UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

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Now showing 1 - 5 of 5
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    Estimating Population Trends in American Woodcock (Scolopax Minor) Using Population Reconstruction Models
    (2016) West, Brent Hopkins; Bowerman, William W; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The American woodcock (Scolopax minor) population index in North America has declined 0.9% a year since 1968 prompting managers to identify priority information and management needs for the species (Sauer et al 2008). Managers identified a need for a population model that better informs on the status of American woodcock populations (Case et al. 2010). Population reconstruction techniques use long-term age-at-harvest data and harvest effort to estimate abundances with error estimates. Four new models were successfully developed using survey data (1999 to 2013). The optimal model estimates sex specific harvest probability for adult females at 0.148 (SE = 0.017) and all other age-sex cohorts at 0.082 (SE = 0.008) for the most current year 2013. The model estimated a yearly survival rate of 0.528 (SE = 0.008). Total abundance ranged from 5,206,000 woodcock in 2007 to 6,075,800 woodcock in 1999. This study represents the first population estimates of woodcock populations.
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    Epidemiology and population structure of Xylella fastidiosa, the causal agent of bacterial leaf scorch, among urban trees in the District of Columbia
    (2014) Harris, Jordan Lee; Balci, Yilmaz; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    A survey of urban trees affected by bacterial leaf scorch caused by Xylella fastidiosa was conducted in the District of Columbia during 2012 and 2013. Disease occurred most frequently with Quercus palustris, Q. rubra, Ulmus americana, and Platanus occidentalis. Eight other symptomatic and five asymptomatic tree species were found infected. The bacterium was also detected on asymptomatic portion of seven tree species. The occurrence of crown dieback was found significantly associated with X. fastidiosa-infection on Q. palustris, Q. rubra, U. americana, and P. occidentalis. A multi-locus sequence typing analysis using 10 housekeeping loci for X. fastidiosa revealed five clonal strains among the urban trees. These strains were host specific, with only one clone being associated with members of the red oak family, American elm, American sycamore, and two clones being associated with mulberry. Long-term management strategies aimed at mitigating the occurrence of bacterial leaf scorch disease are discussed.
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    BALD EAGLE (HALIAEETUS LEUCOCEPHALUS) POPULATION PRODUCTIVITY AND DENSITY DEPENDENT EFFECTS IN MICHGAN, 1961-2010
    (2013) Simon, Kendall Lyn; Bowerman, William W; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The bald eagle (Haliaeetus leucocephalus) population in Michigan has undergone a significant recovery following the ban of the pesticide dichlorodiphenyltrichloroethane (DDT), and its subsequent derivatives, mainly dichlorodiphenyl-dichloroethylene (p,p'-DDE). This recovery however, has not been uniform throughout the state. Michigan is a heterogeneous habitat, causing the best-fit, experienced breeding pairs to settle in high quality breeding areas first. This high quality habitat mainly occurs in the inland regions of Michigan. These areas experienced the greatest productivity until the 1990's, quickly recovering from the detrimental effects of DDT. Great Lakes breeding areas, particularly Lake Michigan and Lake Huron, are now more productive than inland breeding areas. These Great Lakes breeding pairs however, are the least efficient breeders with greater amounts of changeover between nesting pairs within one breeding area in comparison to inland pairs. A constant turnover of breeding pairs may overshadow any underlying effects causing decreased reproductive fitness in Great Lakes adults.
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    The Politics of Population Aging in Germany, Italy, and Japan
    (2008-08-18) Sciubba, Jennifer Dabbs; Pirages, Dennis; Government and Politics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The purpose of this study is to determine the extent to which population aging has led to the emergence of age-based politics in Germany, Italy, and Japan. Many argue that the increase in the share of aged relative to youth has led to the development of gerontocracy--as aging has intensified, so has the political power of the aged. I argue that assuming political power from the size of demographic groups is flawed because political institutions are important vehicles that mediate and articulate the myriad interests of a population. The first pillar of the study explains how different party systems create different pressures for the emergence of age-based politics through the ways they articulate these interests. A second pillar of the study uses recent labor reforms to examine the trajectory of generational winners and losers within the labor policy arena. The study compares quantitative data and includes qualitative reviews of primary source material, such as party doctrine. In Germany, Italy, and Japan, there are few signs that older groups are hijacking the political agenda--gerontocracy is mostly a myth. Labor policy in all three states is adjusting to bring youth into the labor market and reforms often go against the interests of the aged. Though aging issues are present in politics in all three states, the competitive multiparty system in Germany encourages parties to appeal to particular age groups, while Japan's more limited system encourages broad appeals. The fractured Italian system shows signs of both types of appeals. Aging issues do not dominate the agendas of these states and in some cases regional identities are more important than age-based identities. As aging intensifies we should expect that institutions will continue to mediate the interests of different age groups the way they have over the past decade. External pressures, such as those stemming from globalization, will likely continue to encourage convergence in labor policies that bring underutilized groups of all ages into the workforce.
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    Factors Affecting Agricultural Expansion in Forest Reserves of Thailand: The Role of Population and Roads
    (2006-04-27) Puri, Jyotsna; Cropper, Maureen L; Bockstael, Nancy; Agricultural and Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In this dissertation, I examine the role of population and transportation costs in determining agricultural expansion in 670 villages located in Forest Reserves of Thailand, over the period 1986-1996. Specifically, I examine the role of population and transportation costs as drivers of agricultural decisions regarding crop adoption and area planted, and in determining the intensity of cultivation and agricultural expansion. I also contrast the impact of these variables on two groups of villages in Forest Reserves - villages whose residents 'have no secure property rights' and those whose 'land rights are ambiguous'. I examine Feder et al.'s (1988) conclusions about the importance of property rights in Thai forest reserves and find that there is some evidence supporting their conclusions in this study. Differences in property rights account for some difference in the agricultural decisions of the two groups of villages, but that the nature of data does not allow a sharper distinction. Results reported in the study are consistent with other studies of the area. The study suggests that decisions regarding crop adoption and crop area are sensitive to population but the magnitudes of impact are small. Lack of significance of transport costs in determining cropping decisions suggests that rural road building programs will not necessarily promote deforestation in the study area, contrary to evidence in other parts of the world. This is particularly important given the large number of Forest Reserve residents in Thailand, and the fact that, Forest Reserves are the last bastions of forests, and consequently of biodiversity, in Thailand. One policy implication of this is that investments in roads that help to increase access to markets and aid poverty alleviation may not have the deleterious effects on forests that would otherwise be expected.