The Department of Correctional Services is the South African Government Department that is responsible for the smooth running of the South African correctional system. Correctional facilities have to be staffed twenty four hours a day and therefore correctional officials have to work fixed or rotating shifts to ensure that the needs of offenders are taken care of. The number of staff members in many South African correctional centres is not sufficient to ensure proper care and management of offenders, but staff shortages during the night is even more chronic compared to staff shortages experienced during the day. It is vital that correctional officials be alert and vigilant at all times and therefore these staff shortages contribute to high levels of stress, lack of motivation and feelings of being overwhelmed by the work load. Shift work is a phenomenon that is increasing worldwide. It is important to understand the impact of work schedules as more people seem to be working shifts that do not conform to the standard work week. Shift workers seem very healthy when their illnesses are compared to that of the general public. Many health problems have been detected in shift workers, including stress related conditions, as any work schedule can act as a stressor if the needs of the individual worker are not taken into consideration. Sleeping patterns during the day differ from sleeping patterns at night. Shift work disrupts a person’s circadian rhythms and therefore contributes to poorer physical and psychological health. It further causes poorer productivity and increases the possibility of becoming involved in accidents. Working night duty is very stressful to the night shift worker who has to cope with challenges at work and at home. There is a variety of common stressors at work that affect shift workers physiologically (cardiovascular, stroke, digestive problems, back pain and arthritis, headaches, increased blood pressure and hormonal), psychologically (burnout, depression, anxiety, family problems, sleep problems and job dissatisfaction) and behaviouraly (absence, tardiness, substance abuse, accidents, sabotage / violence, poor decision making, poor job performance and a high personnel turnover). This study focused on understanding the positive and negative impact of working permanent night duty on correctional officials. The findings of this study will be helpful to correctional officials who work permanent night duty in addressing employee workplace support. / Dissertation (MSW (Health Care))--University of Pretoria, 2014. / lk2014 / Social Work and Criminology / MSW (Health Care) / Unrestricted

Parkinson's disease (PD) is a progressive disorder that affects movement, muscle control and balance. Second only to Alzheimer's disease, PD is one of the most common neurodegenerative disorders in the United States (Lai & Tsui, 2001:135), affecting approximately one million people in the U.S. alone (Parkinson's disease Foundation [PDF], 2009). While the cause of Parkinson's disease remains unknown, there are certain known risk factors associated with the disease. One of the risk factors is increasing age. PD is most frequently associated with older adulthood, affecting one in 100 Americans 60 years and older (PDF). Over the next five decades, the incidence of PD is expected to triple, as the average age of the population increases (Lai & Tsui, 2001:135). Parkinson's disease is a chronic, progressive disorder, with no known cause or promising cure. While substantial information is known about the medical aspect of Parkinson's disease, little is known about the illness experience of living with the disease. The goal of this study was to explore and describe the experiences of people living with Parkinson's disease. The guiding research question was: What are the experiences of people living with Parkinson's disease? A qualitative research approach was followed, with a collective case study research design. The population for this study included people who are in the late stage of Parkinson's disease, thus being diagnosed with Parkinson's disease before 2012 and who are receiving support services from Parkinson's Association of South Africa (PASA). Non-probability purposive sampling was utilized to generate a sample. Ten participants who met the criteria were selected for this study. Semi-structured individual interviews were conducted with participants. Interviews were voice recorded with the permission of the participants and were transcribed. The data gathered were analysed by the researcher and themes and sub-themes were identified. The research findings were presented and critically discussed. Literature control and verbatim quotes were used to support the findings. The conclusions of this study reflected that the experiences of people living with Parkinson's disease are complex. Throughout the study it was found that Parkinson's disease impacts significantly on the physical, psychological and social well-being of people living with this disease in a number of ways. The recommendations offered by this study can be used by professionals working in the field of chronic, geriatric and neurodegenerative illnesses to understand the experiences of people living with Parkinson's disease. / Mini Dissertation (MSW)--University of Pretoria, 2016. / Social Work and Criminology / MSW / Unrestricted

