between land conversion and crop prices, biofuel policies, biophysical environment. Key findings indicate land-use conversion from grassland to cropland is relatively higher across the ND counties. </p><p> The second essay is designed to investigate the relationship between crop acreage response and socio-economic and environmental drivers. We use prices for crude oil, planted acres of major crops (corn, wheat, soybean, hay) and prices from the period of 1990 to 2015. This essay focuses on corn acreage response due to crop prices, energy policies, climate and other socio-economic factors using a Fixed Effect parameter framework. </p><p> The final essay estimates environmental benefits due to adoption of conservation practices. In other words, it analyzes the economic and environmental benefits of implemented conservation practices at Bad River watershed in South Dakota using an integrated framework. For example, in an article in the Global Journal of Agricultural Economics, Extension and Rural Development (2016), a Benefit Cost Analysis model is utilized to assess soil conservation benefits and evaluate economic impacts of conservation measures at a watershed scale. The economic analysis includes estimation of benefit cost ratio, annual rate of return of conservation practices. Key findings suggest that benefit value of sediment reduction average $2.13 per ton expressed in constant (year = 2000) dollars and the ratio of benefits to costs is greater than 1.</p><p>
363

Plant Responses to Environmental Heterogeneity in Great Basin Sagebrush Steppe

Barga, Sarah C. 14 December 2017 (has links)
<p> Plant populations experience both spatial and temporal environmental heterogeneity, and their strategies for coping with environmental heterogeneity are shaped by their inability to move in response to unfavorable conditions. In addition, human induced land-use change, including changes in grazing regimes and shorter fire-return intervals, has become increasingly common as a source of environmental heterogeneity experienced by plant populations. This research focuses on how native Great Basin plants respond to environmental heterogeneity, studying three stages of plant life-histories: seed germination, seed banks, and mature plants. My dissertation sought to: 1) identify relationships between climate variability and population-level variation in germination strategies of arid land forbs, 2) use occurrence records from herbaria to compare the climate niches for a group of arid land forbs, and 3) investigate the relationship between disturbance history and seed bank dynamics in sagebrush steppe communities. </p><p> The second chapter examines the similarities and differences between the climate niches and the geographic distributions of a set of co-occurring understory forbs found in sagebrush steppe systems. We used distribution models of the potential habitat for our species to estimate the range size, niche breadth, and geographic overlaps between our species. Next, we used model results to identify climate variables most predictive of the distributions of the individual species. Lastly, we compared the mean and variability for precipitation and temperature across known occurrence locations for each species to assess similarities and differences in climate characteristics where these species grow. We found that species varied in their predicted area of occupancy, niche breadth, and the climate characteristics most predictive of their suitable habitat. Only two of the ten species shared a comparable climate niche. This work demonstrated that herbarium records can be used to estimate climate preferences and potential habitat for understudied species. </p><p> The third chapter investigates seed bank dynamics in a Great Basin sagebrush steppe system, comparing sites that differ in their disturbance history. We asked whether shrub cover, ground cover, climate, or disturbance history (fire and grazing) were predictive of the seed densities in the soil, the diversity of native and introduced species, the presence of rare species, and similarity between the above and below-ground species composition. We found that common measures of fire history and grazing use may be overly coarse for predicting the effects of disturbance on seed bank dynamics. We also found that shrub cover was highly predictive of the seed bank dynamics in this system. Shrub cover of early seral shrub species was predictive of patterns consistent with moderate disturbance or recovery from disturbance within the above and below-ground plant community, while increasing cover of later seral species, such as <i>Artemisia tridentata,</i> produced patterns indicating a longer time since disturbance. </p><p> The fourth chapter asks how mean climate and climate variation at individual sites and across a species&rsquo; range affects the specialist-generalist spectrum of germination strategies exhibited by ten arid land forbs. We investigated these relationships using climate data for the western United States, occurrence records from herbaria, and germination trials with field-collected seeds. We found that nine out of ten species exhibited population-level variation in germination, and that generalist strategies were associated with higher spatial variation in actual evapotranspiration at a local scale and higher variation in available water in the spring and annual precipitation at a range-wide scale.</p><p>
364

