An enterprise architecture for environmental information management and reporting
- Authors: Van der Hoogen, Anthea
- Date: 2013
- Subjects: Business enterprises -- Information technology -- Management , Sustainable development reporting , Environmental reporting
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:10499 , http://hdl.handle.net/10948/d1021040
- Description: Organisations globally are communicating their environmental sustainability impact to stakeholders by means of the widely used sustainability report. A key benefit of environmental sustainability reporting is that organisations can gain a positive reputation when these reports are presented to stakeholders. Organisations in South Africa are faced with many challenges regarding managing sustainability information and producing an environmental sustainability report. Two of the primary challenges are the many diverse standards for sustainability reporting and data quality issues. Information Technology (IT) can be used to support and improve the process of sustainability reporting but it is important to align the environmental sustainability strategies with the strategies of business and also with the IT strategy to avoid silos of information and reporting. Enterprise Architecture (EA) can be used to solve alignment problems since it supports business-IT alignment. EA is defined by the International Standards Organisation (ISO) as “The fundamental concepts or properties of a system in its environment embodied in its elements, relationships, and in the principles of its design and evolution”. It can be argued, therefore, that EA can be used to support environmental sustainability information management and the reporting process by means of its support of improved business-IT alignment and ultimately integrated systems. The main objective of this study is to investigate how EA can be used to support environmental information management (EIM) and reporting. A survey study of thirty one prominent South African organisations was undertaken in order to investigate the status of their EA adoption and environmental reporting and EIM processes. An EA for EIM Toolkit and a set of guidelines are proposed which can provide support for EIM through the use of EA. These guidelines were proposed based on best-practice for each of the three process levels of an organisation, namely, the strategic level, the operational level and the technological level. The toolkit and guidelines were derived from theory and the results of the industry survey were then validated by an in-depth analysis of a case study consisting of multiple cases with key employees of seven South African organisations which have proved to be successful at EA and EIM and reporting. The results of the case study show that the EA for EIM Toolkit and related guidelines can assist organisations to align their environmental sustainability strategies with their organisational and IT strategies.
- Full Text:
- Date Issued: 2013
- Authors: Van der Hoogen, Anthea
- Date: 2013
- Subjects: Business enterprises -- Information technology -- Management , Sustainable development reporting , Environmental reporting
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:10499 , http://hdl.handle.net/10948/d1021040
- Description: Organisations globally are communicating their environmental sustainability impact to stakeholders by means of the widely used sustainability report. A key benefit of environmental sustainability reporting is that organisations can gain a positive reputation when these reports are presented to stakeholders. Organisations in South Africa are faced with many challenges regarding managing sustainability information and producing an environmental sustainability report. Two of the primary challenges are the many diverse standards for sustainability reporting and data quality issues. Information Technology (IT) can be used to support and improve the process of sustainability reporting but it is important to align the environmental sustainability strategies with the strategies of business and also with the IT strategy to avoid silos of information and reporting. Enterprise Architecture (EA) can be used to solve alignment problems since it supports business-IT alignment. EA is defined by the International Standards Organisation (ISO) as “The fundamental concepts or properties of a system in its environment embodied in its elements, relationships, and in the principles of its design and evolution”. It can be argued, therefore, that EA can be used to support environmental sustainability information management and the reporting process by means of its support of improved business-IT alignment and ultimately integrated systems. The main objective of this study is to investigate how EA can be used to support environmental information management (EIM) and reporting. A survey study of thirty one prominent South African organisations was undertaken in order to investigate the status of their EA adoption and environmental reporting and EIM processes. An EA for EIM Toolkit and a set of guidelines are proposed which can provide support for EIM through the use of EA. These guidelines were proposed based on best-practice for each of the three process levels of an organisation, namely, the strategic level, the operational level and the technological level. The toolkit and guidelines were derived from theory and the results of the industry survey were then validated by an in-depth analysis of a case study consisting of multiple cases with key employees of seven South African organisations which have proved to be successful at EA and EIM and reporting. The results of the case study show that the EA for EIM Toolkit and related guidelines can assist organisations to align their environmental sustainability strategies with their organisational and IT strategies.
- Full Text:
- Date Issued: 2013
Structural analysis of synthetic ferrihydrite nanoparticles and its reduction in a hydrogen atmosphere
- Authors: Masina, Colani John
- Date: 2013
- Subjects: Ferric hydroxides , Minerals -- Analysis , Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10555 , http://hdl.handle.net/10948/d1020796
- Description: Ferrihydrite (FHYD), a nanocrystalline material has long been described as a poorly crystalline disordered mineral mainly due to its small crystal size which is typically 2−6 𝑛𝑚. The three-dimensional structure of the mineral has long been described by a multi-phase structural model that consists of Fe3+ only in octahedral (Oh) coordination. In this model ferrihydrite is described as a mixture of two major phases (akaganeite/goethite-like f-phase and feroxyhite-like d-phase) and a minor ultradispersed nanohematite phase. This model has been recently challenged and a new, single-phase model was proposed, having a basic structural motif closely related to the Baker-Figgs δ-Keggin cluster and is isostructural with the mineral akdalaite, Al10O14(OH)2. In its ideal form, the proposed new structure of FHYD consist of 80 % Oh and 20 % tetrahedral (Td) Fe3+ polyhedra which can be adequately described by a single-domain model with the hexagonal spacegroup 𝑃63𝑚𝑐 and unit cell dimensions 𝑎=5.95 Å and 𝑐=9.06 Å. In this study, nanoparticles of 2-line FHYD (FHYD2), 2-line FHYD deposited onto SiO2 (FHYD2/SiO2) and 6-line FHYD (FHYD6) synthesised using rapid hydrolysis of Fe(NO3)3.9H2O solutions were characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), Mössbauer spectroscopy (MS) as well as magnetization and magnetic susceptibility measurements. The coordination environment of iron atoms in the structure of FHYD was investigated using TEM and MS. The thermal transformation of FHYD nanoparticles was monitored through changes in the magnetization as a function of temperature and the reduction behaviour in hydrogen environment was studied using temperature programmed reduction (TPR), in-situ XRD and MS. Electron diffraction, TEM/ scanning TEM (STEM) imaging, and electron energy loss (EELS) measurements were carried out on three different microscopes viz. JEOL JEM-2100 LaB6 TEM, aberration corrected Schottky-FEG JEOL JEM-ARM200F HRTEM and cold-FEG Zeiss SESAM TEM. EELS studies were concentrated mainly on the iron 𝐿-edge of FHYD and iron oxides reference spectra with well known crystal structures. The iron oxide Fe 𝐿-edge is usually characterized by two intense sharp peaks termed “white lines”. The fine structures introduced by the crystal field effect on the 𝐿- edge contain information that is highly specific to the Fe3+ site symmetry.
- Full Text:
- Date Issued: 2013
- Authors: Masina, Colani John
- Date: 2013
- Subjects: Ferric hydroxides , Minerals -- Analysis , Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10555 , http://hdl.handle.net/10948/d1020796
- Description: Ferrihydrite (FHYD), a nanocrystalline material has long been described as a poorly crystalline disordered mineral mainly due to its small crystal size which is typically 2−6 𝑛𝑚. The three-dimensional structure of the mineral has long been described by a multi-phase structural model that consists of Fe3+ only in octahedral (Oh) coordination. In this model ferrihydrite is described as a mixture of two major phases (akaganeite/goethite-like f-phase and feroxyhite-like d-phase) and a minor ultradispersed nanohematite phase. This model has been recently challenged and a new, single-phase model was proposed, having a basic structural motif closely related to the Baker-Figgs δ-Keggin cluster and is isostructural with the mineral akdalaite, Al10O14(OH)2. In its ideal form, the proposed new structure of FHYD consist of 80 % Oh and 20 % tetrahedral (Td) Fe3+ polyhedra which can be adequately described by a single-domain model with the hexagonal spacegroup 𝑃63𝑚𝑐 and unit cell dimensions 𝑎=5.95 Å and 𝑐=9.06 Å. In this study, nanoparticles of 2-line FHYD (FHYD2), 2-line FHYD deposited onto SiO2 (FHYD2/SiO2) and 6-line FHYD (FHYD6) synthesised using rapid hydrolysis of Fe(NO3)3.9H2O solutions were characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), Mössbauer spectroscopy (MS) as well as magnetization and magnetic susceptibility measurements. The coordination environment of iron atoms in the structure of FHYD was investigated using TEM and MS. The thermal transformation of FHYD nanoparticles was monitored through changes in the magnetization as a function of temperature and the reduction behaviour in hydrogen environment was studied using temperature programmed reduction (TPR), in-situ XRD and MS. Electron diffraction, TEM/ scanning TEM (STEM) imaging, and electron energy loss (EELS) measurements were carried out on three different microscopes viz. JEOL JEM-2100 LaB6 TEM, aberration corrected Schottky-FEG JEOL JEM-ARM200F HRTEM and cold-FEG Zeiss SESAM TEM. EELS studies were concentrated mainly on the iron 𝐿-edge of FHYD and iron oxides reference spectra with well known crystal structures. The iron oxide Fe 𝐿-edge is usually characterized by two intense sharp peaks termed “white lines”. The fine structures introduced by the crystal field effect on the 𝐿- edge contain information that is highly specific to the Fe3+ site symmetry.
- Full Text:
- Date Issued: 2013
Nonlinear effects with a focus on cross phase modulation and its impact on wavelength division multiplexing optical fibre networks
- Gamatham, Romeo Reginald Gunther
- Authors: Gamatham, Romeo Reginald Gunther
- Date: 2013
- Subjects: Wavelength division multiplexing , Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6302 , vital:21071
- Description: The demand for faster data transmission is ever increasing. Wavelength division multiplexing (WDM) presents as a viable solution to increase the data transmission rate significantly. WDM systems are based on the ability to transmit multiple wavelengths simultaneously down the fibre. Unlike time division multiplexing (TDM) systems, WDM systems do not increase the data transfer by increasing the transmission rate of a single channel. In WDM systems the data rate per channel remains the same, only multiple channels carry data across the link. Dense wavelength division multiplexing (DWDM) promises even more wavelengths packed together in the same fibre. This multiplication of channels increases the bandwidth capacity rapidly. Networks are looking into making use of technology that will ensure no electronic signal regeneration at any point within the DWDM network. Examples are; reconfigurable optical add/drop multiplexers (ROADM) and optical cross connect (OXC) units. These components essentially enable network operators to split, combine and multiplex optical signals carried by optical fibre. WDM allows network operators to increase the capacity of existing networks without expensive re-cabling. This provides networks with the flexibility to be upgraded to larger bandwidths and for reconfiguration of network services. Further, WDM technology opens up an opportunity of marketing flexibility to network operators, where operators not only have the option to rent out cables and fibres but wavelengths as well. Cross phase modulation (XPM) poses a problem to WDM networks. The refractive index experienced by a neighbouring optical signal, not only depends on the signal’s intensity but on the intensity of the co-propagating signal as well. This effect leads to a phase change and is known as XPM. This work investigates the characteristics of XPM. It is shown that, in a two channel WDM network, a probe signal’s SOP can be steered by controlling a high intensity pump signal’s SOP. This effect could be applied to make a wavelength converter. Experimental results show that the degree of polarization (DOP) of a probe signal degrades according to a mathematical model found in literature. The pump and probe signals are shown to experience maximum interaction, for orthogonal probe-pump SOP vector orientations. This may be problematic to polarization mode dispersion compensators. Additionally, experimental results point out that the SOP of a probe signal is much more active in the presence of a high intensity pump, as compared to the single signal transmission scenario.
- Full Text:
- Date Issued: 2013
- Authors: Gamatham, Romeo Reginald Gunther
- Date: 2013
- Subjects: Wavelength division multiplexing , Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6302 , vital:21071
- Description: The demand for faster data transmission is ever increasing. Wavelength division multiplexing (WDM) presents as a viable solution to increase the data transmission rate significantly. WDM systems are based on the ability to transmit multiple wavelengths simultaneously down the fibre. Unlike time division multiplexing (TDM) systems, WDM systems do not increase the data transfer by increasing the transmission rate of a single channel. In WDM systems the data rate per channel remains the same, only multiple channels carry data across the link. Dense wavelength division multiplexing (DWDM) promises even more wavelengths packed together in the same fibre. This multiplication of channels increases the bandwidth capacity rapidly. Networks are looking into making use of technology that will ensure no electronic signal regeneration at any point within the DWDM network. Examples are; reconfigurable optical add/drop multiplexers (ROADM) and optical cross connect (OXC) units. These components essentially enable network operators to split, combine and multiplex optical signals carried by optical fibre. WDM allows network operators to increase the capacity of existing networks without expensive re-cabling. This provides networks with the flexibility to be upgraded to larger bandwidths and for reconfiguration of network services. Further, WDM technology opens up an opportunity of marketing flexibility to network operators, where operators not only have the option to rent out cables and fibres but wavelengths as well. Cross phase modulation (XPM) poses a problem to WDM networks. The refractive index experienced by a neighbouring optical signal, not only depends on the signal’s intensity but on the intensity of the co-propagating signal as well. This effect leads to a phase change and is known as XPM. This work investigates the characteristics of XPM. It is shown that, in a two channel WDM network, a probe signal’s SOP can be steered by controlling a high intensity pump signal’s SOP. This effect could be applied to make a wavelength converter. Experimental results show that the degree of polarization (DOP) of a probe signal degrades according to a mathematical model found in literature. The pump and probe signals are shown to experience maximum interaction, for orthogonal probe-pump SOP vector orientations. This may be problematic to polarization mode dispersion compensators. Additionally, experimental results point out that the SOP of a probe signal is much more active in the presence of a high intensity pump, as compared to the single signal transmission scenario.
