京都大学 / 新制・課程博士 / 博士(経済学) / 甲第25078号 / 経博第685号 / 新制||経||305(附属図書館) / 京都大学大学院経済学研究科経済学専攻 / (主査)教授 久野 秀二, 教授 山田 仁一郎, 講師 岩島 史 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

<p dir="ltr">This PhD dissertation features four research chapters investigating reproductive diversity in Great Lakes fishes. Aspects of reproductive diversity that were studied include reproductive habitat restoration, population genetic variation, variation in reproductive phenology and size variation (sexual size dimorphism). I examined trait variation in lake whitefish (<i>Coregonus clupeaformis</i>) and walleye (<i>Sander vitreus</i>) to examine reproductive patterns and their emergence. Methods include field sampling, genetic sequencing and analysis, historical data synthesis and eco-genetic modeling.</p>

The rapid expansion of urban systems in both area and population represents the most significant landuse/landcover change occurring in the world today. Urbanization is often accompanied by increasing environmental degradation. This degradation is related to stormwater runoff, air temperatures greater than surrounding rural areas, increased air and water pollution, losses of vegetated lands, and lack of access to sufficient and healthy foods in lower-income areas. Urban agriculture (UA), a practice long established in previous eras but neglected for many decades, can mediate such concerns by providing greenspaces to improve ecosystem services. Successful practice of UA requires recognition of interactions between social and environmental patterns. Neglect of these interactions leads to failure in spatially integrating social and environmental dimensions of the urban landscape, limiting the success of UA. This study investigates siting of UA within Roanoke, Virginia, a compact urban region characterized by social and environmental conditions that can be addressed by effective siting and practice of UA. This research takes a broader perspective than prior studies on UA and urban greenspaces. It proposes innovative applications of geospatial technologies for urban assessment. Studies on UA have typically focused on food insecurity, while studies on greenspaces focus on parks and tree canopy cover, without investigating interactions that promote synergies between these two efforts. Research over the past few years is now recognizing potential contributions for urban agriculture to alleviate environmental issues such as stormwater runoff, soil infertility, and the urban heat island effect. Little of this research has been devoted to the actual siting of urban agriculture to specifically alleviate both socio-economic and environmental issues. This research applies geospatial technologies to evaluate spatial patterns characterizing both environmental and socio-economic disparities within the City of Roanoke, Virginia. This approach has identified specific locations that are open and available for urban agriculture, and has appraised varying levels of socio-economic and environmental parameters. This research identified, at the census block group level, areas with varying levels of degradation. Thus, those locations in which a new urban agriculture greenspace can contribute to both socio-economic and environmental reparation. This research has identified spatial dimensions in which UA will assist in restoring ecosystem services to guide various food production activities. These results can be generalized to other urban locations and contribute to efficient use of urban land and space, improving the three pillars of worldwide sustainability – economic, environment, and social. / Ph. D.

In recent decades land use and land cover change (LULCC) has occurred throughout the Intermountain West. The Crown of the Continent Ecosystem (CCE) extends along the Rocky Mountains adjacent to the Canada-U.S. International border. In the U.S. portion of the CCE, located in northwestern Montana, development has increased since the 1990s, largely because of urban to rural migration. The CCE has become an amenity-based destination, which in turn is likely to threaten its terrestrial and aquatic ecological diversity (Quinn and Broberg 2007). Specifically, development pressures on private lands surrounding federally protected lands, are intensifying and thus threatening core habitat of native species and connectivity of forested areas. By characterizing the spatial and temporal patterns of LULCC, we can better understand landscape-scale changes influenced by human-environment interactions. Using National Land Cover Database (NLCD) products, I identified areas that have experienced land cover change for three time periods: 1992-2001, 2001-2006, and 2006-2011. Additionally, I used case studies to further investigate LULCC in the study area. The findings suggest that the highest rates of development in proximity to Glacier National Park were dependent on existing urban land cover, meaning existing roadway infrastructure and established urban areas saw the greatest urban development. Additionally, communities adjacent to Glacier National Park were hotspots for urban development. Based on the results, areas in proximity to federally protected lands are likely to experience continued urban intensification over the next few decades. / Master of Science