Virtualization of Fuelbeds| Building the Next Generation of Fuels Data for Multiple-Scale Fire Modeling and Ecological Analysis

Rowell, Eric Martin 07 March 2018 (has links)
<p> The primary goal of this research is to advance methods for deriving fine-grained, scalable, wildland fuels attributes in 3-dimensions using terrestrial and airborne laser scanning technology. It is fundamentally a remote sensing research endeavor applied to the problem of fuels characterization. Advancements in laser scanning are beginning to have significant impacts on a range of modeling frameworks in fire research, especially those utilizing 3-dimensional data and benefiting from efficient data scaling. The pairing of laser scanning and fire modeling is enabling advances in understanding how fuels variability modulates fire behavior and effects. </p><p> This dissertation details the development of methods and techniques to characterize and quantify surface fuelbeds using both terrestrial and airborne laser scanning. The primary study site is Eglin Airforce Base, Florida, USA, which provides a range of fuel types and conditions in a fire-adapted landscape along with the multi-disciplinary expertise, logistical support, and prescribed fire necessary for detailed characterization of fire as a physical process. Chapter 1 provides a research overview and discusses the state of fuels science and the related needs for highly resolved fuels data in the southeastern United States. Chapter 2, describes the use of terrestrial laser scanning for sampling fuels at multiple scales and provides analysis of the spatial accuracy of fuelbed models in 3-D. Chapter 3 describes the development of a voxel-based occupied volume method for predicting fuel mass. Results are used to inform prediction of landscape-scale fuel load using airborne laser scanning metrics as well as to predict post-fire fuel consumption. Chapter 4 introduces a novel fuel simulation approach which produces spatially explicit, statistically-defensible estimates of fuel properties and demonstrates a pathway for resampling observed data. This method also can be directly compared to terrestrial laser scanning data to assess how energy interception of the laser pulse affects characterization of the fuelbed. Chapter 5 discusses the contribution of this work to fire science and describes ongoing and future research derived from this work. Chapters 2 and 4 have been published in International Journal of Wildland Fire and Canadian Journal of Remote Sensing, respectively, and Chapter 3 is in preparation for publication.</p><p>
365

A Case Study Analysis of Collaborative Conservation| Restoring Bighorn Sheep to the Santa Catalina Mountains

Hawkins, Tricia Oshant 22 March 2018 (has links)
<p> Involving a diversity of stakeholders in conservation issues is an important and growing trend in wildlife management. My thesis provides a case study of a collaborative conservation effort in which representatives from sportsmen&rsquo;s and environmental groups came together to advise the Arizona Game and Fish Department in a project to restore bighorn sheep to the Santa Catalina Mountains near Tucson, Arizona. These stakeholders formed the Catalina Bighorn Sheep Restoration Advisory Committee to help address the human dimension factors of the project, build public support, and guide project planning and implementation. In addition to participant observation and document analysis informing my study, I surveyed 31 stakeholders both on and off the Advisory Committee and interviewed key Advisory Committee members. All stakeholders were in favor of collaborative conservation. However, there were objections to this particular Advisory Committee for this particular project. Although stakeholders had a diversity of values that informed their beliefs, the Advisory Committee members who took the time to understand the science involved, develop mutual trust and respect for others at the table, and held a strong commitment to the project goals were able to shift deeply held, values-based beliefs and find consensus on contentious project elements. This included agreeing on a mountain lion management plan that called for the killing of mountain lions that preyed on the newly reintroduced bighorn sheep. Stakeholders not on the Advisory Committee did not come to agreement on most elements of the project. This study contributes to the understanding of collaborative conservation efforts by providing a case study of a controversial wildlife conservation project that involved diverse stakeholders who worked together, successfully found consensus, and achieved their main goal of getting bighorn sheep back on the mountain.</p><p>
366

