Primary productivity is a fundamental ecosystem process driven by vascular plants in most terrestrial ecosystems and by microbes in more extreme ecosystems. In dense associations, microbial organisms can form visually conspicuous layers on sediment, soil, and rock surfaces, called microbial mats and biological soil crusts (i.e., biocrusts). Both microbial mats and biocrusts consist of cyanobacteria, moss, diatoms, and green algae, and also support diverse heterotrophic taxa. These communities exist in harsh environments worldwide such as hypersaline environments, tundra ecosystems, and hot and cold deserts where they are foundational taxa, providing most of the primary production and nitrogen fixation, as well as promoting cohesion and stability to soil surfaces. In the McMurdo Dry Valleys of Antarctica, microbial mats are the main source of fixed carbon in lentic and lotic environments, but their contribution to soil carbon and nitrogen cycling has not been systematically examined. In my dissertation, I investigated the relationships between microbial mats and the soil environments in which they occur. Using a combination of field surveys, soil analyses, and remote sensing, my objectives were to examine the influence of microbial mats and biocrusts on underlying soils and model the main drivers of their distribution and abundance. In Chapter 2, I investigated the relationships between underlying soil chemistry and microbial mat distribution, composition, and function in the Taylor Valley, finding that microbial mats enrich underlying soils, contributing to soil organic carbon and nitrogen. In Chapter 3, I assessed the spectral detectability of patchy biocrusts using multispectral satellite imagery to examine the environments in which biocrusts occur, finding that spectral unmixing of satellite imagery can successfully detect the presence of biocrust and its association with seasonal snow patches. As a direct continuation, in Chapter 4, I created a habitat suitability model using machine learning algorithms to determine the distribution and abundance of biocrusts in the Lake Fryxell basin. I found that biocrusts contribute a significant amount of carbon to the surface soil in the Lake Fryxell basin, with biocrust presence primarily driven by snow frequency, moisture content, and salinity. This dissertation contributes to ongoing questions about the sources of energy fueling soil food webs and regional carbon balance in the Taylor Valley, and how we can use remote sensing techniques for researching these critical soil communities in the dynamic Antarctic landscape. / Doctor of Philosophy / Photosynthesis is the process where plants and other organisms use sunlight to transform carbon dioxide into chemical energy. This is crucial because it provides the energy and nutrients that support all other life forms. In this dissertation, I focused on colonial microorganisms, which are the main primary producers in extreme environments, like deserts. I used a combination of field surveys and satellite imaging to study these organisms in the McMurdo Dry Valleys, Antarctica, which is a harsh polar desert environment that lacks vascular plants. Microbes colonize the surface of soil and form mm-cm thick microbial mats and biological soil crusts (called biocrusts). These organisms are found within the glacial-melt streams that flow on and off for only a few weeks each year, and they also occur on the stream margins and other periodically wet areas like near snow patches. This dissertation investigates the ecological importance of microbial mats and biocrusts, the ability to measure where they are using satellite imagery, and how much organic material they contribute to the broader landscape. Field work in the McMurdo Dry Valleys and laboratory analyses were required for each of these chapters. In Chapter 2, I investigated the relationships between microbial mats and the soils below them, and I found that microbial mats increase the organic matter and nutrient content in the soils. In Chapter 3, I assessed whether satellite imagery could be used to study the presence of sparse biocrusts and examined the environments in which biocrusts occur. I discovered that satellite imagery can successfully detect the presence of biocrust and that biocrusts occurred near melting snow patches. Lastly, in Chapter 4, I created models to determine where biocrusts occur in the Lake Fryxell basin and why biocrusts occur in those areas. I found that biocrusts occur over a significant area of the Lake Fryxell basin, containing a lot of organic material, and that biocrusts thrive in wet areas near snow patches where the soils are less salty. This dissertation contributes to ongoing questions about the sources of nutrients fueling soil food webs and contributing to the amount of organic material in the McMurdo Dry Valleys, and how we can use satellite imagery for monitoring these important soil communities in the changing Antarctic landscape.

