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Ökologische Nachhaltigkeit in Beherbergungsbetrieben in regionalen Naturparks in der Deutschschweiz
(2014)
The role of tree diversity for individual tree growth, crown architecture and branch demography
(2012)
In the light of the concurrent loss of biodiversity, biodiversity and ecosystem functioning (BEF) research attracted a great deal of attention and emerged as one of the important fields of research in ecology. Since important ecological interactions such as competition occur between individuals, the understanding of individual tree growth was considered to be fundamental for forest related BEF research. Individual tree growth is determined by the above- and belowground interactions of a tree individual with its local neighbourhood. To obtain a deeper understanding of BEF relationships, I broadened the focus from individual tree growth (usually measured as diameter or biomass increment) to the arrangement and dynamics of the above-ground modules of trees in dependence of their local neighbourhood. More precisely, the main objective of the present thesis was to analyse the impact of tree diversity on individual tree growth, crown architectural and branch demographic variables. Thereby I considered crown architectural variables as important indicators of the competition for light. In addition, crown architectural variables impacted ecosystem services such as erosion control. Furthermore, the results of the present thesis contributed to the current discussion on species coexistence theories, which may be differentiated by two opposing views: one that relies on neutral processes and one that implicates a role for meaningful differences in the ecological strategy (niche) of co-occurring species. The studied forest ecosystems were the subtropical broad-leaved evergreen forests of southeast China, which have been under high human pressure due to a long history of intensive land-use. The area is of particular interest for BEF research due to the high species richness of woody plants, including many, yet poorly studied species, and due to the rough terrain with steep slopes, which cause severe soil erosion. The present thesis combines three observational with two experimental studies, applying the local neighbourhood approach along an age gradient from tree saplings to mature trees. In the Gutianshan National Nature Reserve (GNNR), I conducted two observational studies on permanent plots which were chosen according to a space-for-time substitution design. The aim of the first study was to reveal the effects of diversity (species richness, functional diversity) together with other biotic and abiotic variables on morphological growth parameters (crown area, crown displacement and stem inclination) of target trees of four tree species (Castanea henryi, Castanopsis eyrei, Quercus serrata and Schima superba). In the second study, the same target trees together with their neighbours were used to analyse the relation between stand related functional diversity and the horizontal and vertical structure of the canopy. The third study was conducted in a young secondary broad-leaved evergreen forest. Using two target species (Castanopsis fargesii and Quercus fabri), the role of diversity, intra- vs. inter-specific competition and the mode of competition (symmetric vs. asymmetric) on the target individuals was tested by analysing five-year radial growth increments. The two other studies were carried out in an experimentally established plantation, using saplings of four tree species (C. henryi, Elaeocarpus decipiens, Q. serrata and S. superba), which were planted in monoculture, twoand four-species combinations and in three densities. The fourth study focused on mechanisms of coexistence and the role of species richness, species composition, species identity and density on sapling growth. The fifth study tested the effect of sapling density and identity on the througfall kinetic energy, which represents a measure for the erosive power of rain. It was found that functional diversity does affect crown architectural and canopy related parameters of forests in the GNNR. However, no effects of species richness on radial-growth were detected in the younger forest. Since I also did not find strong effects of species richness on saplings in the experimental plantation, diversity effects may evolve at a later age stage. The importance of the diversity effect may be related reversely to that of species identity in an age gradient of forest stands. The findings suggest that different mechanisms of coexistence operate simultaneously but that their relative importance may shift through the life stages of trees. During the sapling stage, species-specific differences in growth and architectural traits support niche theory. In older forest stands, no species-specific differences in growth parameters could be detected. However, I did find effects of functional diversity on horizontal canopy structure. I conclude that mechanisms of coexistence may not only change with forest stand age, but may also differ for distinct traits. The present thesis, being the first to apply the local neighbourhood approach with regard to crown architecture and branch demography within the BEF field of research, stresses the importance of this individual based approach. Although the observed forest systems are very complex, crown architectural and canopy structural variables were found to be affected by diversity. The finding that the degree of erosive power of rain could be elucidated by crown architectural variables, encourages further studies to reveal possible relations between biodiversity and other ecosystem functions or services, which might be mediated by crown architectural and canopy structural variables.