Winter Ecology of Radiomarked Female Mallards in Mississippi's Alluvial Valley

Lancaster, Joseph David 17 May 2018 (has links)
<p> Interactions between animal populations and their environment form the foundation of wildlife management, and provision of resources that enhance fitness produce effectual management. Hunting is a selective force that shapes behavior and other adaptations of harvested species and may subsequently impact diel habitat use. Moreover, linking habitat use to biological outcomes, such as survival, is needed to evidence habitat suitability because of equivocal relations among population density, habitat correlations, or energy availability to population dynamics. The mallard (<i>Anas platyrhynchos</i>) is among the most coveted and harvested waterfowl in North America and is a migratory species of ecological, economic, and social importance. The Mississippi Alluvial Valley (MAV) is an ancestral and continentally important wintering area for North American mallards despite significant anthropogenic wetland transformation. Through targeted objectives and consequence of soil and water conservation, financial assistance programs have expanded waterfowl habitat on private lands in Mississippi. I radiomarked 265 female mallards and tracked their diel habitat use in winters 2010-2015 to evaluate objectives related to their wintering ecology in the MAV of Mississippi. Specifically, I investigated whether waterfowl hunting influenced use of some habitats during hunting season, the effectiveness of financial assistance programs in providing habitat, and habitat suitability through habitat specific survival rates. Females made greatest use of forested and emergent wetlands diurnally and emergent wetlands and flooded cropland at night. Results suggested that mallards did not avoid flooded cropland or emergent wetlands diurnally during hunting season, but conclusions were complicated by significant use of inviolate sanctuaries. Mallards used numerous incentivized conservation program wetlands, but use was less than public and privately managed wetlands. Among conservation programs, those with large enrollment and a focus on restoration (i.e., Wetlands Reserve Program) were most used by mallards. Apparent survival was independent of diurnal habitat use suggesting that mallards use of wetland complexes leads to their winter survival. Restoration of forested wetlands should be a management focus and easement programs provide such inroads on private lands. Public wetlands are an important source of habitat and inviolate sanctuary should be considered where waterfowl hunting is a predominate activity.</p><p>
367

Biogeographic Affinity Across Elevation and Moisture Gradients| Impacts on Land Mollusk Assemblages in the Grand Canyon Ecoregion, Southwestern USA

North, Eric G. 10 August 2017 (has links)
<p> &ldquo;Biogeographic affinity&rdquo; describes the similarities in the flora and fauna of one location compared to those of another location, resulting from their common evolutionary history and/or their contemporary connectivity (Loveland and Merchant 2004). The existence of the biogeographic affinity hypothesis allows the hierarchical classification of regions into faunal, floristic or other biogeographic provinces. Additionally, the latitudinal biodiversity gradient (LBG; Brown and Lomolino 1998) is normally illustrated by a diverse tropical fauna at low latitudes and decreasing species richness with increasing latitude. Here, I compare the relative influences of biogeographic affinity and the primary ecological gradients of the southern Colorado Plateau in the Grand Canyon ecoregion (GCE, Table 2; elevation, litter accumulation, and anthropogenic influences) on the distribution and abundance of land mollusks. I test four specific null hypotheses: (1) Biogeographic affinity does not influence the distribution of GCE land mollusks, (2) GCE land mollusk species and assemblages are uniformly distributed across elevation, analogously reflecting the absence of biogeographic affinity, (3) Habitat patch size (spring area) does not influence GCE land mollusk species richness and (4) The GCE land mollusk assemblage is not strongly influenced by microhabitat factors that are independent of elevation impacts. </p><p> To test my hypotheses, I used classic and contemporary literature and museum collections to build a comprehensive species list for the Grand Canyon ecoregion. This list included spatial (location, elevation) and ecological (biogeographic affinity) data to test hypothesis 1 (proportional representation) and hypothesis 2 (neotropical to boreal distribution. across elevation). I also used randomly sampled terrestrial mollusks in three elevation zones at 19 paired spring and matrix habitat sites, while also recording environmental data on leaf litter depth, isopod presence or absence, grazing presence or absence at each sample, canopy cover and spring area at each site. These data were used to test hypothesis 3 (spring area-species diversity relationships) and 4 (measured site- specific independent variables will predict species diversity). </p><p> The results of this analyses show: 1. The GCE land mollusk fauna is not equally distributed across 7 North American Biogeographic Provinces. Instead, the GCE is overrepresented by boreal, alpine and temperate species. 2. This two-dimensional pattern of overrepresentation was preserved across (3-dimensional) elevational gradients within the GCE. Communities were at least 84% dissimilar between elevation zones, with New- World temperate and wide-ranging circumpolar species being the dominant drivers the mollusk community composition even at low elevation sites. 3. Shannon-Weiner diversity (supporting the Latitudinal Biodiversity Hypothesis) and leaf litter depth (productivity) within springs decreased with increasing elevation. 4. Among the measured physical (spring/matrix, litter depth, canopy cover, species-area) and anthropogenic (isopods, grazing) factors, elevation was the only one found to predict species community composition. </p><p> These results indicate that while springs in the southwest USA are presumed to be relictual habitats, temperate land mollusks still possess an apparent advantage over neotropical species even at low elevation springs, where they are more abundant and diverse. These data support the Latitudinal Biodiversity Gradient (LBG) in a novel and unusual way, where low elevation sites are the most diverse, but are characterized by wide-ranging temperate and boreal species, with significant community compositional change across elevation.</p><p>
368