- Full Text:
- Date Issued: 2013
Strategic adaptive management and the efficiency of invasive alien plant management in South African national parks
- Authors: Loftus, Wynand Johan
- Date: 2013
- Subjects: Biodiversity -- South Africa -- Management , Alien plants -- South Africa , Invasive plants -- South Africa , Ecosystem management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10755 , http://hdl.handle.net/10948/d1020089
- Description: It is well known that invasive alien plants (IAPs) pose a significant threat to natural biodiversity and human well-being. Through various pressures exerted on natural ecosystems, IAPs decrease and alter natural processes that provide important ecosystems services and livelihoods to human communities. These plants also displace and out-compete natural plant communities in the areas in which they invade. Management of IAPs is a complex issue with social, environmental and financial challenges. The long-term sustainable management of IAPs requires a management approach that monitors and measures the outcomes of current management practices, and considers the lessons learnt in future decision making. Adaptive management is such an approach and is characterised by monitoring, assessment, reflection and adaptation. In this dissertation I explore IAP management within the South African National Parks (SANParks) organisation. I focus on the quality of the available IAP clearing data for monitoring and environmental decision-making and explore how strategic adaptive management (SAM) is being applied to IAP management. Strategic adaptive management is a form of adaptive management that SANParks adopted to deal with the inherent unpredictability of the social ecological systems they manage, and is primarily a learning-by-doing approach. In chapter one I describe the various impacts that IAPs have on natural environments. I also discuss management of IAPs, the national Working for Water (WfW) programme and how SANParks control IAPs in partnership with WfW. Clearing of IAPs within the borders of SANParks is funded by the Department of Environmental Affairs‘ (DEA) Natural Resource Management programmes and carried out through the Working for Water programme, under SANParks‘ Biodiversity Social Projects programme and is done on a contract basis. Contract data are stored in the Working for Water Information Management System (WIMS) database. Although IAP clearing is well established, the efficiency of overall clearing operations within the parks, and quality and reliability of the data available in the WIMS, needs to be examined. In Chapter two, I (i) assess the status of IAP clearing and the direct clearing costs in each of the five national parks (costs are inflated to 2012 equivalents using the consumer price index), (ii) assess the accuracy of workload estimations for WfW IAP clearing, and (iii) discuss the utility of WIMS as a system to collate and store accurate data for monitoring purposes, focusing on the integrity and reliability of the data, the accuracy of density estimations and whether it can inform sound decision making. The planning of future clearing contracts lacks efficiency due to inaccuracies and unreliability of input data, specifically estimates of invasive alien plant density. The accuracy of density estimation and cost of clearing varies greatly between parks and does not appear to reflect the reality on the ground. In Chapter 3, through an interview process with IAP managers, I 1) unpack the steps in the SAM ‗cycle‘ and investigate the effectiveness of implementation of each step according to respondents; 2) assess the barriers that are currently keeping managers from implementing effective IAP management; 3) discuss whether learning and adaptation is taking place, and 4) discuss how the SAM process can be modified to promote its effectiveness.
- Full Text:
- Date Issued: 2013
- Authors: Loftus, Wynand Johan
- Date: 2013
- Subjects: Biodiversity -- South Africa -- Management , Alien plants -- South Africa , Invasive plants -- South Africa , Ecosystem management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10755 , http://hdl.handle.net/10948/d1020089
- Description: It is well known that invasive alien plants (IAPs) pose a significant threat to natural biodiversity and human well-being. Through various pressures exerted on natural ecosystems, IAPs decrease and alter natural processes that provide important ecosystems services and livelihoods to human communities. These plants also displace and out-compete natural plant communities in the areas in which they invade. Management of IAPs is a complex issue with social, environmental and financial challenges. The long-term sustainable management of IAPs requires a management approach that monitors and measures the outcomes of current management practices, and considers the lessons learnt in future decision making. Adaptive management is such an approach and is characterised by monitoring, assessment, reflection and adaptation. In this dissertation I explore IAP management within the South African National Parks (SANParks) organisation. I focus on the quality of the available IAP clearing data for monitoring and environmental decision-making and explore how strategic adaptive management (SAM) is being applied to IAP management. Strategic adaptive management is a form of adaptive management that SANParks adopted to deal with the inherent unpredictability of the social ecological systems they manage, and is primarily a learning-by-doing approach. In chapter one I describe the various impacts that IAPs have on natural environments. I also discuss management of IAPs, the national Working for Water (WfW) programme and how SANParks control IAPs in partnership with WfW. Clearing of IAPs within the borders of SANParks is funded by the Department of Environmental Affairs‘ (DEA) Natural Resource Management programmes and carried out through the Working for Water programme, under SANParks‘ Biodiversity Social Projects programme and is done on a contract basis. Contract data are stored in the Working for Water Information Management System (WIMS) database. Although IAP clearing is well established, the efficiency of overall clearing operations within the parks, and quality and reliability of the data available in the WIMS, needs to be examined. In Chapter two, I (i) assess the status of IAP clearing and the direct clearing costs in each of the five national parks (costs are inflated to 2012 equivalents using the consumer price index), (ii) assess the accuracy of workload estimations for WfW IAP clearing, and (iii) discuss the utility of WIMS as a system to collate and store accurate data for monitoring purposes, focusing on the integrity and reliability of the data, the accuracy of density estimations and whether it can inform sound decision making. The planning of future clearing contracts lacks efficiency due to inaccuracies and unreliability of input data, specifically estimates of invasive alien plant density. The accuracy of density estimation and cost of clearing varies greatly between parks and does not appear to reflect the reality on the ground. In Chapter 3, through an interview process with IAP managers, I 1) unpack the steps in the SAM ‗cycle‘ and investigate the effectiveness of implementation of each step according to respondents; 2) assess the barriers that are currently keeping managers from implementing effective IAP management; 3) discuss whether learning and adaptation is taking place, and 4) discuss how the SAM process can be modified to promote its effectiveness.
- Full Text:
- Date Issued: 2013
Exploring interventions for participation of emerging farmers in the Eastern Cape ostrich-industry supply chain
- Authors: Pittaway, Timothy
- Date: 2013
- Subjects: Farmers -- South Africa -- Eastern Cape , Ostrich products industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10596 , http://hdl.handle.net/10948/d1021008
- Description: The changing agricultural environment (dualistic agricultural landscape, land reform programme, market liberalisation and globalisation) has caused emerging ostrich farmers to become increasingly isolated. Governmental agriculture reforms and public sector interventions have been insufficient to address all the challenges faced by rural ostrich farmers in the Eastern Cape. Participation in the ostrich supply chain for emerging farmers in the Eastern Cape is currently unsustainable as a result of avian influenza, control and registration protocols for ostriches (VPN04), structural barriers in marketing, technical constraints and a lack of market participation. People in the rural areas of the Eastern Cape are challenged by inferior infrastructure, poor site conditions, low earnings, poor access to health services and unreliable water sources. The marginal conditions and prevalent complexities in which agriculture is practised require costly resource intervention. Intensive ostrich production necessitates continuous genetic improvement, methodical record keeping, intensive egg incubation methods and highmaintenance chick rearing and ostrich handling while minimising feed costs throughout this process. Rural farmers have not embraced ostrich farming in the same way as they have done with other livestock farming because it does not offer the anthropological functions that traditional livestock farming provides. The ostrich supply chain requires a wide range of activities to bring products to the final consumer. The worth of ostrich production lies mainly in the higher returns which are achieved only through the export markets. Today the ostrich industry has become vulnerable to market cannibalism, a lack of market development, unregulated numbers of ostriches and recurring international meat bans. The deregulation of the ostrich single-channel marketing system had a substantial effect on the value chain on which farmers depended for market access and market protection. As the majority of ostrich products are being exported to the European Union, the role of intermediary agencies is becoming an important factor influencing entry into the high-end markets. This agent structure that represents the South African ostrich industry is vital for the distribution, market penetration and regulation of the ostrich products. The ostrich leather, which is today the main product line, is primarily used for luxury goods and is susceptible to economic downturn and over-supply. The ostrich meat industry has been severely influenced by outbreaks of avian influenza and processors now pre-heat the meat in order to maintain export. However, this preheating meat facility is only for export produce and available to farmers who conform to VPN04 and have officially registered farms. The relevant South African government departments played a crucial role in identifying avian influenza outbreaks and liaising with the European Union about avian influenza isolation strategies. No previous studies have been conducted on the participation of emerging farmers in the Eastern Cape ostrich-industry supply chain and on the interventions required to address the multiple constraints and forces in this sector. This led to a study with research emphasis on the required capacity for supply-chain participation and the supporting mechanisms that would be required for emerging ostrich farmers to integrate successfully into this supply chain. An exploratory research approach was chosen for the investigation, as no earlier research has been undertaken that could serve as a source of reliable data or reference. A triangulation research methodology using both the quantitative and the qualitative approach was applied. The qualitative research entailed an interpretive approach associated with using grounded theory and content analysis for interpreting data. The comparative case study design was the main qualitative research instrument for the multiple-case studies on emerging ostrich farmers in the Eastern Cape. The study was undertaken at five different sites, namely, the Peddie Ostrich Programme, the Rockhurst Ostrich Programme, the Hlumani Co-operative farm, the Zamukwanda Ostrich farm near Pearston and the Mimosadale Ostrich farm. The quantitative methods were applied to capture all the measurable components and representations of the stakeholders and participants, through interviews, questionnaires and focus group interviews. The quantitative study also included an experimental instrument to measure the capacity of emerging farmer programmes for supply chain participation. It was found that the main driver for three of the case studies pertained to land ownership and that ostrich farming was incidental and only seen as means of activity for income. These three humanitarian farming projects had limited capacity for intensive management requirements for ostrich farming. It was found that the VPN04 bio-security protocols and disease control require a higher level of record keeping for EU markets and is prohibitively expensive for poor rural emerging farmers. The study established that the emerging ostrich farming programmes contributed value to the industry and government rural development in land redistribution programmes, vehicles for reduction of poverty and job creation in the rural areas and by acting as out-grower programmes for commercial farmers. The researcher’s observation is that through strategic interventions the programmes have potential to become commercial players in the industry. The following interventions were recommended from this study: Feasibility study of programmes and review of location selection before initiation. Providing supportive interventions for programme start-ups; Improved selection of programme beneficiaries; Improved structure of emerging farmers’ co-operatives; On-going and appropriate training for emerging ostrich farmers; The role of government and mentors needs to be defined; Reducing feed costs; Establishing programmes linkages to informal markets and facilitating increased self-consumption; Developing new export markets; Alternative finance for the no-income months; Alternative marketing channels to export markets; Representation of emerging farmers in the ostrich-industry leadership structures.
- Full Text:
- Date Issued: 2013
- Authors: Pittaway, Timothy
- Date: 2013
- Subjects: Farmers -- South Africa -- Eastern Cape , Ostrich products industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10596 , http://hdl.handle.net/10948/d1021008
- Description: The changing agricultural environment (dualistic agricultural landscape, land reform programme, market liberalisation and globalisation) has caused emerging ostrich farmers to become increasingly isolated. Governmental agriculture reforms and public sector interventions have been insufficient to address all the challenges faced by rural ostrich farmers in the Eastern Cape. Participation in the ostrich supply chain for emerging farmers in the Eastern Cape is currently unsustainable as a result of avian influenza, control and registration protocols for ostriches (VPN04), structural barriers in marketing, technical constraints and a lack of market participation. People in the rural areas of the Eastern Cape are challenged by inferior infrastructure, poor site conditions, low earnings, poor access to health services and unreliable water sources. The marginal conditions and prevalent complexities in which agriculture is practised require costly resource intervention. Intensive ostrich production necessitates continuous genetic improvement, methodical record keeping, intensive egg incubation methods and highmaintenance chick rearing and ostrich handling while minimising feed costs throughout this process. Rural farmers have not embraced ostrich farming in the same way as they have done with other livestock farming because it does not offer the anthropological functions that traditional livestock farming provides. The ostrich supply chain requires a wide range of activities to bring products to the final consumer. The worth of ostrich production lies mainly in the higher returns which are achieved only through the export markets. Today the ostrich industry has become vulnerable to market cannibalism, a lack of market development, unregulated numbers of ostriches and recurring international meat bans. The deregulation of the ostrich single-channel marketing system had a substantial effect on the value chain on which farmers depended for market access and market protection. As the majority of ostrich products are being exported to the European Union, the role of intermediary agencies is becoming an important factor influencing entry into the high-end markets. This agent structure that represents the South African ostrich industry is vital for the distribution, market penetration and regulation of the ostrich products. The ostrich leather, which is today the main product line, is primarily used for luxury goods and is susceptible to economic downturn and over-supply. The ostrich meat industry has been severely influenced by outbreaks of avian influenza and processors now pre-heat the meat in order to maintain export. However, this preheating meat facility is only for export produce and available to farmers who conform to VPN04 and have officially registered farms. The relevant South African government departments played a crucial role in identifying avian influenza outbreaks and liaising with the European Union about avian influenza isolation strategies. No previous studies have been conducted on the participation of emerging farmers in the Eastern Cape ostrich-industry supply chain and on the interventions required to address the multiple constraints and forces in this sector. This led to a study with research emphasis on the required capacity for supply-chain participation and the supporting mechanisms that would be required for emerging ostrich farmers to integrate successfully into this supply chain. An exploratory research approach was chosen for the investigation, as no earlier research has been undertaken that could serve as a source of reliable data or reference. A triangulation research methodology using both the quantitative and the qualitative approach was applied. The qualitative research entailed an interpretive approach associated with using grounded theory and content analysis for interpreting data. The comparative case study design was the main qualitative research instrument for the multiple-case studies on emerging ostrich farmers in the Eastern Cape. The study was undertaken at five different sites, namely, the Peddie Ostrich Programme, the Rockhurst Ostrich Programme, the Hlumani Co-operative farm, the Zamukwanda Ostrich farm near Pearston and the Mimosadale Ostrich farm. The quantitative methods were applied to capture all the measurable components and representations of the stakeholders and participants, through interviews, questionnaires and focus group interviews. The quantitative study also included an experimental instrument to measure the capacity of emerging farmer programmes for supply chain participation. It was found that the main driver for three of the case studies pertained to land ownership and that ostrich farming was incidental and only seen as means of activity for income. These three humanitarian farming projects had limited capacity for intensive management requirements for ostrich farming. It was found that the VPN04 bio-security protocols and disease control require a higher level of record keeping for EU markets and is prohibitively expensive for poor rural emerging farmers. The study established that the emerging ostrich farming programmes contributed value to the industry and government rural development in land redistribution programmes, vehicles for reduction of poverty and job creation in the rural areas and by acting as out-grower programmes for commercial farmers. The researcher’s observation is that through strategic interventions the programmes have potential to become commercial players in the industry. The following interventions were recommended from this study: Feasibility study of programmes and review of location selection before initiation. Providing supportive interventions for programme start-ups; Improved selection of programme beneficiaries; Improved structure of emerging farmers’ co-operatives; On-going and appropriate training for emerging ostrich farmers; The role of government and mentors needs to be defined; Reducing feed costs; Establishing programmes linkages to informal markets and facilitating increased self-consumption; Developing new export markets; Alternative finance for the no-income months; Alternative marketing channels to export markets; Representation of emerging farmers in the ostrich-industry leadership structures.
