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A systematic revision of Aprionyx Barnard, an endemic South African genus of Leptophlebiidae (Ephemeroptera)

  • Authors: Ferreira, Ina Susan
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/466770 , vital:76777 , DOI https://doi.org/10.21504/10962/466770
  • Description: Aprionyx Barnard, 1940 is the most speciose genus of Leptophlebiidae in South Africa and endemic to the southern region. Like the other African Leptophlebiidae, Aprionyx has received limited research. The earliest described Aprionyx species were based only on adults that were then placed in Atalophlebia Eaton, 1881. The first descriptions of nymphs were contributed by Barnard (1932), with the smooth claws of the nymphs being the distinctive feature that allowed him to create Aprionyx for all of the South African species placed in Atalophlebia at that time. This research aimed to improve knowledge of Aprionyx species by revising its molecular and morphological systematics. Molecular phylogenetic analysis of the COI, 16S and 28S genes generated a species tree illustrating the species’ relationships within Aprionyx. Species delimitation analyses (bPTP and GMYC methods) were generally congruent with the molecular phylogenetic species composition. The phylogeny identified up to ten potentially new species, a substantial increase in the species diversity of Aprionyx. Review of the descriptions of the eight named Aprionyx species resulted in major nomenclatural changes concerning A. tabularis (Eaton, 1884), A. phoeocera (Lestage, 1924) stat. rev. and A. intermedius Barnard, 1932 n. syn. With the redescriptions of all currently known species, the nymph of A. rubicundus Barnard, 1932 was described for the first time. An identification key to the species of Aprionyx was compiled from newly recognized descriptive characteristics and, for the first time, includes both imagos and nymphs. Molecular and morphological phylogenetic analyses recovered Aprionyx as monophyletic, although this was poorly supported morphologically. The phylogenies were topologically congruent and identified two clear geographically separated clades, a western and eastern Aprionyx group. Molecularly, morphologically and geographically, these two clades were recovered as two clearly distinct groups within the genus. The analyses further identified three lineages in Aprionyx: rubicundus, pellucidulus and eastern Aprionyx. The estimated age of Aprionyx indicated that initial diversification occurred during the Cretaceous (approximately 100 ma). Aprionyx peterseni (Lestage, 1924) was shown as the oldest of the analysed species, and the main drivers to species diversification were possibly the glacial cycles of the Quaternary period, through the mechanism of river anastomosis during fluctuating sea levels. Further research is needed to strengthen the support for the hypothesis identified in this study, but a substantial foundation has been laid by this work for future research, conservation and environmental decision-making. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
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  • Date Issued: 2024-10-11

Activist radio and the struggle to empower audiences: a case study of the Zimbabwean history

  • Authors: Chaunza, Garikai
  • Date: 2024-10-11
  • Subjects: Activism Zimbabwe , Radio broadcasting Political aspects Zimbabwe , Authoritarianism Zimbabwe , Democracy Zimbabwe , Zimbabwe Social conditions , Zimbabwe Politics and government
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/466907 , vital:76797 , DOI https://doi.org/10.21504/10962/466907
  • Description: This study is grounded in my 18-year career in journalism in Zimbabwe. This journey began in January 2006 at the Zimbabwe Broadcasting Corporation (ZBC), where I started as a news reporter. In June 2008, I left ZBC and transitioned to freelance roles, including work at Radio Voice of the People (VOP), which broadcasted from South Africa using Radio Netherlands' transmitters in Madagascar. Simultaneously, I corresponded for The Zimbabwean Newspaper, edited in the UK, printed in Johannesburg, South Africa, and distributed to Zimbabwe, Radio Netherlands, Free Speech Radio News (USA), KPFA Pacifica Foundation Radio (USA), and DW (German). More recently, my work has expanded into the digital domain, contributing to New Zimbabwe, an online newspaper for the Zimbabwean diaspora in the UK, before transitioning to Community Radio Harare. Throughout my 18-year career as a media practitioner and journalist in Zimbabwe, I faced constant state-sanctioned interference, and even physical violence, while executing my responsibilities. Initially, at the Zimbabwe Broadcasting Corporation (ZBC), several colleagues and I, including our news editor, were politically victimised and ultimately fired for covering opposition political players and human rights activists. Later, when I was operating outside state-established media outlets, I experienced a series of threats, intimidation, arrests and detentions by state security. This was also true during my six-year tenure as the chairperson of the Media Institute of Southern Africa's Harare advocacy committee. This experience underscored the importance of studying the history of media activism in this country, focusing on the role that activists have played sustaining the alternative media despite intimidation by the state. I am convinced of the importance documenting their experiences, capturing their contribution to the creation of alternative communication platforms for marginalised audiences. In exploring the literature I discovered that the traditions of activist media, in which I have been involved myself, are rooted in a much older history that can be traced back to pre-independent Zimbabwe. At that time, colonial authorities also restricted media freedoms and employed violence against pro-democracy activities, referred to as nationalists. I decided, for the purpose of this study, to delve into this pre-history of media activism in Zimbabwe, focusing on radio in particular. I wished to gain insight into the way media activists have, over time, sustained their involvement in the traditions of radio practice that can empower marginalised communities. I was conscious that the continued survival of activist radio in this country has often been arduous, with activists facing harassment, arrests, and detentions by authoritarian administrations resisting the opening up of democratic spaces. I wished to trace this history of resistance from its origins in the mid-twentieth century to the time of my own involvement in such radio in the 21st century. In particular, I hoped to identify shared normative foundations as well as shared practices for the implementation of these ideals. Chapter One of the study explores the history of activist radio from the mid-20th century to the present, identifying five distinct phases in Zimbabwe's socio-political history and illustrating how each phase shaped the media landscape. Building on this, Chapter Two establishes a theoretical framework underpinning the values and principles driving media activists to create people-oriented radio projects to empower marginalized communities. Chapter Three delves into the documented history of activist radio within the broader context of media activism in Zimbabwe, engaging with each of the five key moments detailed in Chapter One. Chapter Four outlines the research plan for the empirical fieldwork and discusses its implementation. In Chapter Five, I present interviews with radio activists from the 1970s' nationalist radio and those involved in the pirate radio tradition that re-emerged at the turn of the millennium, sharing their practical experiences. Chapter Six focuses on interviews with community radio advocates, detailing their involvement in radio activism during the first decade of the millennium. Finally, Chapter Seven examines the activities of community radio practitioners, exploring their experiences with unlicensed radio projects and highlighting their creative endeavours. , Thesis (PhD) -- Faculty of Humanities, Journalism and Media Studies, 2024
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  • Date Issued: 2024-10-11

An analysis of tax incentives offered for investments by individuals in South Africa and the United Kingdom

