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The Impact Of Land Use And Land Cover Change On The Spatial Distribution Of Buruli Ulcer In Southwest Ghana (open access)

The Impact Of Land Use And Land Cover Change On The Spatial Distribution Of Buruli Ulcer In Southwest Ghana

Buruli ulcer (BU) is an environmental bacterium caused by Mycobacterium ulcerans. Modes of transmission and hosts of the disease remain unknown. The purposes of this study are to explore the environmental factors that are possibly explain the spatial distribution of BU, to predict BU cases by using the environmental factors, and to investigate the impact of land use and land cover change on the BU distribution. The study area covers the southwest portion of Ghana, 74 districts in 6 regions. The results show that the highest endemic areas occur in the center and expand to the southern portion of the study area. Statistically, the incidence rates of BU are positively correlated to the percentage of forest cover and inversely correlated to the percentages of grassland, soil, and urban areas in the study area. That is, forest is the most important environmental risk factor in this study. Model from zero-inflated Poisson regression is used in this paper to explain the impact of each land use and land cover type on the spatial distribution of BU. The results confirm that the changes of land use and land cover affect the spatial distribution of BU in the study area.
Date: December 2011
Creator: Ruckthongsook, Warangkana
System: The UNT Digital Library
Assessment of Transportation Emissions for Ferrous Scrap Exports from the United States: Activity-Based Maritime Emissions Model and Theoretical Inland Transportation Model. (open access)

Assessment of Transportation Emissions for Ferrous Scrap Exports from the United States: Activity-Based Maritime Emissions Model and Theoretical Inland Transportation Model.

Industrial ecology is a field of study that encourages the use of closed-loop material cycles to achieve sustainability. Loop closing requires the movement of materials over space, and has long been practiced in the iron and steel industry. Iron and steel (ferrous) scrap generated in the U.S. is increasingly exported to countries in Asia, lengthening the transportation distance associated with closing the loop on the iron and steel life cycle. In order to understand the environmental cost of transporting this commodity, an activity-based maritime transportation model and a theoretical in-land transportation model are used to estimate emissions generated. Results indicate that 10.4 mmt of total emissions were generated, and emissions increased by 136 percent from 2004 to 2009. Increases in the amount of emissions generated are due to increases in the amount of scrap exported and distance it is transported.
Date: December 2011
Creator: Caldwell, Amanda
System: The UNT Digital Library
Lone Star Booster: The Life of Amon G. Carter (open access)

Lone Star Booster: The Life of Amon G. Carter

Abstract Though a very influential Texan during the first half of the twentieth century, Amon Carter has yet to receive a full scholarly treatment, a problem which this dissertation attempts to rectify by investigating the narrative of Carter’s life to see how and why he was able to rise from humble beginnings to become a powerful publisher who symbolized boosterish trends within Texas and the New South. Publisher of the Fort Worth Star-Telegram, philanthropist, oilman, and aviation supporter, Carter used his power and influence to become a leading booster of his city and region seamlessly making the transition from being a business progressive to New Deal supporter to an Eisenhower Democrat. His connections with corporations like American Airlines and General Motors helped bring aviation and industry to his region, and his ability to work with public and private entities helped inspire his failed attempt to make the Trinity River navigable up to Fort Worth. His own success at building the Star-Telegram into the largest circulating newspaper in Texas encouraged him to expand his media empire into radio and television, while the wealth he gained from his oil activities enabled him to form a philanthropic foundation that would provide support for …
Date: December 2011
Creator: Cervantez, Brian
System: The UNT Digital Library
A Multiscalar Analysis of Buruli Ulcer in Ghana: Environmental and Behavioral Factors in Disease Prevalence (open access)

A Multiscalar Analysis of Buruli Ulcer in Ghana: Environmental and Behavioral Factors in Disease Prevalence

