Both global and local chronic environmental stressors associated with climate change and anthropogenic sources are increasing in severity, and can compromise the resilience of key marine ecosystems such as foundational coral reefs. Despite the impacts, however, there are major knowledge gaps in our understanding of direct interactive and compounding effects of multiple chronic environmental stressors on coral animals. Further, chronic stress may have sublethal, downstream impacts; for example, inhibiting the recognition and response to sudden acute stressors in the marine environment. The goal of this study was to determine the direct impacts of multiple chronic environmental stressors - elevated temperature (global), microplastic pollution, light availability, and food availability (local) - on survival and physiological performance of the emerging temperature coral model Astrangia poculata, and to determine how exposure to different chronic stressors affects their ability to deal with sudden acute stress. To achieve this, we exposed individual coral polyps to different combinations of stressors, and quantified the response of the coral host (growth) and symbiont (photosynthetic efficiency, chlorophyll a density). Coral polyps were then challenged with an acute stress near the onset, midpoint, and end of the experiment to quantify the impact of chronic environmental stress on the ability to mount a response to an acute stress. We found that the local stress of microplastic exposure had no impact on lethal or sublethal measures of the coral holobiont, while light was beneficial in maintaining coral mass. In contrast, elevated temperatures (representing global stress) reduced survival, diminished host and symbiont performance, and repressed the coral metabolic response under acute stress challenge. Feeding, however, was beneficial in preserving symbiont function, but has consequences for fitness and coral growth when presented with thermal stress, lending support to the growing hypothesis that this established mutualism shifts towards parasitism in stressful environmental conditions. Despite the magnitude of these combined stressors, over 80% of coral polyps survived, highlighting the overall resilience of A. poculata to diverse environmental challenges. These findings underline the complexity with which anthropogenic stressors interact to affect coral survivorship and resilience to future global change.

Policies intended to pursue climate mitigation through soil carbon sequestration require accurate estimates of soil carbon stocks and projections of how carbon pools will change with future climate. In this study, the process model MIMICS-CN was utilized to explore the potential changes in bulk soil organic carbon (SOC) and protected mineral-associated organic matter (MAOM) with changes in mean annual temperature (MAT) and annual net primary productivity (NPP) for the native range of loblolly pine (Pinus taeda L). A Monte Carlo method was used to calibrate a large ensemble of model parameters using observational data from loblolly pine stands. Spatial projections of carbon pools across the native range of loblolly pine were produced for nine temperature and productivity scenarios representing a range of likely futures. The standard deviation of the mean total SOC pool to a depth of 30 cm was 3.6 kg C m-2 while the standard deviation of potential changes in pool magnitude was 0.96 kg C m-2. Associated with regional climate change projections, increases in MAT caused losses in bulk SOC but did not affect MAOM. Simulated increases in NPP resulted in increased bulk SOC, MAOM and the proportion of SOC that is MAOM (MAOM:SOC) highlighting the importance of productivity in sequestering atmospheric CO2 in general and in protected C pools, specifically. SOC pools did not change consistently across the landscape. Rather, they varied by subregion due to differences in soil texture and changes in forecasted NPP. Soils with clay contents above 18% had the greatest potential to accumulate MAOM and bulk SOC under a realistic future climate scenarios. In regions with low clay content, significant increases in total SOC are driven by the accumulation of C in unprotected SOC sub-pools. With the maximum likely increase in NPP (31.4%), a regionwide increase in total SOC of 29% was projected whereas subregions in which NPP decreases showed no potential to increase soil carbon stocks. We conclude that the management of loblolly pine to increase productivity can increase the amount of SOC and the residence time of bulk SOC over decadal time scales, however regional differences in the proportion of C in MAOM and unprotected pools must be considered when planning silvicultural management. / Master of Science / Managing soil carbon in southeastern U.S. loblolly pine forests creates a sustainable system of producing large quantities of forest products and has the potential to remove carbon dioxide from the atmosphere. Accurate estimates of the amount of carbon in soils at regional scales and projections of changes in soil carbon caused by global change are critical components to successfully determining the effectiveness of this approach to climate change mitigation. In this study, a model of soil carbon designed to describe the range of loblolly pine is utilized to simulate soil carbon changes using three realistic potential increases in temperature and three projections of changing ecosystem productivity to the year 2050. As temperature increases, the total amount of carbon in soils decreases because the rate of decomposition by microbial organisms hastens. However, with increasing productivity, losses of soil carbon due to increased temperatures are mitigated, and, at the highest levels of productivity, soil carbon stocks and the resistance of soil carbon to future losses increase by up to 26 percent. Here, we propose a productivity focused management approach to sequestering carbon in loblolly pine soils and highlight sub regions which may be more vulnerable to soil carbon losses due to environmental factors such as flooding and nutrient limitations.