Measuring Citizens' Preferences for Protecting Environmental Resources| Applications of Choice Experiment Surveys, Social Network Analysis and Deliberative Citizens' Juries

Geleta, Solomon 12 July 2017 (has links)
<p> Many reasons have been suggested as explanation for observed differences in citizens' environmental conservation projects policy choices and willingness-to-pay (WTP) values. Some people attribute this distinctive decision behavior to contrasts in the overall policy outcome expectations (preference heterogeneity) and/or differences in reactions to the changes in the environmental attributes (response heterogeneity). Others attribute this to differences in individual choice rationales, personalities, encounters, and past and present experiences. In other words, regardless of the possibility that outcomes are the same, people do not have the same emotions, convictions, disposition, or motivations. </p><p> In three separate essays, I investigate the possible reasons for the observed differences in citizens' environmental conservation policy choices and examine how preference and response heterogeneity arise. In the first essay, I ask if a priori environmental damage perception is a source of heterogeneity affecting conservation option choice decisions. In the second, I investigate if social networks (interactions among decision-making agents) affect choice decisions. In the third, I investigate if preferences change when decision making agents are allowed to deliberate among peers. </p><p> For the first essay, I conducted an on-line choice experiment (CE) survey. The survey asked questions that help to measure citizen preference for protecting environmental public goods, ascertain the value local residents are willing-to-pay (WTP), and determine how preference heterogeneity arises. CE attributes included groundwater use (measured by share of total water use from groundwater), aquatic habitat (measured by count of spawning kokanee salmon return), natural habitat health (measured by the sensitive ecosystem area reclaimed), and rural character (measured by a decrease in urban sprawl and/or a decrease in population density in rural areas). I used a special property levy as the vehicle of payment. Random parameter logit (RP) and latent class (LC) models were estimated to capture response and preference heterogeneity. The results suggest that (1) both preference and response heterogeneities were found for the choices and all environmental attributes respectively (2) respondents who have a higher value for one environmental good will have a higher value for other environmental goods, and (3) a priori damage perception could be one of the sources of response and preference heterogeneity. </p><p> In the same survey, I included people's egocentric networks, interactions, environment related activities and perceptions to empirically evaluate whether social network effect (SNE) is a source of systematic differences in preference. I estimate consumer preferences for a hypothetical future environmental conservation management alternative described by its attributes within a Nested Logit Model: nesting broader and distinct conservation options within choices impacted by individual&rsquo;s network structure. The results show that some network centrality measures capture preference heterogeneity, and consequently the differences in WTP values in a systematic way. </p><p> Third, I compare the value estimated based on the traditional choice experiment (CE) with the results obtained using the citizen jury (CJ) approach or a group-based approach or also called the "Market Stall" in some literature. I estimate the effect of deliberation on conservation choice outcomes by removing any significant differences between the people who participated in the CJ (people who volunteered to be contacted again after deliberation treatment) and those people who did the survey twice but did not volunteer for CJ (control group) in terms of their socioeconomic status and be able attribute the changes in preferences to deliberation treatment only. CJ approach involved two 90 minute deliberations held over two days to discuss and consider their preferences and WTP values with other household members. Results show that deliberation improves individuals' valuation process and there is observed difference in choice outcomes between the deliberation treatment and control groups. Both preference and response heterogeneity relatively vanish when people were allowed to deliberate among peers.</p>
369