Buruli ulcer (BU), an infectious disease caused by Mycobacterium ulcerans, is the third most common mycobacterial disease after leprosy and tuberculosis and a WHO-defined neglected tropical disease. Despite years of research, the mode of transmission of BU remains unknown. This master’s thesis provides an integrated spatial analysis of disease dynamics in Ghana, West Africa, an area of comparatively high BU incidence. Within a case/matched control study design, environmental factors associated with BU infection and spatial behaviors are investigated to uncover possible links between individual daily activity spaces and terrains of risk across disturbed landscapes. This research relies upon archival and field-collected data and analyses conducted with geographical information systems (GIS).
Date: May 2012
Creator: Ferring, David
System: The UNT Digital Library
Spatial Analysis of Hiv/aids Survival in Dallas and Harris Counties, Texas (open access)

Spatial Analysis of Hiv/aids Survival in Dallas and Harris Counties, Texas

More Texans are living with HIV infection than ever before. in fact, there has been a 6% increase annually, since 2002. This trend is not a result of increased HIV/AIDS incidence, but rather improving life expectancy of those living with HIV. Due to significant advances in HIV/AIDS testing, prevention, and treatment, individuals with HIV are living longer than ever before. However, throughout the state, the life expectancy of a person infected with HIV/AIDS varies spatially. This study investigates and attempts to explain the spatial distribution of HIV/AIDS survival rates by examining neighborhood socioeconomic characteristics. the results suggest that, contrary to expectation, the lowest survival rates occur, not in extreme poverty areas, but rather in moderate SES areas. Too rich to qualify for free treatments, but not rich enough to afford purchasing such treatments, the middle income living with HIV infection are caught between the cracks. the results provide important input for targeting public health interventions to improve HIV/AIDS survival.
Date: May 2012
Creator: Heald, Stephanie
System: The UNT Digital Library
The Geography of Maternal Mortality in Nigeria (open access)

The Geography of Maternal Mortality in Nigeria

Maternal mortality is the leading cause of death among women in Nigeria, especially women aged between 15 and 19 years. This research examines the geography of maternal mortality in Nigeria and the role of cultural and religious practices, socio-economic inequalities, urbanization, access to pre and postnatal care in explaining the spatial pattern. State-level data on maternal mortality rates and predictor variables are presented. Access to healthcare, place of residence and religion explains over 74 percent of the spatial pattern of maternal mortality in Nigeria, especially in the predominantly Muslim region of northern Nigeria where poverty, early marriage and childbirth are at its highest, making them a more vulnerable population. Targeting vulnerable populations in policy-making procedures may be an important strategy for reducing maternal mortality, which would also be more successful if other socio-economic issues such as poverty, religious and health care issues are promptly addressed as well.
Date: May 2012
Creator: Ebeniro, Jane
System: The UNT Digital Library
Installation and Manufacturing of Photovoltaics: an Assessment Using California and New York (open access)

Installation and Manufacturing of Photovoltaics: an Assessment Using California and New York

Renewable energy studies are becoming increasingly important as world energy demand rises and current energy sources are increasingly questioned. Solar photovoltaics (PV) are the focus of this study as a renewable industry still in its infancy. This research examines the geography of solar panel installation and manufacturing from 2007 to 2010 in California and New York. California is the larger of the two markets and has implemented more policy support; programs that appear to have increased the pace of installations, reduce the size of the subsidy, and help lower total costs. Similar trends are observable in New York. US based companies are still making solar panels, but foreign competitors, most notably from China and Mexico, are capturing an increasing share of the market.
Date: August 2012
Creator: Dohanich, Elizabeth
System: The UNT Digital Library
Geography of HIV Infection Among Adults Aged 50 Years and Older in Texas From 1999-2009 (open access)

Geography of HIV Infection Among Adults Aged 50 Years and Older in Texas From 1999-2009

