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The smallholder-dominated landscapes of southwestern Ethiopia support a unique biodiversity with great importance to local livelihoods and high global conservation value. These landscapes, however, are severely threatened by deforestation, forest degradation and the adverse effects of farmland management regimes. These changes have fundamentally altered the structure of the landscapes and threaten their biodiversity and ecosystem services. Managing biodiversity and related services in such rapidly changing landscapes requires a thorough understanding of the effects of land use change and the reliance of local communities on biodiversity. This dissertation examines woody plant biodiversity patterns and services and presents several recommendations regarding biodiversity and multiple ecosystem services in smallholder-dominated landscapes of southwestern Ethiopia. Using a social-ecological systems approach, I conducted four studies on the complex interactions of local people and woody plant diversity. First, I investigated the effects of human-induced forest degradation on woody plant species. My results suggest that forest biodiversity has been affected by the combined effects of coffee management intensity, landscape context and history at the local and landscape level. Specifically, richness of forest specialist species significantly has decreased with coffee management intensity and in secondary compared to old growth forests, but increased with current distance from forest edge in both primary and secondary forests. These findings highlight the need to maintain undisturbed forest sites to conserve forest biodiversity. Second, I examined legacy effects of past agricultural land use on woody plant biodiversity. My results show that historical distance seems to be the most important variable affecting woody plant composition and distribution in farmland sections of the landscapes. I found evidence for immigration credits for generalist and pioneer species but not for extinction debts for forest specialist species which might be rapidly paid off in farmland. The results suggest not only an unrecognized conservation value of old farmland but also a disturbing loss of forest specialist species. To slow this trend, it is necessary to shift to a cultural landscape development approach and to restore forest specialist species in the landscapes. Third, I evaluated the supply of potential multiple ecosystem services and the relationships between the diversity of woody plant and ecosystem service in the three major land use types, namely forests with and without coffee management and farmland. The results revealed a high multifunctionality of landscapes and showed that ecosystem services significantly increase with woody plant diversity in all types of land use. These findings suggest that the woody plant diversity and multifunctionality in southwestern Ethiopian landscapes has to be maintained. Fourth, I explored farmers’ woody plant use to assess their dependency on and maintenance of woody plants and also considered the influence of property rights and management in this context. I found that local farmers used 95 species for eleven major purposes from all major land uses across the landscapes. I also found that most of the widely used tree species regenerated successfully throughout the landscapes, including in farmland. Local people felt, however, that their property and tree use rights were limited, especially in forests, and that some of the most widely used plant species, including important timber species, appeared to have been overharvested in forests. The results suggest that many species are important for local livelihoods, but a perceived low sense of property rights also seems to adversely affect the management of woody plants, particularly in forests. By focusing on woody plants and their ecosystem services to local people, this dissertation documents a dramatic loss of native forest biodiversity and rapid changes in the cultural landscapes of southwestern Ethiopia. This study also reveals low levels of perceived property and tree use rights by local people, particularly when it comes to forests, and the present overharvesting of important tree species in forests in particular. This dissertation also highlights current value of the multifunctionality of the landscapes examined here, the increase in ecosystem services diversity with increasing woody plant biodiversity and the importance of woody plant species for local livelihoods. Overall, my findings suggest the need for preservation of intact forest sites and for cultural landscapes development to safeguard biodiversity and multifunctionality of the landscapes in the future. This, in turn, requires holistic and integrated approaches that involve local people and recognize their basic needs of woody plants and their property rights to foster the management of biodiversity and ecosystem services. Maintaining primary forests in and using cultural landscape approaches to the rapidly changing rural setting of southwestern Ethiopia would also contribute to the global effort to halt biodiversity loss.