The goal of the study was to evaluate the content, implementation and applicability of the Soul City social intervention programme (SCI programme) about HIV and AIDS targeted at the youth in the Northern Cape from an ecosystems perspective. The goal of this study was achieved through the realisation of the objectives of the study. The objectives of the study were: To describe the phenomenon of HIV and AIDS among the youth in the Northern Cape, South Africa from an ecosystems perspective; to describe the NSP 2012-2016 and the Provincial Strategic Plan (PSP) for HIV and AIDS in South Africa; to describe and critically analyse the SCI programme's focus on the youth from the ecosystems perspective; to evaluate the content of the SCI programme for the youth with regard to HIV and AIDS in the Northern Cape in the context of the NSP 2012-2016 on HIV and AIDS from the field workers' perspective; to evaluate the implementation of the SCI programme for the youth on HIV and AIDS in the Northern Cape in the context of the NSP 2012-2016 on HIV and AIDS from the perspective of the youth as service users, and lastly, to provide guidelines for the content, applicability, implementation, monitoring and evaluation of the SCI programme for the youth with regard to HIV and AIDS in the context of the NSP 2012-2016, in order to enhance efforts to mitigate the impact of HIV and AIDS among the youth in the Northern Cape. Furthermore, a mixed-methods research approach was adopted to achieve the research goal. The quantitative and qualitative findings are described in Chapters 6 and 7 respectively. Triangulation, as mixed-method design, was utilised in this study. This enabled the researcher to produce complete and well-validated conclusions. The method of data collection for the part of the study about the youth was a group-administered questionnaire. For the qualitative part of this study, semi-structured interviews, with an interview schedule, were utilised to collect data related to the contents, applicability, implementation, monitoring and evaluation of the SCI programme from trained field workers working in the youth sector and specialising in HIV and AIDS. The quantitative data was analysed using both descriptive and association statistical analyses. In the present study, the researcher strived to ensure a high degree of face validity by allowing experts in the field, for example, social workers practising in the field of HIV and AIDS, to scrutinise the research instrument as part of the pilot test. The questionnaire was piloted with 20 youths to enhance both face and content validity further. In the current study, an acceptable degree of reliability was prioritised and therefore a Cronbach alpha coefficient of 0.70 for all categories of the questionnaire was sought. The qualitative data of the semi-structured interviews with Soul City programme implementers was analysed using thematic analysis. An independent reviewer reviewed the theme generation and analysis to ensure consistency or the interrater reliability of the findings. This aided the researcher to identify patterns or themes from direct quotations and to provide rich data representation. Verbatim quotations from the interviews were used to support the themes. To ensure data trustworthiness, a high premium was placed on credibility, transferability, conformability and dependability. Analyses of three different sources of data, namely the literature review, the youth programme attendees/recipients and interviews with Soul City field workers were undertaken to answer the following research question. "To what extent is the content and implementation of the Soul City social intervention programme applicable to the youth in the Northern Cape?" Subsequently, the sub-question of the study was: "Does the Soul City social intervention programme take the different levels of the ecosystems perspective into account regarding programme content and implementation?" Several key findings were made in the quantitative part of the study, with nine sections of the questionnaire which focussed on: the Biographic details of respondents; Objectives of the Soul City programme for the youth in the Northern Cape; Applicability and relevance of the content of the Soul City Programme; Knowledge gained through attending Soul City; Attitudinal change; Programme delivery; Programme content; Programme facilitation methods and general aspects. Key findings were that there was no statistical association found between any of the variables in most sections of the questionnaire except for combinations of five questions in sections D and G. There was a statistical association found with regard to age where the respondents indicated that the SCP contributed to them achieving their personal life goals. Also in Section D there was a statistical association found where the respondents could see the impact of the SCP on their lives. There was a statistical association found between where respondents indicated that the SCP should focus on ways/strategies to fight poverty in their communities and also when they indicated that the SCP should focus on involving important people/stakeholders such as youth leaders. Lastly, there was a statistical association found between where the respondents indicated that the capacity of the youth in the community to fight the further spread of HIV and AIDS could be built by visiting the community. From an ecosystems perspective, the SCP programme appeared to be influenced by or aligned to micro-, meso-, exo- and macrolevel factors with varying degrees of success and focus areas. The programme's exolevel focus appeared to be more prominent and to a lesser degree the macro- and microlevels. The research found that the SCP is relatively effective regarding programme content and facilitation methods albeit to a limited degree. Furthermore, what was repeatedly clear was a need for the SCP's programme continuation and sustainability, because adequate effort had not been made for this despite the programmes' apparent value when it was operational. / Thesis (DPhil)--University of Pretoria, 2017. / Social Work and Criminology / DPhil / Unrestricted