This thesis makes an important contribution to better understanding biodiversity and ecosystem function relationships across trophic levels in forests - aspects that are still underrepresented in BEF research. Ongoing biodiversity loss can be expected to change important trophic interaction pathways in these ecosystems, making increased efforts in exploring the mechanisms underlying, and the drivers determining, the impact of trophic complexity on the relationships between biodiversity and ecosystem functioning a crucial objective for holistic approaches to BEF research.
The Ili Delta in Kazakhstan is an important ecosystem that offers crucial wetland habitats for several bird species. However, the Ili River, the Ili Delta and the Balkhash Lake are suffering from water shortage due to climate change and human activities. The desertification of the Aral Sea, an obvious point of comparison to the Balkhash region, also involved the degradation of wetland habitats and the related loss of many bird species relying on these habitats. Therefore, water shortage at the Ili Delta may also be the reason for the loss of wetland habitats and bird species. In this study, bird species numbers, species abundances as well as bird diversity at different habitats in the Ili Delta were examined. There are many habitat types provided by the Ili Delta, for example reed bed vegetation, Tugay forest, bare soil floodplains along rivers and steppe. The results of this study showed that the central delta region with habitats of submerged reed vegetation showed the highest number of bird species and the greatest diversity. Threatened bird species at the Ili Delta were also observed only in these wetland habitats. Steppe habitats showed the lowest numbers of bird species and the lowest bird diversity. In general, all habitats at the Ili Delta are important for the ecosystem and essential for the bird species that depend on them for their survival. With expansion of arid steppe habitats due to water shortage, however, previous wetland habitats may be lost. Moreover, bird species that depend on these wetland habitats may also be lost. Therefore, protective measures for the Balkhash region in general and the wetland habitats at the Ili Delta and its distinct avifauna in particular are urgently needed.
Als Fallstudie wird im ersten Paper der Einsatz der Szenarioanalyse als ein zentrales Element des Forschungsdesigns im Projekt „Sustainable University“ beleuchtet. Mit einem formalen Ansatz wurden Szenarien zum zukünftigen Umfeld der Hochschullandschaft entwickelt. Dieses Paper zeigt detailliert die notwendigen Denkschritte bei der Szenarioentwicklung auf und hilft zu verstehen, an welchen Punkten Integrationsschritte in Bezug auf Wissensarten und Perspektiven unterstützt und geleistet werden und somit auch (soziale) Lernprozesse gefördert werden können. Ferner werden die konkreten Ergebnisse der Szenarioanalyse vorgestellt und diskutiert. Zur Untersuchung von Lerneffekten wird die Methode der Szenarioanalyse in einen formalen Bildungskontext transferiert. Das zweite Paper leistet einen konzeptionellen Beitrag. Einleitend werden spezifische individuelle Kompetenzen diskutiert, die aus der Perspektive der Bildung für eine nachhaltige Entwicklung zum Umgang mit dem Klimawandel als komplexes Nachhaltigkeitsproblem und zu einer aktiven Teilnahme an Transformationsprozessen der Gesellschaft wichtig sind. Die Kompetenzen, wie proaktives Denken, der Umgang mit Unsicherheiten und unterschiedlichen Wissensbeständen sowie das vernetze Denken konnten hier beschrieben werden. Anschließend werden zwei Forschungsmethoden, der Syndromansatz und die Szenarioanalyse, für den Kontext der formalen Bildung nutzbar gemacht, und es wird theoretisch abgeleitet, wie in diesen Lernsettings die eingangs identifizierten Kompetenzen gefördert werden können. Die Szenarioanalyse bietet beispielsweise beim Denkschritt der Entwicklung von Zukunftsprojektionen großes Potential für Reflexionsprozesse oder die Integration von Wissen und Perspektiven zur Förderung der Kompetenz des proaktiven Denkens in Alternativen. Die diskursive Bewertung von Konsistenzen während der Szenarioerstellung birgt ähnliches Potential zur Förderung des vernetzten Denkens. Im dritten Paper wird ein Messinstrument für die Kompetenz des vernetzen Denkens (systems thinking) entwickelt. Es leistet einen empirischen Beitrag zur Lehr-Lernforschung, respektive zur Kompetenzmessung im Bereich der BNE. Dieses Instrument erfasst mit Hilfe eines Similarity Judgment Tests (SJT) den Grad der Vernetzung von Konzepten eines bestimmten Kontextes, in dem konkreten Fall von Aspekten des Klimawandels. In einer prä-post-Studie wurden zwei Kontroll und zwei Versuchsgruppen, die an dem zuvor genannten Lernsetting im Rahmen von Seminaren an der Leuphana Universität Lüneburg teilgenommen haben, empirisch begleitet. Auch wenn keine statistisch signifikanten Veränderungen des vernetzten Denkens der Teilnehmenden nachgewiesen werden konnten, bedeutet das