Twenty four percent of all HIV infections in the United States occur among adults aged 50 and older (mature adults), yet little is understood of the dynamics of HIV infection among this group in Texas. Data from 1999 to 2009 examined the relationship between HIV spatial and temporal patterns affecting socio-economic and demographic variables including poverty, gender, race/ethnicity and mode of exposure. Results revealed highest HIV infection rates among White homosexual men, Black males engaged in IV-drug use, Black female heterosexuals and minorities in poverty. Concentrations of HIV infection among mature adults were located primarily in urban centers of Houston and Dallas and indicated increasing HIV infection rates from 1999 to 2009. These results will assist future allocation of resources by zip code in urban areas for this understudied population.
Date: August 2012
Creator: Hedrich, Mara Nicole
System: The UNT Digital Library
The Role of Knowledge and Attitude in Residential Irrigation Efficiency (open access)

The Role of Knowledge and Attitude in Residential Irrigation Efficiency

Residential irrigation efficiency is a long-term concern for any community that faces water supply stress. When ability to raise water prices is constrained, public education and conservation programs can produce reduced water usage. Understanding the factors behind residential irrigation efficiency allows the design of more effective conservation campaigns. Combining site-specific water budgets with usage data for four hundred homes in North Texas enables quantifying efficient irrigation behavior. A survey of homeowners tests for the presence of conservation-positive attitudes and the knowledge required to implement those attitudes. The influence of neighbors’ watering habits is investigated using spatial clustering tools. Findings are analyzed in the context of an attitude, knowledge, and habit model of conservation behavior. The presence of automatic irrigation systems, small irrigated areas, and having knowledge of the amount that one waters one’s lawn are found to contribute to more intensive irrigation. Mixed evidence for small-scale clustering in irrigation intensity is presented.
Date: August 2012
Creator: Nickerson, Joel
System: The UNT Digital Library
Quantitative Comparison of Lidar Data and User-generated Three-dimensional Building Models From Google Building Maker (open access)

Quantitative Comparison of Lidar Data and User-generated Three-dimensional Building Models From Google Building Maker

Volunteered geographic information (VGI) has received increased attention as a new paradigm for geographic information production, while light detection and ranging (LiDAR) data is widely applied to many fields. This study quantitatively compares LiDAR data and user-generated 3D building models created using Google Building Maker, and investigate the potential applications of the quantitative measures in support of rapid disaster damage assessment. User-generated 3D building models from Google Building Maker are compared with LiDAR-derived building models using 3D shape signatures. Eighteen 3D building models are created in Fremont, California using the Google Building Maker, and six shape functions (distance, angle, area, volume, slope, and aspect) are applied to the 18 LiDAR-derived building models and user-generated ones. A special case regarding the comparison between LiDAR data and building models with indented walls is also discussed. Based on the results, several conclusions are drawn, and limitations that require further study are also discussed.
Date: August 2012
Creator: Liu, Yang
System: The UNT Digital Library
A Storm Water Runoff Investigation Using Gis and Remote Sensing (open access)

A Storm Water Runoff Investigation Using Gis and Remote Sensing

Environmental controls are becoming more and more expensive to implement, so environmental management is becoming more technologically advanced and efficient through the adoption of new techniques and models. This paper reviews the potential for storm water runoff for the city of Denton, Texas and with the main objective to perform storm water runoff analyses for three different land use datasets; each landuse dataset created with a different methodology. Also analyzed was the difference between two North Central Texas Council of Governments land use datasets and my own land use dataset as a part of evaluating new and emerging remote sensing techniques. The results showed that new remote sensing techniques can help to continually monitor changes within watersheds by providing more accurate data.
Date: August 2012
Creator: Jennings, Laura
System: The UNT Digital Library
Spatio-temporal Variation of Nitrate Levels in Groundwater in Texas, 1970 to 2010 (open access)

Spatio-temporal Variation of Nitrate Levels in Groundwater in Texas, 1970 to 2010