Business model design and innovation has been identified as a powerful tool for creating competitive advantage, yet empirical studies which identify the mechanisms for creating this competitive advantage are largely absent in the literature. Coupled with this, innovative multi-sided platform firms that depend on the resources of partners have grown to be some of the most valuable firms in the world, disrupting entire industries in the process. However, there is a dearth of empirical studies on business model design strategies that confer competitive advantage on multi-sided platforms. This study explores the business model design and innovation strategies used by owner-managers of multi-sided platforms to create competitive advantage. Data was collected through 13 in-depth, semi-structured interviews with the owner-managers of South African multi-sided platforms. This study found that partners and customers play an important role in co-creating value and influencing the design of multi-sided platforms. In order to create competitive advantage with their business models, the owner-managers in the study used four broad, non-exclusive business model design and innovation strategies. These comprised: design differentiation strategies, value creating innovation strategies, building network effects and locking in customers and partners through relationship management strategies. This study contributes to the literature by identifying business model design strategies that are utilised to create competitive advantage. The study also highlighted the importance of “ecosystemic” thinking in creating multi-sided platforms. A framework is presented that can aid managers in creating multi-sided platform business models that confer competitive advantage. / Mini Dissertation (MBA)--University of Pretoria, 2017. / Gordon Institute of Business Science (GIBS) / MBA / Unrestricted

In depth studies of the vegetation of large parts of southern Africa, including detailed maps and descriptions of vegetation units are mainly limited to small areas. Meanwhile, various agricultural practises have led to destruction or deterioration of the quality of natural grassland ecosystems. The agricultural sector in developed and rapidly developing areas of southern Africa is confronted with problems like veld deterioration and the loss of natural areas that effectively contribute to the depopulation of rural areas. The necessity to identify, classify and describe the vegetation types and communities within the Grassland Biome was stressed by Mentis and Huntley (1982). The aim of the Grassland Biome Project is to integrate knowledge. comprehension and expertise, which will enable scientists to forecast the results of the available options of grassland management programmes. The phytosociological classification of northwestern KwaZulu-Natal forms part of this project. Known previous vegetation studies of this area were conducted on a large scale and a considerable time ago, which underlines the necessity for a more comprehensive and phytosociologically refined investigation of this area. The study area lies in the northern part of KwaZulu-Natal and comprises the Drakensberg mountains and slopes in the west and undulating plains and bushveld valleys in the east and south. Relevés were compiled in 526 stratified random sample plots over an area of 9300 km2, comprising the northwestern part of KwaZulu-Natal. The vegetation was classified by means of TWINSP AN and Braun-Blanquet procedures. A phytosociological investigation of this vegetation revealed great variation in floristic composition. Further refinement of the data disclosed five major vegetation types containing nine plant communities. The topography and geology of the study area contributes greatly to the diversity of the vegetation, but poor agricultural practises have caused deterioration of the vegetation. / Dissertation (MSc)--University of Pretoria, 1998. / Plant Science / unrestricted

The abilities of fungi and bacteria to degrade simple and complex carbon compounds derived from different sources, such as root exudates, litter, soil organic matter or fungal mycelium were studied in this dissertation. Knowledge of functional traits, especially degradation abilities of fungi and bacteria, are important for deciphering the black box of microbial functioning in topsoil and thus aiding in modeling and predicting future directions of microbial communities development in face of global changes. Among fungal cultures form culture collection representing strains with different taxonomy and ecophysiology, the ecophysiology of fungi was more important in manifestation of functional traits than taxonomy. Among bacterial isolates from the litter and soil of spruce forest, Acidobacteria were confirmed to express multiple decomposition enzymes in high rates in vitro and were also abundant and active degraders in acidic spruce forest soil. The expression of degradation capacities of both bacteria and fungi were further studied in situ in spruce forest topsoil, that represents an important environment due to the ubiquity of coniferous forests on the Northern hemisphere. There is an obvious gap of knowledge, when comes to our understanding of seasonal effect on microbial functioning, and this is...