- Full Text:
- Date Issued: 2013
Trends in large carnivore diets in the Addo Elephant National Park, South Africa
- Authors: Wentworth, Julia Claire
- Date: 2013
- Subjects: Game reserves -- South Africa , Carnivorous animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10595 , http://hdl.handle.net/10948/d1020993
- Description: Determining carnivore diets and how they may change over time is important if the management of large carnivores is successful in an enclosed reserve. Carnivore diets are known to shift over time in response to a variety of factors. These factors include prey availability and climatic conditions (rainfall patterns). The re-introduction of lions (Panthera leo) and spotted hyaena (Crocuta crocuta) to Addo Elephant National Park (AENP), South Africa provided the opportunity to study diet trends of lions and spotted hyaena in an enclosed system. The study focused on the diets and overlap of lions and spotted hyaena and how their prey selection changed since their re-introduction in 2003 to 2010. The database included scats collected over a seven year period. A total of 195 spotted hyaena scats and 217 lion scats were analysed using scat analysis. Prey items estimated from scat samples were coupled with prey availabilities to determine preferred prey items. Additionally, from determined carnivore diets, lions and spotted hyaena diet overlap was estimated over time. Lions preferred prey items which included zebra (Equus quagga) and eland (Tragelaphus oryx) during the early portion of the study. Over time preference shifted to include buffalo (Syncerus caffer), bushbuck (Tragelaphus scriptus) and grey duiker (Sylvicapra grimmia). Spotted hyaena preferred zebra and eland in the earlier part of the study, then over time, shifting their selection to grey duiker, buffalo, red hartebeest (Alcephalus busephalus) and bushbuck. Lions and spotted hyaena had a similar diet which increased in overlap during the study (67 percentage - 91 percentage). Our findings suggest that lions and spotted hyaena had a degree of diet specialization; both carnivores avoided and preferred certain prey items relative to their abundance. Their preference excluded the most abundant prey items, thus causing a decline in abundance of rarer species over time. Lions and spotted hyaena did not respond by shifting their diets to consume abundant prey items when their preferred prey items declined in availability. However, this study may be a snap-shot of carnivore’s diet trends. Thus further monitoring of the large carnivore diets should be researched in order to determine which factors drive their prey selection. Additionally, lions and spotted hyaena diet overlap increased overtime. The high diet overlap may be a result from spotted hyaena scavenging off lion kills, thus spotted hyaena diets may be facilitated by lion kills. Finally our data suggests that re-introduced large carnivores in AENP are likely to change the composition of the overall mammal community, potentially eliminating rare but preferred prey species in an enclosed reserve.
- Full Text:
- Date Issued: 2013
- Authors: Wentworth, Julia Claire
- Date: 2013
- Subjects: Game reserves -- South Africa , Carnivorous animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10595 , http://hdl.handle.net/10948/d1020993
- Description: Determining carnivore diets and how they may change over time is important if the management of large carnivores is successful in an enclosed reserve. Carnivore diets are known to shift over time in response to a variety of factors. These factors include prey availability and climatic conditions (rainfall patterns). The re-introduction of lions (Panthera leo) and spotted hyaena (Crocuta crocuta) to Addo Elephant National Park (AENP), South Africa provided the opportunity to study diet trends of lions and spotted hyaena in an enclosed system. The study focused on the diets and overlap of lions and spotted hyaena and how their prey selection changed since their re-introduction in 2003 to 2010. The database included scats collected over a seven year period. A total of 195 spotted hyaena scats and 217 lion scats were analysed using scat analysis. Prey items estimated from scat samples were coupled with prey availabilities to determine preferred prey items. Additionally, from determined carnivore diets, lions and spotted hyaena diet overlap was estimated over time. Lions preferred prey items which included zebra (Equus quagga) and eland (Tragelaphus oryx) during the early portion of the study. Over time preference shifted to include buffalo (Syncerus caffer), bushbuck (Tragelaphus scriptus) and grey duiker (Sylvicapra grimmia). Spotted hyaena preferred zebra and eland in the earlier part of the study, then over time, shifting their selection to grey duiker, buffalo, red hartebeest (Alcephalus busephalus) and bushbuck. Lions and spotted hyaena had a similar diet which increased in overlap during the study (67 percentage - 91 percentage). Our findings suggest that lions and spotted hyaena had a degree of diet specialization; both carnivores avoided and preferred certain prey items relative to their abundance. Their preference excluded the most abundant prey items, thus causing a decline in abundance of rarer species over time. Lions and spotted hyaena did not respond by shifting their diets to consume abundant prey items when their preferred prey items declined in availability. However, this study may be a snap-shot of carnivore’s diet trends. Thus further monitoring of the large carnivore diets should be researched in order to determine which factors drive their prey selection. Additionally, lions and spotted hyaena diet overlap increased overtime. The high diet overlap may be a result from spotted hyaena scavenging off lion kills, thus spotted hyaena diets may be facilitated by lion kills. Finally our data suggests that re-introduced large carnivores in AENP are likely to change the composition of the overall mammal community, potentially eliminating rare but preferred prey species in an enclosed reserve.
- Full Text:
- Date Issued: 2013
Social network analysis of stakeholders in the Duiwenhoks Water Catchment
- Authors: Whyte, Michelle
- Date: 2013
- Subjects: Conservation of natural resources -- South Africa , Conservation plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10756 , http://hdl.handle.net/10948/d1020995
- Description: Social-ecological systems are facing complex social, political, economic and environmental problems beyond the capacity of one group of stakeholders or organization to solve in isolation. Ecosystem degradation causes major environmental and economic concern, due to the loss of ecosystem services which river and wetland ecosystems provide. Stakeholder communities who depend on natural resources need to identify the social processes which are underlying causes to unsuccessful natural resource management and thus environmental degradation. The study is primarily aimed at identifying and understanding the structural and functional properties of the stakeholder network in the Duiwenhoks River catchment in the Western Cape, South Africa. Through analyzing the social network properties the study identifies and describes the main stakeholders involved with natural resource management in the Duiwenhoks water catchment area. How the individual actors from the diverse stakeholder groups are connected through communication ties were assessed. Furthermore, issues and factors which limit the effectiveness of the social network were identified. The main factors include a lack of communication and collaboration between key local resource users and governance officials caused by conflicting perspectives regarding resource management and societal conflicts caused by asymmetries in power distribution favoring government institutions. The lack of collaboration between stakeholders was identified as a contributing factor that links to the resource degradation experienced in the catchment. Ultimately means of overcoming the limitations to effective social networking, in order to manage the challenges related to natural resource management were identified. Management recommendations include the development of bridging ties and collaboration between diverse stakeholders, whilst facilitating participatory processes aimed at participatory problem solving and adaptive co-management of natural resources. Government institutions were identified as being dominant stakeholders in the network and should be mobilized to perform a stronger bridging role to connect disconnected actors. The findings of the study may inform future efforts of researchers and facilitators to implement strategies which promote social networking, social learning and ultimately adaptive co-management in the study area or other similar social-ecological systems. Ultimately, collaboration can be achieved between the diverse stakeholders to successfully improve ecosystem management and resilience in the Duiwenhoks water catchment.
- Full Text:
- Date Issued: 2013
- Authors: Whyte, Michelle
- Date: 2013
- Subjects: Conservation of natural resources -- South Africa , Conservation plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10756 , http://hdl.handle.net/10948/d1020995
- Description: Social-ecological systems are facing complex social, political, economic and environmental problems beyond the capacity of one group of stakeholders or organization to solve in isolation. Ecosystem degradation causes major environmental and economic concern, due to the loss of ecosystem services which river and wetland ecosystems provide. Stakeholder communities who depend on natural resources need to identify the social processes which are underlying causes to unsuccessful natural resource management and thus environmental degradation. The study is primarily aimed at identifying and understanding the structural and functional properties of the stakeholder network in the Duiwenhoks River catchment in the Western Cape, South Africa. Through analyzing the social network properties the study identifies and describes the main stakeholders involved with natural resource management in the Duiwenhoks water catchment area. How the individual actors from the diverse stakeholder groups are connected through communication ties were assessed. Furthermore, issues and factors which limit the effectiveness of the social network were identified. The main factors include a lack of communication and collaboration between key local resource users and governance officials caused by conflicting perspectives regarding resource management and societal conflicts caused by asymmetries in power distribution favoring government institutions. The lack of collaboration between stakeholders was identified as a contributing factor that links to the resource degradation experienced in the catchment. Ultimately means of overcoming the limitations to effective social networking, in order to manage the challenges related to natural resource management were identified. Management recommendations include the development of bridging ties and collaboration between diverse stakeholders, whilst facilitating participatory processes aimed at participatory problem solving and adaptive co-management of natural resources. Government institutions were identified as being dominant stakeholders in the network and should be mobilized to perform a stronger bridging role to connect disconnected actors. The findings of the study may inform future efforts of researchers and facilitators to implement strategies which promote social networking, social learning and ultimately adaptive co-management in the study area or other similar social-ecological systems. Ultimately, collaboration can be achieved between the diverse stakeholders to successfully improve ecosystem management and resilience in the Duiwenhoks water catchment.
- Full Text:
- Date Issued: 2013
The influence of soil properties on the growth and distribution of Portulacaria Afra in subtropical thicket, South Africa
- Authors: Becker, Carina Helene
- Date: 2013
- Subjects: Portulacaria afra -- South Africa , Plant conservation -- South Africa , Shrubs -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10753 , http://hdl.handle.net/10948/d1013046
- Description: Subtropical Thicket is the dominant vegetation biome in the Eastern Cape, and extends through to parts of the Western Cape. It is dominated by Portulacaria afra (spekboom), a woody succulent plant recognised for its importance as an ecosystem engineer and its carbon sequestration potential. Due to excessive grazing from domestic stock, spekboom has been completely removed from some areas. The Subtropical Thicket Restoration Programme (STRP) initiated a large scale restoration programme of planting spekboom cuttings in these degraded areas. Their efforts have been met with varying levels of success and improvement of the programme relies on continuous monitoring and scientific evaluation. I investigated the influence of selected soil properties on spekboom growth, mortality and landscape distribution, at both restoration sites and natural intact areas, and through experiments. Site or location was the most important factor influencing spekboom success at restoration plots, whereby sites in the eastern end of spekboom distribution perform better. Moving westwards slope orientation emerged as an important factor, whereby north facing slopes are preferred by spekboom. Although high levels of soil salinity (NaCl) restricted spekboom growth and affected its health, it could tolerate the levels it was exposed too. Soil pH, above 7, and phosphorous concentration, above 70 mg.kg-1, were the only limiting factors to spekboom survival found in the restoration sites. This preference for acidic soils was mirrored in intact Thicket. However in general, soil is not a major factor influencing spekboom growth and distribution, and spekboom is tolerant of a wide range of soil conditions. Spekbooms constraint is most likely a function of climate, which varies greatly across the biome. This study answered some vital questions regarding the possible influence of soil in spekboom growth and distribution. It disapproved the theory that a catena effect may be responsible for the lack of spekboom growing in bottomland areas. The study also indicates and supports the versatility of spekboom as a plant for restoring degraded lands across a range of different geologies and soil types. To maximise spekboom survival rates, restoration efforts should be focussed towards the eastern end of its distribution and to avoid planting in soils with pH levels higher than 7.
