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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.
51

Modelling native bird diversity in the Greater Toronto Area

Zajc, Elizabeth January 2005 (has links)
Human-dominated landscapes often have habitat loss and fragmentation. These characteristics described at the landscape scale, called landscape elements, influence species diversity and distribution. These landscape elements include such descriptions as the amount of habitat in the landscape and the degree of fragmentation of the habitat. "Optimization of landscape pattern" studies which landscape elements will maximize species diversity and/or distribution. Some general conclusions have emerged from this research. For example, for some bird species the size of the habitat patch in which a species nests has been found to be more important than landscape variables. However, preliminary research suggested that landscape elements such as the matrix are important urban areas. My study addressed this problem by asking: which elements of the landscape are most important for predicting avian species richness and abundance in the Greater Toronto Area? A literature review revealed a number of variables that have been found to influence bird species diversity within a landscape: area of habitat in which the species nests, amount of habitat within the landscape, degree of fragmentation, vegetation characteristics of the habitat patch, and area within the landscape deemed urban in municipal land-use designations (amount of urbanization). From this literature, I formulated four hypotheses describing the most important variables for avian diversity: (1) the area of the habitat patch is most important, (2) only variables describing the habitat patch itself are important, (3) the area of the habitat patch is important, but landscape variables should also be considered and (4) urbanization is most important. These hypotheses were considered competing explanations of bird species diversity at the landscape scale. <br /><br /> A database of breeding bird data and landscape information, in a geographic information system platform, was used to investigate the comparative strength of the competing hypotheses for the Greater Toronto Area. A mathematical expression with a Poisson model format was created to represent each hypothesis. The model selection technique based on Kullback-Leibler information using the Akaike Information Criterion was deemed most appropriate for the comparison of the models. Four separate Poisson model competitions were completed using two habitat types and two response variables: species richness and total abundance. In three of the four competitions, the best model included the habitat area and the amount of urbanization in the landscape. In the forth competition, this model was considered as strong as another model which included habitat area, amount of habitat in the landscape and degree of fragmentation. The results from the model competition support the hypothesis that habitat area is important, but landscape variables must also be considered to explain avian richness and total abundance. It appears that maintaining native bird biodiversity in the Greater Toronto Area should focus on preserving and possibly increasing habitat area and decreasing adjacent urbanization. Exploration of the best model in the forest analysis with the richness response variable found that a 10% increase in habitat area cause approximately a 10% increase in species richness, and a 10% increase in urban area caused approximately a 20% decrease in species richness. Consequently, current natural heritage planning in Ontario should consider urban development as an important negative effect on native birds.
52

Modelling native bird diversity in the Greater Toronto Area

Zajc, Elizabeth January 2005 (has links)
Human-dominated landscapes often have habitat loss and fragmentation. These characteristics described at the landscape scale, called landscape elements, influence species diversity and distribution. These landscape elements include such descriptions as the amount of habitat in the landscape and the degree of fragmentation of the habitat. "Optimization of landscape pattern" studies which landscape elements will maximize species diversity and/or distribution. Some general conclusions have emerged from this research. For example, for some bird species the size of the habitat patch in which a species nests has been found to be more important than landscape variables. However, preliminary research suggested that landscape elements such as the matrix are important urban areas. My study addressed this problem by asking: which elements of the landscape are most important for predicting avian species richness and abundance in the Greater Toronto Area? A literature review revealed a number of variables that have been found to influence bird species diversity within a landscape: area of habitat in which the species nests, amount of habitat within the landscape, degree of fragmentation, vegetation characteristics of the habitat patch, and area within the landscape deemed urban in municipal land-use designations (amount of urbanization). From this literature, I formulated four hypotheses describing the most important variables for avian diversity: (1) the area of the habitat patch is most important, (2) only variables describing the habitat patch itself are important, (3) the area of the habitat patch is important, but landscape variables should also be considered and (4) urbanization is most important. These hypotheses were considered competing explanations of bird species diversity at the landscape scale. <br /><br /> A database of breeding bird data and landscape information, in a geographic information system platform, was used to investigate the comparative strength of the competing hypotheses for the Greater Toronto Area. A mathematical expression with a Poisson model format was created to represent each hypothesis. The model selection technique based on Kullback-Leibler information using the Akaike Information Criterion was deemed most appropriate for the comparison of the models. Four separate Poisson model competitions were completed using two habitat types and two response variables: species richness and total abundance. In three of the four competitions, the best model included the habitat area and the amount of urbanization in the landscape. In the forth competition, this model was considered as strong as another model which included habitat area, amount of habitat in the landscape and degree of fragmentation. The results from the model competition support the hypothesis that habitat area is important, but landscape variables must also be considered to explain avian richness and total abundance. It appears that maintaining native bird biodiversity in the Greater Toronto Area should focus on preserving and possibly increasing habitat area and decreasing adjacent urbanization. Exploration of the best model in the forest analysis with the richness response variable found that a 10% increase in habitat area cause approximately a 10% increase in species richness, and a 10% increase in urban area caused approximately a 20% decrease in species richness. Consequently, current natural heritage planning in Ontario should consider urban development as an important negative effect on native birds.
53