The ideas expressed in this thesis are meant to address the need for a transformation in the identity management systems currently in use in different parts of the world. Specifically, the paper presents a logical deduction of essential processes to allow for communication between individual people, governments, organizations, and private institutions to exchange and manage information pertaining to identity. This thesis proposes a conceptual framework for the design of an ecosystem that supports self-sovereign identity. The research reviews theory, methodology, and technology from subjects such as design, identity, and distributed systems. Through the design process, a set of elements and functions supporting interactions within an ecosystem were developed. The design is revolved around the ideas of privacy, security, distribution, and interoperability. The findings are presented as two parts of a whole, the first being the conceptual framework that describes a set of essential factors that an ecosystem requires in order to fulfill the goals of self-sovereign identity and interoperability. The second is a set of visualizations of how the framework can be used to design systems and interactions, inside and between the systems, to create an ecosystem. / <p>2022-06-20: Author's name has been corrected on the front page.</p>

One of the pronounced global challenges facing ecologists is how to feed the current growing human population while sustaining biodiversity and ecosystem services. To shed light on this, I investigated the impact of human land use on bee diversity and plant-pollinator interactions in Tanzania Savannah ecosystems. The thesis comprises the following chapters: Chapter I: General Introduction This chapter provides the background information including the study objectives and hypotheses. It highlights the ecological importance of bees and the main threats facing bee pollinators with a focus on two land-use practices namely livestock grazing and agriculture. It also highlights the diversity and global distribution of bees. It further introduces the tropical savannah ecosystem, its climate, and vegetation characteristics and explains spectacular megafauna species of the system that form centers of wildlife tourism and inadequacy knowledge on pollinators diversity of the system. Finally, this chapter describes the study methodology including, the description of the study area, study design, and data collection. Chapter II: Positive effects of low livestock grazing intensity on East African bee assemblages mediated by increases in floral resources The impact of livestock grazing intensity on bee assemblage has been subjected to research over decades. Moreover, most of these studies have been conducted in temperate Europe and America leaving the huge tropical savannah of East Africa less studied. Using sweep netting and pan traps, a total of 183 species (from 2,691 individuals) representing 55 genera and five families were collected from 24 study sites representing three levels of livestock grazing intensity in savannah ecosystem of northern Tanzania. Results have shown that moderate livestock grazing slightly increased bee species richness. However, high livestock grazing intensity led to a strong decline. Besides, results revealed a unimodal distribution pattern of bee species richness and mean annual temperature. It was also found that the effect of livestock grazing and environmental temperature on bee species richness was mediated by a positive effect of moderate grazing on floral resource richness. The study, therefore, reveals that bee communities of the African savannah zone may benefit from low levels of livestock grazing as this favors the growth of flowering plant species. A high level of livestock grazing intensity will cause significant species losses, an effect that may increase with climatic warming. Chapter III: Agricultural intensification with seasonal fallow land promotes high bee diversity in Afrotropical drylands This study investigated the impact of local agriculture intensification on bee diversity in the Afro tropical drylands of northern Tanzania. Using sweep netting and pan traps, a total of 219 species (from 3,428 individuals) representing 58 genera and six families were collected from 24 study sites (distributed from 702 to 1708 m. asl) representing three levels of agriculture intensity spanning an extensive gradient of mean annual temperature. Results showed that bee species richness increased with agricultural intensity and with increasing temperature. However, the effects of agriculture intensity and temperature on bee species richness were mediated by the positive effects of agriculture and temperature on floral resource richness used by bee pollinators. Moreover, results showed that variation of bee body sizes increases with agricultural intensification, “that effect”, however, diminished in environments with higher temperatures. This study reveals that bee assemblages in Afrotropical drylands benefit from agriculture intensification in the way it is currently practiced. Further intensification, including year-round irrigated crop monocultures and extensive use of agrochemicals, is likely to exert a negative impact on bee diversity and pollination services, as reported in temperate regions. Moreover, several bee species were restricted to natural savannah habitats. Therefore, to conserve bee communities in Afro tropical drylands and guarantee pollination services, a mixture of savannah and agriculture, with long periods of fallow land should be maintained. Chapter IV: Impact of land use intensification and local features