京都大学 / 新制・課程博士 / 博士(地球環境学) / 甲第25470号 / 地環博第256号 / 新制||地環||52(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 柴田 昌三, 教授 西前 出, 准教授 真常 仁志 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DGAM

Plastics are a highly utilized material in modem society, leading to environmental concerns surrounding plastic pollution. Microplastics, which are defined as plastic particles less than 5mm in size, have additionally become increasingly recognized as a harmful pollutant in aquatic systems. Constructed treatment wetland systems (CTWSs) are highly effective at removal and mitigation of pollutants, including anthropogenic nutrient inputs. This study aims to understand the potential of a CTWS to remove microplastic pollution from tertiary-treated municipal wastewater before discharge into a local natural water body. Microplastic percent removal was determined through the manual quantification of microplastics in triplicate 500mL surface water samples, taken at both an influent and effluent site. Samples were vacuum filtered and particles within the sample were caught on the 0.45μm pore size nitrocellulose filter paper, dried, and transported to a microscope station where microplastics could be identified and quantified according to visual characteristics. Results indicate the CTWS studied is removing, on average, 93 % of microplastic particles across 11 months of data collection, demonstrating an additional ecosystem service provided by treatment wetlands.

Near-natural river corridors (NNRs) provide crucial habitat for a host of biota and support the survival of people and nature worldwide at multiple spatiotemporal scales. Furthermore, NNRs represent fundamental references for river conservation, management, and restration, offering the opportunity to investigate processes under minimal anthropic disturbances. However, in the Anthropocene large near-natural rivers are rare gems in Europe an worldwide, and knowledge of their dynamics and ecosystem services are often scarcedue to a lack of hydromorphological and ecological data, monitoring, and baseline studies. Despite the scarcity and fragmentation of pertinent studies, many national and international guidelines and directives point to NNRs as reference systems for conservation, management, and restoration targets. In this framework, this Ph.D. thesis investigates the value of NNRs in the Anthropocene with an interdisciplinary approach, bridging fluvial geomorphology and environmental planning disciplines to support freshwater management and conservation in international cooperation for development. The first part of the research activity is rooted in fluvial geomorphology and explores the spatiotemporal trajectories of NNRs adopting several remote sensing products, cloud computing, and geomatic. The recent morphological trajectory of the near-natural Vjosa River (GR/AL) is presented as the response of the river to multidecadal climatic oscillations and more recent localized anthropic pressures, warning about the importance of considering and quantifying the geomorphic sensitivity of river systems in management and conservation. Thus, we focused on framing remote sensing-based procedures for characterizing active river channel spatiotemporal dynamics in the Mediterranean biogeoclimatic region. The second part of the research activity deals with the need to improve riverscape science and landscape management dialogue and the valuation of river ecosystem services. Focusing on inland waters ecosystem services, we integrate a socio-cultural approach with spatial analysis for cultural ecosystem services supply assessment in selected Albanian Protected freshwater ecosystems, outlining the relevant role of ecotones in providing cultural ecosystem services and the multifacet value of such dynamic zones. The third part of the research activity strongly links fluvial geomorphology and environmental management and conservation. It proposes the reconstruction of in-channel vegetation age and related ecosystem services spatiotemporal trajectories in targeted reaches of the Vjosa (GR/AL) and Tagliamento (IT) NNRs, integrating cloud computing, multispectral images, and fieldwork data. Developed baseline knowledge and tools can support the study, management, and conservation of highly dynamic river corridors in Mediterranean temperate climates, and the proposed integrated and multidisciplinary set of approaches is promising to cope with data scarcity that often characterizes the few remaining near-natural rivers in the world.

Agricultural ecosystems provide multiple services including food and fiber provision, nutrient cycling, soil retention and water regulation. Objectives of the study were to identify and quantify a selection of ecosystem services provided by agricultural land, using existing geospatial tools and preferably free and open source data, such as the Virginia Land Use Evaluation System (VALUES), the North Carolina Realistic Yield Expectations (RYE) database, and the land cover datasets NLCD and CDL. Furthermore I sought to model tradeoffs between provisioning and other services. First I assessed the accuracy of agricultural land in NLCD and CDL over a four county area in eastern Virginia using cadastral parcels. I uncovered issues concerning the definition of agricultural land. The area and location of agriculture saw little change in the 19 years studied. Furthermore all datasets have significant errors of omission (11.3 to 95.1%) and commission (0 to 71.3%). Location of agriculture was used with spatial crop yield databases I created and combined with models I adapted to calculate baseline values for plant biomass, nutrient composition and requirements, land suitability for and potential production of biofuels and the economic impact of agriculture for the four counties. The study area was then broadened to cover 97 counties in eastern Virginia and North Carolina, investigating the potential for increased regional grain production through intensification and extensification of agriculture. Predicted yield from geospatial crop models was compared with produced yield from the NASS Survey of Agriculture. Area of most crops in CDL was similar to that in the Survey of Agriculture, but a yield gap is present for most years, partially due to weather, thus indicating potential for yield increase through intensification. Using simple criteria I quantified the potential to extend agriculture in high yield land in other uses and modeled the changes in erosion and runoff should conversion take place. While the quantity of wheat produced though extensification is equal to 4.2 times 2012 production, conversion will lead to large increases in runoff (4.1 to 39.4%) and erosion (6 times). This study advances the state of geospatial tools for quantification of ecosystem services. / Ph. D.