- Full Text:
- Date Issued: 2013
- Authors: Becker, Carina Helene
- Date: 2013
- Subjects: Portulacaria afra -- South Africa , Plant conservation -- South Africa , Shrubs -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10753 , http://hdl.handle.net/10948/d1013046
- Description: Subtropical Thicket is the dominant vegetation biome in the Eastern Cape, and extends through to parts of the Western Cape. It is dominated by Portulacaria afra (spekboom), a woody succulent plant recognised for its importance as an ecosystem engineer and its carbon sequestration potential. Due to excessive grazing from domestic stock, spekboom has been completely removed from some areas. The Subtropical Thicket Restoration Programme (STRP) initiated a large scale restoration programme of planting spekboom cuttings in these degraded areas. Their efforts have been met with varying levels of success and improvement of the programme relies on continuous monitoring and scientific evaluation. I investigated the influence of selected soil properties on spekboom growth, mortality and landscape distribution, at both restoration sites and natural intact areas, and through experiments. Site or location was the most important factor influencing spekboom success at restoration plots, whereby sites in the eastern end of spekboom distribution perform better. Moving westwards slope orientation emerged as an important factor, whereby north facing slopes are preferred by spekboom. Although high levels of soil salinity (NaCl) restricted spekboom growth and affected its health, it could tolerate the levels it was exposed too. Soil pH, above 7, and phosphorous concentration, above 70 mg.kg-1, were the only limiting factors to spekboom survival found in the restoration sites. This preference for acidic soils was mirrored in intact Thicket. However in general, soil is not a major factor influencing spekboom growth and distribution, and spekboom is tolerant of a wide range of soil conditions. Spekbooms constraint is most likely a function of climate, which varies greatly across the biome. This study answered some vital questions regarding the possible influence of soil in spekboom growth and distribution. It disapproved the theory that a catena effect may be responsible for the lack of spekboom growing in bottomland areas. The study also indicates and supports the versatility of spekboom as a plant for restoring degraded lands across a range of different geologies and soil types. To maximise spekboom survival rates, restoration efforts should be focussed towards the eastern end of its distribution and to avoid planting in soils with pH levels higher than 7.
- Full Text:
- Date Issued: 2013
Assessing soil carbon and carbon dioxide effluxes under different vegetation cover conditions in the Eastern Cape Province, South Africa
- Authors: Zengeni, Rebecca
- Date: 2013
- Subjects: Soils -- Carbon content -- Measurement , Carbon dioxide mitigation -- South Africa , Greenhouse gas mitigation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10665 , http://hdl.handle.net/10948/d1018676
- Description: Albany thicket is prevalent in the Eastern Cape Province of South Africa. Its spread has diminished through overgrazing and heavy browsing by animals, land clearance and urban expansion. The result is highly degraded land characterized by invasion of alien species. There is a wealth of documented evidence on the high carbon sequestration ability of thicket biome, but not much has been done to assess its effect on carbon dioxide emissions from the soil. Given that the concentration of atmospheric greenhouse gases has been constantly rising since the industrial era, it is imperative to assess the influence of thicket biome as a source or sink of these gases. There is evidence of shifts in the climate in southern Africa as reflected by changes in rainfall patterns, increased temperatures, recurrent droughts and fires. As such, the historical rainfall variability in an Albany thicket region and its interaction with the temporal land use / cover changes was studied. This served to give some background information about the study area for more detailed study on C and carbon dioxide effluxes in thicket vegetation under different levels of degradation. This study thus aimed to determine the influence of thicket vegetation at various levels of degradation on soil carbon and carbon dioxide fluxes. The impact of plant photosynthetic pathway on soil C residence time and gas effluxes were analysed to elucidate on the land-use and cover patterns occurring in the area. All this was done to shed some light on the role of soil and thicket vegetation on carbon dioxide emissions and C storage in the spectrum of a shifting climate. The main area of research was Amakhala reserve in an Albany thicket in Eastern Cape Province; and it concentrated on three land cover types namely intact thicket, degraded thicket and grassland. The objectives mentioned above were achieved by assessing historical rainfall variability from 1970 to 2010 through trend and time series analysis at nine rainfall stations located at Amakhala reserve, Grahamstown, Bathurst, Port Alfred, Uitenhage and Port Elizabeth. The land use changes that have occurred in the Albany thicket region covering Amakhala reserve, Grahamstown, Bathurst and Port Alfred were also assessed for 1989, 1999 and 2009 through satellite image analysis with Idrisi Andes GIS software; then their interaction with rainfall variability were determined. To elucidate on the vegetation species composition and land use / cover changes that have occurred in the study area, plant biomass as well carbon (C) and nitrogen (N) isotope measurements were done. Plant biomass was assessed for the dominant species through use of pre-existing allometric equations that required data on plant basal diameter, canopy area, stem numbers and height. The plant carbon was then estimated through use of a conversion factor of 0.48 on above-ground biomass, while soil organic C was determined through the modified Walkely - Black method. Carbon and N isotope ratios were determined from the foliar material of three replicate samples of dominant plant species then analyzed through mass spectrometry. Soil carbon dioxide effluxes were then monitored in each of the intact thicket (IT), degraded thicket (DT) and grassland (G) over a 10 month period; by measuring the net carbon dioxide exchange rate (NCER) through the dynamic chamber method. An automated carbon dioxide exchange analyzer, coupled to a soil temperature probe and photosynthetic active radiation (PAR) sensor was used; with NCER measurements taken every 20-30 days. Soil temperature, moisture, penetration resistance and PAR readings were taken during each assay and later used to interpret the NCER. Results showed that long term variability in annual rainfall had a declining trend at Grahamstown (r = -0.59), Uitenhage and Bathurst stations (r = -0.32 at both stations), but was not significant at Amakhala, Port Alfred and Port Elizabeth stations. Most reductions in rainfall occurred in the 1980s and 1990s with the autumn, winter and summer rainfalls, the daily rainfall index and the daily rainfall subclasses of 10 mm and above showing a similar trend. The land use change detection gave a significant increase in proportion of degraded and transformed (moderately degraded) land between 1989 and 2009 with most of the increases occurring from 1989 to 1999, while farmland area decreased by 1.8 percent over the years. Thus the Albany region had over 30 percent of its land occupied by transformed vegetation, with heavy browsing and uncontrolled grazing being attributed to the destruction of pristine vegetation. Land-use change to game ranching and goat pastoralism was attributed to the reduction in farmland. Rainfall variability – land use change linkages were most significant in 1999 that recorded the least rainfall and had the lowest mean, maximum and sum of the NDVI. Grahamstown had the most significant rainfall-NDVI trends as it had the lowest NDVIs in 1999 when rainfall was lowest, the highest NDVI in 1989 when rainfall was highest and moderate NDVIs in 2009 when rainfall was moderate. Vegetation at the IT was characterized by a dense thicket with diverse growth forms of canopy trees, woody shrubs, succulent shrubs and ephemerals which mostly had the C3 type of pathway. This was in contrast with the IT soil isotopy that showed more positive C isotope ratios, indicating a switch between C3 and CAM photosynthesis in original vegetation. Most of the canopy trees had disappeared in the DT to be replaced by herbs, shrubs and grasses. As such, there was a huge difference in isotope ratios between DT plants and soils with the plants having mostly C3 metabolism while the soil showed a predominance of CAM plants in previous vegetation, indicating significant changes in land cover. The G site mostly comprised the grasses Themeda triandra and Panicum maximum and a few herbs. It maintained a dominance of C4 metabolism in both plants and soils showing very little change in species composition over the years. Because of the higher species diversity at IT, its soil organic C was quite high reaching levels of 3.4 percent (i.e. 3.4 t C / ha) in the top 10 cm then decreasing with depth (p < 0.001); but was moderate at DT (1.1-1.3 percent) and very low at G ( 0.5 percent C) (p < 0.001). In the same manner above-ground biomass was highest at IT i.e. 330 000 kg/ha; but was only 22 000 kg/ha in DT and as low as 6 700 kg/ha in G vegetation. High biomass at IT was mostly attributed to the succulent shrub Portulacaria afra and the canopy trees Euclea undulate, Rhus longispina and Schotia afra. This above-ground biomass translated to biomass C amounts of 158 000 kg/ha at IT, 10 600 kg/ha at DT and 3 200 kg/ha at G. Thus the IT had the highest while G the least and DT moderate plant and soil C sequestration ability. In all, the conversion of IT to DT led to a net loss of 147 000 Kg of biomass C / ha and 12 000kg less organic C / ha of land. Soil carbon dioxide effluxes were however variable between seasons as they were affected by differences in soil properties and seasonal weather patterns. High soil moisture levels (up to 16 percent gravimetric moisture) resulted in reduced soil penetration resistance (1 to 4 Kg/cm2) which raised effluxes at G and DT sites (up to 1.2 μmols m-2 sec-1) in winter, while low moisture (2 percent) resulted in hard dry soil (14 Kgm-2 penetration resistance) with suppressed CO2 effluxes in spring (0.2 μmols m-2 sec-1) especially in DT and G soils. Rising temperature generally caused accelerated gas emissions but only when moisture was not limiting (as was the case in IT). Thus the high summer temperatures (up to 40oC) gave lower effluxes especially in DT and G (< 1 μm-2sec-1) due to limited moisture supply (< 10 percent); while the Autumn period that had very high temperature (up to 48 oC) and good moisture (up to 16 percent) saw accelerated soil CO2 emissions (averaging 2 μmols m-2 sec-1) from all cover types. The high biomass and litter fall at IT served as ready substrate for soil respiration as long as moisture was not limiting and temperatures were favourable, while reduced cover at DT resulted in poor moisture conservation and creation of hard dry soils in spring and summer with reduced respiration. It was concluded that the DT had high CO2 effluxes in winter and reduced emissions in summer; while the opposite was true for the IT. All the cover types had minimal CO2 effluxes in spring and accelerated emissions in autumn. The grassland on the other hand was a fairly moderate source or sink of CO2 in most seasons compared with the other two covers. It was observed that an environment of good moisture and low-moderate temperatures (such as that in the winter) minimises effluxes while maintaining good plant productivity. It was concluded that thicket vegetation is a good sink of carbon that should be preserved in its natural condition to optimize its carbon sequestration potential. All three land covers served as sources or sinks of CO2 depending on soil and seasonal conditions. Thus high moisture and low penetration resistance generally increased effluxes of thicket ecosystems. The effect of increasing temperature on effluxes was only significant when moisture was not limiting. Conditions of good moisture and low-moderate temperatures gave reasonable amounts of effluxes while maintaining good plant productivity. Though the dry soil conditions significantly reduced effluxes in all land covers; they were not desirable since they decreased plant productivity and ultimately its C sequestration potential. Moreover, prolonged dry conditions only serve to exacerbate recovery of thicket plants as they increase mortality of canopy species in degraded and transformed areas in comparison with intact thicket.
