Open Access

Die Agenda 2030 der Vereinten Nationen und diverse daraus abgeleitete Nachhaltigkeitsstrategien wie beispielsweise die Deutsche Nachhaltigkeitsstrategie (Neuauflage 2016) setzen einen zeitlich fest definierten Rahmen bis in das Jahr 2030. Für die Umsetzung dieser Strategien sind zwei Aspekte entscheidend - ein fundiertes inhaltliches Verständnis von politischer Strategie und ein darauf aufbauendes praxistaugliches Instrument, das den politischen Strategen bei einer erfolgreichen Umsetzung und Implementierung einer Strategie unterstützt. Diese Arbeit möchte zu beiden Aspekten einen Beitrag leisten. Zum einen soll aus der Zusammenführung von Theorie und Praxis die Natur des inhaltlichen politischen Strategiebegriffs erforscht werden und zum anderen soll darauf aufbauend ein praxis- und erfahrungsorientiertes Anwendungsmodell entwickelt werden, das typische potentielle Herausforderungen und entsprechende potentielle Handlungsoptionen je Strategieabschnitt benennt. Durch die Subsumierung von Erfahrungswissen unterstützt das Modell dabei vor allem das praktische Urteilsvermögen des politischen Strategen bei der Erreichung politikstrategischer Ziele. Um zu dem praxisrelevanten Anwendungsmodell zu gelangen ist es notwendig, sich zuvor Klarheit über die besonderen Anforderungen und Herausforderungen des speziellen politischen Strategiebegriffs zu verschaffen. Die politische Umwelt mit ihren spezifischen Mechanismen unterscheidet sich fundamental von den bisher bekannten Strategiefeldern Militär und Betriebswirtschaft. Da eine Strategie immer die konkrete Umweltsituation und die individuellen Situationsmerkmale berücksichtigen muss, ist - wie diese Arbeit zeigen wird - eine simple Übertragung strategischer Allgemeinplätze aus Militär und Ökonomie von vornherein zum Scheitern verurteilt.

The aim of our work was to investigate the habitat preferences of, and specific management measures for, the endangered spider species Eresus kollari Rossi 1846 and the eurytopic species Trochosa terricola Thorell 1856. For this purpose extensive field study data were collected for both spider species in the area of the nature reserve Lueneburg Heath. The ecological niches of the two spider species were also compared. The specific habitat preference of E. kollari was clarified and described in the course of the present studies. Heathland management measures that result in a thin organic layer on the ground, a high temperature at the depth of the spiders’ burrows (10 cm below ground level), and at the same time a relatively high heath cover satisfy the habitat requirements of E. kollari. Comparing the ecological niche of the stenotopic species E. kollari with that of the eurytopic species T. terricola in terms of habitat parameters demonstrated that the two species only differ in the following three factors: ‘tree cover’, ‘thickness of organic layer’ and ‘grass cover’. The reaction scheme of E. kollari appears as a subset of that of T. terricola. In this respect, E. kollari could serve not only as a characteristic species but also as an umbrella species in the Lueneburg Heath region. Against the background of the findings of the habitat modeling, management measures such as prescribed burning and choppering - carried out variably in space and time – seem to be particularly appropriate for maintaining E. kollari’s (but also T. terricola’s) microhabitat requirements in the long term. Due to the poor dispersal power of E. kollari some suitable habitats will probably not be re-colonized by the species. However, long-term monitoring as well as a recolonization experiment for this species should be carried out in the near future in areas providing suitable conditions for lasting conservation of E. kollari in this region of northwest Germany.