Drought-induced tree mortality is an emerging global phenomenon that appears related to climate change and rising temperatures in particular, and may be an early indication of vegetation change. However, vegetation response to climate change is uncertain, particularly for future novel climates. Notably, no current models of vegetation change attempt to mechanistically predict plant mortality, and in particular, mortality of trees, which exerts strong influences on ecological function. Resolving uncertainties surrounding the physiological mechanism and temperatures sensitivity of tree mortality is a current challenge in global change ecology. The objectives of this dissertation were to 1) consider tree mortality consequences for earth system processes related to carbon, water, and energy exchange that include climate regulation; 2) explore tree mortality effects on the water cycle by developing hypotheses and research needs; 3) quantify the temperature sensitivity of drought-induced tree mortality and gain insight into the physiological mechanism of mortality; 4) quantify the relationships among temperature, stored carbohydrate resources, and gas exchange to further elucidate physiological tree mortality mechanisms; and 5) quantify the sensitivity of two species of pine seedlings to progressively elevated temperatures and relate mortality to the effect of temperature on carbon metabolism. Major findings of this dissertation relate to the temperature sensitivity, physiological mechanism, and implications of tree mortality. Assessment of the potential consequences of tree mortality for earth system processes documented the contrasting influences of tree mortality on the terrestrial C cycle and land-surface energy exchange, the balance of which will determine the net effects on climate regulation (Appendix A). Following a survey of the ecohydrology literature, thresholds for tree mortality to cause watershed changes were hypothesized at ~20% loss of canopy cover, ~500 mm of annual precipitation, and whether flows are snowmelt dominated (Appendix B). Elevated temperature (~+4°C) accelerated tree mortality by 28% during experimental drought, a difference related to cumulative respiration dynamics in piñon pine (Appendix C). Stored carbohydrate resources were declined during lethal drought but were not entirely depleted prior to mortality (Appendix D). Seedlings exhibited progressive declines in time-to mortality with increased temperatures, a response related to C metabolism (Appendix E).

Rural households in the West African Sahel have developed livelihood systems that allow them to survive in one of the most challenging social-ecological systems on Earth. These households have experienced environmental shocks including droughts, floods, and extreme heat for hundreds of years, and have well-established coping and adaptation mechanisms that allow them to recover from all but the most severe shocks. Climate change, particularly increased climatic variability, may stress Sahelian livelihood systems to the point that households must deploy a new set of coping and adaptation strategies in order to survive. This research, conducted as three interrelated mixed-method studies, explores the coping and adaptation strategies used by Tuareg transhumant pastoralists in Niger starting with the deep drought of 1968-1974.The first study involves rural households in the Tahoua Region of central Niger. These households have adapted to climate change and other livelihood stressors primarily by diversifying their assets, utilizing new technologies, and reducing the length of their annual transhumance. While there are donor-funded programs designed to assist rural households with adaptation to climate change, the households in this study have not been the beneficiaries of such programs. The second study attempts to disentangle climate shocks from other factors driving rural-urban migration while also exploring which households migrate to urban areas, and why. Climate change is perceived as the main factor driving rural-urban migration, as well as other livelihood changes. Household-level preferences, management skills, and luck played a greater role that asset endowments in determining which households would migrate to urban areas. The third study focused on livelihood strategies of households that had migrated to, and settled in, urban areas. These households worked hard to maintain social capital with their rural kin while also building social capital in their new urban environment. Social capital with expatriates and urban elites was an important element of urban households' asset endowment. Urbanized households possess significantly fewer livestock than their rural counterparts, and struggle to manage the cash earned from relatively low-paying wage labor. These three studies demonstrate that pastoralists perceive climate change as a significant driver of changes in livelihood strategies. Pastoralists' perceptions of climate change broadly match climate data. Furthermore, pastoralists, with little to no assistance from the state or development organizations, are successfully adapting to climate change in ways that are likely to increase their resilience to future climate shocks.