- Full Text:
- Date Issued: 2013
- Authors: Zengeni, Rebecca
- Date: 2013
- Subjects: Soils -- Carbon content -- Measurement , Carbon dioxide mitigation -- South Africa , Greenhouse gas mitigation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10665 , http://hdl.handle.net/10948/d1018676
- Description: Albany thicket is prevalent in the Eastern Cape Province of South Africa. Its spread has diminished through overgrazing and heavy browsing by animals, land clearance and urban expansion. The result is highly degraded land characterized by invasion of alien species. There is a wealth of documented evidence on the high carbon sequestration ability of thicket biome, but not much has been done to assess its effect on carbon dioxide emissions from the soil. Given that the concentration of atmospheric greenhouse gases has been constantly rising since the industrial era, it is imperative to assess the influence of thicket biome as a source or sink of these gases. There is evidence of shifts in the climate in southern Africa as reflected by changes in rainfall patterns, increased temperatures, recurrent droughts and fires. As such, the historical rainfall variability in an Albany thicket region and its interaction with the temporal land use / cover changes was studied. This served to give some background information about the study area for more detailed study on C and carbon dioxide effluxes in thicket vegetation under different levels of degradation. This study thus aimed to determine the influence of thicket vegetation at various levels of degradation on soil carbon and carbon dioxide fluxes. The impact of plant photosynthetic pathway on soil C residence time and gas effluxes were analysed to elucidate on the land-use and cover patterns occurring in the area. All this was done to shed some light on the role of soil and thicket vegetation on carbon dioxide emissions and C storage in the spectrum of a shifting climate. The main area of research was Amakhala reserve in an Albany thicket in Eastern Cape Province; and it concentrated on three land cover types namely intact thicket, degraded thicket and grassland. The objectives mentioned above were achieved by assessing historical rainfall variability from 1970 to 2010 through trend and time series analysis at nine rainfall stations located at Amakhala reserve, Grahamstown, Bathurst, Port Alfred, Uitenhage and Port Elizabeth. The land use changes that have occurred in the Albany thicket region covering Amakhala reserve, Grahamstown, Bathurst and Port Alfred were also assessed for 1989, 1999 and 2009 through satellite image analysis with Idrisi Andes GIS software; then their interaction with rainfall variability were determined. To elucidate on the vegetation species composition and land use / cover changes that have occurred in the study area, plant biomass as well carbon (C) and nitrogen (N) isotope measurements were done. Plant biomass was assessed for the dominant species through use of pre-existing allometric equations that required data on plant basal diameter, canopy area, stem numbers and height. The plant carbon was then estimated through use of a conversion factor of 0.48 on above-ground biomass, while soil organic C was determined through the modified Walkely - Black method. Carbon and N isotope ratios were determined from the foliar material of three replicate samples of dominant plant species then analyzed through mass spectrometry. Soil carbon dioxide effluxes were then monitored in each of the intact thicket (IT), degraded thicket (DT) and grassland (G) over a 10 month period; by measuring the net carbon dioxide exchange rate (NCER) through the dynamic chamber method. An automated carbon dioxide exchange analyzer, coupled to a soil temperature probe and photosynthetic active radiation (PAR) sensor was used; with NCER measurements taken every 20-30 days. Soil temperature, moisture, penetration resistance and PAR readings were taken during each assay and later used to interpret the NCER. Results showed that long term variability in annual rainfall had a declining trend at Grahamstown (r = -0.59), Uitenhage and Bathurst stations (r = -0.32 at both stations), but was not significant at Amakhala, Port Alfred and Port Elizabeth stations. Most reductions in rainfall occurred in the 1980s and 1990s with the autumn, winter and summer rainfalls, the daily rainfall index and the daily rainfall subclasses of 10 mm and above showing a similar trend. The land use change detection gave a significant increase in proportion of degraded and transformed (moderately degraded) land between 1989 and 2009 with most of the increases occurring from 1989 to 1999, while farmland area decreased by 1.8 percent over the years. Thus the Albany region had over 30 percent of its land occupied by transformed vegetation, with heavy browsing and uncontrolled grazing being attributed to the destruction of pristine vegetation. Land-use change to game ranching and goat pastoralism was attributed to the reduction in farmland. Rainfall variability – land use change linkages were most significant in 1999 that recorded the least rainfall and had the lowest mean, maximum and sum of the NDVI. Grahamstown had the most significant rainfall-NDVI trends as it had the lowest NDVIs in 1999 when rainfall was lowest, the highest NDVI in 1989 when rainfall was highest and moderate NDVIs in 2009 when rainfall was moderate. Vegetation at the IT was characterized by a dense thicket with diverse growth forms of canopy trees, woody shrubs, succulent shrubs and ephemerals which mostly had the C3 type of pathway. This was in contrast with the IT soil isotopy that showed more positive C isotope ratios, indicating a switch between C3 and CAM photosynthesis in original vegetation. Most of the canopy trees had disappeared in the DT to be replaced by herbs, shrubs and grasses. As such, there was a huge difference in isotope ratios between DT plants and soils with the plants having mostly C3 metabolism while the soil showed a predominance of CAM plants in previous vegetation, indicating significant changes in land cover. The G site mostly comprised the grasses Themeda triandra and Panicum maximum and a few herbs. It maintained a dominance of C4 metabolism in both plants and soils showing very little change in species composition over the years. Because of the higher species diversity at IT, its soil organic C was quite high reaching levels of 3.4 percent (i.e. 3.4 t C / ha) in the top 10 cm then decreasing with depth (p < 0.001); but was moderate at DT (1.1-1.3 percent) and very low at G ( 0.5 percent C) (p < 0.001). In the same manner above-ground biomass was highest at IT i.e. 330 000 kg/ha; but was only 22 000 kg/ha in DT and as low as 6 700 kg/ha in G vegetation. High biomass at IT was mostly attributed to the succulent shrub Portulacaria afra and the canopy trees Euclea undulate, Rhus longispina and Schotia afra. This above-ground biomass translated to biomass C amounts of 158 000 kg/ha at IT, 10 600 kg/ha at DT and 3 200 kg/ha at G. Thus the IT had the highest while G the least and DT moderate plant and soil C sequestration ability. In all, the conversion of IT to DT led to a net loss of 147 000 Kg of biomass C / ha and 12 000kg less organic C / ha of land. Soil carbon dioxide effluxes were however variable between seasons as they were affected by differences in soil properties and seasonal weather patterns. High soil moisture levels (up to 16 percent gravimetric moisture) resulted in reduced soil penetration resistance (1 to 4 Kg/cm2) which raised effluxes at G and DT sites (up to 1.2 μmols m-2 sec-1) in winter, while low moisture (2 percent) resulted in hard dry soil (14 Kgm-2 penetration resistance) with suppressed CO2 effluxes in spring (0.2 μmols m-2 sec-1) especially in DT and G soils. Rising temperature generally caused accelerated gas emissions but only when moisture was not limiting (as was the case in IT). Thus the high summer temperatures (up to 40oC) gave lower effluxes especially in DT and G (< 1 μm-2sec-1) due to limited moisture supply (< 10 percent); while the Autumn period that had very high temperature (up to 48 oC) and good moisture (up to 16 percent) saw accelerated soil CO2 emissions (averaging 2 μmols m-2 sec-1) from all cover types. The high biomass and litter fall at IT served as ready substrate for soil respiration as long as moisture was not limiting and temperatures were favourable, while reduced cover at DT resulted in poor moisture conservation and creation of hard dry soils in spring and summer with reduced respiration. It was concluded that the DT had high CO2 effluxes in winter and reduced emissions in summer; while the opposite was true for the IT. All the cover types had minimal CO2 effluxes in spring and accelerated emissions in autumn. The grassland on the other hand was a fairly moderate source or sink of CO2 in most seasons compared with the other two covers. It was observed that an environment of good moisture and low-moderate temperatures (such as that in the winter) minimises effluxes while maintaining good plant productivity. It was concluded that thicket vegetation is a good sink of carbon that should be preserved in its natural condition to optimize its carbon sequestration potential. All three land covers served as sources or sinks of CO2 depending on soil and seasonal conditions. Thus high moisture and low penetration resistance generally increased effluxes of thicket ecosystems. The effect of increasing temperature on effluxes was only significant when moisture was not limiting. Conditions of good moisture and low-moderate temperatures gave reasonable amounts of effluxes while maintaining good plant productivity. Though the dry soil conditions significantly reduced effluxes in all land covers; they were not desirable since they decreased plant productivity and ultimately its C sequestration potential. Moreover, prolonged dry conditions only serve to exacerbate recovery of thicket plants as they increase mortality of canopy species in degraded and transformed areas in comparison with intact thicket.
- Full Text:
- Date Issued: 2013
On meshless methods : a novel interpolatory method and a GPU-accelerated implementation
- Authors: Hamed, Maien Mohamed Osman
- Date: 2013
- Subjects: Engineering mathematics , Numerical analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10509 , http://hdl.handle.net/10948/d1018227
- Description: Meshless methods have been developed to avoid the numerical burden imposed by meshing in the Finite Element Method. Such methods are especially attrac- tive in problems that require repeated updates to the mesh, such as problems with discontinuities or large geometrical deformations. Although meshing is not required for solving problems with meshless methods, the use of meshless methods gives rise to different challenges. One of the main challenges associated with meshless methods is imposition of essential boundary conditions. If exact interpolants are used as shape functions in a meshless method, imposing essen- tial boundary conditions can be done in the same way as the Finite Element Method. Another attractive feature of meshless methods is that their use involves compu- tations that are largely independent from one another. This makes them suitable for implementation to run on highly parallel computing systems. Highly par- allel computing has become widely available with the introduction of software development tools that enable developing general-purpose programs that run on Graphics Processing Units. In the current work, the Moving Regularized Interpolation method has been de- veloped, which is a novel method of constructing meshless shape functions that achieve exact interpolation. The method is demonstrated in data interpolation and in partial differential equations. In addition, an implementation of the Element-Free Galerkin method has been written to run on a Graphics Processing Unit. The implementation is described and its performance is compared to that of a similar implementation that does not make use of the Graphics Processing Unit.
- Full Text:
- Date Issued: 2013
- Authors: Hamed, Maien Mohamed Osman
- Date: 2013
- Subjects: Engineering mathematics , Numerical analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10509 , http://hdl.handle.net/10948/d1018227
- Description: Meshless methods have been developed to avoid the numerical burden imposed by meshing in the Finite Element Method. Such methods are especially attrac- tive in problems that require repeated updates to the mesh, such as problems with discontinuities or large geometrical deformations. Although meshing is not required for solving problems with meshless methods, the use of meshless methods gives rise to different challenges. One of the main challenges associated with meshless methods is imposition of essential boundary conditions. If exact interpolants are used as shape functions in a meshless method, imposing essen- tial boundary conditions can be done in the same way as the Finite Element Method. Another attractive feature of meshless methods is that their use involves compu- tations that are largely independent from one another. This makes them suitable for implementation to run on highly parallel computing systems. Highly par- allel computing has become widely available with the introduction of software development tools that enable developing general-purpose programs that run on Graphics Processing Units. In the current work, the Moving Regularized Interpolation method has been de- veloped, which is a novel method of constructing meshless shape functions that achieve exact interpolation. The method is demonstrated in data interpolation and in partial differential equations. In addition, an implementation of the Element-Free Galerkin method has been written to run on a Graphics Processing Unit. The implementation is described and its performance is compared to that of a similar implementation that does not make use of the Graphics Processing Unit.
- Full Text:
- Date Issued: 2013
The response of maize to selected ratios of organic fertilizers mixed with inorganic fertilizers in Ndlambe Local Municipality, Eastern Cape, South Africa
- Authors: Solontsi, Mhlangabezi
- Date: 2013
- Subjects: Fertilizers -- South Africa -- Eastern Cape , Corn -- Yields -- South Africa -- Eastern Cape , Leaf area index -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10594 , http://hdl.handle.net/10948/d1020902
- Description: The majority of small-scale farmers in the Eastern Cape apply inadequate quantities of manure, inorganic (NPK) fertilizer and Gromor as lone fertilizers or tend to mix manure or Gromor with chemical fertilizers for crops, without any scientific basis (Mkile, 2001). Hence this study – aimed at achieving effective and efficient use of chemical fertilizers, manure and Gromor, either as lone fertilizers or mixed with one another, in maize production – was established. A three-year dry land field experiment, arranged in a RCBD with 3 replicates where cattle manure, chemical fertilizer and Gromor were mixed at different ratios – as treatments FM1 (10 percent fertilizer + 90 percent manure); FM2 (25 percent fertilizer + 75 percent manure); FM3 (50 percent fertilizer + 50 percent manure); MAP (100 percent fertilizer); M (100 percent cattle manure); FG1 (10 percent fertilizer + 90 percent Gromor); FG2 (25 percent fertilizer + 75 percent Gromor); FG3 (50 percent fertilizer + 50 percent Gromor); G (100 percent Gromor) and a control (with nothing applied) – was conducted at the Nolukhanyo agricultural project at Bathurst in the Ndlambe Local Municipality. Maize cultivars PAN 6480 and Sahara were used as test crops. Manure, Gromor and soil were analyzed for their nutrient composition. Data recorded involving number of kernels per cob-1, grain and dry matter (DM) yields for the 2010-11, 2011-12 and 2012-13 seasons, and leaf area index (LAI) – were subjected to Genstat Version 14.1 for statistical analysis. Grain yields of PAN 6480 and Sahara recorded in seasons 2010-11, 2011-12 and 2012-13 were significantly higher (p≤0.05) than those of the controls. In 2012-13, PAN 6480 on treatments FG3 and FG1 produced the highest grain yields (5 327 and 5 107kg ha-1) respectively, while in 2010-11 the highest yield was 3 780kg ha-1. In the 2012-13 season, Sahara on F treatment was the highest with 4 553kg ha-1 whilst there were no significant differences in F and M treatments. Dry matter yields of Sahara were higher than those of PAN 6480 in all seasons. The highest Sahara LAI obtained on FM2 was 5.85 in the 2012-13 season, whereas PAN 6480 had LAI of 4.77 on F treatment, followed by FG3 with 4.72 LAI. PAN 6480 number of leaves for 6 plants in m2 and LAI in week 8 of the 2012-13 season had a positive correlation, r2=0.84. PAN 6480 number of kernels and cob length in the same area correlated quite well (r2 =0.91). Chemical fertilizer corrects the imbalances of nutrients inherent in organic manures and increases both maize grain yields and dry matter yields, and also influences number of leaves and LAI. Treatments FG1, FG3 and FM1 of PAN 6480 resulted in high maize grain yields when planted 13 in late November of the 2012-13 growing season and when water in the soil profile was conserved as a result of good rains received prior to planting. Treatments FG1 (10 percent fertilizer + 90 percent Gromor), FG3 (50 percent fertilizer + 50 percent Gromor) of PAN 6480 produced the highest grain yields (5 107kg ha-1 and 5 327kg ha-1 respectively) in the 2012-13 season, whilst FM1 (10 percent fertilizer + 90 percent manure) gave the highest grain yield (of 4 277kg ha-1) for the same cultivar in the 2010-11 season.