Vocational integration of refugees : chances and challenges of refugee (social) entrepreneurship
(2019)
In recent years, especially since 2015, Germany and other European countries have accepted high numbers of refugees. The social and vocational integration of these refugees and of those yet to come represents a challenge. (Social) entrepreneurship is one means to achieve this goal, to fully tap into the potential of refugees and to give them a chance to make a living in host countries. This dissertation examines the potential of vocational integration of refugees through (social) entrepreneurial activities. It includes a detailed literature review and suggests possible direction in the emerging field of refugee (social) entrepreneurship. This dissertation shows that to foster refugee (social) entrepreneurship, the identification and evaluation of specific and potential needs for support is essential. Incubators in particular have a high potential for supporting refugee entrepreneurs, in part it is possible for them to address some of the challenges faced by this target group, which differ from those of locals or migrant entrepreneurs. More specifically, this dissertation aims to answer two research questions: (1) What are relevant (social) entrepreneurial concepts that can contribute to the vocational integration of refugees? (2) What are the distinct contributions of and challenges faced by refugees when it comes to their vocational integration through (social) entrepreneurial activities? Analyzing select practical cases, this dissertation has several important implications for researchers who seek to bridge the gap between academia and society in the context of refugee entrepreneurship and refugee social entrepreneurship research. The findings presented here are also relevant for practitioners, for example those working at business incubators, who aim to facilitate the vocational and social integration of refugees in general and refugees with entrepreneurial aspirations in particular.
We are in a phase of an alarming biodiversity loss, by scientist already referred to as Earth’s sixth mass extinction. According to estimations, the current extinction rates are 100 to 1000 times higher than those predicted from fossil records. To counteract species loss and preserve the remaining biodiversity, with its important ecosystem functioning and services essential to human well-being, there is an urgent need to develop promising and long-term conservation strategies. In order to achieve these goals, extensive research to gain a better understanding of the general mechanisms underlying community diversity is of greatest importance. Especially, the identification of intrinsic ecological and distributional species traits is receiving increased attention in ecology and conservation biology research. Depending on the expression of their traits, species perform particular ecosystem functions and respond in a specific manner to environmental conditions. The identification of the effect of certain traits on community compositions can therefore significantly improve our understanding of species extinction processes and help to develop valuable and appropriate recommendations for conservation management. As trait-based analyses are applicable to different geographical, temporal and taxonomical scales, they may even allow for a broader generalization if similar results are found on different scales, i.e. for local species pools, the complete species pools of different habitat types or the entire species pool across several habitat types including different climatic regions. Although insects make up the largest part of animal diversity and provide essential ecosystem services in form of e.g. pollination, pest control, and decomposition, the majority of studies on extinctions have mainly focused on vertebrates. Among invertebrates either charismatic taxa or those targeted by conservation laws have been investigated until now (e.g. butterflies or saproxylic beetles). Being highly species-rich and trait-diverse, ground beetles (Coleoptera: Carabidae) should be even more suitable for conducting trait-based analyses. Thus, using ground beetles as a model taxon, four case studies focusing on the analyses of traits form the basis of this doctoral thesis. The work of this thesis was conducted with the aim of gaining general insights on the influence of species traits on ground beetle community compositions, such as habitat occupancy and species vulnerability to extinction, for instance. An important aspect when investigating species traits is the consideration of confounding factors which could influence the results, such as dependent relations between the different traits. Compiling a large dataset of 566 Central European species, I identified that dependent relations between the six tested traits of ground beetles (distribution range size, habitat specialization, body size, hind-wing morphology, breeding season and trophic level) are highly common. Across all identified dependent trait relations, the relation between body size and hind wing morphology or range size and hind wing morphology showed the strongest significant dependencies. Since the consideration of trait relations is necessary to provide reliable interpretations, all analyses of this thesis tested several traits simultaneously and considered possible trait interactions. Studies on local communities found specific traits characterizing the local species pools of certain habitat types. Here, the species pools of seven different habitat types (coastal, forest, mountain, open, riparian, wetland and special habitat) were used to determine habitat-specific trait filters. The identified traits, characteristic for certain habitat types, were in most cases in accordance with the previous findings on local communities. Across Germany, the species of frequently disturbed habitat types, namely coastal, riparian and wetland habitats were characterized by small body size, high amount of macroptery, intermediate to high habitat specialization, spring breeding, and predatory feeding behavior. The species of stable habitat types (forest, mountain, and open habitats), however, were found to be generally larger in body size and more frequently