Algae-bacteria-based biotechnology has received more and more attention in recent years, especially in the subtropical and tropical regions, as an alternative method of conventional multistep wastewater treatment processes. Moreover, the algal biomass generated during wastewater treatment is regarded as a sustainable bioresource which could be used for producing biofuel, agricultural fertilizers or animal feeds. Although this technology is attractive, a number of obstacles need to be solved before large-scale applications. The main purposes of this work are to find more effective biomass harvesting strategies and develop high-effective algal-bacterial systems to improve wastewater treatment performance, biomass generation rate and biomass settleability. A wastewater-borne algal-bacterial culture, cultivated and trained through alternate mixing and non-mixing strategy, was used to treat pretreated municipal wastewater. After one month cultivation and training, the acclimatized algal-bacterial system showed high carbon and nutrient removal capacity and good settleability within 20 minutes of sedimentation. Algal biomass uptake was the main removal mechanism of nitrogen and phosphorus. The biomass productivity, nitrogen and phosphorus accumulation in biomass during the wastewater treatment process were investigated. The characterization of the microbial consortium composition in the enriched algal-bacterial system provided new insights in this research field. Aerobic activated sludge which already showed good settleability was used as bacterial inoculum to enhance the wastewater treatment performance and biomass settleability of algal-bacterial culture. The influence of different algae and sludge inoculum ratios on the treatment efficiency and biomass settleability was investigated. There was no significant effect of the inoculation ratios on the chemical oxygen demand (COD) removal. But algae/sludge inoculum ratio of 5 showed the best nitrogen and phosphorus removal efficiencies (91.0 ± 7.0% and 93.5 ± 2.5%, respectively) within 10 days. Furthermore, 16S rDNA gene analysis showed that the bacterial communities were varying with different algae and sludge inoculation ratios and some specific bacteria species were enriched during the operation. Four commonly used and high-potential microalgae species including one cyanobacteria (Phormidium sp.) and three green microalgae species (Chlamydomonas reinhardtii, Chlorella vulgaris and Scenedesmus rubescens) were cultivated and trained through alternate mixing and non-mixing strategy for tertiary municipal wastewater treatment. After one month of cultivation, the four microalgae species were compared in terms of biomass settleability, nutrient removal rates and biomass productivity. The three green microalgae showed good settleability within 1 h sedimentation and had higher biomass generation rates (above 6 g/m2/d). The nutrient removal efficiencies were 99% for the four selected microalgae species but within different retention time, resulting in 3.66 ± 0.17, 6.39 ± 0.20, 4.39 ± 0.06 and 4.31 ± 0.18 mg N/l/d (N removal rate) and 0.56 ± 0.07, 0.89 ± 0.05, 0.76 ± 0.09 and 0.60 ± 0.05 mg P/l/d (P removal rate) for Phormidium sp., Chlamydomonas reinhardtii, Chlorella vulgaris and Scenedesmus rubescens, respectively. A mixed algal culture composed of three selected high-effective green microalgae (Chlamydomonas reinhardtii, Chlorella vulgaris and Scenedesmus rubescens) was used for tertiary municipal wastewater treatment. The key biotic factor (algal inoculum concentration) and abiotic factors such as illumination cycle, mixing velocity and nutrient strength were studied. Based on the nitrogen and phosphorus balance, it was found that assimilation into algal biomass was the main removal mechanism.