- Full Text:
- Date Issued: 2013
- Authors: Solontsi, Mhlangabezi
- Date: 2013
- Subjects: Fertilizers -- South Africa -- Eastern Cape , Corn -- Yields -- South Africa -- Eastern Cape , Leaf area index -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10594 , http://hdl.handle.net/10948/d1020902
- Description: The majority of small-scale farmers in the Eastern Cape apply inadequate quantities of manure, inorganic (NPK) fertilizer and Gromor as lone fertilizers or tend to mix manure or Gromor with chemical fertilizers for crops, without any scientific basis (Mkile, 2001). Hence this study – aimed at achieving effective and efficient use of chemical fertilizers, manure and Gromor, either as lone fertilizers or mixed with one another, in maize production – was established. A three-year dry land field experiment, arranged in a RCBD with 3 replicates where cattle manure, chemical fertilizer and Gromor were mixed at different ratios – as treatments FM1 (10 percent fertilizer + 90 percent manure); FM2 (25 percent fertilizer + 75 percent manure); FM3 (50 percent fertilizer + 50 percent manure); MAP (100 percent fertilizer); M (100 percent cattle manure); FG1 (10 percent fertilizer + 90 percent Gromor); FG2 (25 percent fertilizer + 75 percent Gromor); FG3 (50 percent fertilizer + 50 percent Gromor); G (100 percent Gromor) and a control (with nothing applied) – was conducted at the Nolukhanyo agricultural project at Bathurst in the Ndlambe Local Municipality. Maize cultivars PAN 6480 and Sahara were used as test crops. Manure, Gromor and soil were analyzed for their nutrient composition. Data recorded involving number of kernels per cob-1, grain and dry matter (DM) yields for the 2010-11, 2011-12 and 2012-13 seasons, and leaf area index (LAI) – were subjected to Genstat Version 14.1 for statistical analysis. Grain yields of PAN 6480 and Sahara recorded in seasons 2010-11, 2011-12 and 2012-13 were significantly higher (p≤0.05) than those of the controls. In 2012-13, PAN 6480 on treatments FG3 and FG1 produced the highest grain yields (5 327 and 5 107kg ha-1) respectively, while in 2010-11 the highest yield was 3 780kg ha-1. In the 2012-13 season, Sahara on F treatment was the highest with 4 553kg ha-1 whilst there were no significant differences in F and M treatments. Dry matter yields of Sahara were higher than those of PAN 6480 in all seasons. The highest Sahara LAI obtained on FM2 was 5.85 in the 2012-13 season, whereas PAN 6480 had LAI of 4.77 on F treatment, followed by FG3 with 4.72 LAI. PAN 6480 number of leaves for 6 plants in m2 and LAI in week 8 of the 2012-13 season had a positive correlation, r2=0.84. PAN 6480 number of kernels and cob length in the same area correlated quite well (r2 =0.91). Chemical fertilizer corrects the imbalances of nutrients inherent in organic manures and increases both maize grain yields and dry matter yields, and also influences number of leaves and LAI. Treatments FG1, FG3 and FM1 of PAN 6480 resulted in high maize grain yields when planted 13 in late November of the 2012-13 growing season and when water in the soil profile was conserved as a result of good rains received prior to planting. Treatments FG1 (10 percent fertilizer + 90 percent Gromor), FG3 (50 percent fertilizer + 50 percent Gromor) of PAN 6480 produced the highest grain yields (5 107kg ha-1 and 5 327kg ha-1 respectively) in the 2012-13 season, whilst FM1 (10 percent fertilizer + 90 percent manure) gave the highest grain yield (of 4 277kg ha-1) for the same cultivar in the 2010-11 season.
- Full Text:
- Date Issued: 2013
Evaluation of plant extracts : artemisia afra and annona muricata for inhibitory activities against mycobacterium tuberculosis and human immunodeficiency virus
- Authors: Pruissen, Megan Colleen
- Date: 2013
- Subjects: Plant extracts , Medicinal plants -- South Africa , Tuberculosis -- Alternative treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10341 , http://hdl.handle.net/10948/d1019845
- Description: Mycobacterium tuberculosis and Human Immuno-Deficiency Virus (HIV) have a high prevalence in South Africa. The development and spread of drug resistant tuberculosis is a serious problem which is exacerbated by tuberculosis (TB) co-infection in HIV patients. Traditional medicinal plants like Annona muricata and Artemisia afra are used for respiratory ailments and antiviral therapies respectively. The aim of this study was to evaluate Annona muricata (ethanolic extract) and Artemisia afra (ethanolic and aqueous extracts) for inhibitory activities against M. tuberculosis and HIV. In vitro bioassays for anti-TB activity included: microplate alamar blue assay (MABA), flow cytometry and ρ-iodonitrotetrazolium chloride assays while anti-HIV activity was determined using an HIV-1 reverse transcriptase colorimetric ELISA kit and an HIV-1 integrase colorimetric immunoassay. Cytotoxicity of plant extracts were assessed by the MTT assay on Chang Liver and HepG2 cells. Potential synergistic effects were determined using the basis of Combination Index. Potential interactions of plant extracts with drug metabolic pathways were evaluated with the Glutathione-S-Transferase assay kit as well as the CYP3A4 assay kit. A. muricata ethanolic extract exhibited anti-TB activity with MIC 125 μg/mL. MABA was shown to be the most sensitive and effective method for the detection of anti-TB activity. Artemisia afra aqueous extract showed HIV-1 reverse transcriptase inhibition exhibiting ˃85 percent inhibition at 1 mg/mL while the ethanolic extracts of A. afra and A. muricata showed inhibition of HIV-1 integrase activity at ˃86.8 percent and ˃88.54 percent respectively at concentrations >0.5 - 4 mg/mL. The aqueous extract of A. afra displayed inhibition of HIV-1 integrase ˃52.16 percent at 0.5 mg/mL increasing to 72.89 percent at 4 mg/ml of the extract. A. muricata was cytotoxic at an IC50 of 30 μg/mL and 77 μg/mL on Chang Liver and HepG2 cells respectively, whilst A. afra aqueous and ethanol extracts were not cytotoxic to both cell lines. The ethanolic extract of A. muricata showed both antagonistic and synergistic properties at various IC values, when used in conjunction with rifampicin. A. afra ethanolic extract interrupted GST activity while aqueous extracts of A. afra and A. muricata had a slight effect. All extracts interrupted CYP3A4 activity, however the ethanolic extracts of A. muricata and A. afra showed greater inhibition than the aqueous extract of A. afra. These extracts should be investigated further as they could be an important source of compounds for treatment of M. tuberculosis and HIV respectively.
- Full Text:
- Date Issued: 2013
- Authors: Pruissen, Megan Colleen
- Date: 2013
- Subjects: Plant extracts , Medicinal plants -- South Africa , Tuberculosis -- Alternative treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10341 , http://hdl.handle.net/10948/d1019845
- Description: Mycobacterium tuberculosis and Human Immuno-Deficiency Virus (HIV) have a high prevalence in South Africa. The development and spread of drug resistant tuberculosis is a serious problem which is exacerbated by tuberculosis (TB) co-infection in HIV patients. Traditional medicinal plants like Annona muricata and Artemisia afra are used for respiratory ailments and antiviral therapies respectively. The aim of this study was to evaluate Annona muricata (ethanolic extract) and Artemisia afra (ethanolic and aqueous extracts) for inhibitory activities against M. tuberculosis and HIV. In vitro bioassays for anti-TB activity included: microplate alamar blue assay (MABA), flow cytometry and ρ-iodonitrotetrazolium chloride assays while anti-HIV activity was determined using an HIV-1 reverse transcriptase colorimetric ELISA kit and an HIV-1 integrase colorimetric immunoassay. Cytotoxicity of plant extracts were assessed by the MTT assay on Chang Liver and HepG2 cells. Potential synergistic effects were determined using the basis of Combination Index. Potential interactions of plant extracts with drug metabolic pathways were evaluated with the Glutathione-S-Transferase assay kit as well as the CYP3A4 assay kit. A. muricata ethanolic extract exhibited anti-TB activity with MIC 125 μg/mL. MABA was shown to be the most sensitive and effective method for the detection of anti-TB activity. Artemisia afra aqueous extract showed HIV-1 reverse transcriptase inhibition exhibiting ˃85 percent inhibition at 1 mg/mL while the ethanolic extracts of A. afra and A. muricata showed inhibition of HIV-1 integrase activity at ˃86.8 percent and ˃88.54 percent respectively at concentrations >0.5 - 4 mg/mL. The aqueous extract of A. afra displayed inhibition of HIV-1 integrase ˃52.16 percent at 0.5 mg/mL increasing to 72.89 percent at 4 mg/ml of the extract. A. muricata was cytotoxic at an IC50 of 30 μg/mL and 77 μg/mL on Chang Liver and HepG2 cells respectively, whilst A. afra aqueous and ethanol extracts were not cytotoxic to both cell lines. The ethanolic extract of A. muricata showed both antagonistic and synergistic properties at various IC values, when used in conjunction with rifampicin. A. afra ethanolic extract interrupted GST activity while aqueous extracts of A. afra and A. muricata had a slight effect. All extracts interrupted CYP3A4 activity, however the ethanolic extracts of A. muricata and A. afra showed greater inhibition than the aqueous extract of A. afra. These extracts should be investigated further as they could be an important source of compounds for treatment of M. tuberculosis and HIV respectively.
- Full Text:
- Date Issued: 2013
The effect of modified fuel loads on fire behaviour in Pinus patula and Eucalyptus macarthurii stands in the Mpumalanga Highveld forestry region of South Africa
- Authors: Pool, Christiaan Frederik
- Date: 2013
- Subjects: Wildfires , Forest fires , Fire management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10742 , http://hdl.handle.net/10948/d1010958 , Wildfires , Forest fires , Fire management
- Description: The effectiveness of harvesting slash treatments are questionable when wild fires, fuelled by post harvesting slash, burn out of control. In order to quantify effectiveness of various slash treatments, fire behaviour in Pinus patula and Eucalyptus macarthurii compartments in the Highveld area (Piet Retief) of Mpumalanga, South Africa, were assessed after application of five different post-harvesting slash treatments. Treatments included mulching, chopper rolling, windrowing, removal of slash (inter-windrowing) and broadcasting. Independent fuel and environmental variables were measured prior and during application of fire to the study areas and effects on fire behaviour were compared afterwards. Dependant fire behaviour variables such as the rate of spread, fire temperature and flame height were measured in respective slash treatment plots and compared. Results of the study indicated that fire behaviour assessed in mulched areas in both the P. patula and E. macarthurii compartments were significantly less intense when compared to fire behaviour in chopper roll, broadcast and windrow treatments. Fire behaviour in mulched plots compared favourably with areas where harvesting slash was removed (inter-windrow treatment). Comparisons between fuel loads of different treatments also indicated accelerated mineralization of organic material in mulched areas. Mulching of harvesting slash seems to be an effective method to restrict fire behaviour in post-harvesting compartments and should be considered as part of a fire management strategy.
- Full Text:
- Date Issued: 2013
- Authors: Pool, Christiaan Frederik
- Date: 2013
- Subjects: Wildfires , Forest fires , Fire management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10742 , http://hdl.handle.net/10948/d1010958 , Wildfires , Forest fires , Fire management
- Description: The effectiveness of harvesting slash treatments are questionable when wild fires, fuelled by post harvesting slash, burn out of control. In order to quantify effectiveness of various slash treatments, fire behaviour in Pinus patula and Eucalyptus macarthurii compartments in the Highveld area (Piet Retief) of Mpumalanga, South Africa, were assessed after application of five different post-harvesting slash treatments. Treatments included mulching, chopper rolling, windrowing, removal of slash (inter-windrowing) and broadcasting. Independent fuel and environmental variables were measured prior and during application of fire to the study areas and effects on fire behaviour were compared afterwards. Dependant fire behaviour variables such as the rate of spread, fire temperature and flame height were measured in respective slash treatment plots and compared. Results of the study indicated that fire behaviour assessed in mulched areas in both the P. patula and E. macarthurii compartments were significantly less intense when compared to fire behaviour in chopper roll, broadcast and windrow treatments. Fire behaviour in mulched plots compared favourably with areas where harvesting slash was removed (inter-windrow treatment). Comparisons between fuel loads of different treatments also indicated accelerated mineralization of organic material in mulched areas. Mulching of harvesting slash seems to be an effective method to restrict fire behaviour in post-harvesting compartments and should be considered as part of a fire management strategy.
- Full Text:
- Date Issued: 2013
Statistical model for risk diversification in renewable energy
- Authors: Ahame, Edmund
- Date: 2013
- Subjects: Renewable energy sources -- Statistics , Diversification in industry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10564 , http://hdl.handle.net/10948/d1008399 , Renewable energy sources -- Statistics , Diversification in industry
- Description: The growth of the industry and population of South Africa urges to seek new sources of electric power, hence the need to look at alternative power sources. Power output from some renewable energy sources is highly volatile. For instance power output from wind turbines or photovoltaic solar panels fluctuates between zero and the maximum rated power out. To optimize the overall power output a model was designed to determine the best trade-off between production from two or more renewable energy sources putting emphasis on wind and solar. Different measures of risk, such as coefficient of variation (CV) and value at risk (VAR), were used to determine the best hybrid renewable energy system (HRES) configuration. Depending on the investors’ expected returns (demand) and risk averseness, they will be able to use the model to choose the best configuration that suites their needs. In general it was found that investing in a diversified HRES is better than investing in individual power sources.
- Full Text:
- Date Issued: 2013
- Authors: Ahame, Edmund
- Date: 2013
- Subjects: Renewable energy sources -- Statistics , Diversification in industry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10564 , http://hdl.handle.net/10948/d1008399 , Renewable energy sources -- Statistics , Diversification in industry
- Description: The growth of the industry and population of South Africa urges to seek new sources of electric power, hence the need to look at alternative power sources. Power output from some renewable energy sources is highly volatile. For instance power output from wind turbines or photovoltaic solar panels fluctuates between zero and the maximum rated power out. To optimize the overall power output a model was designed to determine the best trade-off between production from two or more renewable energy sources putting emphasis on wind and solar. Different measures of risk, such as coefficient of variation (CV) and value at risk (VAR), were used to determine the best hybrid renewable energy system (HRES) configuration. Depending on the investors’ expected returns (demand) and risk averseness, they will be able to use the model to choose the best configuration that suites their needs. In general it was found that investing in a diversified HRES is better than investing in individual power sources.