on plants and pollinators in Sub-Saharan smallholder farms For the first time in the region, this study explores the impact of land-use intensification on plants and pollinators in Sub-Saharan smallholder farms. The study complemented field surveys of bees with a modern DNA metabarcoding approach to characterize the foraged plants and thus built networks describing plant-pollinator interactions at the individual insect level. This information was coupled with quantitative traits of landscape composition and floral availability surrounding each farm. The study found that pollinator richness decreased with increasing impervious and agricultural cover in the landscape, whereas the flower density at each farm correlated with pollinator richness. The intensification of agricultural land use and urbanization correlated with a higher foraging niche overlap among pollinators due to the convergence of individuals' flower-visiting strategies. Furthermore, within farms, the higher availability of floral resources drove lower niche overlap among individuals, greater abundance of flower visitors shaped higher generalization at the networks level (H2I), possibly due to increased competition. These mechanistic understandings leading to individuals’ foraging niche overlap and generalism at the network level, could imply stability of interactions and the pollination ecosystem service. The integrative survey proved that plant-pollinator systems are largely affected by land use intensification and by local factors in smallholder farms of Sub-Saharan Africa. Thus, policies promoting nature-based solutions, among which the introduction of more pollinator-friendly practices by smallholder farmers, could be effective in mitigating the intensification of both urban and rural landscapes in this region, as well as in similar Sub-Saharan contexts. Chapter V: A synopsis of the Bee occurrence data of northern Tanzania This study represents a synopsis of the bee occurrence data of northern Tanzania obtained from a survey in the Kilimanjaro, Arusha, and Manyara regions. Bees were sampled using two standardized methods, sweep netting and colored pan traps. The study summed up 953 species occurrences of 45 species belonging to 20 genera and four families (Halictidae, Apidae, Megachilidae, and andrenidae) A. This study serves as the baseline information in understanding the diversity and distribution of bees in the northern parts of the country. Understanding the richness and distribution of bees is a critical step in devising robust conservation and monitoring strategies for their populations since limited taxonomic information of the existing and unidentified bee species makes their conservation haphazard. Chapter VI: General discussion In general, findings obtained in these studies suggest that livestock grazing and agriculture intensification affects bee assemblages and floral resources used by bee pollinators. Results have shown that moderate livestock grazing intensity may be important in preserving bee diversity. However, high level of livestock grazing intensity may result in a strong decline in bee species richness and abundance. Moreover, findings indicate that agriculture intensification with seasonal fallow lands supports high floral resource richness promoting high bee diversity in Afrotropical drylands. Nonetheless, natural savannahs were found to contain unique bee species. Therefore, agriculture intensification with seasonal fallow should go in hand with conserving remnant savannah in the landscapes to increase bee diversity and ensure pollination services. Likewise, findings suggest that increasing urbanization and agriculture cover at the landscape level reduce plant and pollinator biodiversity with negative impacts on their complex interactions with plants. Conversely, local scale availability of floral resources has shown the positive effects in buffering pollinators decline and mitigating all detrimental effects induced by land-use intensification. Moreover, findings suggest that the impact of human land use (livestock grazing and agriculture) do not act in isolation but synergistically interacts with climatic factors such as mean annual temperature, MAT. The impact of MAT on bee species richness in grazing gradient showed to be more detrimental than in agriculture habitats. This could probably be explained by the remaining vegetation cover following anthropogenic disturbance. Meaning that the remaining vegetation cover in the agricultural gradient probably absorbs the solar radiations hence reducing detrimental effect of mean annual temperature on bee species richness. This one is not the case in grazing gradient since the impact of livestock grazing is severe, leaving the bare land with no vegetation cover. Finally, our findings conclude that understanding the interplay of multiple anthropogenic activities and their interaction with MAT as a consequence of ongoing climate change is necessary for mitigating their potential consequences on bee assemblages and the provision of ecosystem services. Morever, future increases in livestock grazing and agriculture intensification (including year-round crop irrigated monocultures and excessive use of agrochemicals) may lead to undesirable consequences such as species loss and impair provision of pollination services. / Eine der größten globalen Herausforderungen für Ökologen ist die Beantwortung der Frage, wie die wachsende menschliche Bevölkerung ernährt und gleichzeitig die biologische Vielfalt und die Ökosystemleistungen erhalten werden können. Um dies zu beleuchten, habe ich die Auswirkungen der