Human activities have converted natural ecosystems worldwide, mostly for agricultural purposes. This change in land use has been recognized as one of the key drivers causing mass extinction of biodiversity. Yet, there are species which persist particularly in traditional, low-intensity agricultural areas. However, this farmland biodiversity is increasingly threatened by the consequences of land-use intensification and land abandonment. One effect of these two processes is the change in existing landscape structures. This dissertation aimed at quantifying the relationship between biodiversity and landscape structures because a better understanding of current biodiversity patterns and their drivers is needed to navigate biodiversity conservation for a sustainable development. Specifically, this dissertation anticipates the impacts of land-use change on biodiversity in Southern Transylvania, focusing on butterflies and plants as study groups. In a first step, a methodological baseline for subsequent biodiversity studies is developed by exploring an optimal survey strategy, allocating the available resources in a study design that enables high statistical power and covers a wide range of environmental conditions. This study shows that in the highly heterogeneous farmland mosaic of Southern Transylvania, survey effort can be moderately reduced while still showing similar patterns of species richness, species turnover and species composition (Chapter 2). In a second step, biodiversity patterns of plants and butterflies are empirically investigated in response to different landscape structures, particularly towards heterogeneity and woody vegetation cover. These studies provide evidence that all main land-use types in Southern Transylvania, namely arable land, grassland and forests, contribute to an overall landscape pool. Species richness of plants, but not of butterflies, differed significantly between arable land and grassland. Presence of woody vegetation in farmland had a positive effect on plant species richness. Heterogeneity has been found beneficial for butterfly species richness in arable land, but not in grasslands. Species composition of plants was determined by land-use, but butterfly species composition was widely overlapping in arable land and grassland (Chapters 3 & 4). Investigations on the potential spread of invasive plant species in the Transylvanian landscape exhibited that distance to roads and heterogeneity, especially in arable land, were key variables determining the invasibility of the landscape (Chapter 5). By studying movement patterns of butterflies in agricultural landscapes, land-use intensity could be revealed having an impact on butterfly movements. Furthermore, butterflies were found to prefer non-arable patches within farmland (Chapter 6). In a third step, this dissertation conceptually embeds socio-economic considerations into the local and international discourse on sustainable rural development: Reflections on a participatory projects on establishing butterfly monitoring in Romania conclude that involving citizens in biodiversity conservation is possible in Romania, but need tailored approaches which consider the unique social and cultural settings (Chapter 7). Current recommendations from scientific literature to increase the agricultural yield, for example in Eastern European landscapes, through ´sustainable intensification´ for global food security are scrutinized for their engagement with sustainability. This dissertation concludes that genuine sustainable solutions need to respect the various aspects of sustainability, including procedural and distributive justice. Furthermore, it is clarified that general recommendations for agricultural intensification, for instance in Romania, may lead to devastating impacts on biodiversity and ecosystem functions (Chapter 8). This dissertation provides evidence that the beneficial characteristics of the Translvanian farmland are linked to the fine spatial scale of the agricultural mosaic, the amount and distribution of semi-natural elements and the scattered woody vegetation throughout the landscape. Hence, the future of biodiversity depends on human interventions in the ancient cultural landscape. Navigating biodiversity conservation in Southern Transylvania thus needs genuine sustainable solutions, which integrate socially acceptable and ecological meaningful landscape management.

Die Verringerung des Material- und Ressourcenverbrauchs ist eine wesentliche Herausforderung nachhaltiger Entwicklung. Bislang standen und stehen politische Maßnahmen zur Energieeffizienz im Vordergrund. Maßnahmen zur Verbesserung der Materialeffizienz gewinnen jedoch verstärkt an Bedeutung. Der Erfolg oder Misserfolg politischer Instrumente im Umwelt- und Klimaschutzbereich wird maßgeblich davon abhängen, ob die Instrumente die Fähigkeit besitzen, eine Entkoppelung von Lebensqualität und Ressourcenverbrauch zu erzeugen. Insbesondere im Rahmen der Ökodesign-Richtlinie, aber auch anderer Instrumente der Europäischen Union, sind Ansatzpunkte zur politischen Gestaltung einer ressourcenleichten Langfristökonomie angelegt. Die Dissertation wird schwerpunktmäßig die Governance-Instrumente im Produktbereich der Europäischen Union behandeln. Die Dissertation folgt der Theorie, dass die Produkte der Industriegesellschaft einzeln mehr oder weniger harmlos, in ihrer Menge jedoch die Quelle fast aller Umweltprobleme sind. Zur Erstellung der Dissertation sieht das spezifische Methodendesign die Anwendung eines Kriterienkatalogs zur Bewertung der Steuerungsinstrumente für Langfristökonomie im Produktbereich vor. Darüber hinaus werden die Hauptakteure in Form von Interviews befragt.