- Full Text:
- Date Issued: 2013
Sustainable harvesting of wild populations of Cyclopia intermedia in Kouga, Eastern Cape, South Africa
- Authors: Barnardo, Nadia
- Date: 2013
- Subjects: Wild plants, Edible -- South Africa -- Eastern Cape , Rooibos tea industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10639 , http://hdl.handle.net/10948/d1020195
- Description: Cyclopia intermedia E. Mey is harvested from the wild to produce honeybush tea. The presence of a lignotuber and its slow growth seems to hinder the cultivation of this species and wild harvesting is likely to continue. Species distribution modelling indicated that C. intermedia has a climate envelope that spans from the Eastern Cape to the Western Cape along the Cape Fold mountains. This regional distribution is threatened under future climate change scenarios with a range loss and shift identified for climate conditions predicted for 2050. More specifically, its niche was identified as south-facing slopes with sandy to loamy sand soils and water holding capacity that is higher than the surrounding areas. Some keystone Fynbos species were found to share this niche: Leucadendron salignum, Leucospermum cuneiforme, Protea neriifolia, Protea repens, Elegia filacea and Rhodocoma fruticosa. Cyclopia intermedia grows throughout the summer with flowering buds developing in autumn. These enlarge during winter with the flowers opening in early spring. Pods develop in November and seed set occurs during December. Harvesting plants increases their fecundity with cut plants producing more than twice the number of pods and seeds compared to their non-harvested counterparts. This is because resprouting plants produce more flowering stems than uncut plants. Controlled harvesting or localised short-cycle burning could be considered as a management option to improve fecundity of declining Cyclopia intermedia populations in protected areas. C. intermedia harvesting could occur every third year and stem colour was identified as a measure of harvest maturity. Where at least 30 percent of the population has orange (RHS colour 163A) stems the population is suitable for harvesting.
- Full Text:
- Date Issued: 2013
- Authors: Barnardo, Nadia
- Date: 2013
- Subjects: Wild plants, Edible -- South Africa -- Eastern Cape , Rooibos tea industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10639 , http://hdl.handle.net/10948/d1020195
- Description: Cyclopia intermedia E. Mey is harvested from the wild to produce honeybush tea. The presence of a lignotuber and its slow growth seems to hinder the cultivation of this species and wild harvesting is likely to continue. Species distribution modelling indicated that C. intermedia has a climate envelope that spans from the Eastern Cape to the Western Cape along the Cape Fold mountains. This regional distribution is threatened under future climate change scenarios with a range loss and shift identified for climate conditions predicted for 2050. More specifically, its niche was identified as south-facing slopes with sandy to loamy sand soils and water holding capacity that is higher than the surrounding areas. Some keystone Fynbos species were found to share this niche: Leucadendron salignum, Leucospermum cuneiforme, Protea neriifolia, Protea repens, Elegia filacea and Rhodocoma fruticosa. Cyclopia intermedia grows throughout the summer with flowering buds developing in autumn. These enlarge during winter with the flowers opening in early spring. Pods develop in November and seed set occurs during December. Harvesting plants increases their fecundity with cut plants producing more than twice the number of pods and seeds compared to their non-harvested counterparts. This is because resprouting plants produce more flowering stems than uncut plants. Controlled harvesting or localised short-cycle burning could be considered as a management option to improve fecundity of declining Cyclopia intermedia populations in protected areas. C. intermedia harvesting could occur every third year and stem colour was identified as a measure of harvest maturity. Where at least 30 percent of the population has orange (RHS colour 163A) stems the population is suitable for harvesting.
- Full Text:
- Date Issued: 2013
The diversity and distribution patterns of intertidal fish in the Agulhas bioregion
- Authors: Roux, Maryanne
- Date: 2013
- Subjects: Intertidal fishes , Marine fishes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10723 , http://hdl.handle.net/10948/d1019712
- Description: This study aimed to expand the existing knowledge on the diversity and distribution patterns of intertidal fishes in the Sardinia Bay MPA and adjacent open access areas. It focussed particularly on in intertidal fish communities along the Agulhas Bioregion coast which has been understudied, especially in recent years. Typical resident species belonging to the family Clinidae were the most abundant, conforming to previous studies. Species from the family Gobiidae were the second most abundant in this study but this family was not previously recorded as being abundant. Transient species were unimportant in the current study which is in contrast to previous studies in the region and suggests a change in species composition. Certain transient species utilised intertidal rockpools as part of their nursery areas in the Eastern Cape, as has previously been found around Algoa Bay. A decrease in species richness from east to west was recorded in this study which has been noted by previous authors and the diversity and distribution patterns of the intertidal fish in the current study conformed to patterns found previously. The position of the biogeographic boundary between the Agulhas and Natal Bioregions could not be confirmed but Wavecrest (along the Transkei coastline) appeared to be part of a transition zone rather than a fixed break. More sampling around this area is recommended to determine the location and understand the dynamic nature of this boundary. The fish species were found to be vertically distributed across the shore with most of the resident species being more abundant across the low shore while the transient species were more abundant in the middle to low shore pools. This vertical distribution has been found at many sites around the world. The volume of the pools proved to be the primary controlling factor while the effect of temperature on vertical distribution could not be demonstrated. The benefits of the Sardinia Bay Marine Protected Area on this unexploited community of fishes could not be demonstrated but the long term benefit of protection has yet to be shown. Results from this study suggest that despite the correspondence with general biogeographic trends, the intertidal fish community has changed in composition (at least in terms of transient species) during the last 30 years and the cause for these changes may in part be reduced recruitment from exploited linefish.
- Full Text:
- Date Issued: 2013
- Authors: Roux, Maryanne
- Date: 2013
- Subjects: Intertidal fishes , Marine fishes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10723 , http://hdl.handle.net/10948/d1019712
- Description: This study aimed to expand the existing knowledge on the diversity and distribution patterns of intertidal fishes in the Sardinia Bay MPA and adjacent open access areas. It focussed particularly on in intertidal fish communities along the Agulhas Bioregion coast which has been understudied, especially in recent years. Typical resident species belonging to the family Clinidae were the most abundant, conforming to previous studies. Species from the family Gobiidae were the second most abundant in this study but this family was not previously recorded as being abundant. Transient species were unimportant in the current study which is in contrast to previous studies in the region and suggests a change in species composition. Certain transient species utilised intertidal rockpools as part of their nursery areas in the Eastern Cape, as has previously been found around Algoa Bay. A decrease in species richness from east to west was recorded in this study which has been noted by previous authors and the diversity and distribution patterns of the intertidal fish in the current study conformed to patterns found previously. The position of the biogeographic boundary between the Agulhas and Natal Bioregions could not be confirmed but Wavecrest (along the Transkei coastline) appeared to be part of a transition zone rather than a fixed break. More sampling around this area is recommended to determine the location and understand the dynamic nature of this boundary. The fish species were found to be vertically distributed across the shore with most of the resident species being more abundant across the low shore while the transient species were more abundant in the middle to low shore pools. This vertical distribution has been found at many sites around the world. The volume of the pools proved to be the primary controlling factor while the effect of temperature on vertical distribution could not be demonstrated. The benefits of the Sardinia Bay Marine Protected Area on this unexploited community of fishes could not be demonstrated but the long term benefit of protection has yet to be shown. Results from this study suggest that despite the correspondence with general biogeographic trends, the intertidal fish community has changed in composition (at least in terms of transient species) during the last 30 years and the cause for these changes may in part be reduced recruitment from exploited linefish.
- Full Text:
- Date Issued: 2013
In silico and in vitro screening of marrubiin and marrubiin derivatives for antidiabetic activity on PTP1ß, C2C12 myocytes, chang liver hepatocytes and 3T3-L1 adipocytes
- Authors: Nicholas, Rudi Berto
- Date: 2013
- Subjects: Hypoglycemic agents , Diabetes -- Treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10347 , http://hdl.handle.net/10948/d1020638
- Description: Diabetes mellitus (DM) is a life changing disease which affects a large portion of the population and the economy through high medical costs and loss of productivity. Marrubiin (MAR), a diterpenoid isolated from Leonotis leonurus, a plant indigenous to Southern Africa, is used by traditional healers to alleviate DM symptoms. This study aims to screen the inhibitory potential of MAR and MAR derivatives on PTP1β and glucose uptake properties of Chang liver, C2C12 and 3T3-L1 cells. Marrubiin and 19 of its derivatives were tested to determine the inhibition constants for PTP1β. A Ki of 21 μM and 0.047 μM was detected for oleanolic acid in silico and in vitro, respectively. All other diterpene derivatives did not display substantial levels of inhibition of PTP1β. Treatment of Chang liver cells with the various MAR derivatives (10 μM) did not significantly increase glucose uptake beyond metformin, a known antidiabetic drug. The various treatments showed a protective/proliferative effect on the C2C12 muscle cells with two MAR treatments (DC16 and DC18) significantly increasing glucose uptake as compared to metformin in C2C12 muscle cells. It was noted that DC17, DC18 and MAR significantly increased glucose uptake in 3T3-L1 adipocytes, relative to the control. Contrary to cytotoxicity studies with Chang liver and C2C12 muscle cells, adipocytes displayed no cytotoxicity to treatments while a significant increase in cell viability was seen for DC9 and DC15. To unravel the mechanism of action, Western blotting analysis was completed and an increased expression of PTP1β was observed for treatments with DC17 and DC6 was seen in adipocytes, while DC18 and metformin decreased expression significantly. This correlated with a significant decrease of Ser 612 phosphorylation of insulin receptor substrate (IRS1) for DC17. Real time qPCR of IRS1 and GLUT4 highlighted that DC17 and MAR were able to significantly increase expression of IRS1 and GLUT4, respectively. The results show that MAR and the selected derivatives (DC6, DC17, DC18) have been found to increase glucose uptake in peripheral tissue types with IRS1, GLUT4 and PTP1β being associated with the mechanism of action. However, a complete understanding of the mechanisms is yet to be established.
- Full Text:
- Date Issued: 2013
- Authors: Nicholas, Rudi Berto
- Date: 2013
- Subjects: Hypoglycemic agents , Diabetes -- Treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10347 , http://hdl.handle.net/10948/d1020638
- Description: Diabetes mellitus (DM) is a life changing disease which affects a large portion of the population and the economy through high medical costs and loss of productivity. Marrubiin (MAR), a diterpenoid isolated from Leonotis leonurus, a plant indigenous to Southern Africa, is used by traditional healers to alleviate DM symptoms. This study aims to screen the inhibitory potential of MAR and MAR derivatives on PTP1β and glucose uptake properties of Chang liver, C2C12 and 3T3-L1 cells. Marrubiin and 19 of its derivatives were tested to determine the inhibition constants for PTP1β. A Ki of 21 μM and 0.047 μM was detected for oleanolic acid in silico and in vitro, respectively. All other diterpene derivatives did not display substantial levels of inhibition of PTP1β. Treatment of Chang liver cells with the various MAR derivatives (10 μM) did not significantly increase glucose uptake beyond metformin, a known antidiabetic drug. The various treatments showed a protective/proliferative effect on the C2C12 muscle cells with two MAR treatments (DC16 and DC18) significantly increasing glucose uptake as compared to metformin in C2C12 muscle cells. It was noted that DC17, DC18 and MAR significantly increased glucose uptake in 3T3-L1 adipocytes, relative to the control. Contrary to cytotoxicity studies with Chang liver and C2C12 muscle cells, adipocytes displayed no cytotoxicity to treatments while a significant increase in cell viability was seen for DC9 and DC15. To unravel the mechanism of action, Western blotting analysis was completed and an increased expression of PTP1β was observed for treatments with DC17 and DC6 was seen in adipocytes, while DC18 and metformin decreased expression significantly. This correlated with a significant decrease of Ser 612 phosphorylation of insulin receptor substrate (IRS1) for DC17. Real time qPCR of IRS1 and GLUT4 highlighted that DC17 and MAR were able to significantly increase expression of IRS1 and GLUT4, respectively. The results show that MAR and the selected derivatives (DC6, DC17, DC18) have been found to increase glucose uptake in peripheral tissue types with IRS1, GLUT4 and PTP1β being associated with the mechanism of action. However, a complete understanding of the mechanisms is yet to be established.
- Full Text:
- Date Issued: 2013
Effects of crop rotation and tillage system on the control of ryegrass (lolium multiflorum X perenne) in wheat (triticum aestivum) in the Swartland production area of South Africa's Western Cape Province
- Authors: Nteyi, Sinovuyo Mava
- Date: 2013
- Subjects: Cropping systems , Conservation tillage -- South Africa -- Western Cape , Ryegrasses
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10738 , http://hdl.handle.net/10948/d1020990
- Description: A major challenge facing agriculture today is to sustain the productivity of agricultural systems with the reduction of weed invasion. The Swartland region in the Western Cape (South Africa) is intensively cropped, producing wheat (Triticum aestivum) as the major crop. As a result of the weedy ryegrass invasion the wheat yield is reduced. In addition, ryegrass has developed resistance to grass herbicides (graminicides). This situation has increased the need to use alternative practices for controlling the invasion of ryegrass in wheat fields. In this regard, crop rotation and tillage systems were proposed as techniques to suppress the ryegrass invasion. This could thus maintain a sustainable long-term wheat production system with less application of herbicides, decreased input costs and increased total grain yield. Against this background, the effects of crop rotation and tillage were determined on ryegrass seedling emergence in a field and shade netting experiment, while seed dormancy was determined in the laboratory. The objectives were to compare the wheat production of two crop rotations with mono-cropped wheat and assess the impact on the ryegrass population in no-till and minimum tillage systems. Analyses of variance on data sets of ryegrass seeds from 2009, 2010 and 2011 were used to determine germination and dormancy percentages in laboratory experiments. The performance of laboratory treatments was evaluated on the basis of germination percentage of seeds. In the field and shade netting experiments, analyses of variance for data from 2007, 2011 and 2012 were used to determine crop rotation x tillage system response. Field and shade netting performance were evaluated on the basis of ryegrass population inhibition and stimulation respectively. Ryegrass seeds from 2009 and 2010 showed higher germination percentages (80 per cent and 73 per cent) than 2011 (42 per cent). Primary dormancy prevented high germination of newly harvested seeds as dormancy release increase with age of the seed. Results of field and shade netting experiments showed stimulation of the ryegrass weed population in wheat monoculture under minimum tillage. However, when wheat was rotated with leguminous crops under both tillage systems (minimum-till and no-till) ryegrass was significantly inhibited. It was concluded that the critical period for weed competition is the first six weeks after planting. Results from this study provide a basis for producers of cereals to make good decisions with regards to timing weed control measures. It is essential to use competitive crop sequences which will inhibit weeds. The challenge is getting this practice adopted and implemented by producers as it will promote conservation agriculture within the region. This study promotes long-term sustainable wheat production systems with an efficient weed management programme that is environmentally friendly using less herbicides within the Swartland region.