breeding in autumn, further displaying greater variations in the other traits. The gained knowledge on the habitat-specific filtering of traits improve our understanding of the organization and assembly of communities, and can thereby help to detect alterations in the habitat-specific species pool due to natural or human-induced environmental changes. Furthermore, traits can provide evidence on species occurrences and vulnerability to extinction. Three case studies of this thesis aimed to gain new insights on this topic, through the investigations on the following research questions; I. Which traits drive species extinction risks of Central European ground beetle species, II. How traits influence the species occurrences of 28 forest species within a large area in Central Europe, and III. Whether certain traits are related to long-term population trends of the species pool from an ancient forest in northern Germany. The results indicated, that depending on the habitat type and tested species pool, different traits prove to be good predictors for the vulnerability of species. Nevertheless, across different geographical and taxonomical scales, especially species with small range sizes and high habitat specialization faced a greater risk of extinction. Therefore, the two traits distributional range size and habitat specialization emerge as reliable predictors of ground beetles vulnerability to extinction. Interestingly, body size did not display a consistent response; while increasing body size led to higher extinction risk in riparian, wetland and open habitats and large macropterous species showed higher extinction risks across the entire species pool, smaller species showed long-term population declines in an ancient forest. To summarize, this thesis presents a comprehensive picture of ground beetle species traits, providing valuable insights and a better understanding of the mechanisms driving changes in ground beetle diversity. On the basis of the results presented in this work, the efficiency of biodiversity protection can be increased by developing appropriate management and recovery plans, especially targeting species of threatened habitat types or ‘functional groups’ of species, exhibiting trait values strongly associated with a greater vulnerability to extinction.
Achieving the ‘Great Transformation’ demands a closer consideration of the material basis of technologies, whose broad-scale implementation is often associated with efficiency improvements and progress towards a post-fossil society, but which is largely disregarded as of today. At the same time, the discourse on resource-related issues only rarely evolves around achieving an actual fundamental shift towards sustainability in the sense of a ‘material transition’. The notion of this mutual disconnect – a ‘transformation-material gap’ that exists in both research and practice – is the main driver for this dissertation. Metals fulfill crucial functions in areas as diverse as renewable energy, digitization and life style appliances such as smart home concepts, mobility, communication, or medicine. In the context of sustainability, achieving a more sustainable metal use means (i) minimizing the adverse effects associated with metal production and use and (ii) sustaining the availability of metals in a way that benefits present and future generations. Urgent need to act to avoid bottlenecks as well as meeting the challenge of possible conflicts of use among those areas of application calls for appropriate strategy making to intervene in the complex field of metal production and use that involves various, often interlinked operating levels, actors, and spatial and temporal scales. Located within the field of sustainability science, this dissertation focuses on strategies as a means to intervene in a system. It pursues the question, which design features could guide future strategy making to foster sustainability along the whole metal life cycle, and especially, how a better understanding of temporalities – i.e. understanding time in a diverse sense – could improve strategy design and help to bridge the assumed ‘transformation-material gap’. My research converges the results from four research studies. A conceptual part explores the role of temporalities for interventions in complex and interlinked systems, which adds to the conceptual basis, on which the empirical part builds up to explore present and future interventions in metal production and use. The research revealed three essential needs that future strategies must tackle: (i) managing the complex interlinkages of processes and activities on various operational levels and spatial and temporal scales, (ii) providing clear guidance concerning the operationalization of sustainability principles, and (iii) keeping activities within the planet’s carrying capacity and embracing constant change as an inherent system characteristic. In response to these needs, I developed three guidelines with two design features each (one relating to content, and one to the process of formulating and implementing the strategy) to guide future strategy making: 1. Design strategies based on a profound understanding of the system and its interrelations, but bear in mind context-specific characteristics. (Comprehensive, but tailored.) 2. Design strategies to achieve fundamental change in a cooperative and inclusive manner. (Ambitious, but manageable.) 3. Design strategies to strengthen resilience in a constantly changing environment. (Dynamic, but consistent.) My results show that TIME MATTERS in this respect. If considered in close relation to space and diversely understood in the sense of temporalities, it serves to (i) understand the impact (duration and magnitude) of an intervention, (ii) recognize patterns of change that go beyond establishing linear, one-dimensional connections, and (iii) design interventions in a way that considers the resilience of a system. While these findings can contribute to closer considering our understanding of transformation processes towards sustainability in future interventions in metal production and use, more research is needed on approaches that bring the material basis into closer consideration of transformation processes in research and practice.