Internal communication is the heart in all actions in every organization and plays a key role in a successful change project. Volvo Cars is a global company in an implementation phase of the change project ”One Finance”. The purpose of the change project is to standardize the financial processes which will change the organization structure in the financial departments. Since this is a global change project there are several factors that can affect the internal communication and can result in affecting the success of a change project. The purpose of this thesis is to study the internal communication during a global change project and to analyze what factors are affecting the internal communication from a global perspective. The thesis will also include what impact internal communication has on the organization. The study will mainly be on the internal communication between the headquarter in Gothenburg and the developing financial department in America. Collecting primary data in terms of semi-structure interviews has provided an understanding about Volvo Cars internal communication. Using electronic communication channels and cascade-communication model the organization has informed well about the concept and the purpose of the change. Some respondents are still requesting information about how they should work according to the change. Overall the acceptance of this change has created job-satisfaction and increased the engagement for employees, this can lead to business success. All respondents agree that there are factors that affect the internal communication during this global change project. Organization culture, multi-cultured organizations, organization change, power structures and globalization are all affecting the internal communication in ways of how to communicate, the amount of internal communication, and the currents of the internal communication and can create misunderstandings. The thesis is including an internal communication matrix that gives a clear overview of how different internal stakeholders are working with the internal communication at different levels within the organization. This is creating an effective internal commutation system.

The National Ecological Observatory Network (NEON) will monitor ground beetle populations across a network of broadly distributed sites because beetles are prevalent in food webs, are sensitive to abiotic factors, and have an established role as indicator species of habitat and climatic shifts. We describe the design of ground beetle population sampling in the context of NEON's long-term, continentalscale monitoring program, emphasizing the sampling design, priorities, and collection methods. Freely available NEON ground beetle data and associated field and laboratory samples will increase scientific understanding of how biological communities are responding to land-use and climate change.

Les microorganismes, par leurs fascinantes capacités d’adaptation liées à l’extraordinaire diversité de leurs capacités métaboliques, jouent un rôle fondamental dans les tous les processus biologiques. Ils interviennent notamment au niveau des changements globaux, comme le réchauffement climatique, en partie occasionné par les émissions croissantes de méthane dans l’atmosphère, mais également par les pollutions résultant de la dispersion de molécules comme les Hydrocarbures Aromatiques Polycycliques. Ainsi, les communautés microbiennes vont participer à réduire ou à augmenter les effets délétères de l’anthropisation des écosystèmes. La régulation des changements globaux passe donc par une meilleure connaissance de ces communautés qui doivent être explorées dans leur globalité au sein des environnements. Néanmoins en raison de leur forte complexité, une telle exploration n’est possible qu’en utilisant des outils d’analyse haut-débit. Cependant, l’emploi d’outils moléculaires à haut-débit comme les biopuces à ADN passe par la détermination de sondes combinant à la fois une forte sensibilité, une très bonne spécificité et un caractère exploratoire. Pour concevoir de telles sondes un nouveau logiciel KASpOD a donc été développé. De même, en utilisant des sondes présentant les mêmes caractéristiques, le développement d’une nouvelle approche innovante en écologie microbienne de capture de gènes en solution été entrepris. Cette nouvelle méthode d’enrichissement de gènes d’intérêt couplée à du séquençage haut-débit a été appliquée pour l’exploration des communautés méthanogènes du lac Pavin. Les résultats obtenus montrent la pertinence de l’approche qui assure une meilleure évaluation de diversité de l’écosystème avec notamment l’identification de populations appartenant à la biosphère rare. L’autre ajout majeur de cette approche est qu’elle autorise l’identification de grandes régions d’ADN génomique exploitable pour caractériser de nouveaux gènes ou de nouveaux processus adaptatifs. / Microorganisms play a crucial role in all biological processes related to their huge metabolic potentialities. They are involved in global changes such as global warming partially caused by the growing methane emissions in the atmosphere, but also by the release of pollutants such as Polycyclic Aromatic Hydrocarbons. Thus, microbial communities will contribute to reduce or increase the negative effects of human impacts on ecosystems. The regulation of global changes needs a better knowledge of the microbial communities involved in complex environments functioning. Nevertheless, a complete exploration of such environments requires the use of high-throughput tools, due to the extraordinary diversity of microorganisms within the ecosystems. The use of DNA microarrays requires a probe design step allowing the selection of highly sensitive, specific and explorative oligonucleotides. For this purpose, we have developed KASpOD, a new software, allowing the generation of efficient probes dedicated to environmental applications. Using high quality probe sets, an innovative in solution-based gene capture method combined with Next Generation Sequencing, was developed and applied for the exploration of the methanogen communities in lake Pavin, Results showed the relevance of this approach that allows a better evaluation of the methanogen diversity with an efficient detection of populations belonging to the rare biosphere. The other main advantage of this approach is the identification of large regions of genomic DNA, useful for the characterization of new genes or adaptive processes.