menschlichen Landnutzung auf die Bienenvielfalt und die Wechselwirkungen zwischen Pflanzen und Bestäubern in den Ökosystemen der Tansania-Savanne untersucht. Die Arbeit umfasst die folgenden Kapitel: Kapitel I: Allgemeine Einführung Dieses Kapitel enthält die Hintergrundinformationen, einschließlich der Studienziele und Hypothesen. Es hebt die ökologische Bedeutung von Bienen und die Hauptbedrohungen für Bienenbestäuber hervor, wobei der Schwerpunkt auf zwei Landnutzungspraktiken liegt, nämlich Viehbeweidung und Landwirtschaft. Außerdem werden die Vielfalt und die globale Verbreitung der Bienen herausgearbeitet. Des Weiteren werden das Ökosystem der tropischen Savanne, sein Klima und seine Vegetationscharakteristika vorgestellt und die spektakulären Megafauna-Arten des Systems erläutert, die Zentren des Wildtiertourismus bilden, sowie die unzureichenden Kenntnisse über die Vielfalt der Bestäuber in diesem System. Schließlich wird in diesem Kapitel die Methodik der Studie beschrieben, einschließlich der Beschreibung des Untersuchungsgebiets, des Studiendesigns und der Datenerhebung. Kapitel II: Positive Auswirkungen einer geringen Beweidungsintensität auf ostafrikanische Bienengemeinschaften, vermittelt durch eine Zunahme der floralen Ressourcen Die Auswirkungen der Weideintensität auf die Bienenbestände sind seit Jahrzehnten Gegenstand von empirischen Untersuchungen. Die meisten dieser Studien wurden jedoch in den gemäßigten Breiten Europas und Amerikas durchgeführt, während die riesigen tropischen Savannen Ostafrikas weniger untersucht wurden. Mit Hilfe von Wurfnetzen und Schwenkfallen wurden insgesamt 183 Arten (von 2.691 Individuen) aus 55 Gattungen und fünf Familien an 24 Untersuchungsstandorten, die drei Stufen der Viehweideintensität im Savannen-Ökosystem im Norden Tansanias repräsentieren, gesammelt. Die Ergebnisse zeigen, dass eine mäßige Beweidung mit Weidevieh den Artenreichtum der Bienen leicht erhöht. Eine hohe Beweidungsintensität führte jedoch zu einem starken Rückgang. Außerdem zeigten die Ergebnisse ein unimodales Verteilungsmuster des Bienenartenreichtums und der mittleren Jahrestemperatur. Es wurde auch festgestellt, dass die Auswirkungen von Viehbeweidung und Umwelttemperatur auf den Bienenartenreichtum durch eine positive Auswirkung von mäßiger Beweidung auf den Reichtum an floralen Ressourcen vermittelt wurden. Die Studie zeigt daher, dass Bienengemeinschaften in der afrikanischen Savanne von einer geringen Beweidung durch Vieh profitieren können, da dies das Wachstum blühender Pflanzenarten fördert. Eine hohe Beweidungsintensität führt zu erheblichen Artenverlusten, die sich infolge der Klimaerwärmung noch verstärken können. Kapitel III: Intensivierung der Landwirtschaft mit saisonalem Brachland fördert hohe Bienenvielfalt in afrotropischen Trockengebieten In dieser Studie wurden die Auswirkungen der Intensivierung der lokalen Landwirtschaft auf die Bienenvielfalt in den afrotropischen Trockengebieten im Norden Tansanias untersucht. An 24 Untersuchungsstandorten (zwischen 702 und 1.708 m ü.N.N.), die drei Intensitätsstufen der Landwirtschaft repräsentieren und einen weiten Gradienten der Jahresmitteltemperatur abdecken, wurden 219 Arten (von 3.428 Individuen) gesammelt, die 58 Gattungen und sechs Familien repräsentieren. Die Ergebnisse zeigten, dass der Artenreichtum der Bienen mit der Intensität der Landwirtschaft und mit steigender Temperatur zunahm. Die Auswirkungen der Intensität der Landwirtschaft und der Temperatur auf den Artenreichtum der Bienen wurden jedoch durch die positiven Auswirkungen der Landwirtschaft und der Temperatur auf den Reichtum der von den Bienenbestäubern genutzten Blütenressourcen vermittelt. Außerdem zeigten die Ergebnisse, dass die Variation der Körpergröße der Bienen mit der Intensivierung der Landwirtschaft zunimmt, diese jedoch in Umgebungen mit höheren Temperaturen abnimmt. Diese Studie zeigt, dass die Bienengemeinschaften in afrotropischen Trockengebieten von der Intensivierung der Landwirtschaft, wie sie derzeit praktiziert wird, profitieren. Eine weitere Intensivierung, einschließlich ganzjährig bewässerter Monokulturen und intensiver Einsatz von Agrochemikalien, wird sich wahrscheinlich negativ auf die Bienenvielfalt und die Bestäubungsleistung auswirken, wie dies auch in den gemäßigten Regionen beobachtet wurde. Außerdem war das Vorkommen einiger Bienenarten auf natürliche Savannenlebensräume beschränkt. Um die Bienengemeinschaften in afrotropischen Trockengebieten zu erhalten und die Bestäubungsleistungen zu gewährleisten, sollte daher eine Mischung aus Savanne und Landwirtschaft mit Langzeitig-Brachflächen beibehalten werden. Kapitel IV: Auswirkungen der Intensivierung der Landnutzung und lokaler Gegebenheiten auf Pflanzen und Bestäuber in kleinbäuerlichen Betrieben südlich der Sahara In dieser Studie werden zum ersten Mal in der Region die Auswirkungen der Intensivierung der Landnutzung auf Pflanzen und Bestäuber in kleinbäuerlichen Betrieben südlich der Sahara untersucht. Hierbei wurden Felduntersuchungen von Bienen um einen modernen DNA-Metabarcoding-Ansatz ergänzt, um die beflogenen Pflanzen zu charakterisieren und so Netzwerke aufzudecken, die die Interaktionen zwischen Pflanzen und Bestäubern auf der Ebene einzelner Insekten beschreiben. Diese Informationen wurden mit quantitativen Merkmalen der Landschaftszusammensetzung und der Blütenverfügbarkeit in der Umgebung der einzelnen landwirtschaftlichen Betriebe verknüpft. Die Studie ergab, dass der Reichtum an Bestäubern mit zunehmendem Landschaftsanteil an undurchlässiger und landwirtschaftlicher Fläche abnahm, während