  • Authors: Muzenda, Nokuthula Tafadzwa
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/463516 , vital:76416
  • Description: This research analysed the tax incentives available for investments by individuals in South Africa and compared them to investments in the United Kingdom. It answered the question whether, based on incentives provided in the United Kingdom, recommendations can be made for investment incentives to be implemented in South Africa. The type of investments described were venture capital schemes, tax-free investments, retirement savings, endowment policies, purchased annuities, workplace investment schemes, and fixed interest bonds. These classes of investments were discussed together with the tax incentives offered for them in South Africa and the United Kingdom. An interpretative paradigm was adopted for this research, together with a doctrinal methodology and a qualitative method. This research analysed the legislative provisions in South Africa and the United Kingdom. Information was also collected from secondary sources such as textbooks and articles written on investments and taxes. There were no ethical considerations in this research as the data that was used are publicly available. The tax incentive provisions in South Africa have not proven to be effective in increasing household savings, which remain low. The comparison of the taxes and incentives in South Africa and the United Kingdom indicated that there are some similarities on how certain investments are taxed, but for most types of investments, the United Kingdom provided more favourable tax incentives than South Africa. Recommendations were made for the venture capital company incentive previously applying to be reinstated, or to introduce some form of income tax and capital gains tax relief for direct investment into venture capital companies. The removal of the penalty for tax-free investments in excess of the maximum permitted was recommended, and to charge income tax according to the tax tables on contributions exceeding the limit. With regard to purchased annuities, it was recommended that no income tax should apply to annuities received in the case of disability, sickness, and similar circumstances. For the section 8B Broad-Based Share Incentive Scheme recommendations were made to not levy dividends tax on cash dividends retained for reinvestment into the scheme, and for employees not to be liable for income tax when shares are disposed of, where they are no longer in the relevant employment due to circumstances beyond their control. A recommendation was also made to consider introducing workplace savings schemes similar to the savings schemes applying in the United Kingdom. An education campaign by the South African Revenue Service was recommended, to inform the public of investment incentives. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2024
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  • Date Issued: 2024-10-11

An analysis of the precarious livelihoods of Zimbabwean migrants in the informal economy in Makhanda, South Africa

  • Authors: Nderere, Nompumelelo Agnes
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/466262 , vital:76712
  • Description: The movement of people across borders is a complex phenomenon that has far-reaching social, political, and economic implications. In recent years, Zimbabwean migrants have become increasingly visible in the informal economy across South Africa. Through qualitative data collection methods, this study sought to broaden our understanding of the precarious livelihoods of Zimbabwean migrants working in the informal economy in South Africa. This study examined Zimbabwean migrants in the informal economy in Makhanda, Eastern Cape in South Africa. Underpinned by the Sustainable Livelihoods Approach (SLA) as the theoretical anchor, this thesis offers a comprehensive examination of not only the challenges but also the opportunities faced and presented to Zimbabwean migrants in the informal economy in Makhanda. The Sustainable Livelihoods Approach was used as a framework to guide the analysis aimed at understanding the precarious livelihoods of Zimbabwean migrants working in the informal economy in terms of the vulnerability context they find themselves in, the assets they use, the organizations or institutions that affect their activities and the results they get out of their efforts in the informal economy. Data was collected from a sample of 10 participants, consisting of 4 self-employed participants and 6 “employed” in the informal economy. Through in-depth interviews and thematic analysis, this thesis examined the strategies that the migrants adopt to cope with the challenges they face and the impact that these strategies have on their livelihoods. The findings suggest that working in the informal economy evolves as a sustainable livelihood strategy, which depends on external support for it to flourish. , Thesis (MSocSci) -- Faculty of Humanities, Sociology, 2024
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  • Date Issued: 2024-10-11

An assessment of the status of psylloid species (Hemiptera: Psylloidea) as potential pests of commercial citrus in southern Africa: implications for pest management

  • Authors: Moagi, Raynold
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/464417 , vital:76509
  • Description: Psylloids (Hemiptera: Psylloidea), constitute a group of plant sap-sucking insects, some of which are economically significant pests in different ecosystems due to their potential to transmit Gram-negative bacteria, such as the Candidatus Liberibacter species. The African citrus triozid (ACT), Trioza erytreae (Del Guercio), which transmits African citrus greening and the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, which transmits Asian citrus greening are significant threats to citrus. Asian citrus psyllid poses a global economic threat due to its ability to vector “Candidatus Liberibacter asiaticus” (CLas), which can rapidly kill citrus trees. However, both ACP and CLas are currently not present in southern Africa but are present in East and West Africa. In the Afrotropical region, 71 triozid species are known to occur and approximately 41 described Diaphorina species in southern Africa. Currently, two indigenous Diaphorina species, Diaphorina punctulata and Diaphorina zebrana have been documented to feed on citrus. There is a significant knowledge gap regarding the ecological roles of other indigenous psylloid species occurring within the citrus environments. Therefore, this study aimed to: (i) determine the diversity and community structure of psylloid species in citrus environments, and (ii) their host ranges through DNA analysis of gut contents to determine if they fed on citrus. Field surveys were carried out across 12 distinct commercial citrus environments across Limpopo and Mpumalanga provinces between 2022 and 2023. Psylloids were collected using yellow sticky traps and an insect sweep-net. Collected psylloid specimens were preserved in 70% ethanol vials and identified to the lowest possible taxonomic level (i.e. genus or species) using both published and unpublished dichotomous identification keys. Furthermore, citrus leaf samples were collected from the same plants on which psylloids were found in the orchards. Genomic DNA (gDNA) was extracted from both leaf and psylloid samples using two different DNA extraction methods. To confirm if citrus DNA could be detected in the psylloid guts, all leaf gDNA samples were initially amplified using the rbcLaF/R primer pair, targeting a 530-bp region of the chloroplast rbcL gene through the polymerase chain reaction (PCR). Lastly, gut content analysis was performed on 11 psylloid species using the same primer pair through PCR to detect citrus DNA. A total of 4,900 psylloids belonging to five families (i.e. Aphalaridae, Carsidaridae, Liviidae, Psyllidae and Triozidae), 19 genera and 47 species, were collected in citrus environments. More psylloids were recorded in Limpopo (3,754) than in Mpumalanga (1,146). The most abundant species were Pauropsylla trichaeta (1,680), followed by Diaphorina punctulata (466), Trioza erytreae (426), Diaphorina virgata (371), Euryconus sp. (358), Cacopsylla sp. (311), Retroacizzia mopanei (263), Acizzia russellae-group (240), Acizzia sp.3 (216) and Acizzia sp.2 (140). Yellow sticky traps captured 3,265 psylloids in citrus orchards, while an insect sweep-net collected 1,635 psylloids (477 from citrus orchards and 1,158 from adjacent natural vegetation). Data from the insect sweep-net revealed that 22 psylloid species were recorded on citrus. In comparison, nine psylloid species were found on Vachellia spp. and unidentified plant species separately, whereas six, three and two psylloid species were recorded on marula, Ficus sp. and mopane, respectively. The abundance, richness and community structure of psylloids differed significantly between the collection methods, provinces and among plant species. The rbcLaF/R primer pair amplified all citrus leaf gDNA samples, producing amplicons of the targeted 530-bp size. The PCR analysis of 11 psylloid species showed that the rbcLaF/R primer pair amplified plant DNA, with PCR-amplified plant DNA samples producing amplicons between 500-bp and 750-bp in the gut contents of five psyllid species: Diaphorina punctulata, Diaphorina virgata, Diaphorina zebrana, Euryconus sp. and Trioza erytreae. However, the targeted 530-bp plant DNA region was only amplified from the gut contents of Euryconus sp. and Diaphorina punctulata. This study documented psylloid diversity and community structure within commercial citrus environments. The findings indicate that the community of psylloids was diverse in citrus environments, with yellow sticky traps being more effective in monitoring different psyllid species within these environments. Furthermore, the PCR analysis detected citrus DNA in the gut contents of Euryconus sp. and Diaphorina punctulata, suggesting that they could be nibbling on citrus when their specific or main host-plants adjacent to citrus orchards are depleted. However, these insects do not lay their eggs or complete their life cycle on citrus, further confirming that citrus is not their host-plant. Thus, further studies, including Sanger sequencing of PCR-amplified plant DNA, are recommended to confirm the ingested plant species, and host-specific testing including infection trials needs to be conducted. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2024
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  • Date Issued: 2024-10-11