Climate change has varying effects across the world. In North America, arid and semi-arid regions are subject to creeping warming together with more extreme climate variations, decreasing precipitation, and decreasing river flows that risk livelihoods of human populations living in these areas, and push their capacity to adapt beyond known boundaries. Environmental impacts act together with effects of socio-economic globalization and challenges imposed by institutional and policy events. These multiple forms of globally-driven changes interact with local communities and produce winners and losers depending on their levels of vulnerability and adaptive capacity, as well as on the specific stressors and shocks affecting the livelihood resources on which they depend. Rural communities often are hot spots of global change impacts because many livelihoods depend on the community’s natural resource base, and in several cases, they are also subject to market fluctuations and crashes due to their participation in international chains of food and producer goods. They will face a larger burden of the global change impacts due to this multi-tiered exposure. The socio-economic and institutional changes affecting rural communities have also produced de-agrarianization of livelihoods. Diversified livelihoods based on extractive industries and manufacturing or urban-based jobs coexist with traditional small-scale ranching and farming. In terms of water and land access and use, the modifications in user sectors and necessities, combined with increased demand by social and ecological components of the watershed systems, creates more complexity of environmental governance regimes and institutions. The purpose of this research is to identify and understand how rural communities of arid Northwest Mexico—with reference to the San Miguel Watershed (SMW) in central Sonora State—experience and respond to globally driven environmental, socio-economic, and institutional changes. The SMW is in a rapidly changing arid transboundary region, and exhibits a variety of institutional arrangements for land and water management, which makes it a case suitable for the study of adaptation in the face of global change. The study employs a combination of quantitative and qualitative methodologies in three municipalities representing the upper, middle, and lower SWM. Rural households and producers, governmental agents, and local leaders were the participants of direct data collection, while documentary analysis and a broader literature review on rural adaptation in Mexico and the arid Southwest United States complemented primary data. The main contributions of the research are: 1) identifying multiple types of rural livelihoods and their importance in understanding adaptation to global change; 2) emphasizing institutional events and factors acting as both stressors and regulators in these adaptation processes, 3) describing how interactions between institutions can produce diverse governance outcomes in terms of access and management of resources for livelihoods' adaptation; and 4) providing empirical evidence for improving adaptation policies in rural arid Northwest Mexico, and other rural arid communities of the world. The study also includes a series of findings and lessons regarding advances in understanding human adaptation in rural communities, contributions to the theory and methods of adaptation science, and policy guidelines based on the findings.

Rapid increases in air temperature in Arctic and subarctic regions are driving significant changes to surface water. These changes and their impacts are not well understood in sensitive high Arctic ecosystems. This thesis explores changes in surface water in the high Arctic pond complexes of western Banks Island, Northwest Territories, and examines the impacts of this change on vegetation communities. Landsat imagery (1985-2015) was used to detect trends in surface water, moisture, and vegetation productivity, aerial imagery change detection (1958 and 2014) quantified shifts in the size and distribution of waterbodies, and field sampling investigated factors contributing to observed changes. The impact of expanding lesser snow goose populations on observed changes in surface water was investigated using the aerial imagery change detection of 2409 waterbodies and an information theoretic model selection approach, while their impact on vegetation was assessed using data from field surveys. Our analyses show that the pond complexes of western Banks Island are drying, having lost 7.9% of the surface water that existed in 1985. This loss of surface water disproportionately occurred in smaller sized waterbodies, indicating that climate is the main driver. Model selection showed that intensive occupation of lesser snow geese was associated with more extensive drying and draining of waterbodies and suggests this intensive habitat use may reduce the resilience of pond complexes to climate warming. Evidence from field surveys suggests that snow goose foraging is also contributing to patches of declining vegetation productivity within drying wetland areas. Diminishing and degrading high Arctic pond complexes are likely to alter permafrost thaw and greenhouse gas emissions, as well as the habitat quality of these ecosystems. Additional studies focused the mechanisms of surface water loss, the direct impacts of wetland drying on vegetation, and the contributions of snow geese to these processes, are necessary to better understand the changes occurring on Banks Island. / Graduate