Factors affecting movement patterns of mule deer (<i>Odocoileus hemionus</i>) in southern Saskatchewan : implications for chronic wasting disease spread

Silbernagel, Erin Rae 08 April 2010 (has links)
Chronic wasting disease (CWD) has been a known threat to Saskatchewans wild cervid populations for more than a decade. As host movements can affect the spread of a disease across the landscape, disease models and management strategies should incorporate information regarding movement patterns of the host population in question. I used radio telemetry to study mule deer (<i>Odocoileus hemionus</i>) captured between 2006 and 2008 in a CWD-endemic region of southern Saskatchewan. Using location data from 152 individuals, I investigated home range size and patterns of direct and indirect contact (measured using proximity and shared space use) in relation to sex, habitat, and landscape structure. <p>Home ranges (95% fixed kernel) of GPS-collared deer in this study averaged 21.4 km² (n = 94). Male home ranges (mean = 29.5 km², n = 56) were larger than those of females (mean = 16.1 km², n = 38), which could have implications for CWD prevalence differences between sexes. Of the landscape variables tested, topographic ruggedness was inversely related to home range size and Shannons diversity (a measure of both habitat richness and evenness) was positively related to home range size. <p>Potential direct contact events were identified when two deer were located within 25 m of each other at the same point in time. These events occurred more often between February and April, agreeing with the tendency of mule deer to aggregate into large groups during the late winter months, and suggesting that this may be an important time period for disease transmission. Contact also occurred more than expected in cropland, whereas areas of shared use occurred more than expected in grassland, shrub/wood habitat, and rugged terrain. Smaller home ranges and greater degree of shared space use within areas of rough topography may lead to greater risk of environmental contamination with the infectious CWD agent in these areas. In contrast, the relationship between cropland and probability of direct contact may imply greater risk of direct CWD transmission between deer occupying this habitat. <p>These results identify connections between particular landscape factors and risk of CWD transmission and will be used, in combination with results of related studies, to develop a model of CWD spread in Saskatchewan. This will in turn aid management agencies in developing methods to more effectively manage the disease and control its movement outside of affected regions.
54

Study of the Impact and Planning Strategies for Local Green Resource Distribution after City-County Consolidation:Case Study on Border Districts Between Kaohsiung City and County

Chien, Che-Wen 08 September 2011 (has links)
The delineation of administrative boundaries not only determines the spatial distribution of urban and rural areas but also affect the natural resources related to conservation, utilization, and management. In Taiwan, various institutional factors such as the urban development gap, the scale of administrative areas, and the administrative system level often result in uneven distribution of resources of social injustice. In this study, the starting point for the discussion on the annexation of the city and county of Kaohsiung is a comparison of similar properties in the area of space but with differences due to administrative boundaries in the distribution of local green resources, in addition to an exploration of the expansion of urban areas when there is regional integration within the resource advantages for fine-scale observations under the impact of the community. The study area will include Kaohsiung City's Lingya in the Cianjhen District and Fengshan City in Kaohsiung County. In addition, the counties and cities are the respective executive authorities within the study area; this point highlights the unique place and historical development of the human context. The research methods of this study will focus on the distribution of spatial location and different specific administrative units with respect to the local green resources analysis and evaluation. In the quantitative analysis, which will, through the landscape ecology indicators among computing tools (Fragstats 3.3R), quantify the characteristics of the landscape within the urban scale, and a geographic information system (ArcGIS 9.3R) spatial analysis module will be applied to evaluate the accessibility of the green space resources. Then a qualitative survey will be carried out using an on-site observation method and a local interview method to reach an understanding of local community resources with respect to the interactive effects and differences. The results show the existence of administrative boundaries for local green resource allocation and planning, which will produce different degrees of impact, so when the city changes in administrative areas, local green resources management institutions may also be involved in the adjustment of planning and assessment opportunities. Finally, we hope to do for the community through the development of local sustainable practices and to determine the appropriate direction for local green resource strategic planning.
55