Die schlechte Qualität von Binnengewässern ist ein weit verbreitetes und herausforderndes Problem für die Menschheit. Das Konzept der Komplexität ist ein besonders vielversprechendes Konzept zur Analyse und Lösung dieses Problems und von Problemen der öffentlichen Ordnung im Allgemeinen. Der Hauptgrund ist die Stärke des Konzepts, strukturelle Problemmerkmale innerhalb eines umfassenderen strukturellen Ansatzes für die politische Problemlösung zusammenzufassen. Bislang blieben diese möglichen Vorteile jedoch verborgen, da kein klares Verständnis der Komplexität vorhanden war, was letztendlich eine systematische Analyse der Auswirkungen der Komplexität auf Lösungen und Governance-Strategien behinderte. Diese Studie zielt darauf ab, den Wert des Komplexitätsbegriffs für systematische vergleichende Analysen von Wasserproblemen und von Problemen der öffentlichen Politik im Allgemeinen zu stärken. Um dieses Ziel zu erreichen, werden in dieser Arbeit das Konzept der Komplexität sowie die Implikationen der Komplexität für Lösungen und Governance-Strategien sowohl aus theoretischer als auch aus empirischer Sicht spezifiziert. Zu diesem Zweck werden fünf grundsätzliche Ansätze angewandt, die sich auf die zugrunde liegenden Prämissen, die Rolle eines interdisziplinären Ansatzes, die Europäische Wasserrahmenrichtlinie als empirischen Bezugspunkt, die Integration von praktischem Wissen und den Fokus auf externe Validität beziehen. Hauptergebnisse sind: Operationalisierung und Messung: Diese Dissertation bietet eine detaillierte Operationalisierung der Komplexität in Bezug auf die Dimensionen der Ziele, Variablen, Dynamiken, Vernetzungen und Informationsunsicherheiten. Sie zeigt zudem, dass sich Wasserqualitätsprobleme in Deutschland entlang dieser fünf Komplexitätsdimensionen unterscheiden. Dies gilt für 37 Typen von Wasserqualitätsproblemen und vier Problemcluster, die sich hier auf ´zahme´, ´bösartige´, ´sysytemkomplexe´ und ´mit Unsicherheit behaftete´ Probleme beziehen. Implikationen von Komplexität für Lösungen: Diese Dissertation legt nahe, dass die Beziehungen zwischen Komplexität und Politikumsetzung sowohl positiv als auch negativ sein können und je nach Dimension der Komplexität und Politikumsetzung variieren können. In Bezug auf die untersuchten Wasserqualitätsprobleme zeigt diese Arbeit zudem verschiedene Auswirkungen der Komplexität auf die Politikumsetzung auf, sowohl bei den 37 Problemtypen als auch bei den vier Problemclustern. Implikationen von Komplexität für die Governance: Diese Dissertation schlägt einen differenzierten theoretischen Ansatz vor, um Governance-Strategien für komplexe Problemlösungen zu definieren. Dabei wird gezeigt, dass die Rolle verschiedener Institutionen, Akteure und Interaktionen für Lösungen entlang der fünf Schlüsseldimensionen der Komplexität (Ziele Variablen, Dynamiken, Vernetzungen und Informationsunsicherheiten) sowie entlang verschiedener Managementstrategien (Informationsgenerierung, Modellierung, Verwendung von Entscheidungsunterstützungs-instrumenten, Priorisierung von Maßnahmen, Konfliktlösung, Entscheidung unter Unsicherheit und Anpassungsfähigkeit und Flexibilität) variieren. Zukünftiger Forschung wird empfohlen, auf diesen Ergebnissen aufzubauen, indem weitere empirische Nachweise geliefert werden und der Governance-Ansatz für komplexe Problemlösungen weiter kontextualisiert wird. Auf diesem Weg kann dazu beigetragen werden, die ´Logik des Scheiterns´ (Dörner 1996) in Bezug auf komplexe Problemlösungen in eine ´Erfolgslogik´ umzuwandeln, um Probleme unterschiedlicher Komplexität im Wasserressourcenmanagement und bei Problemen öffentlicher Ordnung anzugehen.