An evaluation study of the climate change adaptation plans for a provincial conservation authority in South Africa

  • Authors: Van den Berg-McGregor, Eleanor Charmell
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/461930 , vital:76252
  • Description: While there are natural changes in climate over time, the climate change phenomenon of global warming that the Earth is currently experiencing is human-induced. The impact of human-induced climate change has led to unprecedented global warming and has become evident as there have been increases in the frequency and intensity of extreme weather events such as inter alia, heatwaves, droughts and floods. This climate change trajectory poses a risk to the Earth’s ability to continue providing sustainable ecosystem services necessary to sustain life on Earth. Therefore, considering the risks and impacts of climate change, there is a need to strengthen the global response to the threat of climate change, and hence, there is a need for climate change adaptation (CCA). Some benefits of CCA include the reduction of risks to nature and people, biodiversity conservation, food security, livelihoods and human well-being. Through a CCA lens within the biodiversity and conservation sector, underpinned by Resilience Theory, this research study sets out to identify and evaluate the CCA plans of a provincial conservation authority. By reviewing the current literature for CCA, the insights gained allowed for the emergence of key characteristics for good CCA in the biodiversity and conservation sector, and the evaluation of CapeNature’s (a provincial conservation authority situated in the Westen Cape of South Africa) CCA plans against these key characteristics that emerged for CCA and resilience planning in protected areas and ecosystems. Qualitative data was gathered via focus groups and individual semi-structured interviews with seven key knowledge holders of CapeNature’s CCA planning processes, plans and management approaches, and through document analysis of the entity’s CCA plans, whereafter it was evaluated against the key characteristics. Challenges towards CCA and opportunities that can be explored for CCA were identified as well. This research study has revealed that CapeNature does not have a single all-encompassing CCA plan but has various CCA approaches that consider the key characteristics necessary for good CCA. However, the entity faces various challenges regarding its intention to implement these approaches over the long term. Challenges ranged from a fragmented approach to CCA to compromised capacity and capability to implement their CCA plans over time. A recurring challenge was the lack of financial resources, and this, combined with the entity’s current inability to secure sustainable financing, was emphasised as the key factor to be addressed towards facilitating the success of the entity’s CCA plans. It also emerged that CCA approaches are interdependent and linked as in various instances, when one key CCA characteristic was compromised, it had a detrimental effect on other CCA approaches. The study concludes by making recommendations to enhance CapeNature’s CCA and resilience planning, noting that these may be of relevance to other conservation agencies as well. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2024
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  • Date Issued: 2024-10-11

An exploration of the influence of gender dynamics on the experience of NGO staff members in Makhanda

  • Authors: Hove, Taguma Florence
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/466139 , vital:76700
  • Description: This research explores gender dynamics within non-governmental organisations (NGOs) and examines whether, and to what extent women in the NGO sector perceive gender dynamics as playing instrumental roles in NGO organisational processes and structures. In conjunction with this, this research aims to explore the relationship between gender stereotypes and career progression. Black feminism and postcolonial feminism will be implemented as theoretical frameworks to explore how social or gender, age, race, and class interact with the organisational process of NGOs. The concepts of intersectionality and subjectivity are useful in understanding how interactions between race, class, and gender play a role in the subjective experiences of women of all backgrounds in post-apartheid South Africa. A postcolonial feminist approach focuses on the representation of African women, and allows an exploration of the knowledge of South African women within NGOs that will provide more perspectives to organisational studies. Traditional perspectives of gender stereotypes are widespread, but several respondents are indifferent to gender stereotypes while some of them feel that they are non-existent. The findings indicate that gender stereotypes continue to exist with forward movements in social progress, where progress might be stalled because of ingrained patriarchal norms, making it difficult to eradicate gender inequality. The findings from the research also suggest that there are tensions and contradictions involved when it comes to how female NGO staff members perceive gender discrimination, providing nuance to existing research. This research acknowledges the period of transition that society is in and recognises how complexities emerge. The findings capture the present state of gender identity, and applying an intersectional approach has indicated that other factors such as race, ethnicity and age take precedence. The research also recognises the importance of tracking and responding to changing societal attitudes in times of transition. Finally, the research also contributes to a broader understanding of the perceptions of gender identity and equality and ensures that discussions on patriarchy do not depend on established discussions that present reality in a stark way that does not leave space for nuance. , Thesis (MSocSci) -- Faculty of Humanities, Sociology, 2024
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  • Date Issued: 2024-10-11

An exploratory study of the benefits of reading clubs for learners in English First Additional Language classrooms

  • Authors: Mbebe, Xolela Desmond
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/463724 , vital:76435
  • Description: The study explored how reading clubs inculcate the love of reading in Komani, Eastern Cape Province, South Africa. Reports indicate that learners at secondary schools do not understand the vocabulary used in comprehension passages. They need exposure to a variety of texts to promote reading comprehension. This study is situated in the interpretive paradigm. The participants were three educators with 24 learners in the reading clubs. Vygotsky’s Socio-Cultural Theory was the theoretical framework to explore how reading clubs promote the love of reading. Data was analysed by using an inductive, thematic approach. The findings indicate that the reading clubs instilled the love of reading among the learners, improving their comprehension skills. The other benefits were that reading clubs are a source of pleasure, instil the culture of reading, and develop the learners’ confidence. The implications of the findings of the study are that reading boosted thinking, reading skills, fluency, knowledge, writing, and vocabulary use. Reading clubs were beneficial to both teachers and learners. Teachers improved their practice and could determine, through oral and written reviews, whether reading took place during the silent reading sessions. Involvement in reading clubs had social benefits for learners. , Thesis (MEd) -- Faculty of Education, Institute for the Study of Englishes of Africa, 2024
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  • Date Issued: 2024-10-11