die Blütendichte mit dem Reichtum an Bestäubern korrelierte. Die Intensivierung der landwirtschaftlichen Nutzung und die Urbanisierung korrelierten mit einer stärkeren Überlappung der Nischen für die Nahrungssuche von Bestäubern, was auf die Konvergenz der Strategien der Individuen bei der Suche nach Blüten zurückzuführen ist. Darüber hinaus führte innerhalb der landwirtschaftlichen Betriebe die höhere Verfügbarkeit von Blütenressourcen zu einer geringeren Nischenüberschneidung zwischen den Individuen, während eine größere Anzahl von Blütenbesuchern zu einer stärkeren Generalisierung auf der Ebene der Netzwerke führte (H2I), was möglicherweise auf einen erhöhten Wettbewerb zurückzuführen ist. Diese mechanistischen Erkenntnisse, die zur Überlappung der Nischen der Individuen bei der Nahrungssuche und zum Generalismus auf der Netzwerkebene führen, könnten die Stabilität der Interaktionen und der Ökosystemdienstleistung Bestäubung implizieren. Die integrative Untersuchung hat gezeigt, dass die Bestäubersysteme in den kleinbäuerlichen Betrieben Afrikas südlich der Sahara weitgehend von der Intensivierung der Landnutzung und von lokalen Faktoren beeinflusst werden. Daher könnten politische Maßnahmen zur Förderung naturbasierter Lösungen, zu denen auch die Einführung bestäuberfreundlicher Praktiken durch Kleinbauern gehört, die Intensivierung sowohl städtischer als auch ländlicher Landschaften in dieser Region wie auch in ähnlichen Kontexten südlich der Sahara wirksam abmildern. Kapitel V: Ein Überblick über die Daten zum Bienenvorkommen im Norden Tansanias Diese Studie gibt einen Überblick über die Daten zum Bienenvorkommen im Norden Tansanias, die im Rahmen einer Erhebung in den Regionen Kilimanjaro, Arusha und Manyara gewonnen wurden. Die Bienen wurden mit zwei standardisierten Methoden erfasst: mit Keschern und Farbschalen. Im Rahmen der Studie wurden 953 Individuen aus 45 Arten aus 20 Gattungen und vier Familien (Halictidae, Apidae, Megachilidae und Andrenidae) nachgewiesen. Diese Studie dient als Grundlage für das Verständnis der Vielfalt und Verbreitung von Bienen in den nördlichen Teilen des Landes. Das Verständnis des Reichtums und der Verbreitung von Bienen ist ein entscheidender Schritt bei der Entwicklung robuster Erhaltungs- und Überwachungsstrategien für deren Populationen, da die begrenzten taxonomischen Informationen über die vorhandenen und nicht identifizierten Bienenarten deren Erhaltung ungewiss erscheinen lassen. Kapitel VI: Allgemeine Diskussion Im Allgemeinen deuten die Ergebnisse dieser Studien darauf hin, dass die Beweidung mit Vieh und die Intensivierung der Landwirtschaft Auswirkungen auf die Bienenbestände und die von Bienenbestäubern genutzten Blütenressourcen haben. Die Ergebnisse haben gezeigt, dass eine mäßige Beweidungsintensität für die Erhaltung der Bienenvielfalt von Bedeutung sein kann. Eine hohe Beweidungsintensität kann jedoch zu einem starken Rückgang des Artenreichtums und der Abundanz von Bienen führen. Außerdem deuten die Ergebnisse darauf hin, dass die Intensivierung der Landwirtschaft mit saisonalem Brachland einen hohen Reichtum an floralen Ressourcen aufweist, der eine hohe Bienenvielfalt in afrotropischen Trockengebieten fördert. Nichtsdestotrotz zeigte sich, dass natürliche Savannen eine einzigartige Artenzusammensetzung aufweisen. Daher sollte die Intensivierung der Landwirtschaft mit saisonalem Brachland mit der Erhaltung von Savannenresten in den Landschaften einhergehen, um die Bienenvielfalt zu erhöhen und die Bestäubungsleistung sicherzustellen. Ebenso deuten die Ergebnisse darauf hin, dass die zunehmende Urbanisierung und landwirtschaftliche Nutzung auf Landschaftsebene die biologische Vielfalt von Pflanzen und Bestäubern verringert, was sich negativ auf ihre komplexen Interaktionen mit Pflanzen auswirkt. Umgekehrt hat sich die Verfügbarkeit von Blütenressourcen auf lokaler Ebene als positiv erwiesen, da sie den Rückgang der Bestäuber abpuffert und alle durch die Intensivierung der Flächennutzung verursachten negativen Auswirkungen abmildert. Darüber hinaus deuten die Ergebnisse darauf hin, dass die Auswirkungen der menschlichen Landnutzung (Viehbeweidung und Landwirtschaft) nicht isoliert wirken, sondern synergetisch mit Klimafaktoren wie der mittleren Jahrestemperatur (MAT) zusammenwirken. Die Auswirkung von MAT auf den Artenreichtum der Bienen in Weidegebieten erwies sich als nachteiliger als in landwirtschaftlich genutzten Lebensräumen. Dies könnte wahrscheinlich durch die verbleibende Vegetationsdeckung nach einer anthropogenen Störung erklärt werden. Das bedeutet, dass die verbleibende Vegetationsdeckung im landwirtschaftlichen Gradienten wahrscheinlich die Sonneneinstrahlung absorbiert und damit die nachteiligen Auswirkungen der mittleren Jahrestemperatur auf den Artenreichtum der Bienen verringert. Dies ist im Weidegradienten nicht der Fall, da die Auswirkungen der Beweidung durch das Weidevieh schwerwiegend sind und kahles Land ohne nennenswerte Vegetationsbedeckung zurücklassen. Unsere Ergebnisse lassen den Schluss zu, dass ein Verständnis des Zusammenspiels verschiedener anthropogener Aktivitäten und ihrer Interaktion mit MAT als Folge des fortschreitenden Klimawandels notwendig ist, um die potenziellen Folgen für die Bienenbestände und die Bereitstellung von Ökosystemleistungen zu mildern. Darüber hinaus können die künftige Zunahme der Viehbeweidung und die Intensivierung der Landwirtschaft (einschließlich ganzjährig bewässerter Monokulturen und übermäßiger Einsatz von Agrochemikalien) zu unerwünschten Folgen wie dem Verlust von Arten und Bestäubungsleistungen führen.