Foodweb Dynamics in Shallow Tidal Sloughs of the San Francisco Estuary

Montgomery, Jacob R. 01 December 2017 (has links)
<p> Non-parametric ANOVA tests, ordination, and Bayesian generalized linear models (GLMs) revealed strong physical, chemical, and biological differences among the study sites. Lower trophic foodweb indexes (<i>i.e.</i>, chlorophyll-a (chl-a) concentration, zooplankton biomass, and planktivorous fish abundance) were investigated in association with environmental variables in three terminal sloughs within the upper San Francisco Estuary. Non-metric multidimensional scaling (NMDS) showed tight clustering of data from each site. Kruskal-Wallis tests confirmed the NMDS by identifying statistically-significant differences among sites and between paired sites within each of the three regions (<i>i.e.</i>, Cache Slough, Lindsey Slough, Suisun Marsh). Bayesian GLMs identified temperature and dissolved inorganic nitrogen as primary correlates with chl-a concentration, and temperature and chl-a concentration as primary correlates with zooplankton biomass. Planktivorous fish data were insufficient to fit a GLM. Up-slough sites in Cache Slough and Suisun Marsh consistently showed greater abundances of chl-a and zooplankton relative to down-slough sites in each region. However, that pattern was reversed in Lindsey Slough. Possible reasons for this discrepancy include adjacent land-use and management practices, relative importance of alternate foodweb pathways, and the presence of a major water diversion. This study emphasizes the importance of site-specific foodweb dynamics and local anthropogenic effects, particularly in relation to design of tidal wetland restoration projects.</p><p>
370

Remote Sensing Evaluation of Compensatory Wetland Mitigation Regulated under the Clean Water Act in California, USA

McMeechan, Melissa Margaret 16 December 2017 (has links)
<p> Impacts to wetlands protected under Clean Water Act Sections 401 and 404, can require mitigation with the goal of no net loss of acreage and function. Several studies of compensatory mitigation concluded this goal has not been met, resulting in cumulative losses. Many of these studies were completed by permit review or post-mitigation field survey. However, few studies evaluated condition before and after impact and mitigation activities as a comparison of losses and gains to assess net loss of wetlands.</p><p> Ambrose et al. (2007) evaluated both compliance and wetland condition for CWA &sect;401 mitigation projects throughout California. As a continuance of the studies of Ambrose et al. (2007), this thesis evaluated the change in condition as a result of impact and mitigation activities to address whether no net loss was achieved. A rapid assessment methodology was adapted to evaluate wetland condition using aerial photographs.</p><p> As hypothesized, impact activities decreased the wetland condition at the majority of sites. However, mitigation activities often did not increase condition. Therefore, no net loss was not achieved for most projects. Furthermore, this study illustrates the pitfalls in an evaluation of no net loss based solely on the mitigation site condition after the project implementation. The observed wetland condition may have been present at the site prior to mitigation activities. This is a misleading assumption in the assessment of gains from the project. Therefore, the change in wetland condition should be assessed through an initial evaluation of site conditions, as well as part of on-going monitoring.</p><p>

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