An investigation into the causes and effect of rising public debt in South Africa, 2009-2019

  • Authors: Mzumala, Mirriam
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/461918 , vital:76251
  • Description: This study delves into the intricate factors contributing to the rising public debt in South Africa between 2009 and 2019, while also scrutinising the efficacy of public debt expenditure during this period. By examining data sourced from the SA National Treasury of South Africa and the South African Reserve Bank (SARB), the research endeavours to elucidate the underlying causes behind the burgeoning public debt and assess the impact of expenditure patterns on economic outcomes. The global financial crisis of 2008/2009 marked a pivotal juncture for South Africa's economy, precipitating a series of fiscal challenges that reverberated throughout the subsequent decade. Against this backdrop, this study embarks on a dual mission: firstly, to decipher the drivers underpinning the surge in public debt, and secondly, to gauge the efficacy of public expenditure vis-à-vis economic growth and development objectives. From 2009 to 2019, fiscal analysis shows a clear pattern of growing budget deficits, with government spending surpassing revenue growth. South Africa's fiscal policy has heavily favoured deficit spending, relying on debt to cover revenue shortfalls and maintain expenditure growth. Most government spending goes towards current payments and social transfers, leaving little for capital formation. Despite the National Development Plan's emphasis on investing in productive assets, both public and private sector investments have consistently fallen below targets, hindering significant contributions to economic growth. The rising public debt in South Africa stems from numerous factors, including excessive spending on unproductive areas like government compensation and social transfers, alongside high borrowing costs. This consumption-focused economic approach, coupled with insufficient investment in productive assets, has hindered South Africa's economic progress compared to global counterparts. Given these challenges, it is crucial to shift fiscal priorities towards strategies focused on investment-led growth. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2024
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  • Date Issued: 2024-10-11

An investigation into the impact of geographical location on the phytochemical composition, pharmacological and toxicological activities of Tulbaghia violacea collected from the Eastern Cape and Gauteng Province

  • Authors: Kader, Tasmeera
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/461819 , vital:76242
  • Description: Introduction: The number of communicable and non-communicable diseases continues to rise and has become more prevalent. While drugs exist to manage and/ or treat majority of the communicable and non-communicable diseases, the rise in disease prevalence puts pressure on researchers to find new drug molecules to treat and manage these ailments. Traditional medicine refers to the knowledge, skills and practices which are based on the beliefs and experiences indigenous to cultures and is used to maintain health. Most of the research into traditional medicine focuses on the medicinal plants used. Medicinal plants are any plants in which one or more of its organs contain substances which are used for therapeutic purposes or for the synthesis of drugs. Tulbaghia violacea is a monocotyledonous genus of herbaceous perennial bulbs which is native to Africa and can be readily found throughout South Africa. It is popular for its antimicrobial, antifungal, anticoagulant, antioxidant and anticancer properties. It has been that ecological factors influence the composition and quantity of phytochemicals present in a plant. Aim of the study: The aim of the study was to investigate the impact of geographical location on the phytochemical composition, pharmacological and toxicological activities of T. violacea collected from the Eastern Cape and Gauteng Province. Methods: The leaves of T. violacea were collected from the Eastern Cape and Gauteng Province. The leaves were dried and extracted using serial maceration with solvents hexane, acetone and methanol. The resulting extracts were subjected to qualitative preliminary phytochemical analysis and a quantitative total phenol content test was carried out using gallic acid as the standard. Thin layer chromatography (TLC) was performed to identify classes of compounds present in T. violacea. xix Antioxidant activity of T. violacea was determined qualitatively using a dot-plot and quantitatively using a DPPH radical scavenging activity assay. Ascorbic acid was used as the standard. Anti-diabetic properties of T. violacea were assessed using an α- amylase inhibition assay and an α- glucosidase inhibition assay. Acarbose was used as the standard for these assays. The anti-Alzheimer properties of T. violacea leaf extracts was determined using and acetylcholinesterase (AChE) inhibition assay. Donepezil was used as the standard for this assay. The DPPH radical scavenging activity, the α- amylase inhibition assay, the α- glucosidase inhibition assay and the AChE inhibition assay was combined with linear regression to determine the IC50 values of the T. violacea extracts and the standards. Statistical analysis was conducted to determine any differences between the plant samples and the standards as well as any differences between the EC and GP sample. Results: The results of the qualitative phytochemical analysis revealed the presence of saponins, flavonoids, tannins, alkaloids, steroids, cardiac glycosides and phenolic compounds present in T. violacea collected from EC and GP. However, their presence in the samples were different based on where the plant was cultivated. The results of the total phenolic content test, revealed that the hexane, acetone and methanol extracts of T. violacea contained phenolic compounds with the highest quantity of phenolic compounds being present in the methanol extracts. Significant statistical difference in total phenolic content between the EC and GP samples were seen for the hexane and methanol extracts. The results of the TLC revealed the presence of multiple bands which confirmed the presence of multiple phytochemicals in T. violacea. All of the extracts of T. violacea from EC and GP, showed antioxidant activity using both the dot-plot and the DPPH radical scavenging activity assay. The highest DPPH radical scavenging activity was seen by the hexane extract of the EC sample of T. violacea. The results showed significant statistical difference between the DPPH radical scavenging activity of the EC and GP samples. , Thesis (Msc (Pharmacy)) -- Faculty of Pharmacy, Pharmacy, 2024
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  • Date Issued: 2024-10-11

An investigation of geospatial technologies in precision agriculture: a case study on a citrus orchard in the Eastern Cape

  • Authors: Nish, Declan Mark
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/465080 , vital:76571
  • Description: Citrus production is an input-intensive farming practice that carries a high cost of production. A multitude of both local and global factors continue to put pressure on farmers to produce enough food for local consumption as well as international exports. Despite these challenges production and exports continue to increase, fighting to meet the growing rise in global demand for citrus (Genis, 2018). Growers are continuously in search of anything that may provide them with the ‘edge’ or an advantage to overcoming some of these challenges (Jupp, 2018). One way in which these issues could be addressed is the use of precision agriculture (PA). Precision agriculture, particularly that of commercial, Unmanned Aerial Vehicle (UAV) based PA, provides growers with solutions to these issues in the form of high quality, near real-time data, and provides access and benefits from technology driven agriculture to growers at all levels (Sishodia et al. 2020). The aim of this research therefore was to investigate the potential of high resolution, multi-spectral UAV, and satellite imagery to help citrus farmers manage their inputs better, save costs and increase their yields in a sustainable manner. Supervised image classification using a support vector machine (SVM) was applied to map and classify a citrus farm in the Eastern Cape. The approach aided the identification of Phytophthora spp in the section of interest and implies that remotely sensed data can be used to detect changes in citrus health. Guidelines for applying geospatial technologies at farm level were developed to provide a framework for enabling growers to enhance data driven farm management strategies. , Thesis (MSc) -- Faculty of Science, Geography, 2024
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  • Date Issued: 2024-10-11