nicht, dass die zuvor abgeleiteten Einflüsse der Szenarioanalyse widerlegt sind. Hier sind weitere Studien und die Weiterentwicklung des Messinstruments nötig. Zudem wurde nur ein Teil möglicher Einflüsse auf die Kompetenzentwicklung untersucht. Für die Szenarioanalyse als Lernsetting lässt sich schlussfolgern, dass zum einen der Moderation von Reflexions- und Diskussionsprozessen während unterschiedlicher Phasen eine sehr wichtige Rolle zukommt und sie einen wesentlichen Einfluss auf Lernprozesse hat. Zum anderen ist den Phasen, in denen Lernen stattfinden kann, genügend Zeit einzuräumen, so dass transdisziplinäre oder interdisziplinäre Forschungsprozesse mit der Methode Szenarioanalyse auch das Potential für Lernprozesse entfalten können. So kann mit Hilfe der Szenarioanalyse ein Setting geschaffen werden, in dem individuelle mentale Modelle und Handlungsmuster hinterfragt und Kompetenzen im Umgang mit komplexen Problemen gefördert werden, und somit individuelles und soziales Lernen für eine nachhaltige Entwicklung stattfinden kann.
Sustainability and Justice - Conceptual Foundations and Cases in Biodiversity and Fishery Policy
(2014)
Sustainability aims at justice in a threefold sense: intragenerational justice, intergenerational justice, and justice towards nature. However, the justification, specific content and practical implications of justice claims and obligations in the sustainability context often remain underspecified. This dissertation therefore asks: How can the concept of justice be structured systematically? How can justice be specified in the context of sustainability? Which specific problems of justice arise in sustainability policy? And what are the respective contributions of (sustainability) economics and (sustainability) ethics? The five papers of this cumulative dissertation approach these issues from different angles, working at the conceptual level and at the level of cases from biodiversity and fishery policy. In Paper 1, a formal conceptual structure of justice is developed, which lists the conceptual elements of justice conceptions: the community of justice including claim holders and claim addressees, their claims (and corresponding obligations), the judicandum (that which is to be judged as just or unjust), the informational base for the assessment, the principles of justice, and on a more practical level, the instruments of justice. By specifying these conceptual elements of justice, it is possible to analyse and compare different conceptions of justice. In Paper 2, the normative dimension of sustainability is discussed in terms of justice. Based on the identification of certain core characteristics of the concept of sustainability, we determine the specific challenges of justice in the context of sustainability along the conceptual structure of justice (from Paper 1). Inter alia, we show that sustainability calls for the integration of justice claims in the relationships with contemporaries, future humans and nature in a non-ideal context characterized by uncertainty, systemic mediation and limits. Paper 3 addresses the contribution of economics to the assessment of trade-offs between intergenerational and intragenerational justice. Economic analysis can delineate the opportunity set of politics with respect to the two justice objectives and identify the opportunity cost of attaining one justice to a higher degree. While the two justices are primary normative objectives, the criterion of efficiency - when directed at the attainment of these justice objectives - has the status of a secondary normative objective. Paper 4 constitutes a case study, reconstructing the ´biopiracy´ debate from a justice perspective. The paper links to the so called Access and Benefit-Sharing framework of the Convention on Biological Diversity, and addresses the question, which problems of justice arise regarding the utilization of genetic resources and traditional knowledge, especially if associated with patenting. It is shown that the predominant perspective of justice-in-exchange is insufficient and therefore complementary conceptions, namely of distributive justice, corrective justice and structural justice have to be taken into account. Paper 5 empirically assesses the justice notions of stakeholders in the Newfoundland fishery, building on qualitative semi-structured interviews and a combination of inductive and deductive coding. A central result is that inshore fishers are seen as the main claim holders, with a claim to participate and being listened to, and the opportunity to make a living from the fishery. Recognition, participation and distribution are all important domains of justice in the context of the Newfoundland fishery. The paper also discusses the relationship between normative theorizing and empirical justice research. Overall, this thesis integrates ideal and non-ideal normative theorizing, economic analysis, empirical justice research and hints at institutional implementation in the debate on sustainability and justice.