The capacity of the world’s coastal ecosystems to sequester carbon dioxide (CO2), termed “Blue Carbon,” has been a major focus of research in recent decades due to its potential to mitigate climate change. Vegetated coastal ecosystems such as mangroves, seagrass beds, and salt marshes represent a global area that is one to two orders of magnitude smaller than that of terrestrial forests, yet their contribution to long-term carbon sequestration is much greater per unit-area, in part because of their high productivity and efficiency in trapping suspended matter and associated organic carbon. Despite the value that Blue Carbon (BC) systems offer in sequestering carbon, as well as providing numerous other goods and services, these habitats are being lost at critical rates and require urgent action in order to prevent further degradation and loss. Recognition of the carbon sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration, and global efforts are now underway to include BC ecosystems into global carbon offset budgets, focusing on their optimal management to optimize CO2 sequestration and minimize CO2 emissions. Here, BC was investigated in the Cowichan Estuary in relation to habitat type (salt marsh, eelgrass meadow, non-vegetated mudflats, and oyster shell beds), and habitat degradation. Stored organic carbon (OC) and inorganic carbon (IC) were quantified in the top 20 cm depth of sediment cores, as well as in eelgrass and salt marsh vegetation, and then extrapolated to the areal extent of each habitat type based on a high resolution 1:12,000 scale base map of the estuary. Rates of sedimentation and carbon sequestration were quantified in each habitat type using 210Pb radiometric dating, and organic matter (OM) sources and quality were assessed in each habitat type using δ13C, C/N ratios and photopigment content in the sediments. A particular focus on the lower intertidal zone allowed us to examine the potential impact of industrial activity (log transport and storage) on the estuary’s capacity for carbon storage, as a result of a reduction of suitable habitat for eelgrass and microphytobenthos (MPB). Additionally, IC was quantified in aboveground oyster shell beds and buried oyster shell to assess inorganic storage. Finally, potential valuation of Blue Carbon in the Cowichan Estuary was investigated by comparing carbon sequestration to provincial greenhouse gas (GHG) emission equivalents as well as carbon sequestration in B.C. forests. We found that the salt marsh was the most important carbon reservoir, with a mean per-hectare sediment organic carbon (SOC) stock of 49.1 ± 19.9 Mg C ha-1, total ecosystem carbon stock (TECS) of 5443.75 Mg C, and carbon accumulation rate of 74 ± 23 g C m-2 yr-1. In the other habitats, we found SOC stocks and TECS respectively 19.1 ± 3.78 Mg C ha-1 and 3651.6 ± 72.3 Mg C in the upper mudflats, 16.9 ± 4.36 Mg C ha-1 and 1058.85 Mg C in the lower mudflats, 17.9 ± 1.21 Mg C ha−1 and 324.57 Mg C in the eelgrass meadow, and 9.43 ± 1.50 Mg C ha-1 and 59.4 Mg C in the oyster beds. The eelgrass meadow had a carbon accumulation rate of 38 ± 26 g C m-2 yr-1, while the mudflats could not successfully be dated due to erosion and/or mixing. Furthermore, the salt marsh contained the highest proportion of recalcitrant, terrestrial-derived root material which was more protected from hydrodynamic forces compared to other habitats. No pattern differences were observed between the carbon reservoirs or bulk properties of the log boom area (lower mudflat) compared to the upper mudflat, and thus there was no evidence that the log booms significantly decrease carbon sequestration in the areas where they make frequent contact with the seafloor. However, decreased chlorophyll a (chl a) concentrations in the lower mudflat sediment suggests a possible detrimental impact on microphytobenthos in addition to preventing the recolonization of the seagrass Zostera marina (Z. marina). Carbon stocks in the eelgrass meadow were similar to those of the mudflats. These carbon stocks were lower than global averages but consistent with those recently reported in low Z. marina meadows in the Pacific Northwest. Evidence of significant eelgrass vegetation outwelling necessitates further investigation to elucidate the degree to which these primary products are being decomposed or buried elsewhere in the estuary or open ocean. Since approximately half of the historical salt marsh habitat is currently reclaimed for agricultural and industrial use, consideration should be given to the role of the marsh system as a carbon reservoir in future land-use policy in the Cowichan Estuary. / Graduate / 2022-04-30

Mangrove forests are unique coastal ecosystems, formed through a complex network of terrestrial, estuarine, and marine processes that have provided a diverse assortment of societal benefits across time. Compounding anthropogenic pressures are driving critical mangrove degradation worldwide, threatening the wellbeing of coastal populations historically associated with these systems. The Ciénaga Grande de Santa Marta (CGSM) in northern Colombia is the largest coastal lagoon-delta in the Caribbean. It is inhabited by stilt-house communities who have developed an intricate livelihood and cultural relationship with the mangroves. The CGSM has experienced sustained social and ecological degradation over the last 6 decades, triggered by land-use change and disruption of hydrological connections. This study integrates Social-Ecological Memory and Palaeoecology to develop a historical contextualization of the biophysical and social dimensions of environmental change in CGSM. Integration of geochemical sediment analysis, C14 radiocarbon dating, and demographic inferences from archaeological evidence revealed three distinct periods over the last 5000 years. During this time sea level rise and hydroclimatic variability shaped the transition from freshwater to prevailing marine conditions, and modulated human occupation patterns in the area around 2000 years ago. In addition, participatory reconstructions with local communities offered nuanced descriptions about the spatial, temporal and contextual aspects of the degradation process, with profound social-ecological consequences. The interdisciplinary approach of this study indicates that CGSM is a highly dynamic social-ecological system that has been changing and reconfiguring across different time scales in response to both natural and human-induced processes, and contributes to the preservation of collective memory in this unique stilt-house community. Finally, it reveals the relative effects of biophysical and social drivers on driving social-ecological change under both millennial and decadal scales.