Responsibility for sustainability is an action guiding concept which relates the abstract norm of sustainability with concrete action contexts. It thereby specifies what bearers of responsibility ought to do. In this thesis, I introduce the concept of responsibility to economic theory, focusing specifically on individual and governmental responsibility for sustainability. Some of the questions I examine are: how should responsibility be distributed among agents? How can agents, who are responsible for several normative aims, solve trade-offs? Do governmental policies affect individuals’ ability to assume responsibility? How can individuals efficiently induce governments to act responsibly? In Paper 1, A utilitarian notion of responsibility for sustainability, I conceptualize and formalize a utilitarian notion of responsibility for sustainability which I then relate to established normative criteria for assessing intertemporal societal choice. I show that responsibility for sustainability can be unambiguously conceptualized in economic models. Furthermore, I affirm that responsibility may provide action guidance even if the aim of sustainability is not feasible. In Paper 2, Verantwortung von Konsumenten für Nachhaltigkeit, I study consumers’ responsibility for sustainability. Particularly, I specify crucial components of this responsibility in order to analyze the relation of consumers’ private and political responsibility. I show that the responsibility for sustainability of consumers comprises three indispensable obligations of which only one concerns consumers’ consumption choices. In Paper 3, Regulation of morally responsible agents with motivation crowding, I focus on the impact of governmental policies on the motivation of an individual to assume moral responsibility. In particular, I study the regulation of a morally responsible individual with motivation crowding in the context of a negative externality. I show that combining consumption taxes with the provision of perfect information is, in many cases, superior to consumption taxes alone. In Paper 4, Endogenous Environmental Policy when Pollution is Transboundary, I examine how individuals which form lobby groups affect the determination of environmental policy when governments seek not only to maximize welfare, but simultaneous maximize support by lobby groups. More specifically, I consider the case in which two countries are linked through transboundary pollution. Environmental policies adopted by self-interested governments may be more stringent than by social welfare maximizing governments. Furthermore, due to the interaction of distortions the space of optimal policies increases: politically optimal tax rates may be too high or too low to optimally internalize the environmental externality.

Traditional farming landscapes have been created in coexistence of rural dwellers and local ecosystems over long time spans, and can be considered tightly coupled ´social-ecological systems´ (SES). Since these landscapes typically embody exceptionally high levels of biological diversity and multiple socio-cultural values, their protection is critical from a sustainability perspective. Due to the pressures of globalization and social change, however, rural livelihoods and farmland biodiversity are at risk. While the focus of research is often on the Southern hemisphere, there are traditional farming landscapes in the former socialist countries of Central and Eastern Europe (CEE) which are equally affected by rapid change, and thus deserve particular attention. Since the institutional breakdown of socialism in 1989, the CEE states have not only been confronted with an unprecedented socio-economic and environmental transition. Their integration into the multi-level governance regime of the European Union (EU) further resulted in the transformation of decision-making structures and competition within the EU common market. In light of the profound changes traditional farming landscapes of Central and Eastern Europe are confronted with, they serve as a valuable source of learning about the institutional design necessary to harmonize socio-economic development and biodiversity conservation within regional social-ecological systems worldwide. This thesis is the result of an in-depth analysis of one traditional farming landscape of Central and Eastern Europe, namely Southern Transylvania (Romania). Based on empirical research involving diverse stakeholder groups, this thesis assessed the impact of EU policy on the area, the institutional features characterizing local-level governance in Southern Transylvania, and the barriers and bridges towards sustainable rural development. This thesis finds that while rural dwellers are highly dependent on smallholder farming and local ecosystems for their livelihoods, Southern Transylvania is currently confronted with a range of structural development barriers. These are likely to be exacerbated by a governance system consisting of historically grounded ´elite social networks´, and by EU policies which often do not fit rural realities. The findings of this dissertation underline that entrenched informal institutions, political will, and historical legacies play a critical role for the governance of traditional social-ecological systems since these ´social system features´ do not only mediate how external policies act on the local level. They may further restrict local adaptive and innovation capacities which, however, are critical for the transformation towards sustainable development. This thesis further finds that there are no blueprint solutions for the design of rural development strategies. Instead, (supra-) national policies should take better account of local socio-economic and cultural particularities.