The Study of Coastal Land-use Change for Ecological Impact Assessment

Huang, Shiuan-Guo 08 September 2011 (has links)
With the rapid growing of economic activities and populations, available land resources have become unable to meet the demand. Originally considered as a mere frontier between land and sea, the coastal zone has become an essential zone for human development. As any kind of human exploitation of the coastal zone is likely to induce some changes in the local environment. Gradual and permanent alterations in coastal ecosystems have led to losses in abundance in numerous species, such as the black-faced spoonbill. To mitigate the impact, the government declares the North bank of the Tsengwen River Estuary as a protected area. However, land-use changes outside the protected area, such as the development of fish ponds or changes in the spatial patterns of farmlands and bodies of water, are still affecting birds¡¦ survival. This study is based on landscape ecology, using several analytical tools including Geographic Information System (GIS), Spatial Analysis, Landscape metric and Markov Chains. Changes in landscape structure at Chi-Gu between 2003 and 2008, and long-term birds census have been combined in order to discuss the relations between land-based activities and bird¡¦s abundance. Furthermore, a Markov chain was built to predict the most likely land-use pattern in 2013 and its eventual impacts on birds¡¦ conservation. The results of this study show that the reduction of spatial segregation in Chi-Gu has, on average, mitigated the adverse effects on birds. However, further analysis showed that migrant birds are increasing whereas resident birds are decreasing. We therefore suggest that the land-uses, closely related to resident birds¡¦ conservation, such as forests, should be managed with special care in order to assure an effective protection of both migrant and resident birds.
56

Egg laying on patchy resources and the importance of spatial scale : a thesis submitted to the Victoria University of Wellington in fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology & Biodiversity /

Hasenbank, Marc. January 2010 (has links)
Thesis (Ph.D.)--Victoria University of Wellington, 2010. / Includes bibliographical references.
57

Surface mines as landscape features contrasting microclimate and forest composition among open, edge, and interior /

Kazar, Sheila A. January 2003 (has links)
Thesis (M.A.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains vii, 56 p. : ill. (some col.), maps (some col.). Vita. Includes abstract. Includes bibliographical references (p. 50-55).
58

Factors affecting movement patterns of mule deer (Odocoileus hemionus) in southern Saskatchewan : implications for chronic wasting disease spread

04 1900 (has links)
Chronic wasting disease (CWD) has been a known threat to Saskatchewan’s wild cervid populations for more than a decade. As host movements can affect the spread of a disease across the landscape, disease models and management strategies should incorporate information regarding movement patterns of the host population in question. I used radio telemetry to study mule deer (Odocoileus hemionus) captured between 2006 and 2008 in a CWD-endemic region of southern Saskatchewan. Using location data from 152 individuals, I investigated home range size and patterns of direct and indirect contact (measured using proximity and shared space use) in relation to sex, habitat, and landscape structure. Home ranges (95% fixed kernel) of GPS-collared deer in this study averaged 21.4 km² (n = 94). Male home ranges (mean = 29.5 km², n = 56) were larger than those of females (mean = 16.1 km², n = 38), which could have implications for CWD prevalence differences between sexes. Of the landscape variables tested, topographic ruggedness was inversely related to home range size and Shannon’s diversity (a measure of both habitat richness and evenness) was positively related to home range size. Potential direct contact events were identified when two deer were located within 25 m of each other at the same point in time. These events occurred more often between February and April, agreeing with the tendency of mule deer to aggregate into large groups during the late winter months, and suggesting that this may be an important time period for disease transmission. Contact also occurred more than expected in cropland, whereas areas of shared use occurred more than expected in grassland, shrub/wood habitat, and rugged terrain. Smaller home ranges and greater degree of shared space use within areas of rough topography may lead to greater risk of environmental contamination with the infectious CWD agent in these areas. In contrast, the relationship between cropland and probability of direct contact may imply greater risk of direct CWD transmission between deer occupying this habitat. These results identify connections between particular landscape factors and risk of CWD transmission and will be used, in combination with results of related studies, to develop a model of CWD spread in Saskatchewan. This will in turn aid management agencies in developing methods to more effectively manage the disease and control its movement outside of affected regions.
59