The challenges of sustainable development have spurred the complexity of management reality, unveiling considerable risks and opportunities for companies. The past twenty years of development in management science and practice have refined the understanding of the linkages between corporate success and sustainability aspects of business. Nevertheless, numerous management tools and concepts have been criticised for failing to contribute to improved sustainability performance. Management accounting is an indispensable system for generating, preparing and providing information for recognising decision situations and informing decisions. Building on the relevance of information, sustainability accounting has received considerable attention in the past decade. Related research has emphasised the contribution of sustainability accounting to tackling sustainability challenges in specific settings. A systematic investigation of the role of sustainability accounting is virtually non-existent to date. To overcome this limitation and provide an insight into the practice of sustainability accounting and its role in sustainability management and ultimately in corporate success, this doctoral thesis approaches the question How does sustainability accounting contribute to improved information management and management control? The direct contribution is two-fold. First, a number of decision situations are explicated. Examples for such decision situations include utilising certain types of information for specific decisions, engaging various functions in different ways, etc. Making a decision within these decision situations was observed to contribute to achieving corporate goals. Second, the overarching view on the results reveals an interesting pattern. It is the existence of this pattern that supports the view that sustainability accounting can help companies in the pursuit of improved sustainability performance and (thereby) corporate success. The findings enable both practitioners and researchers gain an insight into how sustainability accounting can be deployed so that the company’s limited resources are focused on the crucial decisions in information management and management control. Subsequent recommendations are supported by up-to-date examples. The nature and the scope of the research constituting this doctoral thesis also highlight the path for future research to expand and refine the propositions made herein.
One of the consequences of the manifold uses of various organic substances in households, agriculture, and industry is that these can eventually end up in the aquatic environment. Each of these anthropogenic substances represents a potential harmful contamination for the different water resources. Therefore, a constant and comprehensive monitoring of organic trace substances in the resources used for drinking water treatment is essential to protect of the quality of drinking water. In addition to the commonly used target screening, the non-target screening with high performance liquid chromatography-mass spectrometry (HPLC-MS) has gained in importance in recent years and became a useful tool for the monitoring of organic trace substances in water This work describes new strategies for the screening and identification of unexpected or unknown organic trace substances in water. The approaches consider all compounds detectable by the used analytical method for further data evaluation. That is the fundamental meaning of non-target screening. However, focusing on relevant contaminants during the screening process is required as large numbers of substances are being detected for each sample. Consequently, a sample is not regarded as an isolated specimen, but rather evaluated in relation to a set of other samples based on considerations of their temporal, spatial, or process-related connections. The efficiency of the different developed strategies were demonstrated successfully for the identification of unknown contaminants in monitoring samples of different water resources as well as for the screening and structural elucidation of ozonation by-products of known contaminants (4- and 5-methyl-1H-benzotriazole) of the Danube water. In addition, to effectively support the identification of compounds, the concept of the DAIOS (Database-Assisted Identification of Organic Substances) was introduced. The new described strategies for the screening and identification of organic trace substances in water opens the possibilities of various other applications in environmental analysis, for example in the environmental remediation of contaminated sites, as well as for the evaluation of the process steps during drinking and waste water treatment.
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.