Numerous studies have looked at biotic succession at the aboveground level; however, there are no studies describing fungal community change associated with long-term ecosystem development. To understand ecosystem development, the organisms responsible for shaping and driving these systems and their relationships with the vegetation and soil factors, it is critical to provide insight into aboveground and belowground linkages to ultimately include this new information into ecosystem theory. I hypothesized that fungal communities would change with pedogenesis, that these changes would correlate with vegetation community change, and that they should show change of composition and diversity as the seasons change. Chapter 1 discusses the main topics related to this dissertation. Chapter 2 includes a publication draft that describes a study of sand-dune soil samples from northern Michigan that were analyzed to pinpoint the structural change in the fungal community during the development of the ecosystem. The samples were analyzed by pyrosequencing the soil DNA, targeting the internal transcribed spacer region. Chapter 3 contains a coauthored published paper that describes plant invasion of fields in Virginia to determine how they impact soil bacterial and fungal communities. The bacterial and fungal communities that were invaded by 3 different plant species exhibited similar changes, regardless of plant species, suggesting that some functional traits of invasives may have similar impacts on belowground communities. Chapter 4 remarks the conclusions of this research. / Master of Science / Ecosystems, including the soils underneath, are the environments that surround us perform a large number of critical human-relevant functions (playing roles in production of food, filtration of water for drinking, sequestration of carbon and nitrogen to build soil organic matter, and buffer against flooding). Yet, how these systems naturally develop over time are still in need of detailed study. One particular area of interest and need is the study of belowground fungal communities. It is not commonly known, but plants and ecosystems are highly dependent on the underground web of fungal hyphae that transform nutrients and provide water to plants. A first step in gaining this understanding utilized a natural ecosystem development gradient known as a chronosequence. It was expected that fungal communities would change as soil and ecosystem development progressed and that they would mimic changes in soil and vegetative properties. Discerning if these linkages occur is the first step to assessing how they work together to create ecosystems and their valuable environmental services. Chapter 1 provides a discussion of the main topics in this dissertation. Chapter 2 is at the heart of the dissertation via a study of fungal communities in a developmental soil ecosystem in northern Michigan in addition, in Chapter 3, I include a coauthored published paper that describes plant invasion of fields in Virginia. Chapter 4 remarks on the major conclusions of this Master thesis, supporting the role that vegetation and fungal community change in soil are associated with one another.

Invasive plant species threaten native plant communities and inhibit efforts to restore disturbed landscapes. Surface coal mines in the Appalachian Mountains are some of the most disturbed landscapes in North America. Moreover, there is not a comprehensive understanding of the land cover characteristics of post- mined lands in Appalachia. Better information on mined lands' vegetative cover and ecosystem recovery status is necessary for implementation of effective environmental management practices. The invasive autumn olive (Elaeagnus umbellata) is abundant on former coal surface mines, often outcompeting native trees due to its faster growth rate. The frequent revisit time and spatial and spectral resolution of Landsat satellites make Landsat imagery well suited for mapping and characterizing land cover and forest recovery on former coal surface mines. I performed a multitemporal classification using a random forest analysis to map autumn olive on former and current surface coal mines in southwest Virginia. Imagery from the Operational Land Imager on Landsat 8 were used as input data for the study. Calibration and validation data for use in model development were obtained using high-resolution aerial imagery. Results indicate that autumn olive cover is sufficiently dense to enable detection using Landsat imagery on approximately 12.6% of the current and former surface coal mines located in the study area that have been mined since the early 1980s. The classified map produced here had a user's and producer's accuracy of 85.3% and 78.6% respectively for the autumn olive coverage class. Overall accuracy in reference to an independent validation dataset was 96.8%. These results indicate that autumn olive growing on reclaimed coal mines in Virginia and elsewhere in the Appalachian coalfields can be mapped using Landsat imagery. Additionally, autumn olive occurrence is a significant landscape feature on former surface coal mines in the Virginia coalfields. / Master of Science

Climate and human activities impact the timing and quantity of streamflow and floods in different ways, with important implications for people and aquatic environments. Impacts of landscape changes on streamflow and floods are known, but few studies have explored the magnitude, duration and count of floods the landscape can influence. Understanding how floods are influenced by landscape structure provides insight into how, why and where floods have changed over time, and facilitates mapping the capacity of watersheds to regulate floods. In this study, I (1) compared nine flood-return periods of 31 watersheds across North Carolina and Virginia using long-term hydrologic records, (2) examined temporal trends in precipitation, stream flashiness, and the count, magnitude and duration of small and large floods for the same watersheds, and (3) developed a methodology to map the biophysical and technological capacity of eight urban watersheds to regulate floods. I found (1) floods with return periods ≤ 10 years can be managed by manipulating landscape structure, (2) precipitation and floods have decreased in the study watersheds while stream flashiness has increased between 1991 and 2013, (3) mapping both the biophysical and technological features of the landscape improved previous efforts of representing an urban landscape's capacity to regulate floods. My results can inform researchers and managers on the effect of anthropogenic change and management responses on floods, the efficacy of current strategies and policies to manage water resources, and the spatial distribution of a watershed's capacity to regulate flooding at a high spatial resolution. / Master of Science