Thermal Pollution in Urban Streams of the North Carolina Piedmont

Somers, Kayleigh January 2013 (has links)
<p>Currently, cities comprise 52% of the Earth's land surface, with this number expected to continue to grow, as most of the predicted 2.3 billion increase in population over the next 40 years is expected to occur in urban areas (United Nations Population Division 2012). Urban areas necessarily concentrate food, energy, and construction materials, and as a result tend to be hotter and more polluted than the surrounding landscape. All urban ecosystems are thus quite altered from their pre-urban state, but urban streams are particularly impacted. As low lying points on the landscape, streams are subject to the degradation caused by urban stormwaters, which are transmitted rapidly from the surfaces of pavements, roofs, and lawns through stormwater infrastructure to streams.</p><p> The systematic changes seen in many urban streams have been described as the "Urban Stream Syndrome" (USS) and serve as an organizing conceptual framework for urban stream research (Walsh et al. 2005b). A primary symptom of USS is increased flashiness in hydrographs, as stormwater in urban areas is routed efficiently into streams (Booth and Jackson 1997, Konrad and Booth 2005). With this stormwater runoff comes intense scour leading to deeply incised channels, large amounts of contaminants and nutrients, and, as will be discussed in this thesis, heat surges (Booth 1990, Tsihrintzis and Hamid 1997, Walsh et al. 2005a, Nelson and Palmer 2007, Bernhardt et al. 2008). At baseflow, urban streams are contaminated by sanitary sewage leakages, are unable to exchange water with their floodplains due to incision and with groundwater due to lower water tables, and are warmer due to canopy loss and urban heat island effects (Paul and Meyer 2001, Pickett et al. 2001, Groffman et al. 2002, 2003). These baseflow and stormflow changes lead to the loss of sensitive taxa and increase in tolerant biota, as well as changes in ecosystem function, including carbon and nitrogen processing (Paul and Meyer 2001, Meyer et al. 2005, Imberger et al. 2008, Cuffney et al. 2010). </p><p> The urban heat island effect can increase air temperatures up to 10°C above those in surrounding, non-urban areas, while impervious surfaces can reach temperatures up to 60°C (Asaeda et al. 1996, Pickett et al. 2001, Kalnay and Cai 2003, Diefenderfer 2006). These changes are particularly troublesome, as research has shown that temperature is a controlling factor in aquatic systems for both stream biota and ecosystem processes (Allen 1995, Kingsolver and Huey 2008). Thermal changes control and can alter basic morphological features of biota, such as size and growth rates (Gibbons 1970, Kingsolver and Huey 2008). USS synthesis reports have called for further research into the processes by which urban areas influence the temperature of streams and the resulting effects on the ecosystems, but until recently have largely been ignored (Paul and Meyer 2001, Wenger et al. 2009). This dissertation explores the timing, magnitude, and pattern of thermal pollution for streams within urban heat islands, with the goal of understanding what aspects of watershed development most strongly influence the thermal regimes of streams. In order to explore thermal pollution in urban streams, I asked three overarching questions:</p><p> 1) How much hotter are highly urban streams than streams in less developed watersheds?</p><p> 2) How far do urban heat pulses propagate downstream of urban inputs?</p><p> 3) How can development configuration mitigate or exacerbate development amount in mediating urban thermal pulses?</p><p> In Chapter 2, I explore the differences in baseflow and stormflow temperatures in 60 watersheds across the North Carolina Piedmont that ranged across a gradient of urbanization. I asked:</p><p> 1) How do maximum temperatures at baseflow and maximum temperature surges at stormflow differ across watersheds with varying development intensity? </p><p> 2) What reach- and watershed-scale variables are most correlated with these 2 aspects of stream thermal regimes? </p><p> 3) Do stream management approaches (riparian buffers, channel restoration) address the links between these variables and stream temperature?</p><p> I found that the 5 most urban streams were on average 0.6°C hotter at baseflow than the 4 most forested streams. During a single storm event, urban streams showed an increase over five minutes of up to 4°C, while forested streams showed little or no thermal increase. Reach-scale characteristics, specifically canopy closure and width, primarily controlled baseflow temperatures. These local factors were not important drivers of stormflow temperature changes, which were best explained by watershed-scale development and road density. Management that focuses on baseflow temperatures, such as riparian buffers and reach-scale restoration, ignores the intense urban impacts that occur regularly during storm events.</p><p> Next, in Chapter 3, I explore longitudinal temperature patterns in a single stream, Mud Creek, in Durham, North Carolina. Mud Creek's headwaters are suburban, and the stream travels through a number of housing developments before entering a 100-year-old forest. I placed 62 temperature loggers over a 1.5 km reach of this stream. To explore the mechanisms by which stormflow heat pulses dissipate along this stream reach, I asked:</p><p> 1) What is the range of heat pulse magnitudes that occur over a year?</p><p> 2) What is the maximum distance that a heat pulse travels downstream of urban inputs?</p><p> 3) How do the magnitude and distance vary with storm characteristics, including antecedent air temperature and amount and intensity of precipitation?</p><p> I found that heat pulses with amplitude of greater than 1°C traveled more than 1 km downstream of urban inputs in 11 storm events over one year. This long dissipation distance, even in a best-case management scenario of mature and protected forest, implies that urban impacts across a developing landscape travel far downstream of the impacts themselves and into protected areas. Heat pulses greater than 1°C occurred in storms with greater intensity of and total precipitation and greater time of elevated storm flow. Air temperature, flow intensity, maximum flow, and total precipitation controlled the magnitude of the heat pulse, while the distance of dissipation was controlled by the magnitude of the heat pulses and total precipitation. The importance of air temperature, flow, and precipitation metrics imply that both magnitude and distance of dissipation of heat pulses are likely to increase with climate change, as air temperatures increase and sudden, intense storms become more frequent. This translates to even greater ecological impacts in urban landscapes like Durham municipality, where the 98.9% of streams less than 1 km downstream of a stormwater outfall will become even more likely to be impacted by urban stormwaters.</p><p> In Chapter 4, I examine which aspects about development best explain thermal differences observed at baseflow and stormflow. To do this, I selected 15 similarly sized watersheds in the North Carolina Piedmont region within 45 to 55% development that varied in other development characteristics, specifically density of stormwater infrastructure and aggregation of development patches. I asked two questions:</p><p> 1) How does the configuration and connectivity of development within a watershed influence baseflow and stormflow temperatures in receiving streams? </p><p> 2) How do baseflow and stormflow temperatures vary with development characteristics?</p><p> I found that aspects of development varied greatly within this urban intensity subset, with ranges for some metrics nearly equal to the variation observed across all watersheds in the landscape. Longer pipe lengths, shading from incised channels, and shaded impervious surfaces resulted in cooler baseflow temperatures. As in Mud Creek, stormflow metrics were influenced through two physical pathways: air temperature and either flow intensity, to explain overall thermal change, or antecedent flow, to explain intensity of thermal change. Greater sub-surface connectivity of development to the stream network increased thermal responsiveness to storms through faster delivery and greater amount of heated runoff. Greater proportions of forest in a watershed decreased the amount and temperature of runoff delivered to the stream, while development within the riparian zone throughout a watershed led to warm baseflow temperatures and lack of response to stormflow heat surges. By decreasing the connectivity of development to the stream network, thermal regimes of streams can be less impacted even in relatively urban watersheds.</p><p> Thermal pollution in urban streams is a problem that will only be exacerbated by predicted climate change and urban expansion. These findings imply that thermal pollution is a problem throughout urban landscapes, even far downstream of urban inputs and within protected areas, and must be managed as an important component of the USS. Future research should focus on the transferability of these findings to regions outside of the southeastern United States and to the movement of other urban pollutants, and on exploring the potential to manage these systems by decreasing sub-surface connectivity.</p> / Dissertation
60