This PhD thesis presents the spatio-temporal distribution of terrestrial carbon fluxes for the time period of 1982 to 2002 simulated by a combination of the process-based dynamic global vegetation model LPJ and a 21-year time series of global AVHRR-fPAR data (fPAR – fraction of photosynthetically active radiation). Assimilation of the satellite data into the model allows improved simulations of carbon fluxes on global as well as on regional scales. As it is based on observed data and includes agricultural regions, the model combined with satellite data produces more realistic carbon fluxes of net primary production (NPP), soil respiration, carbon released by fire and the net land-atmosphere flux than the potential vegetation model. It also produces a good fit to the interannual variability of the CO2 growth rate. Compared to the original model, the model with satellite data constraint produces generally smaller carbon fluxes than the purely climate-based stand-alone simulation of potential natural vegetation, now comparing better to literature estimates. The lower net fluxes are a result of a combination of several effects: reduction in vegetation cover, consideration of human influence and agricultural areas, an improved seasonality, changes in vegetation distribution and species composition. This study presents a way to assess terrestrial carbon fluxes and elucidates the processes contributing to interannual variability of the terrestrial carbon exchange. Process-based terrestrial modelling and satellite-observed vegetation data are successfully combined to improve estimates of vegetation carbon fluxes and stocks. As net ecosystem exchange is the most interesting and most sensitive factor in carbon cycle modelling and highly uncertain, the presented results complementary contribute to the current knowledge, supporting the understanding of the terrestrial carbon budget. / In der vorliegenden Arbeit wird anhand der Kombination eines dynamischen globalen Vegetationsmodells mit einer Zeitreihe von 21 Jahren optischer Satellitendaten eine realistische Abschätzung der terrestrischen Quellen und Senken von CO2 ermöglicht. Grundlage des hier vorgestellten neuen Modells stellt das dynamische globale Vegetationsmodell LPJ dar, ein prozessorientiertes Vegetationsmodell, das basierend auf ökophysiologischen Grundlagen die Vegetationsverteilung und -dynamik, Störungen (z.B. Feuer) und den Kohlenstoff- sowie den Wasserkreislauf modelliert. Die Kopplung des LPJ-DGVM erfolgte mit einer Zeitreihe globaler AVHRR-fPAR Daten (fPAR – Anteil photosynthetisch aktiver Strahlung), für den Zeitraum 1982 bis 2002 in einer räumlichen Auflösung von 0.5°. Als Ergebnis liegt nun eine globale raum-zeitliche Verteilung aller relevanten Kohlenstoffflüsse vor: Nettoprimärproduktion, Bodenrespiration, Nettoökosystemproduktion, durch Feuer und Ernte emittierter Kohlenstoff, sowie der in Biomasse und Boden gespeicherte Kohlenstoff. Verglichen mit dem Originalmodell haben sich durch die Einspeisung der Satellitendaten alle relevanten Kohlenstoffkomponenten verringert und zeigen nun bessere Übereinstimmung mit Literaturwerten. Die geringeren Kohlenstoffflüsse resultieren aus einer Kombination verschiedener Effekte: geringere Vegetationsbedeckung, Berücksichtigung der landwirtschaftlichen Nutzfläche, realistischere Abbildung der Saisonalität, Veränderung der Vegetationsverteilung und Verschiebung der Artenzusammensetzung. Die globalen Kohlenstoffflüsse werden mit dem vorgestellten Modell realistischer abgebildet als mit Ansätzen, die nur die potentiell natürliche Vegetation simulieren. Insbesondere die Quellen- und Senkendynamik unterliegt vielfältigen Prozessen, die mit einem Modell, dass auch die Bodenrespiration prozessorientiert berücksichtigt, verlässlich geschätzt wird.