- Full Text:
- Date Issued: 2013
- Authors: Nteyi, Sinovuyo Mava
- Date: 2013
- Subjects: Cropping systems , Conservation tillage -- South Africa -- Western Cape , Ryegrasses
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10738 , http://hdl.handle.net/10948/d1020990
- Description: A major challenge facing agriculture today is to sustain the productivity of agricultural systems with the reduction of weed invasion. The Swartland region in the Western Cape (South Africa) is intensively cropped, producing wheat (Triticum aestivum) as the major crop. As a result of the weedy ryegrass invasion the wheat yield is reduced. In addition, ryegrass has developed resistance to grass herbicides (graminicides). This situation has increased the need to use alternative practices for controlling the invasion of ryegrass in wheat fields. In this regard, crop rotation and tillage systems were proposed as techniques to suppress the ryegrass invasion. This could thus maintain a sustainable long-term wheat production system with less application of herbicides, decreased input costs and increased total grain yield. Against this background, the effects of crop rotation and tillage were determined on ryegrass seedling emergence in a field and shade netting experiment, while seed dormancy was determined in the laboratory. The objectives were to compare the wheat production of two crop rotations with mono-cropped wheat and assess the impact on the ryegrass population in no-till and minimum tillage systems. Analyses of variance on data sets of ryegrass seeds from 2009, 2010 and 2011 were used to determine germination and dormancy percentages in laboratory experiments. The performance of laboratory treatments was evaluated on the basis of germination percentage of seeds. In the field and shade netting experiments, analyses of variance for data from 2007, 2011 and 2012 were used to determine crop rotation x tillage system response. Field and shade netting performance were evaluated on the basis of ryegrass population inhibition and stimulation respectively. Ryegrass seeds from 2009 and 2010 showed higher germination percentages (80 per cent and 73 per cent) than 2011 (42 per cent). Primary dormancy prevented high germination of newly harvested seeds as dormancy release increase with age of the seed. Results of field and shade netting experiments showed stimulation of the ryegrass weed population in wheat monoculture under minimum tillage. However, when wheat was rotated with leguminous crops under both tillage systems (minimum-till and no-till) ryegrass was significantly inhibited. It was concluded that the critical period for weed competition is the first six weeks after planting. Results from this study provide a basis for producers of cereals to make good decisions with regards to timing weed control measures. It is essential to use competitive crop sequences which will inhibit weeds. The challenge is getting this practice adopted and implemented by producers as it will promote conservation agriculture within the region. This study promotes long-term sustainable wheat production systems with an efficient weed management programme that is environmentally friendly using less herbicides within the Swartland region.
- Full Text:
- Date Issued: 2013
Relating vegetation condition to grazing management systems in the central Keiskamma catchment, Eastern Cape Province, South Africa
- Authors: Ndou, Naledzani Nyahman
- Date: 2013
- Subjects: Grazing -- Management , Grazing -- South Africa -- Management , Vegetation and climate -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10673 , http://hdl.handle.net/10948/d1020645
- Description: Vegetation degradation in South Africa has been identified as a serious environmental problem, especially impacting communal areas. This study investigated the spatial distribution of vegetative condition, along with related changes, deterioration and trends, across the communal villages of the central Keiskamma catchment, Eastern Cape Province. The principal hypothesis of this study was that differences in grazing management strategies may explain the variations in vegetation condition within these communal areas. This investigation assessed the status and condition of vegetation in relation to local institutional grazing management systems, in association with factoring in relevant topographical and physical elements. Topographic homogeneity of the study area was tested by extracting topographic parameters from a DEM and performing a Chi squared test. Remote sensing techniques were used to analyse the spatial and temporal variations in vegetation condition between the villages. Landsat TM images, from 1984 and 1999, in conjunction with SPOT imagery of 2011, were used to assess the spatial trends in vegetation. Land use and cover maps were generated, comprising five categories of land cover, viz. intact vegetation; transformed vegetation; degraded vegetation; bare surfaces; and water. The classification of the images was achieved using the supervised object-oriented classification techniques, which aggregates pixels of each class into homogeneous objects. Information regarding existence and functionality of local institutional structures was obtained through structured interview method. Vegetation condition was correlated to grazing management systems, with the logistic regression confirming a significant relationship between vegetation condition and grazing management systems. Analysis of vegetation condition trends revealed a decline in pristine vegetation with an increase in degraded vegetation and exposed soil throughout the villages. However, it was observed that the decrease in pristine vegetation, with the associated increase in degraded vegetation and soil, do not occur evenly among the villages of the central Keiskamma catchment; the communal areas surrounding certain villages exhibited severe degradation of soil and vegetation, while other villages demonstrated less or minimal deterioration in their environs. The topographic homogeneity of the study locale lent credence to the theory that the uneven distribution of vegetation conditions between the villages is not controlled by topographic factors. Analysis of the data, collected through interviews, revealed differences in the functionality of institutional structures between villages. A statistically significant correlation between the vegetative condition and implementation of grazing management systems, supports the postulated concept that the variances in vegetation condition of the central Keiskamma catchment reflect the efficacy or inefficiency of the settlements‘ grazing management systems. Through gathering, analysing and assessing all the data, a conclusion was drawn, which advances that the primary requirement for remedial action in reversing the current decline in vegetation condition is strengthening the local institutional management regimes throughout all villages under study.
- Full Text:
- Date Issued: 2013
- Authors: Ndou, Naledzani Nyahman
- Date: 2013
- Subjects: Grazing -- Management , Grazing -- South Africa -- Management , Vegetation and climate -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10673 , http://hdl.handle.net/10948/d1020645
- Description: Vegetation degradation in South Africa has been identified as a serious environmental problem, especially impacting communal areas. This study investigated the spatial distribution of vegetative condition, along with related changes, deterioration and trends, across the communal villages of the central Keiskamma catchment, Eastern Cape Province. The principal hypothesis of this study was that differences in grazing management strategies may explain the variations in vegetation condition within these communal areas. This investigation assessed the status and condition of vegetation in relation to local institutional grazing management systems, in association with factoring in relevant topographical and physical elements. Topographic homogeneity of the study area was tested by extracting topographic parameters from a DEM and performing a Chi squared test. Remote sensing techniques were used to analyse the spatial and temporal variations in vegetation condition between the villages. Landsat TM images, from 1984 and 1999, in conjunction with SPOT imagery of 2011, were used to assess the spatial trends in vegetation. Land use and cover maps were generated, comprising five categories of land cover, viz. intact vegetation; transformed vegetation; degraded vegetation; bare surfaces; and water. The classification of the images was achieved using the supervised object-oriented classification techniques, which aggregates pixels of each class into homogeneous objects. Information regarding existence and functionality of local institutional structures was obtained through structured interview method. Vegetation condition was correlated to grazing management systems, with the logistic regression confirming a significant relationship between vegetation condition and grazing management systems. Analysis of vegetation condition trends revealed a decline in pristine vegetation with an increase in degraded vegetation and exposed soil throughout the villages. However, it was observed that the decrease in pristine vegetation, with the associated increase in degraded vegetation and soil, do not occur evenly among the villages of the central Keiskamma catchment; the communal areas surrounding certain villages exhibited severe degradation of soil and vegetation, while other villages demonstrated less or minimal deterioration in their environs. The topographic homogeneity of the study locale lent credence to the theory that the uneven distribution of vegetation conditions between the villages is not controlled by topographic factors. Analysis of the data, collected through interviews, revealed differences in the functionality of institutional structures between villages. A statistically significant correlation between the vegetative condition and implementation of grazing management systems, supports the postulated concept that the variances in vegetation condition of the central Keiskamma catchment reflect the efficacy or inefficiency of the settlements‘ grazing management systems. Through gathering, analysing and assessing all the data, a conclusion was drawn, which advances that the primary requirement for remedial action in reversing the current decline in vegetation condition is strengthening the local institutional management regimes throughout all villages under study.
- Full Text:
- Date Issued: 2013
A comparative study of the comfort related properties of commercial apparel fabrics containing natural and man-made fibres
- Authors: Stoffberg, Marguerite Ester
- Date: 2013
- Subjects: Textile fabrics , Materials -- Thermal properties
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10455 , http://hdl.handle.net/10948/d1020931
- Description: The relationship between the fabric parameters, as independent variables, and the comfort related properties, as dependent variables, of commercial suiting fabrics, containing both natural and man-made fibres, have been studied. The fabric parameters measured in the study were mass, thickness, density, and air permeability. The comfort related properties, tested on a Permetest instrument, included water vapour permeability, water vapour resistance, and thermal resistance, with the moisture permeability index being derived. A total of 26 commercial suiting fabrics, covering a wide range of mass, as well as different fibre types and blends and fabric structures, was tested. The fibres covered, included wool, polyester, viscose, and cotton, while the fabric structures covered were 1x1 plain weave, 2x1 twill and 2x2 twill weave. The objectives of this study were to determine the empirical relationships between the measured fabric properties and the measured comfort related properties, and to determine the role, if any, of fibre type and fabric structure, since many claims are made in practice concerning the relative advantages, in terms of comfort, of a specific fibre type or blend, or fabric structure, over others, some of which being supported by research results. Since the fabrics covered, were commercial and were not engineered so that the different fabric parameters (independent variables) and fibre type and blend, as well as fabric structure could be varied independently of each other, the effects of the various fabric parameters on the fabric comfort related properties were determined and quantified by multiple regression analyses (multi-linear and multi-quadratic), and the best fit regression equations, and contribution of each parameter to the overall fit established. It was found that fabric thickness and fabric mass had the largest effect on the comfort related properties as measured here, fabric mass determining, to a large extent, water vapour permeability, and fabric thickness, thermal resistance. The rest of the fabric parameters included in the study had only a relatively small effect on the measured comfort related properties. The influence of fabric parameters, with particular reference to mass and thickness, on the measured comfort related properties, were much greater than that of fibre type or blend, or fabric structure. It was, therefore, concluded from this study, that the fabric parameters, as opposed to the intrinsic characteristics of a particular fibre, whether natural or man-made, largely determined those fabric comfort related properties measured here.
- Full Text:
- Date Issued: 2013
- Authors: Stoffberg, Marguerite Ester
- Date: 2013
- Subjects: Textile fabrics , Materials -- Thermal properties
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10455 , http://hdl.handle.net/10948/d1020931
- Description: The relationship between the fabric parameters, as independent variables, and the comfort related properties, as dependent variables, of commercial suiting fabrics, containing both natural and man-made fibres, have been studied. The fabric parameters measured in the study were mass, thickness, density, and air permeability. The comfort related properties, tested on a Permetest instrument, included water vapour permeability, water vapour resistance, and thermal resistance, with the moisture permeability index being derived. A total of 26 commercial suiting fabrics, covering a wide range of mass, as well as different fibre types and blends and fabric structures, was tested. The fibres covered, included wool, polyester, viscose, and cotton, while the fabric structures covered were 1x1 plain weave, 2x1 twill and 2x2 twill weave. The objectives of this study were to determine the empirical relationships between the measured fabric properties and the measured comfort related properties, and to determine the role, if any, of fibre type and fabric structure, since many claims are made in practice concerning the relative advantages, in terms of comfort, of a specific fibre type or blend, or fabric structure, over others, some of which being supported by research results. Since the fabrics covered, were commercial and were not engineered so that the different fabric parameters (independent variables) and fibre type and blend, as well as fabric structure could be varied independently of each other, the effects of the various fabric parameters on the fabric comfort related properties were determined and quantified by multiple regression analyses (multi-linear and multi-quadratic), and the best fit regression equations, and contribution of each parameter to the overall fit established. It was found that fabric thickness and fabric mass had the largest effect on the comfort related properties as measured here, fabric mass determining, to a large extent, water vapour permeability, and fabric thickness, thermal resistance. The rest of the fabric parameters included in the study had only a relatively small effect on the measured comfort related properties. The influence of fabric parameters, with particular reference to mass and thickness, on the measured comfort related properties, were much greater than that of fibre type or blend, or fabric structure. It was, therefore, concluded from this study, that the fabric parameters, as opposed to the intrinsic characteristics of a particular fibre, whether natural or man-made, largely determined those fabric comfort related properties measured here.
- Full Text:
- Date Issued: 2013