Urbanization can negatively affect the capacity of ecosystems to provide services that support human life. Edible green infrastructure (EGI) can increase cultural and environmental services in urban and peri-urban communities. Instrumental in the use of EGI are local governments, who are in a position to pass supportive policies. For this research, we completed a qualitative study of EGI policy processes in U.S. cities and a mixed-methods study of EGI challenges and opportunities in small towns. Our first objective was to understand how and why EGI policy develops. We interviewed twelve policy actors from six U.S. cities that have formalized EGI ordinances. Major drivers of EGI policy were: 1) improving public health; 2) securing land tenure; 3) managing vacant lands; 4) accommodating for population growth; and 5) the local food movement. Common policymaking steps included: 1) local communities initiate EGI policy process; 2) city governments respond by working with communities to draft EGI ordinances; 3) abrupt changes to land use policies result in a policy image supportive of EGI as a public land management strategy; and 4) during emergence of the new land use paradigm, incremental changes reinforce this image. We also learned how certain challenges and policy actor recommendations for minimizing obstacles affect the policy process. Our second objective was to understand EGI adoption in small towns. We surveyed 68 mayors of small towns (<25,000) in Virginia to study local leader perspectives regarding implementation and policy. The greatest perceived barrier to EGI adoption was long-term maintenance, whereas opportunities included civic benefits such as education and community-building. Most towns had not intentionally used EGI on public land, nor did they have compatible land use codes. Open-ended responses suggest that mayors have different views about the role policy should play in EGI adoption. We used mayoral perceptions about the constituent support for public green space, the implementation of edible woody perennial species, and available public space for EGI to group towns into unique types. Four groups were identified in a K-means cluster analysis: 1) Ambivalent and Resource-Poor; 2) Optimistic and Capable; 3) Doubtful and Unsupported; and 4) Unsure with Potential. One-way ANOVA and Tukey's HSD post-hoc analysis (α=0.05) showed that Optimistic and Capable were significantly more likely than Doubtful and Unsupported to intend to plant EGI and benefit from government support for edible, woody perennials on public land. EGI may be more practical for towns with greater backing for public green space, more available land, and higher rates of favorable attitudes. / Master of Science / The global movement of people from rural to urban and suburban areas has impacted ecosystem health and human well-being. A land management strategy that can improve environmental and public health is edible green infrastructure (EGI), which is small-scale food production in and around built structures. Local governments can pass policies that increase the use of EGI in public spaces. To learn more about how local governments view EGI and the role that policy might play, we completed two studies. In our first study, we interviewed 12 people from 6 U.S. cities who were involved in the development of EGI policies. The purpose of this study was to learn how and why cities pass EGI policies. Reasons for policy adoption included: 1) improving public health for their residents; 2) ensuring EGI as a permanent rather than temporary land use; 3) finding a better use for vacant properties; 4) setting aside green space for current and future populations; and 5) increasing local and healthy food access. Cities shared the following policy development steps: 1) local community leaders demonstrated that EGI policy was needed; 2) government leaders worked together with residents to draft an EGI ordinance; 3) ordinances were passed that significantly changed how public land could be used; and 4) they passed other, smaller policies to make the use of EGI easier for residents. In our second study, we surveyed 68 mayors of small towns (< 25,000 people) in Virginia, U.S. The purpose of this study was to learn what local leaders think about the use of EGI in the public spaces and whether EGI policies would be useful. Long-term maintenance was the biggest barrier and the greatest opportunities included education, recreation, social gathering, and community building. Mayors had differing opinions on whether policies pertaining to EGI on public land were a good idea for their towns, and several pointed out that residents already had access to private land for food production. Using mayors' responses, we grouped towns based on the following characteristics: 1) how much public land could be used for food production; 2) how supportive residents were of existing green space; and 3) how residents thought about the use of EGI on public land. We found that small towns in Virginia could be described as; 1) Ambivalent and Resource-Poor; 2) Optimistic and Capable; 3) Doubtful and Unsupported; or 4) Unsure with Potential. "Optimistic and Capable" towns were more likely to be supported by municipal policies and budgets and to use EGI for managing public land, whereas "Doubtful and Unsupported" towns were least likely to be supported by local government and to use EGI. In summary, EGI may be more practical for towns with greater backing for public green space, more available land, and more favorable views on food production on public land.