An investigation of the knowledge of and attitudes towards cervical cancer among female students at Rhodes University

  • Authors: Pila, Anastacia Mosima
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/466267 , vital:76713
  • Description: South African and African studies on the knowledge of cervical cancer show that there is generally a limited understanding and knowledge of cervical cancer among women. It is for this reason that this qualitative study examines the knowledge of and attitudes towards cervical cancer among female students at Rhodes University, with the aim of determining whether or not this specific group of women (young and educated) has a better understanding and knowledge of cervical cancer. Semi-structured in-depth interviews were conducted with ten female RU students, and two members of staff at RU campus. Using thematic analysis, the study found that there is also a lack of understanding and knowledge of cervical cancer among the participants. Participants were mostly unaware of its causes, preventative methods, screening methods, and they did not know any cervical cancer-based organisations or initiatives in their communities. The two RU members of staff participants confirmed the latter as they stated that the Rhodes University First Thing’s First is the only organisation in Makhanda that deals with cervical cancer awareness and screening. , Thesis (MSocSci) -- Faculty of Humanities, Sociology, 2024
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  • Date Issued: 2024-10-11

Analysing the equity dimensions and governance drivers of water security challenges in Hammanskraal, City of Tshwane, South Africa

  • Authors: Mahlatsi, Malaika Lesego Samora
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/465011 , vital:76565
  • Description: South Africa is faced with a national water security challenge that is increasingly worsening due to a myriad of structural and governance factors. Over the past few years, several municipalities across the country have experience temporary loss of water access, while some have come dangerously close to Day Zero – a day when water levels of the major dams supplying water to residents would become critically low, resulting in households having no running water. But for the people of the township of Hammanskraal in the City of Tshwane metropolitan municipality, water insecurity has reached crisis point. Since 2005, the township has been battling with a chronic lack of access to safe drinking water. The water quality in Hammanskraal has been so dire that in 2019, the South African Human Rights Commission declared it unfit for human consumption and deemed it a violation of human rights. Despite this, the crisis has persisted. In 2023, Hammanskraal became the epicentre of a cholera outbreak that claimed a number of lives in several provinces across the country. Using a qualitative approach, this study analyses the equity dimensions and governance drivers of water security challenges in Hammanskraal. Through interviews with residents in Hammanskraal and government officials in the City of Tshwane metropolitan municipality and the Gauteng Provincial Government, the study explores the lived experiences of those affected by the water insecurity, as well as the governance drivers that inform the crisis. The study, using water justice theory and conflict theory/Marxism, contends that the water security challenges in Hammanskraal are driven by physical, economic and political factors. These factors have their roots in the geo-history of the township as well as contemporary responses to spatial development and water resource management by the post-apartheid government. The study finds that there are equity dimensions to the water security challenges in Hammanskraal. Contextually, the legacy of apartheid’s policy of separate and uneven development, coupled with contemporary failings of the implementation of the National Water Act, impact water access. In terms of water governance, while factors such as climate change and urbanisation are contributing determinants, the water security challenges in Hammanskraal are fundamentally the result of institutional failings that include lack of planning and investment as well as lack of infrastructure maintenance. The implications for South Africa in general is that failure to resolve water inequities and to strengthen water governance will result in the reproduction and persistence of structural inequalities. Key recommendations of the study include the expansion of the Temba Water Purification Plant, strengthening and coordination of institutions for water security, the setting of water allocation ceilings in Gauteng municipalities and investment in alternative water sources and tools for water conservation. The study also recommends further study into the extent to which water security challenges impact social unrest in South Africa. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2024
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  • Date Issued: 2024-10-11

Analysis of saprolite-hosted Rutile-Graphite deposit: a case study of Malingunde saprolite-hosted Rutile-Graphite project in Central Malawi

  • Authors: Zabula, Ansel Aliko
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/464970 , vital:76562
  • Description: The Malingunde graphite project, owned by Sovereign Metals Ltd (SML), has revealed significant potential for rutile and high-grade graphite in saprolite. This study addresses the complexity of mineral assemblages in the Malingunde area, emphasizing the coexistence of graphite and rutile. SML's exploration activities, including extensive drilling and soil sampling, have uncovered variations in associated minerals, such as muscovite, kyanite, garnets, and ilmenite. Rutile, initially discovered incidentally, has prompted further investigation, impacting the financial model of the project. This research aims to analyse the Malingunde deposit, focusing on understanding its mineralogy, formation, and potential for elements like vanadium. Geological surveys reveal the distribution of graphite in the Precambrian to lower Palaeozoic age basement complex, hosted in saprolite resulting from tropical weathering of graphitic gneisses. Exploration techniques, including remote sensing, and geophysics, are crucial in targeting graphite and rutile deposits. Ground electromagnetic surveys, airborne electromagnetic data, and GIS applications aid in identifying and quantifying mineralised areas. Geochemical analysis and metallurgical tests further contribute to understanding the ore body and processing methods. Results indicate an inverse relationship between graphite and rutile concentrations, influencing the economic viability of different regions within the project area. Correlation matrices and regression analyses reveal distinct geological conditions influencing the association of vanadium and graphite in Lifidzi and Malingunde. The study concludes with exploration potential outside the Malingunde project, highlighting regional prospects and potential byproducts like vanadium pentoxide. The ongoing metallurgical tests and pilot plant design signify the project's evolution toward production. Additionally, neighbouring licenses show potential, emphasizing the need for comprehensive research to define and quantify resources in the region. This research provides valuable insights for the mining industry, informing strategies for exploration, resource assessment, and potential byproduct utilization in similar geological settings. , Thesis (MSc) -- Faculty of Science, Geology, 2024
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  • Date Issued: 2024-10-11

Analyzing Microsporidia sp. MB from sequence to biology: comprehensive exploration of the genome, protein structures, and functions through extensive bioinformatics analysis