Stoffstromnetzbasierte Optimalplanung des Ressourceneinsatzes industrieller Produktionssysteme
(2011)
Die Steigerung ihrer Ressourceneffizienz ist heute für viele Unternehmen des produzierenden Gewerbes sowohl aus Gründen des Umweltschutzes als auch zur Steigerung ihrer Wettbewerbsfähigkeit ein wichtiges Anliegen. Als ein in vielfältiger Hinsicht geeignetes Planungsinstrument für das industrielle Energie- und Stoffstrommanagement hat sich in den letzten Jahren die in den 1990er Jahren entwickelte Methode der Stoffstromnetze erwiesen. Ihr Manko besteht hauptsächlich darin, dass bislang keine automatische Suche nach Systemkonfigurationen mit optimalem Ressourcenverbrauch möglich ist. Gängige Optimierungsmethoden des Operations Research wie die mathematische Programmierung sind hierfür prinzipiell geeignet. Aufgrund ihres hohen Abstraktionsniveaus lassen sie sich jedoch nur schwer in betriebliche Planungsprozesse, insbesondere in mittelständischen Unternehmen, einbinden. Daher wird in dieser Arbeit eine neuartige Methode für die Optimalplanung industrieller Produktionssysteme entwickelt, die die Vorteile der Stoffstromnetze mit denen der Parameteroptimierung verbindet: die stoffstromnetzbasierte Optimalplanung. Als formale Schnittstelle zwischen Stoffstromanalyse und Operations Research wird durch die Einbettung eines Stoffstromnetzes in ein Parameteroptimierungsproblem das stoffstromnetzbasierte Optimierungsproblem (SSNOP) definiert. Dabei wird deutlich, dass aus der methodischen Integration nur dann ein sinnvolles Planungswerkzeug resultiert, wenn auch die jeweiligen Modellierungsparadigmen von Stoffstromanalyse und Optimalplanung miteinander verschmolzen werden. Das SSNOP ermöglicht daher nicht nur die angestrebte Erweiterung des Stoffstrommanagements um den Aspekt der automatischen Systemoptimierung. Es induziert darüber hinaus einen Perspektivwechsel von der traditionell eher beschreibenden zu einer entscheidungsorientierten Stoffstromanalyse. Nur durch die systematische Berücksichtigung der Freiheitsgrade eines Produktionssystems in Form von vorhandenen oder potenziellen Handlungs- und Gestaltungsspielräumen entstehen Stoffstrommodelle, die gleichzeitig als Optimierungsmodelle einsetzbar sind. Weiterhin werden in dieser Arbeit konkrete Lösungsansätze für das SSNOP untersucht. In Abhängigkeit von den Eigenschaften des eingebetteten Stoffstromnetzes gibt es zwei Möglichkeiten für die Optimierung: Einerseits die algebraische Reformulierung als mathematisches Programm, welches anschließend mit analytischen Optimierungsalgorithmen gelöst werden kann, andererseits die Anwendung direkter Suchalgorithmen im Rahmen einer simulationsbasierten Optimierung. Weiterhin wird ein Optimierungsmodul für eine stoffstromnetzbasierte Stoffstromanalysesoftware konzipiert, welches beide Lösungsansätze integriert. Mittels numerischer Experimente wird schließlich die Eignung verschiedener direkter Optimierungsalgorithmen zur Lösung des SSNOP untersucht.
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.
Ökologische und soziale Themen werden für Marken zunehmend erfolgsrelevant. Jedoch können Nachhaltigkeitsversprechen einer Marke zu Vertrauensvorbehalten seitens der Stakeholder führen, weshalb die Glaubwürdigkeit einer Nachhaltigkeitsmarke besonders wichtig ist. Zudem wird die Wahrnehmung einer Nachhaltigkeitsmarke heutzutage verstärkt durch Stakeholder mitbestimmt, da sie mittels Social Media eigene Inhalte verfassen und im Social Web veröffentlichen können. Vor diesem Hintergrund wurde in der Dissertation erörtert, wie ein Unternehmen seine Marke durch ökologische und soziale Themen stärken kann. Außerdem wurde untersucht, wo in diesem Entwicklungsprozess soziale Medien gezielt eingesetzt werden können. In diesem Kontext wurde auch der Frage nachgegangen, wie die von Stakeholdern im Social Web verfassten Inhalte in Übereinstimmung mit einer intendierten Nachhaltigkeitsmarke gebracht und deren Kraft genutzt werden können. Zentrales Ergebnis der Dissertation stellt ein anwendungsorientiertes Modell für die systematische Social-Media-Verwendung zur Unterstützung des Nachhaltigkeitsmarkenmanagements dar.