This study looks at spatial variation of groundwater nitrate in Texas and its fluctuations at 10 year increments using data from the Texas Water Development Board. While groundwater nitrate increased in the Ogallala and Seymour aquifers across the time period, the overall rate in Texas appears to be declining as time progresses. However, the available data is limited. Findings show that a much more targeted, knowledge based strategy for sampling would not only reduce the cost of water quality analysis but also reduce the risk of error in these analyses by providing a more realistic picture of the spatial variation of problem contaminants, thereby giving decision-makers a clearer picture on how best to handle the reduction and elimination of problem contaminants.
Date: December 2012
Creator: Rice, Susan C.
System: The UNT Digital Library
Geoarchaeological Analysis of Two New Test Pits at the Dmanisi Site, Republic of Georgia (open access)

Geoarchaeological Analysis of Two New Test Pits at the Dmanisi Site, Republic of Georgia

This thesis presents the results of geoarchaeological investigations conducted at two new test pits, M11 and M12, at the paleoanthropological site of Dmanisi during the 2012 field season. This research is important for understanding the site formation processes occurring along the north-south axis of the Dmanisi site and how that affects the chronostratigraphic sequence and interpretation of archaeological materials here. With these excavations we can build a stronger interpretation for how broader areas of this site formed and changed both geologically and archaeologically. The geologic results of this study indicate that changes in sediment deposition and development episodes can affect interpretations of how long these sediments accumulated, how likely bones are to preserve, as well as how secondary gravel deposition can influence several archaeological interpretations. The archaeological results suggest that there could have been changes in occupation intensity between the stratum A and B phases although different rates of sediment deposition and surface stability could affect such artifact accumulations. In addition, during the stratum B phase there appears to be little change in artifact procurement behaviors and reduction characteristics by these hominins. The overall results of this research indicate that geologic factors should be addressed and cautions should be taken …
Date: May 2013
Creator: Zack, Winston S.
System: The UNT Digital Library
Assessing the Role of Smaller Format Retailers on the Food Desert Landscape in Dallas, Texas (open access)

Assessing the Role of Smaller Format Retailers on the Food Desert Landscape in Dallas, Texas

Many policy and business decisions regarding food deserts in the U.S. are based on the United States Department of Agriculture (USDA) definition of a food desert. This definition only includes large/national chain grocery retailers, based on the assumption that these major retailers are the only affordable sources of food contributing to balanced diets. As alternative distribution channels, including smaller stores, start to include groceries in their product offering, the need to consider the role of other businesses in the food retailing environment should be addressed. This thesis assesses the role of smaller format grocery retailers (small local grocers, convenience stores, gas stations, dollar stores, and drug stores) in shaping the food desert landscape in Dallas, Texas. The analysis evaluates the products offered in these stores, and then identifies the difference these stores make when included in the USDA analysis. This was done by collecting in-store data to determine the variety of products offered, the affordability of those products, and the overall healthfulness of the store. In addition, the gaps in supply and demand were identified in the USDA-defined food deserts in order to identify the impact any smaller format retailer may have. The findings suggest that, overall, smaller format retailers …
Date: May 2013
Creator: Regan, Amanda D.
System: The UNT Digital Library
Automated Treetop Detection and Tree Crown Identification Using Discrete-return Lidar Data (open access)

Automated Treetop Detection and Tree Crown Identification Using Discrete-return Lidar Data

Accurate estimates of tree and forest biomass are essential for a wide range of applications. Automated treetop detection and tree crown discrimination using LiDAR data can greatly facilitate forest biomass estimation. Previous work has focused on homogenous or single-species forests, while few studies have focused on mixed forests. In this study, a new method for treetop detection is proposed in which the treetop is the cluster center of selected points rather than the highest point. Based on treetop detection, tree crowns are discriminated through comparison of three-dimensional shape signatures. The methods are first tested using simulated LiDAR point clouds for trees, and then applied to real LiDAR data from the Soquel Demonstration State Forest, California, USA. Results from both simulated and real LiDAR data show that the proposed method has great potential for effective detection of treetops and discrimination of tree crowns.
Date: May 2013
Creator: Liu, Haijian
System: The UNT Digital Library
Finding Terroir in Southwest Iowa (open access)