This doctoral thesis examines how Sustainability-Oriented Innovations (SOIs) are emerging at small and medium-sized enterprises (SMEs) and how they can be managed. SOIs in the form of new products that lessen negative environmental impact, or even create a positive impact can play an important role, particularly at established SMEs who see business opportunities in sustainable development and consider a possible diversification into new sustainability markets. Whereas the extant literature discusses what SOIs are and why firms develop them, little is known about how they are developed. To enable firms to innovate for sustainability, it is essential to know more about the processes underlying SOI development, which are considered as very difficult, with many firms failing. Drawing on several academic papers and relying on qualitative research methods, the thesis uses the Fireworks model to examine how innovation processes unfold at established SMEs. The main contribution of the thesis is to advance the Fireworks model to the context of SOIs unfolding at SMEs. The findings reveal that SOIs unfold in an emergent, somewhat chaotic way, that duration and outcome are uncertain, that the overall journey is composed of multiple intertwined innovation paths, of which several will likely lead to setbacks. To manage this complex process, the thesis suggests to set four management foci: first, to create a dedicated organizational unit for exploration, second to create conditions allowing intelligent learning for efficient exploration, third to carry out in-depth investigation of the related technological innovation systems, and fourth to plan carefully the re-integration of the innovation into the core business for commercialization. This research contributes to the SOI literature by advancing the Fireworks model and thereby proposing a meta-model of how SOIs may dynamically unfold. Being both holistic and detailed, the model opens several avenues for future research. Finally, the research contributes to management practice by providing a heuristic to manage SOI development at SMEs.
This thesis deals with the influence of sustainability communication on the purchase decision of sustainable tourism products involving German specialist tour operators. Sustainability communication is a challenge, because sustainable tourism is an abstract and vague concept which consumers find it difficult to grasp and about which they are sceptical, and the service characteristics of tourism products complicate the decision making stage, which is a high-involvement situation of uncertainty to which sustainable product attributes add complexity. As an introduction, an interdisciplinary theory discussion reveals knowledge gaps in terms of the value-belief-norm theory and the elaboration likelihood model (ELM). The first article, which is the first systematic literature review on the topic, reveals that there is a limited theoretical understanding of sustainability communication, a lack of practical understanding of how to design sustainability messages, and an inadequate set of methodologies for its research. It identifies knowledge gaps concerning: the holistic approach to sustainability communication; its role in the attitude-behaviour gap; an interdisciplinary theoretical understanding focusing on belief-based social psychological theories and theories of persuasion; qualitative methods; and experimental design. The second article investigates the role of sustainability communication in the attitude-behaviour gap, employing the value-belief-norm theory to explain how information is processed by special interest customers. Interview findings show that ineffective sustainability communication is the reason for the gap and that customers unintentionally booked sustainably. The study identifies eight groups of beliefs which explain the processing of sustainability attributes. Sustainability information is effective when it is value-congruent, that is, when customers perceive they can make a difference, they begin to ascribe a responsibility to themselves. The third article investigates how to design an effective sustainability message in tour operator advertising. Drawing on the ELM, the study shows that appeal type does not significantly influence persuasion but the topic presented is important. Cultural sustainability is the sustainability topic that is most persuasive for cultural tourists, while consumer prior knowledge and issue-involvement with the topic promote successful information processing. The thesis has contributed to a target-group specific understanding of effective sustainability product communication and contributes to knowledge in terms of theory, methodology, and practical solutions.