Surface mining in the central Appalachian coalfield disturbs landscapes. Post-mining reforestation efforts now achieve successful reestablishment and growth; however, it is unclear whether reforestation efforts also restore the native forest ecosystem functions. We quantified rates of return of key ecosystem functions and structural attributes of the post-mining forested ecosystem. A chronosequence of four reforested mine sites and an unmined reference stand were studied in southwestern Virginia. Total soil nitrogen (N) and component (mineral soil, forest floor, root, and aboveground biomass) ecosystem carbon (C) pools were quantified. Throughout the growing season, soil gas fluxes [i.e., carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4)], soil inorganic-N [nitrate (NO3-) and ammonium (NH4+)], and total and active microbial biomass were measured. Soil organic C (SOC) and total ecosystem C are returning to the mined landscape. Ecosystem C was correlated with N (r= 0.80; p= 0.0003) and with total and active microbial biomass (r= 0.92; p=<.0001 and r= 0.86; p=<.0001). Available soil inorganic-N and CO2 and N2O fluxes showed no significant differences among study sites; however, the reforested mine soils showed a diminished capacity for CH4 uptake. Although some ecosystem components and functions rapidly returned to the mined landscape, others did not. Our results indicate that reforestation on surface mined lands is largely successful at restoring many ecosystem functions, yet certain functions are decoupled from the redeveloping ecosystem structure. Improved understanding of relationships between ecosystem functions and structural measures in this context can aid development of ecosystem restoration science and mine reclamation practice. / Master of Science

Urbanization is an intensive form of habitat disturbance associated with detrimental effects on biodiversity. However, few studies have investigated its effects on the number, identity and structure of species interactions while considering seasonal fluctuations in communities. Avian seed dispersal is a vital ecosystem service, and the interplay of urbanization and seasonality may impact seed dispersal in ways not predicted by either factor alone. In this study, we evaluate the effects of urbanization and season on avian seed dispersal networks in the southern Appalachians. We found that the number and richness of interactions was unaffected, but the identity of interacting bird species differed based on landscape type. We also found that species strength was impacted by urbanization and season, but other network metrics were unaffected. These results suggest that species identity should be considered when making comparisons of seed dispersal networks, as it may reveal differences between networks with implications for dispersal quality and future plant communities.

The conversion of grasslands to woodlands is an ecosystem transformation that threatens grassland biodiversity, the provision of important ecosystem services, and the sustainability of rural livelihoods. A global phenomenon, woody plant encroachment (WPE) has been particularly problematic in the Southern Great Plains of the United States where the actions of private landowners are integral to sustaining grasslands. Increased diversity in landowners’ motivations for owning land have shifted the social landscape of rural areas necessitating a better understanding of landowners’ perspectives about WPE and their subsequent management actions. Towards this purpose, I employed a mail survey to private landowners in the Edwards Plateau of Texas, Central Great Plains of Oklahoma, and Flint Hills of Kansas to investigate landowner perceptions and management responses to WPE. First, I assessed landowners’ acceptance of WPE as a function of how they relate to their land (i.e., sense of place), their beliefs about the positive and negative consequences of woody plants, and their perceived threat of grassland conversion. Then, I examined the drivers of landowners’ goal intentions to manage woody plants and their current use of five adaptive management practices that prevent WPE. My results demonstrate that landowners vary in their sensitivity to WPE based on how they feel connected to their land. This was true even though most landowners had low acceptance thresholds for WPE, believed it led to numerous negative outcomes, and perceived it as increasingly threatening at greater levels of encroachment. Most landowners wanted to control or remove woody plants and were actively engaged in management practices to do so. These findings address uncertainties about landowners’ acceptance of WPE and grassland conservation actions and provide broad implications for how people perceive and respond to ecosystem transformation. / Master of Science / Around the world, grasslands are converting to tree and shrub woodlands at an unprecedented rate. This transformation profoundly reduces habitat available for grassland plants and animals and diminishes many ecosystem services that people and rural communities rely on. This loss of grasslands has been especially far-reaching throughout the Southern Great Plains of the United States. Because most of this region is privately owned, the management actions of landowners play a crucial role in preventing or allowing this conversion to continue. Recent shifts in land ownership motivations expanding beyond traditional agricultural production have created increased uncertainty about how private landowners view and react to this change. To investigate how landowners perceive and respond to this woody plant encroachment (WPE) phenomenon, I conducted a mail survey of landowners in the Edwards Plateau of Texas, the Central Great Plains of Oklahoma, and the Flint Hills of Kansas. Using sense of place, landowners’ beliefs about the potential positive and negative consequences of woody plants, and their perceptions of how threatening grassland conversion is, I assessed the thresholds at which landowners’ do or do not accept WPE. Then, I examined how acceptance of WPE relates to landowners’ management goals and current use of management practices to control or reduce woody plants. I found that most landowners believed that woody plants had many negative consequences and perceived increasing levels of threat at greater levels of encroachment. This related to low levels of acceptance for woody plants in grasslands. However, landowners’ threat perceptions and acceptance of WPE varied based on their sense of place. Finally, most landowners wanted to control or remove woody plants and were actively engaged in management practices to do so. My results provide critical information regarding how current landowners’ view and respond to grassland conversion and offer broad implications for how people perceive and respond to large-scale environmental change.