Finding Terroir in Southwest Iowa

Terroir combines the physical landscape of the vineyard with the grapevines and the methods and techniques used to produce wine from the grapes. This study used a GIS to identify the characteristics of the physical landscape in Pottawattamie, Mills, Montgomery, Fremont, and Page counties in southwestern Iowa. The components were combined in the GIS using a weighted linear index to identify areas suitable for vineyard development and to identify the general characteristics of the area. Vineyard owners were interviewed to help determine the weighting system to use in the GIS and to determine their perceptions of how the physical landscape impacts their vineyards, as well as to determine what grape varieties they plant in their vineyards and their decisions on making wine from these grapes. This information was collected to identify whether the vineyard owners had developed a sense of place for their vineyards and how this sense might aid them in the development of a terroir for their wines. The resulting perceptions about the individual wineries were then considered in conjunction with the results from the GIS modeling to understand how the physical landscape influences the concepts of sense of place and terroir in southwest Iowa. The physical landscape …
Date: August 2013
Creator: Deines, Dory
System: The UNT Digital Library
Examining the Role of Latitude and Differential Insolation in Asymmetrical Valley Development (open access)

Examining the Role of Latitude and Differential Insolation in Asymmetrical Valley Development

Valley development through erosional processes typically tends to create symmetrical valleys. Over time, water cuts through the substrate to create valleys, gorges, and canyons for which the sides are the valley are evenly sloped. However, there are anomalies to this process. Asymmetrical valleys have been well-documented even in areas of uniform substrate or little tectonic uplift. One proposed explanation for the asymmetry of these valleys is differential insolation. This may lead to different microclimates from one slope to another which alter the rate and extent of erosion. Since the differences in received insolation vary with latitude (especially in streams that flow along an east/west axis), it follows that the degree of asymmetry should also vary with latitude if differential insolation is a primary driving factor in the development of these valleys. To evaluate if insolation plays a role in the development of asymmetrical valleys, this study examines variability in asymmetry across 447 valleys in nine study areas located at different latitudes. The degree of asymmetry for each valley was measured by using 30 meter resolution digital elevation models (DEMs) to determine the slope angle of each side of the valley. Asymmetry was measured by computing a ratio of the average …
Date: August 2013
Creator: Curran, Lorna L.
System: The UNT Digital Library
Contribution of Hurricane Ike Storm Surge Sedimentation to Long-term Aggradation of Coastal Marshes in Southeastern Texas and Southwestern Louisiana (open access)

Contribution of Hurricane Ike Storm Surge Sedimentation to Long-term Aggradation of Coastal Marshes in Southeastern Texas and Southwestern Louisiana

Coastal marshes and wetlands are vital natural resources that offer habitats for plants and animals, serve as ecological filtration for soil and water pollutants, and act as protection for coastlines. Fishing, both commercial and sport, has a large economic impact in the study area – the Gulf Coast between Galveston Bay, TX and Oak Grove, LA. The objective of this research was to determine the contribution of Hurricane Ike storm surge sedimentation to long-term marsh aggradation in Texas and Louisiana coastal marshes. The research hypothesized that Hurricane Ike’s storm surge deposit would be equal to decades and possibly even a century’s worth of the average annual non-storm sedimentation. A quantitative field study was performed. The storm surge deposit was examined in a series of 15 transects covering approximately 180 km east of Hurricane Ike’s landfall. Nine of the 15 transects were re-surveyed a year after the initial measurement to assess preservation of the deposit. The results demonstrate that Hurricane Ike contributed between 10 to 135 years’ worth of sediment to coastal marshes along the coasts of Texas and Louisiana, and the sediment deposits have been preserved for over two years.
Date: August 2013
Creator: Denlinger, Emily E.
System: The UNT Digital Library
Site Formation Processes and Bone Preservation Along the Trinity River Basin, North Central Texas (open access)