Forest ecosystems significantly contribute to global carbon (C) sequestration and therefore play a crucial role for climate change mitigation. At the same time, forests were and are subjected to past and current environmental changes with consequences for the functioning of forest ecosystems and their associated ecosystem services. Forests in Central Europe are highly influenced by former settlement activities and land-use changes, as well as silvicultural management measures. Until the beginning of the 19th century anthropogenic activities caused a tremendous decline of the forest area. The resulting timber shortage led to large scale afforestations on previously agriculturally used land (e.g. heathlands, grasslands and croplands) during the 19th and 20th century. Widespread afforestation programs created recent forest ecosystems (i.e. young forest systems in terms of their development history). Despite the positive effect of increasing the forest area of Central Europe, the ecological effects of these land-use changes on forest ecosystems remain poorly understood. In addition, most forests in Central Europe are under silvicultural management, while the knowledge about the consequences of management measures on forest ecosystem functioning, particularly in the face of ongoing global environmental changes, is also still limited. In order to increase the understanding of ecosystem processes in forests, an assessment of conceivable shifts in ecosystem functions caused by former land-use changes and forest management is required. By analysing aboveground growth rates of European beech (Fagus sylvatica L.) in response to environmental change drivers, such as climate extremes and nitrogen (N) deposition, the presented thesis aims to assess the role of land-use and management legacies in modulating present responses to drivers of environmental change. To this end, annual radial growth rates of individual trees were measured in mature beech stands. The investigated stands differed either in their land-use history (i.e. ancient forest sites with a forest continuity > 230 years versus recent forests afforested on former arable land ~ 100 years ago) or their forest management history (i.e. managed forest sites versus short-term and long-term unmanaged forest sites). Measurements of radial growth rates were complemented by analyses of the fine root systems, soil chemical properties and crown projection areas to gain insights into the mechanisms underlying alterations in tree growth. Within the projects of the presented thesis, shifts in the climate-growth relationships driven by land-use and management legacies were analysed. In addition, land-use legacy mediated differences in the climate-nitrogen-growth relationships were assessed. The key findings are: (I) Soil legacy driven alterations in the fine root systems cause a higher sensitivity of radial increment rates to water deficits in summer for trees growing on recent forest sites than for trees growing on ancient forest sites. (II) Management legacies (in terms of tree release) enhance the sensitivity of beech’s radial growth to water deficits in spring through changes in crown sizes. (III) Interacting effects of spring water deficits and co-occurring high deposition of reactive N compounds lead to stronger radial growth declines in trees growing in ancient forests. This is likely caused by resource allocation processes towards seed production, which is, in turn, mirrored by decreasing radial growth rates. In this context, high N deposition likely boosts mass fructification in beech trees. Overall, it has been demonstrated that the ecological continuity plays a crucial role in modulating both climate sensitivity and the growth response to interacting effects of water deficits and nitrogen deposition in beech trees. The presented thesis identified a trade-off between the climate sensitivity and maximised growth rates within beech trees, depending on forest history. The results show that the growth of beech in ancient, unmanaged beech forests is less sensitive to water deficits than in recent and managed beech forests. Additionally, interacting effects of spring water deficits and N deposition likely increase the reproductive effort of beech trees, particularly in ancient forests. Thus, the results of this thesis once again underpin the uniqueness of ancient, unmanaged beech forests, whose importance for the conservation of biodiversity has been widely acknowledged. In summary, the presented thesis highlights the need to consider the ‘ecological memory’ of forest ecosystems when predicting responses to current and future environmental changes.
