Projektionen der Effekte von Umweltveränderungen auf sozio-ökologische Systeme sind ein fester Bestandteil der Nachhaltigkeitsforschung. Solche Projektionen beruhen auf Modellen und Modellketten. In jedem Modellierungsschritt werden modelspezifische Unsicherheiten bezüglich Parameterwerten, Eingabedaten und Modelstruktur akkumuliert und führen zu einer Kaskade der Unsicherheiten. Ziel dieser Dissertation ist es, die Kaskade der Unsicherheiten der Wirkungen von Umweltveränderungen am Beispiel der Waldökosystemmodellierung zu behandeln. Dies führt zu zwei übergreifenden Forschungsfragen: 1. Wie beeinflussen unterschiedliche Typen von Unsicherheiten die Projektionen der Wirkungen sich verändernder Umweltbedingungen auf Waldökosysteme? 2. Gibt es einen übergeordneten Rahmen für nachhaltiges Ressourcenmanagement in sozio-ökologischen Systemen, in den Unsicherheiten eingebettet werden können? Diese Dissertation zeigt, dass die Produktivität von Wäldern unter Bedingungen des Klimawandels in kühleren und feuchteren Regionen zunehmen und in wärmeren und trockeneren abnehmen kann. Diese Ergebnisse sind qualitativ konsistent über eine Vielzahl von Modellstrukturen, Klimaszenarien und Modelparameter, die jedoch quantitativ zu nennenswerten Unsicherheiten in Projektionen führen. Diese Arbeit zeigt, dass es Methoden gibt, um bestimmte Unsicherheiten einzuschätzen, aber auch, dass viele Klimawirkungsstudien die Wirkung von Veränderungen im Mittelwert von Klimavariablen betrachten und nicht die von Extremwerten. Außerdem zeigt diese Arbeit, dass adaptive, sektorenübergreifende Strategien für ein nachhaltiges Ressourcenmanagement existieren, die mit Unsicherheiten von Klimawirkungen umgehen können und nachhaltige, regionale Entwicklungen fördern. Die Kaskade der Unsicherheiten ist eine zentrale Herausforderung für nachhaltiges Ressourcenmanagement. Eine systematischere Behandlung von Unsicherheiten ermöglicht robuste Projektionen der Wirkungen sich verändernder Umweltbedingungen. / Projecting the effects of environmental change on social-ecological systems is a crucial component of sustainability science. Such projections rely on models and modeling chains. At each modeling step, model-specific uncertainties about parameter values, input data or structure accumulate and lead to a cascade of uncertainty. The aim of this thesis is to explore the cascade of uncertainties in responses to environmental change in a structured way at the example of forest ecosystem modeling. This leads to two overarching research questions: 1. How do different types of uncertainties affect projections of the effects of environmental change on forest ecosystems? 2. What is the general framework of sustainable natural resource management in coupled social-ecological systems in which uncertainties need to be integrated? This thesis shows that forest productivity under climate change may increase in cool and wet regions and decrease in already warm and dry regions. These findings are robust despite large differences in model structure, climate change scenarios and model parameters that induce considerable uncertainty into future projections. It also stresses that there are methods available to assess uncertainties but also that many climate change impact studies have focused on testing the response of plants to changes in mean climate rather than climatic extremes. Finally, this thesis shows that adaptive, cross-sectoral natural resource management strategies exist that accommodate uncertain impacts of environmental and societal change and foster sustainable regional development. I conclude that the cascade of uncertainty challenges sustainable natural resource management and that a more systematic treatment of uncertainties is strongly needed to generate robust projections of the impacts of environmental change. The findings of this thesis provide a general framework in which both modelers and decision-makers can integrate model results and assess their robustness.

In the light of growing concerns regarding the quality of higher education after a period of rapid expansion, in 2003, the Chinese government launched the Undergraduate Teaching Evaluation (UTE), the first nation-wide evaluation of universities. In 2008, the UTE was replaced by the Quality Project, which signalled a change in its quality assurance approach, with a move from evaluations to the issuing of awards. In order to investigate the impact of the two national quality assurance policies, along with the impact of two long-standing internal quality assurance mechanisms employed by universities - class observation and student evaluation of teachers - on teaching, the researcher adopted policy analysis and a case study approach. Three different universities in the same region were selected as cases. Semi-structured interviews with 56 heads of department and teachers across three departments at each university were conducted. National and university policy documents, as well as interview data, were analysed thematically in the light of concepts derived from the political sciences, namely Knoepfel et al.'s (2007; 2011) framework for policy analysis and Schneider and Ingram's (1990) classification of policy tools. University policies and interview data revealed the patterns of impact of these two quality assurance policies. Faced with the UTE inspection, universities shifted their focus from assuring the quality of teaching to achieving good results in the exercise and therefore engaging in 'game-playing'. In order to ensure good UTE results, universities even resorted to the manipulation of data. University policies resulting from the UTE required teachers to produce standardised documents and to follow particular procedures. The majority of interviewed teachers regarded the impact of the UTE with cynicism, seeing it as a waste of time and effort, an interference with academic freedom, and believing it had the effect of undermining ethics. However, some teachers reported as positive impact of the fact that the UTE helped to keep teachers disciplined, and that it provided an impetus for ensuring teaching quality. Interview data showed that the Quality Project awards only had an impact on the award winners, who perceived the incentives on offer to be substantial. These award winners considered the acknowledgement given by the awards and the information obtained through reflection and good examples as valuable impacts. However, the Quality Project awards did not have impact on non-award winners, i.e. the majority of teachers. This study revealed that in order to have impact the institutional practices of class observation and the student evaluation of teachers relied on a number of conditions being in place. These practices had impact when the stakes were high or when university teachers received valid and reliable feedback. Whilst high stakes were found to lead to mixed impact, valid and reliable feedback contributed to the improvement of teaching. This study contributes to the understanding of the impact of quality assurance policies and mechanisms on teaching in Chinese higher education, an area that has not yet been the subject of significant empirical research. Covering the two major quality assurance policies in recent years, and also the institutional mechanisms teachers face, this research was able to capture the interdependence between these policies. No such research has previously been conducted in the context of Chinese higher education. In regard to the theoretical aspect of the research, the empirical evidence that was collected and a comprehensive review of other empirical research enabled the development of an Impact Framework. The Impact Framework identified patterns in the impact of various quality assurance policy tools and revealed their inherent strengths and weaknesses. Hence, the Impact Framework can serve in the future as an important reference for policy-makers who are seeking to design and implement effective quality assurance policy tools.