Site Formation Processes and Bone Preservation Along the Trinity River Basin, North Central Texas

This thesis presents the results of geoarchaeological investigations of several archaeological sites along the Elm Fork of the Trinity River in north central Texas. Archaeological data recorded from mitigation excavations in Denton and Cooke counties were analyzed to understand the geologic impacts on faunal preservation resulting from site formation processes. The faunal assemblages are highly fragmented, even in settings known for good preservation. A combined approach using geoarchaeological and taphonomic techniques was implemented to examine how fragmentation, evidence of soil weathering, and differential preservation were impacted by differing geologic conditions throughout the river basin. Intrasite and intersite results of the sites show that a great deal of variability of faunal preservation is present at difference scales of analysis.
Date: August 2013
Creator: Colvin, Jessica
System: The UNT Digital Library
Effects of Vegetation Structure and Canopy Exposure on Small-scale Variation in Atmospheric Deposition Inputs to a Mixed Conifer Forest in California (open access)

Effects of Vegetation Structure and Canopy Exposure on Small-scale Variation in Atmospheric Deposition Inputs to a Mixed Conifer Forest in California

Data on rates of atmospheric deposition is limited in many montane ecosystems, where high spatial variability in meteorological, topographic, and vegetation factors contributes to elevated atmospheric inputs and to the creation of deposition hotspots. Addressing the ecological consequences of increasing deposition in these areas will require a better understanding of surface controls influencing atmospheric deposition rates at both large and small-scales. The overarching objective of this thesis research was to understand the influence of vegetation structure and canopy exposure on small-scale patterns of atmospheric sulfate, nitrate, and chloride deposition inputs to a conifer forest in the Santa Cruz Mountains, California. Throughfall ion fluxes (i.e., ions delivered in water that pass from the forest canopy to the forest floor), bulk deposition (i.e., primarily wet deposition), and rainfall data were collected during the rainy period from October 2012 to May 2013. Throughfall SO42-, Cl-, and NO3- fluxes were measured beneath eight clusters of Douglas fir (Pseudotsuga menziesii) trees (three trees per cluster) differing in tree size (i.e., diameter at breast height; DBH) and canopy exposure. In each cluster, a throughfall collector was placed 1-meter from the bole of an individual tree, for a total of 24 individual collectors. The position of each …
Date: May 2014
Creator: Griffith, Kereen
System: The UNT Digital Library
Spatial Mismatch Between Hiv Infection and Access to Hiv Service Facilities in Texas (open access)

Spatial Mismatch Between Hiv Infection and Access to Hiv Service Facilities in Texas

Since 2004, the number of people living with HIV (PLWH) has steadily increased by about 5% and currently, the number in Texas is about 86,000. Though the National HIV/AIDS Strategic Plan seeks to ensure “unfettered access to quality healthcare”, barriers to access still exist especially among minority populations. This study examines the relationship between HIV infection rates and the geographic location of HIV service centers with a focus on 4 counties: namely, Dallas, Denton, Harris and Tarrant. The goal is to show whether there is a spatial mismatch between HIV rates and service providers. Are service facilities located in zip codes where they are most needed? Using the vulnerability framework and the Inverse Care Law (ICL), we address the research question using demographic variables (race/ethnicity, sex, poverty, education attainment) and HIV data. Our results show that extreme vulnerable zip codes have high HIV rates and closest proximity to HIV service providers.
Date: August 2013
Creator: Aggrey Korsah, Emmanuel
System: The UNT Digital Library
A Quantitative Assessment of Site Formation at the Dmanisi Archaeological Site, Republic of Georgia (open access)

A Quantitative Assessment of Site Formation at the Dmanisi Archaeological Site, Republic of Georgia