This cumulative thesis extends the econometric literature on testing for cointegration in nonstationary panel data with cross-sectional dependence. Its self-contained chapters consist of two publications and two publication manuscripts which present three new panel tests for the cointegrating rank and an empirical study of the exchange rate pass-through to import prices in Europe. The first chapter introduces a new cointegrating rank test for panel data where the dependence is assumed to be driven by unobserved common factors. The common factors are first estimated and subtracted from the observations. Then an existing likelihood-ratio panel cointegration test is applied to the defactored data. The distribution of the test statistic, computed from defactored data, is shown to be asymptotically equivalent to that of a test statistic computed from cross-sectionally independent data. The second chapter proposes a new panel cointegrating rank test based on a multiple testing procedure, which is robust to positive dependence between the individual units’ test statistics. The assumption of a certain type of positive dependence is shown by simulations not to be violated in panels with dependence structures commonly assumed in practice. The new test is applied to find empirical support of the monetary exchange rate model in a panel of eight OECD countries. The third chapter puts forward a new panel cointegration test allowing for both cross-sectional dependence and structural breaks. It employs known individual likelihood-ratio test statistics accounting for breaks in the deterministic trend and combines their p-values by a novel modification of the Inverse Normal method. The average correlation between the probits is inferred from the average cross-sectional correlation between the residuals of the individual VAR models in first differences. The fourth chapter studies the exchange rate pass-through to import prices in a panel of nineteen European countries through the prism of panel cointegration. Empirical evidence supporting a theoretical long-run equilibrium relationship between the model’s variables is found by the newly proposed panel cointegration tests. Two different panel regression models, which take both cointegration and cross-sectional dependence into account, provide most recent estimates of the exchange rate pass-through elasticities.
This cumulative dissertation deals with the association between corporate governance, corporate finance and corporate tax avoidance in four scientific articles. The aim of this dissertation is to explain corporate tax avoidance by (a) focusing on corporate governance institutions as determinants of tax avoidance and (b) focusing on financial consequences of tax avoidance. Due to the close association between corporate governance and the concept of corporate social responsibility (CSR), the relationship between CSR and tax avoidance is also addressed. The first article with the title „The impact of corporate governance on corporate tax avoidance – A literature review“, using structured literature review methodology, analyzes extant research on the association between corporate governance and tax avoidance based on stakeholder-agency theory. However, also classical principal-agent theory is taken into account as its classical foundation. The first article identifies a number of open research questions and thereby serves as a theoretical basis for the subsequent articles. The second article with the title „CSR and tax avoidance: A review of empirical research“, also using structured literature review methodology, analyzes extant research on the association between CSR and tax avoidance. This article is also based on stakeholder-agency theory and identifies open research questions. The third article with the title „Tax Avoidance in Family Firms: Evidence from Large Private Firms“, based on results of the first article, investigates tax avoidance by German private family firms as a specific variant of corporate governance, using an empirical quantitative approach. The article finds that (a) German private family firms avoid more tax than non-family firms, that (b) tax avoidance is positively associated with the capital stake of the family and that (c) tax avoidance is positively associated with the number of shareholders in both family and non-family firms. Results reinforce that corporate tax avoidance is associated to conflicts among the shareholders of private firms. The fourth article with the title „Tax avoidance, tax risk and the cost of debt in a bank-dominated economy“ investigates the cost of debt of German public firms as a function of tax avoidance and tax risk. The article finds that (a) tax avoidance is negatively associated to the cost of debt, that (b) tax risk is positively associated to the cost of debt and that (c) the association between tax avoidance and the cost of debt becomes negative when a high level of tax risk is present.