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.
Scaling Strategies of Social Entrepreneurship Organizations – an Actor-Motivation Perspective
(2014)
Despite their sometimes ingenious solutions, many social entrepreneurs fail to scale which is at odds with their overall objective of social change. Yet, though considered highly important in practice, scaling is still under-researched. Taking this imbalance as a starting point, my PhD thesis contributes to the social entrepreneurship literature by shedding new light on the role of the actor-motivation in scaling social ventures. Put together, papers 1-3 try to answer the general research questions of how do actors and their specific motivations, particularly the social entrepreneur, influence the scaling strategies (and success) of social ventures? Based on a brief review of the literature on scaling, I identify social franchising as a promising scaling strategy that requires more research. Here, paper 1 argues that the social mission of the involved actors can serve as an informal functional equivalent to formal contracts as well as a means to safeguard the local small group logic. Paper 2 discusses the effects of stewardship on social franchising coming to the conclusion that stewardship relationships may impede speed of and degree of scaling. Based on these insights, paper 3 more closely analyzes the motivations of social entrepreneurs in a post-founding stage. It empirically constructs a taxonomy of (social) entrepreneurs based on their motivations. To this end, paper 3 employs a three-step methodological approach that combines the inductive insights from 80 interviews with entrepreneurs with a statistical cluster analysis. Following, this paper then discusses contributions of and implications for scaling research as well as to social entrepreneurship, entrepreneurship, and management research.
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 Entfernung von Phosphor aus Abwasser bleibt ein Forschungsthema, das in Zukunft nur an Wichtigkeit gewinnen kann. Das wird durch die Umweltauswirkungen der Eutrophierung und den Verlust eines essentiellen Nährstoffes für die Nahrungsmittelproduktion dessen Knappheit immer offensichtlicher wird, immer deutlicher. Auf Kläranlagen werden heute hauptsächlich zwei Techniken verwendet um Phosphor zu entfernen, biologisch aktive Verfahren wie das Enhanced Biological Phosphorus Removal (EBPR) Verfahren und Fällungstechniken unter Verwendung von Metallsalzen. Bei beiden Methoden gibt es gegenwärtig Schwierigkeiten wie z.B. die Instabilität des EBPR Prozesses wegen des Mangels an Wissen über die Grundlagen des Stoffwechselprozesses. Bei der Verwendung von Fällungsmitteln kommt es zu vielen Nachteilen im Zusammenhang mit der Nachbehandlung des Schlammes, bei der Entsorgung kommt es zu dem Verlust der Schlammmassen und damit auch des Phosphors aus dem Nährstoffkreislauf. Das Ergebnis dieser Forschung ist, dass es möglich ist, die Phosphorspeicherkapazität von Belebtschlamm zu erhöhen wenn dieser spezifische Anforderungen erfüllt. Diese Anforderungen werden wie folgt zusammengefasst: Die Schlammmasse muss in der Lage sein, EBPR Prozesse zu entwickeln, auch muss der Schlamm aus einem Belebungsbecken-System kommen, weil die Schlammflocken unter den Umgebungsbedingungen des Reaktors stabilisiert worden sind. Schließlich muss der Belebtschlamm aus einem Verfahren kommen, bei dem man für die Phosphorentfernung keine Metallsalze verwendet. Die erhöhte Phosphorstoffspeicherkapazität der Belebtschlammmassen in Verbindung mit der Möglichkeit den Phosphor aus dem Belebtschlamm über Rücklösung in die wässrige Phase wieder gewinnen zu können, bietet großes Potential in der Zukunft einen in der Abwasserwirtschaft geschlossenen Phosphorkreislauf zu entwickeln und so den Verlust des wichtigen Nährstoffes nachhaltig zu verhindern.