Modelling landscape connectivity for highly-mobile terrestrial animals: a continuous and scalable approach

Galpern, Paul 08 1900 (has links)
Assessments of landscape connectivity are increasingly required in natural resource management. Understanding how landscape structure affects the movement and dispersal of animals may be essential for ensuring the long-term persistence of species of conservation concern. Functional connectivity models describing how features on the landscape influence animal movement behaviour have been produced in two different ways. The resistance surface models landscape connectivity as its inverse, the resistance to movement and dispersal, while the landscape graph represents landscape connectivity by describing the relationships among resource patches. Both methods have limitations that make them less effective for modelling highly-mobile and wide-ranging species such as ungulates and carnivores. This thesis develops a method called grains of connectivity that combines the continuous representation of landscape connectivity provided by resistance surfaces and the scalability provided by landscape graphs to create a flexible modelling framework for these species. The first half of the thesis reviews the conceptual origins of the grains of connectivity method and examines its properties using simulated landscapes. In the second half, empirical evidence of movement and dispersal in a boreal woodland caribou (Rangifer tarandus caribou) population is used to validate functional connectivity hypotheses generated using the method. Connectivity for caribou at the temporal scale of generations is examined using a landscape genetics approach, while connectivity at the seasonal scale is assessed using the distribution of caribou telemetry locations. Grains of connectivity may be most useful for study systems where animals are not found exclusively in well-defined resource patches and there is uncertainty in the behavioural parameters influencing movement and dispersal. Additionally, the scalability of the analysis can be used to selectively remove spatial heterogeneity that may be uncorrelated with movement and dispersal giving an improved description of the pattern affecting the landscape connectivity process.

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