  • Authors: Ang'ang'o, Lilian Mbaisi
  • Date: 2024-10-11
  • Subjects: Microsporidia , Whole genome sequencing , Proteins Structure , Symbiont , Malaria Prevention , Vector control
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/466480 , vital:76734 , DOI https://doi.org/10.21504/10962/466480
  • Description: Microsporidia are spore-forming intracellular organisms classified as the earliest divergent group within the Fungi kingdom. Microsporidia have been found widely affecting different hosts, including both vertebrates and invertebrates. The pathogenicity of microsporidia depends on their species and the host species they infect. Due to their obligate intracellular nature, microsporidia have extensively evolved. This is illustrated by their highly variable genome sizes and gene content. Being minimalist eukaryotes, the microsporidia genome is often associated with extreme gene reduction and compaction. However, these interesting microorganisms retain particular genes that help them acquire specific host nutrients, thereby relying heavily on their host for survival and proliferation. The mode of sexual reproduction of microsporidia has not been well-studied. Harnessing microsporidia in the laboratory is often a challenge, however, the advances in computational tools have made it cheaper and quicker to accurately predict and annotate these organisms to understand their mechanism of infection. Understanding the protein structure and function of these unique organisms is the baseline for providing insights into their biology and survival in their respective hosts. Microsporidia genomes contain a large proportion of hypothetical proteins of which their functions are not described. Vittaforma corneae ATCC 50505 was used as a model to highlight the functions and structure of these otherwise unknown proteins. A systematic annotation pipeline employing exhaustive computational tools was devised to carefully annotate the hypothetical proteins of V. corneae, aiming to characterize their structure and function.The genome of the novel microsporidian, Microsporidia sp. MB, a Plasmodium-transmission-blocking symbiont isolated from Anopheles mosquitoes in Sub-Saharan Africa, was sequenced, assembled, and annotated. The genome was found to contain over 2000 putative genes spanning its 5.9 Mb size and contained minimal repeats. Comparative phylogenomic analysis of Microsporidia sp. MB grouped this symbiont within the Enterocytozoonida (clade IV) microsporidia, clustering with its closest relative – V. corneae. Using robust computational techniques, prediction and characterization of the putative proteins of Microsporidia sp. MB was conducted. The decay of several proteins in the glycolytic pathway is one unique characteristic associated with microsporidia. The proteins retained or lost often vary across the microsporidian taxon. This study highlights the retention of most of the proteins involved in the glycolytic pathway in Microsporidia sp. MB. The available genome dataset of Microsporidia sp. MB was further used to infer its mode of sexual reproduction. The symbiont appears to have several meiotic-related gene orthologs, suggesting that it is capable of sexual reproduction. These findings describe the basic biology of Microsporidia sp. MB and provide a basis for future Next-Generation Sequencing, RNA sequencing experiments ultimately informing the application of this microorganism as a biological malaria control tool. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Bioinformatics, 2024
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  • Date Issued: 2024-10-11

Application of SWAT+ model to assess the hydrology of irrigated agricultural catchments in Western Cape, South Africa

  • Authors: Mabohlo, Sakikhaya
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/464986 , vital:76563
  • Description: Agricultural activities can modify hydrological processes in catchments. An in-depth investigation of the impact of agriculture on hydrological processes is thus crucial for sustainable water management and utilisation planning in agricultural catchments. Hydrological models are widely used as practical tools to estimate and understand hydrological processes at various scales in catchments. However, it is often challenging to represent hydrological processes accurately in agriculture-dominated areas due to their complexity and the structural inadequacy of models. Complexities driven by agricultural developments such as reservoirs, cultivation irrigation, and water transfers are often intricate and difficult to represent in detail. The current study applied the SWAT+ hydrological model to the agriculture-dominated Twee and Leeu catchments in the Western Cape Province of South Africa. The SWAT+ model was preferred because it is versatile in representing multiple reservoirs and irrigation from multiple sources. The model application aimed to enhance the understanding of hydrological processes and the impact of agricultural water use on catchment hydrology, explore the capabilities and performance of this relatively new version of the SWAT in a complex catchment and provide baseline hydrology input for systems models that were used to formulate a water management plan for the catchment. The SWAT+ model was able to represent the significant number of reservoirs in the catchment. In some cases, small farm dams had to be lumped together to deal with the model's structural inadequacy. The model performed well in terms of observed and simulated streamflow comparison. NSE and R2 values above the standard of 0.5 were obtained for both catchments. Moreover, an NSE of 0.7 at a daily time-step simulation was obtained for the Leeu Catchment validation period, indicating a generally impressive SWAT+ performance. The model indicated that hydrological processes in the area were largely dominated by evapotranspiration, which is expected of semi-arid regions. 55% of the total water input into the Twee quaternary catchment is lost through evapotranspiration, while 22% is converted into surface runoff. Interflow and groundwater flow account for 9% and 9% of the catchment water, respectively. The remaining 5% is distributed to soil moisture and groundwater storage. For the Leeu, the model simulated a loss of 67% of the precipitation through evapotranspiration. Interflow and surface runoff were estimated to be 25% and 24%, respectively. Groundwater contribution to the stream accounts for 7%. Therefore, evapotranspiration and surface runoff are the dominant processes from a water balance perspective, whereas groundwater flow is also significant. Agricultural activities impacted the hydrological system significantly, and this is mainly attributed to the construction of numerous reservoirs and the subsequent intensive irrigation in the dry summer periods. The model simulation revealed that the reservoir and irrigation reduced the annual average streamflow by 71% in the Twee Catchment. In the Leeu Catchment, reservoirs and irrigation resulted in an annual average streamflow reduction of 77%. Therefore, agriculture has significantly altered flow patterns in the catchment, particularly downstream areas, during drier years. In conclusion, understanding of hydrological processes, reservoir and irrigation impact on catchment flow dynamics are the key outcomes that support decision-making regarding sustainable water management and utilisation planning. The broader outcomes, including spatially distributed flows and irrigation demand for different crop types, were used as baseline inputs for systems models that explored various water management options. SWAT+ thus played a crucial role in developing a water management plan for the area. Although the model exhibited some structural deficiencies in representing some catchment complexities, it fairly represented and enhanced our understanding of the hydrological dynamics of the Twee and Leeu Catchments. Additionally, the model has proven to be a versatile tool that can be applied for practical catchment water management in the agriculture-dominated catchments of South Africa. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2024
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  • Date Issued: 2024-10-11

Artificial Intelligence (AI) and blockchain technologies in advancing sustainable healthcare development in Kenya: a critique of dependency theory

  • Authors: Monethi, Tlhokomelo Brigette Rethabile
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/466016 , vital:76677
  • Description: This thesis explores the transformative potential of artificial intelligence (AI) and blockchain technologies in advancing healthcare delivery in Kenya through a critique of Dependency Theory. It investigates how these technologies contribute to improving accessibility, efficiency, and quality of care—particularly in underserved regions, while also addressing the structural dependencies that limit Kenya’s healthcare autonomy. Using a qualitative methodology, this study examines five case studies—Sophie Bot, Ilara Health, Tambua Health, AfyaRekod, and PanaBIOS—to highlight both the opportunities and challenges AI and blockchain present in reducing external reliance. Although AI-powered diagnostics and blockchain-based patient data management systems have revolutionised healthcare in Kenya, these technologies remain dependent on foreign capital and expertise for their development and maintenance. The research finds that while AI and blockchain technologies offer a path to leapfrog traditional barriers in healthcare delivery, their implementation critiques traditional notions of dependency theory. Nonetheless, the thesis identifies significant ethical considerations—including digital inequality, data privacy, and AI biases—that must be addressed to ensure equitable, self-sufficient healthcare provision. This study concludes with recommendations for fostering technological autonomy in Kenya's healthcare system, focusing on building local capacity, addressing infrastructural challenges, and aligning AI and blockchain integration with ethical and socio-cultural contexts. By doing this, this research contributes to the broader discourse on technology and healthcare in developing nations, offering pathways for reducing dependency and achieving sustainable healthcare development in Kenya. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2024
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  • Date Issued: 2024-10-11