Urban landscapes homogenize our world at global scales. This sameness contributes to "extinction of experience", where people feel increasingly disconnected from native ecosystems and the services they provide. Numerous approaches have been proposed for combatting extinction of experience, all of which require community support to be successful. Because comparative assessments are relatively rare, however, it is difficult to say which options are most supported. We addresses this knowledge gap using human subject surveys and multi-criteria decision analysis to evaluate landscape preferences and their implications for three approaches recommended to combat extinction of experience: ecosystem conservation, turf replacement and nature-based solutions. Our study focuses on universities in Southern California, where native ecosystem remnants, nature-based solutions, lawns, and ornamental gardens co-exist, which is necessary to compare community support for transitions among them. Our results suggest that conservation of native ecosystems, particularly sage scrub (top ranked landscape overall), is well supported by campus communities, as are turf replacement programs (lawns ranked lowest overall). Support for nature-based solutions was more intermediate (and variable), which may reflect their relative newness, both on university campuses and in urban spaces more generally. Not all university populations preferred the same landscapes; preferences differed with degree of pro-environmentalism and university status (undergrad, graduate student, staff). Even so, all groups exhibited landscape preferences consistent with at least one approach for combatting extinction of experience. This suggests we have a viable set of tools for increasing native ecosystem exposure on university campuses, and ultimately, in the next generation of urban homeowners. / Master of Science / Urban areas around the world are more like one another than the natural landscapes they replace. This can make people feel more at home in a city far away than they do in the landscapes that belong in their home state. Changing urban areas to reconnect people with nature requires community support to be successful. Whether this support is available, however, is not well understood. This study focuses on evaluating community support for three actions intended to bring people closer to nature. These include 1) protection of natural landscapes, 2) replacing lawns with natural plants, and 3) using nature instead of pipes and channels to manage the water that runs off paved surfaces during storms in urban areas. The community we focus on is university students and staff because they have access to all the different landscape types involved in the three actions described above. Our approach was to survey people on four campuses in Southern California and rank their landscape preferences to determine if they are likely to support these actions. We found that people tend to be supportive of protecting native landscapes and replacing turf grass with native plants. Support for nature-based alternatives to pipes and channels was more variable. This may be because they are presently uncommon, and people don't know how they feel about them yet. Not everyone on campus preferred the same landscapes, but most people's preferences were consistent with at least one approach for connecting people with nature. This suggests that there may be strong support for changing campus landscapes in ways that bring people closer to nature.

This investigation examined the role that racial concordance, defined as the percentage of African Americans in one's environment, play in the relation between racial socialization and racial identity. African American (n=-160) students evaluated their perception of parental socialization, racial concordance, and racial identity. As hypothesized, racial socialization significantly predicted racial identity. As well, racially concordant environments moderated the relation between racial socialization and racial identity. Minority and cultural socialization were the best predictors of racial identity. Conclusions emphasize the importance of proactive racial socialization and supportive environments. Future research and mental health implications are also examined. / Ph. D.