The focus of this thesis was to gather and analyze micromorphological and petrographic data on soils at the archaeological site of Dmanisi in order to better understand the extent to which the deposition and alteration of the sediments has affected the preservation of artifacts and faunal remains. A major goal of this research was to test hypothesis related to why bone material is discovered in some strata and not in others. This research focuses on the application of micromorphology (supplemented with other methods) to the soils through the use of petrographic analysis of thin sections and scanning electron microscopy. These techniques complement previous field analyses by providing a quantitative assessment of individual strata through point counting and chemical mapping. The results of this research support the hypothesis that the sediments are predominantly mafic ashes, while showing that there is very little soil development in the strata. This suggests quick episodic burial in a relatively dry climate, confirming the hypothesis for a short time sequence in the strata. Additionally, differential weathering probably did not play a significant role in the differential abundance of bone remains among the strata at Dmanisi.
Date: August 2013
Creator: Crislip, Peter S.
System: The UNT Digital Library
Neural Tube Defect, Heart Defect, Oral Cleft and Their Geospatial Associations with Supermarket and Convenience Stores in the City of Dallas, Texas (open access)

Neural Tube Defect, Heart Defect, Oral Cleft and Their Geospatial Associations with Supermarket and Convenience Stores in the City of Dallas, Texas

Birth defects are the leading cause of infant death in the United States. Research has linked poor maternal micronutrient intake to birth defects including neural tube defects, heart defects, and oral clefts. After investigating spatial patterns of these birth defects in the City of Dallas and the neighborhood characteristics within clusters, geospatial access to supermarkets and convenience stores measured by proximity and concentrations are examined as environmental risk factors for nutrition-related birth defects. Spatial clusters of all three nutrition-related birth defects exist in the City of Dallas. Cluster for NTD occurs in vulnerable places with lower income and high minority population specifically Hispanics with no supermarkets. Cluster for heart defects mostly occurs in high income and predominantly white neighborhoods with many supermarkets. Clusters of oral clefts mostly occurs in middle-class income with relatively high minority populations with many convenience stores. For the entire study area, geographical access to supermarkets that include healthy foods are shown to be spatially reachable from most of mothers of infants with nutrition-related birth defects as well as convenience stores that typically include the majority of unhealthy processed foods with very few nutrients. Thus, not only easy geographical access to healthy food vendors but to convenience …
Date: August 2013
Creator: Miyakado, Haruna
System: The UNT Digital Library
Importance and Spatial Distribution of Phytophthora Ramorum Host Species in a Coast Redwood Forest (open access)

Importance and Spatial Distribution of Phytophthora Ramorum Host Species in a Coast Redwood Forest

Phytophthora ramorum, an exotic forest pathogen known as ‘sudden oak death’ (SOD), has received considerable attention in recent years because of its effects on vegetation structure, composition, and fire disturbance regimes in western U.S. coastal forests. This research examines differences in the importance (e.g., density, dominance, and frequency) and distribution of five host species of P. ramorum–– Umbellularia californica (California bay laurel), Quercus agrifolia (coast live oak), Pseudotsuga menziesii (Douglas fir), Sequoia sempervirens (Coast redwood), and Arbutus menziesii (Madrone)––in Soquel, California. A stratified random sampling design was used to select 66 plots surrounding a managed forest edge in Soquel Demonstration State Forest. Vegetation measurements were conducted in summer 2013. In each plot, all trees ≥3 cm diameter at breast height (DBH) were identified to species, counted, and DBH, height, and canopy position measured. Leaf area index (LAI) of bay laurel was measured to quantify the amount of leaves available for pathogen dispersal with a LiCOR 2200 Plant Canopy Analyzer. In addition, morning (9:00 am) and afternoon (1:00 pm) photosynthetically active radiation (PAR) were quantified using a quantum light sensor. This paper examines the influence of environmental variables, including distance to edge, aspect, slope, and light availability on host species spatial …
Date: May 2014
Creator: Gray, Alicia E.
System: The UNT Digital Library