Aspects of the sustainability of the wild honeybush industry

  • Authors: McGregor, Gillian Kathleen
  • Date: 2024-10-11
  • Subjects: Cyclopia intermedia , Renewable natural resources South Africa , Sustainability , Local ecological knowledge , Harvesting
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/464266 , vital:76493 , DOI 10.21504/10962/464266
  • Description: Honeybush products are uniquely South African, derived from plants of the fynbos genus, Cyclopia. Cyclopia intermedia is the most widespread species, distributed across 11 496 km2 of the Cape Fold Mountains, and provided the bulk of supply for the industry until 2022. While the industry is small, it is a locally significant industry affecting the livelihoods of harvesters, farmers and processors in the greater Langkloof region of the Eastern and Western Cape provinces of South Africa. The industry has evolved from a cottage one, to a commercial scale, and concerns have been raised over the sustainability of the wild resource specifically, and the industry in general. The research aimed to improve our understanding of aspects of the sustainability of the wild honeybush industry. A mixed methods design was adopted, which allowed for the inclusion of data collection approaches and analysis which tell a richer story than one with a singular modus. Four objectives were identified, which entailed: (i) mapping the resource to establish the distribution range of C. intermedia; (ii) recording of local ecological knowledge (LEK) and traditional ecological knowledge (TEK) around best practice harvesting; (iii) assessing the sustainability of harvest enterprise types through analysis of yield history and harvester loads; (iv) identifying differences between harvested and unharvested C. intermedia populations. Mapping of the resource drew on a variety of existing data sources, field mapping, GIS-based analysis, species distribution modelling and expert mapping to create a comprehensive and accurate map of the species distribution. The species is estimated to occupy a distribution range of 11 496 km2, 49% of which occurs in formally protected areas. Based on local scale mapping by experts, 100km2 is estimated to be in use for wild harvesting in the production area of the Langkloof. Information on best practice harvesting was collected through in-depth interviews with harvesters, harvest managers, processors and farmers (in the field at harvest events) and through questionnaire surveys and focus group discussions at a honeybush stakeholder workshop. In combination with harvest event surveys at which harvester practice was observed and recorded, and surveys were conducted of the harvest yield and of plants in the harvested population, the information was used to produce the first formal account of best practice for sustainable harvesting of wild honeybush. To assess the sustainability of harvest enterprises and associated harvester livelihoods, harvester managers were interviewed to create profiles of typical harvesting enterprises based on their practices and harvest yield histories. Of the three harvest enterprises considered, two showed sustained yields over time, while those of a large contract type enterprise were less sustainable with declining yields on three out of six farms. From a statistical analysis of the records it was found that the most effective team size was 10 or less harvesters in terms of livelihood sustainability. They could earn a fair livelihood (ZAR67 680.00) per annum, based on a 94 kg load per daily harvest event, sold to the processor at ZAR 5.00, for nine months of the year, working a four-day week. For a team to operate sustainably, it was found that it should consist of experienced harvesters harvesting conservatively, at intervals of at least four years, and be responsive to local environmental conditions. Detailed field surveys of C. intermedia plants at 38 sites representing harvested and unharvested populations were carried out to understand the impact of harvesting on the plants. A statistical analysis of the plant's dimensions related to the physical environment, fire and harvest history using generalised linear models revealed that while unharvested plants were slightly larger, only crown diameter and stem counts were significantly so. Seedlings were noticeably scarce at all sites, including recently burnt sites. A significant finding of the research was that in a fecundity survey, unharvested plants produced significantly more pods. The impact of this is unknown, but it has implications for management and the sustainable use of wild resources in the long term. Further understanding of the impact of harvesting came from surveys of cultivated stands of C. intermedia (different ages and harvest histories, but all harvested at three-year intervals) and surveys of a wild population, which was subjected to unregulated harvesting. For the cultivated stand: after 12 years, plants declined in all measured dimensions, while in the wild population, 45% of the plants died over a seven-year period. The surveys proved that a three-year interval or frequent, unregulated harvest is unsustainable. The research was used to produce the wild harvesting guidelines, which have become the accepted standard for the industry. It has demonstrated that under the right circumstances, harvesting of the wild C. intermedia resource is broadly sustainable. However, there needs to be informed management of the use of the resource in terms of harvest team types and their protocols, particularly with regard to harvest intervals and possible interventions to improve seed production to achieve sustainable use of the resource in social, economic and ecological terms. , Thesis (PhD) -- Faculty of Science, Geography, 2024
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  • Date Issued: 2024-10-11

Aspects of the water use of Cannabis sativa L. under dryland cultivation in the Eastern Cape

  • Authors: Zenani, Kamva Trevor Songo
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/465035 , vital:76567
  • Description: Cannabis spp is one of the oldest cultivated plants, with its origin in Asia. It has two species, namely C. indica and C. sativa. This research focuses on C. sativa, which is widely cultivated locally and globally. C. sativa has a wide range of uses, including industrial, medicinal, religious, and recreational. This study will be focusing on the water use of medicinal and recreational C. sativa grown under dryland conditions. In recent years, there has been a growing interest in increasing its cultivation, but there are reports of it having high water usage. The global interest has led many governments to review the laws governing this plant as it is a controlled substance in many countries. Due to its legal status, there is a dearth of knowledge about its growth and water use. It is against this backdrop that the Water Research Commission (WRC) commissioned this study into the water use of this plant. This will provide evidence-based support for the issuing of water use licenses by the Department of Water and Sanitation. The Eastern Cape and KwaZulu Natal have many small-scale legacy farmers who have been growing C. sativa illegally for decades. The findings of this research will seek to fill some of these knowledge gaps and assist legacy farmers in the cultivation of this plant. This research had four approaches, which include 1) planting the crop in a dryland location that will mimic the conditions experienced by legacy growers, 2) the collection of plant biophysical variables in the study site in order to gain a better understanding of the plant’s health, growth, progress, and to use these variables to parameterize a mechanistic eco-physiological model, 3) the installing of a large aperture scintillometer (LAS) together with a micro-meteorological station to measure the evapotranspiration (ET) and meteorological parameters over a crop cycle, 4) to use MEDRUSH evapotranspiration model to predict the ET and compare these results against that of the LAS. The results show that water provision had a significant impact on plant biophysical variables and water use. The plants received 154 mm (2 mm day-1) of rain during the crop cycle. The large aperture scintillometer recorded a total ET of 126.8 mm (1.76 mm day-1) during the same period. The MEDRUSH model (2.5 mm day-1) overestimated the LAS ET (1.79 mm day-1), and the results from the daily ET revealed that C. sativa had higher daily ET when compared to the local grass Eragrostis plana. These results confirm that at this location in the Eastern Cape, C. sativa requires regular irrigation during the growing season to grow and secure a crop. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2024
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  • Date Issued: 2024-10-11

Assessing the impacts of Lantana camara and opportunities for ecological restoration after its removal: does clearing facilitate both soil and native vegetation recovery?