Antibiotic resistance is ubiquitous due to high usage of antibiotics and the capability of bacteria to transfer genes both horizontally and vertically. While this has dire implications for human health, the potential to disturb microbial communities and ecosystem functions they regulate is under appreciated. Antibiotics are commonly used in the livestock sector, accounting for 80% of antibiotic use domestically. This dissertation addresses three facets of this problem. Chapter 2 is a nation-wide survey of antibiotic resistance at dairy operations, aimed at understanding how ecosystem function is affected in situ. Chapter 3 describes a field-experiment, seeking to determine whether antibiotics have effects beyond soil through impacts on plant-microbe-soil feedbacks, thus potentially altering terrestrial ecosystem function. Chapter 4 investigates how rising global temperature interacts with antibiotic exposure through a microcosm-incubation experiment. These multiple stressors (i.e. temperature and antibiotics) could alter microbial community composition or physiology with repercussions on function. Additionally, chapter 4 seeks to determine whether microbes acclimate to continued antibiotic exposure. In chapter 2 I present evidence that increased antibiotic resistant gene (ARG) abundance with exposure to antibiotics and manure, and a correlation between ARGs and microbial stress. This increase in microbial stress results in elevated soil carbon loss. Chapter 3 shows that antibiotic exposure can change plant function – presumably through impacts on rhizospheric microbial community composition. Plants assimilate more nitrogen, but more carbon is lost from the system overall seemingly due to plant-soil-microbe tradeoffs. Chapter 4 shows a temporally dependent temperature–antibiotic interactive effect. Initially, pirlimycin increased microbial respiration at high temperatures, however this diminishes with time. Additional studies of microbial respiration at a range of temperatures show that microbial acclimation to antibiotic exposure may be taking place. However, interactive effects of high temperature and antibiotics appear to inhibit active microbial biomass production. Possible explanations to both of these patterns are the underlying differences in microbial community composition, specifically the fungal:bacterial. My results show that antibiotics not only lead to increased ARG abundance, but also have wide ranging effects on communities and ecosystem processes that are likely to be compounded in the face of global change. / Ph. D. / Antibiotic resistance is becoming ubiquitous. While implications for human health are dire, underappreciated are the potential effects on environmental microbes, given that microbes are drivers of ecosystem function. Antibiotics are commonly used in livestock production, accounting for 80% of antibiotic use domestically, with a substantial proportion of the administered antibiotics passing through livestock while still functional. Therefore understanding how antibiotics may be impacting livestock-associated soils is critical. This dissertation is divided into three data-driven chapters, each addressing a facet of this question. In chapter 2 I show that antibiotic exposure can increase microbial stress and decrease microbial efficiency. This reduction in microbial efficiency results in increased soil carbon loss. In chapter 3 I show that antibiotic exposure can change carbon and nitrogen cycling in plants, presumably through impacts on root-associated microbial composition. Plants assimilated more nitrogen, but more carbon was lost from the system overall, when soil was exposed to manure from cattle administered the antibiotic pirlimycin. Chapter 4 describes an interactive effect between temperature and antibiotic exposure, however, this effect appears to diminish with time. The pirlimycin treatment increased microbial respiration at high temperatures, however this effect was not observed in the second year of v the field portion of this study. Additional experimentation showed some evidence of microbial acclimation to multiple stressors. However other evidence described within this chapter paints a different picture, as interactive effects of high temperature and antibiotics appeared to inhibit active microbial biomass production. Possible explanations to both of these patterns are the underlying differences in microbial community composition, specifically broad differences in the ratio of fungi to bacteria. Therefore antibiotics not only lead to reduced microbial efficiency, but also have wide ranging effects on communities and ecosystem processes that are likely to be compounded in the face of global change.

The increasing rate of deforestation, which began decades ago, has significantly impacted on ecosystem services. In this context, secondary forests have emerged as crucial elements in mitigating environmental degradation and restoration. This study is motivated by the need to understand the reforestation management in secondary forests to prevent irreversible ecosystem damage. We begin by setting the drift and volatility in stochastic primary forests. However, it is more manageable to take control of replantation. We employ a dynamic programing approach, integrating ecological and economic perspectives to assess ecosystem services. To simulate a real-world case, we investigate the model in the Brazil Amazon Basin. Special attention is given to the outcome at the turning point, tipping point, and transition point, considering a critical threshold beyond which recovery becomes implausible. Our findings suggest that reducing tenure costs has advantages, while substitution between primary and secondary forests is not necessarily effective in postponing ecosystem collapse. This research contributes to a broader goal of sustainable forest management and offers strategic guidance for future reforestation initiatives in the Amazon Basin and similar ecosystems worldwide. / Master of Science / Deforestation has been drawing attention from institutions since the 1940s, and this global issue has been discussed for its negative impacts and the ways to restore what has been lost. Reforestation initiatives introduced by global environmental organizations consider forest plantations essential in re-establishing trees and the natural ecosystem. This study aims to investigate how different techniques target the growth of secondary forests to mitigate the irreversible damage of ecosystem services. Our research begins by defining the uncertain primary forests. Primary forests and deforestation face long-term climate changes and immediate shocks like fires, droughts, and human activities, meanwhile, policymakers have difficulties predicting and fully controlling them. We integrate considerations of ecology and economy to the ecosystem functioning, introducing stochasticity in deforestation into our dynamic optimization problem. We apply our models to the Brazil Amazon Basin, a region known for its diverse tropical forests and vast cases of deforestation. We pay close attention to the timing of tipping point that leads to ecosystem collapse, the turning point where reforestation rate catches up with deforestation rate, and the moment of forest type transition. Through simulation and sensitivity analysis, we gain a better grasp on guiding the management of secondary forests under uncertain conditions. Our results indicate that reforestation approaches that lower tenure costs can be beneficial, but merely substituting primary forests cannot necessarily delay an ecosystem collapse. This paper provides practical insights for policymakers, local communities, and international organizations.