  • Authors: Bolosha, Uviwe
  • Date: 2024-10-11
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/466524 , vital:76738 , DOI https://doi.org/10.21504/10962/466524
  • Description: Invasive alien plants (IAPs) are one of the major contributing factors to biodiversity loss, and Lantana camara is among the top ten alien invaders worldwide. Lantana camara threatens native biodiversity and human health, prevents natural succession, and has an economic and environmental impact globally. With current climate change and future predictions, these IAPs are anticipated to continue posing huge threats to ecosystem composition, structure, and function. Even though L. camara is a widespread IAP, there is still limited knowledge in South Africa on how it influences soil physicochemical properties at the species level, vegetation communities, and soil seed banks at the community level following its invasion. There is also minimal knowledge on the management and control (i.e., clearing for restoration purposes) of L. camara in South Africa, especially in the Eastern Cape province of South Africa. To address the knowledge gap, this thesis was structured into three main aspects: understanding L. camara invasion mechanisms, evaluating invasion impacts on both the aboveground and belowground communities, and invasion management. The main objectives of this thesis were (i) to examine how L. camara invasion (at a species level) affected soil physicochemical properties across different seasons, (ii) to assess how L. camara influences natural vegetation (at a community level), (iii) to examine the effects of L. camara invasion (at the community level) on belowground soil seed banks and also assess the availability of pioneer native species and IAPs in the soil seed banks, and (iv) to evaluate soil and vegetation responses following L. camara clearing in comparison to invaded and uninvaded conditions. To answer these objectives, different studies were carried out in the Eastern Cape province, South Africa, on various farms within the Albany Thicket Biome. The results (Chapter 3) show that L. camara alters and modifies some soil physical properties, such as soil infiltration rate, repellency, and soil penetration resistance, in the communities it invades. A significant decrease in soil penetration under the L. camara canopy was observed compared to soils from the edge and out position. Moreover, significantly faster infiltration rates were observed in the canopy and edge positions than in the out position. The study also observed that these modifications in soil physical properties vary depending on the season. A seasonal comparison in soil penetration showed that soil was more compact in the dry season than the wet season, and significantly faster infiltration rates were observed in summer than in the other seasons. The soil collected under the invaded sampling positions was mostly wettable (80–100%), and not strongly, severely, or extremely repellent across all the seasons. The changes in soil properties caused by L. camara could create favourable conditions for its growth and invasion. Seasonal changes in soil properties also highlight how environmental conditions, especially temperature and rainfall patterns, can affect soil physical properties. The findings in Chapter 4 observed both the negative and positive impacts of L. camara, where the species did not have negative effects on species richness, diversity, or cover of some native species growth forms (i.e., graminoids and forbs). For all species, both species richness and Shannon-Wiener (H’) were significantly higher in the L. camara invaded condition compared to the uninvaded condition. The Simpson’s (J’) and Pielou’s evenness (D’) indices, however, showed no differences between the invasion conditions. Furthermore, the effects of L. camara on vegetation cover were growth form-dependent, with differences being noted for trees and shrubs but not for graminoids and forbs. Changes in vegetation structure and composition were also noted where L. camara created favourable conditions for some species to co-occur with it, meaning that its known trait of changing soil physicochemical properties could benefit some species. Generally, the results of this study showed that the effects of L. camara on vegetation are varied and do not have a predictable pattern, so they should not be generalised. The findings (Chapter 5) also indicate that the L. camara invasion had a negative impact on seedling abundance and composition but not species diversity and richness. This is evident through the decrease in seedling abundance of forbs and graminoids in the L. camara invaded condition. Lantana camara also acted as a refuge for some plant species, mostly native forbs and grasses, including Aptenia cordifolia, Chamaesyce prostrata, Oxalis spp., and Setaria spp., as well as alien forbs such as Bidens pilosa, Plantago lanceolata, and Taraxacum officinale, suggesting L. camara does not entirely eliminate less competitive plant species but can co-exist with them. Lantana camara also displaced some native species, and this could be associated with their displacement in the standing vegetation. Moreover, the species also displaced the seed banks of some alien species, thus showing its competitive ability. Overall, L. camara invasion negatively influenced soil seed bank seedling abundance and composition of some species, but not diversity and richness. The results in Chapter 6 indicated that clearing L. camara is an effective method for reducing its population. However, our findings suggest that clearing alone may not be enough to re-establish these communities with native species. This is because the results of this study showed varied changes in soil properties and native vegetation (species richness, species diversity, percentage cover, and composition) after L. camara clearing. For example, soil moisture and soil penetration resistance showed no significant differences among the invasion conditions; only monthly variations were observed. This is an indication that seasonality influenced these properties. Significantly lower soil infiltration rates were observed in the cleared condition compared to the other conditions and were influenced by the months and the interaction of the clearing conditions and months. The water droplet penetration time showed no significant difference among the clearing conditions over the three months, and all the soil collected from the three clearing conditions was mostly wettable. Soil chemical properties showed that the L. camara invaded and cleared conditions had significantly lower soil pH compared to the uninvaded condition, and an increase in soil pH was observed after clearing L. camara. Vegetation characteristics showed that both the Shannon-Wiener index (H') and the Simpson’s index (D') were lower in the invaded and cleared conditions compared to the uninvaded condition, and significant differences were observed. A slight increase in the H' and D' indices was also observed after clearing L. camara. The mean percentage cover for trees and shrubs was significantly higher in the invaded condition than in the cleared and uninvaded conditions. However, the mean percentage cover of forbs and graminoids was similar among the invaded, cleared, and uninvaded conditions, and no significant differences were observed. When L. camara was cleared, native species recovery was observed and was more notable in the understory species. Overall, some signs of vegetation recovery were observed, although challenges such as secondary invaders and re-invasion by L. camara were noted in the cleared areas. This chapter then concluded that active restoration interventions should be incorporated during restoration to fast-track soil and vegetation recovery. The findings of this thesis will make several significant contributions to the field of biological invasions and provide baseline information that can be used in future studies. These are discussed in the various research chapters. Overall, the thesis concludes that L. camara invasion has varied impacts on native vegetation and soil, and its clearance, should be prioritised to reduce the negative impacts. However, L. camara cleared areas (by WfW in South Africa) require follow-up and monitoring at an early stage to assess vegetation and soil restoration success. In addition, active management measures after L. camara’s removal should be considered for clearing programmes to yield positive ecosystem recovery. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2024
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  • Date Issued: 2024-10-11
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