"But what story?": a narrative-discursive analysis of "white" Afrikaners' accounts of male involvement in parenthood decision-making
- Authors: Morison, Tracy
- Date: 2011
- Subjects: Family planning -- South Africa -- Psychological aspects Family size Birth intervals Men -- South Africa -- Attitudes Men -- South Africa -- Psychology Couples -- South Africa -- Psychology Afrikaners -- Attitudes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3025 , http://hdl.handle.net/10962/d1002534
- Description: Despite the increased focus on men in reproductive research, little is known about male involvement in the initial decision/s regarding parenthood (i.e., to become a parent or not) and the subsequent decision-making that may ensue (e.g., choices about timing or spacing of births). In particular, the parenthood decision-making of “White”, heterosexual men from the middle class has been understudied, as indicated in the existing literature. In South Africa, this oversight has been exacerbated by the tendency for researchers to concentrate on “problematic” men, to the exclusion of the “boring, normal case”. I argue that this silence in the literature is a result of the taken for granted nature of parenthood in the “normal” heterosexual life course. In this study, I have turned the spotlight onto the norm of “Whiteness” and heterosexuality by studying those who have previously been overlooked by researchers. I focus on “White” Afrikaans men’s involvement in parenthood decision-making. My aim was to explore how constructions of gender inform male involvement in decision-making, especially within the South African context where social transformation has challenged traditional conceptions of male selfhood giving rise to new and contested masculine identities and new discourses of manhood and fatherhood. In an effort to ensure that women’s voices are not marginalised in the research, as is often the case in studies of men and masculinity, I conducted in-depth, semi-structured interviews about male involvement in decision-making with both “White” Afrikaans women and men. There were 23 participants in total, who all identified as heterosexual and middle-class. The participants were divided into two age cohorts (21 – 30 years and >40 years), which were then differentiated according to gender, reproductive status, and relationship status. Treating the interviews as jointly produced narratives, I analysed them by means of a performativity/performance lens. This dual analytic lens focuses on how particular narrative performances are simultaneously shaped by the interview setting and the broader discursive context. The lens was fashioned by synthesising Butler’s theory of performativity with Taylor’s narrative-discursive method. This synthesis (1) allows for Butler’s notion of “performativity” to be supplemented with that of “performance”; (2) provides a concrete analytical strategy in the form of positioning analysis; and (3) draws attention to both the micro politics of the interview conversation and the operation of power on the macro level, including the possibility of making “gender trouble”. The findings of the study suggest that the participants experienced difficulty narrating about male involvement in parenthood decision-making, owing to the taken for granted nature of parenthood for heterosexual adults. This was evident in participants’ sidelining of issues of “deciding” and “planning” and their alternate construal of childbearing as a non-choice, which, significantly served to bolster hetero-patriarchal norms. A central rhetorical tool for accomplishing these purposes was found in the construction of the “sacralised” child. In discursively manoeuvring around the central problematic, the participants ultimately produced a “silence” in the data that repeats the one in the research literature.
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- Date Issued: 2011
A framework to enhance the mobile user experience in an Mlearning interaction
- Authors: Botha, Adele
- Date: 2011
- Subjects: Educational technology , Information technology , Educational innovations , Teaching -- Aids and devices
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9753 , http://hdl.handle.net/10948/d1008163 , Educational technology , Information technology , Educational innovations , Teaching -- Aids and devices
- Description: The new millennium is witness to a telecommunications world that is vastly different from even the recent past with developments in the mobile sector having dramatically changed the Information and Communication Technology (ICT) landscape. Mobile cellular technology has proliferated faster than any previous technology and is now the most ubiquitous technology in the world. The focus of this thesis is the development of a framework to enhance the Mobile User Experience in an Mlearning interaction. This research is contextualised by the goal-oriented use of mobile cellular technologies in a formal educational environment. As such the study, although residing in the field of Human-Computer Interaction (HCI), acknowledges issues arising in the Education Domain as a specific field of application. The aim of the research was to investigate the components of a framework to enhance the Mobile User Experience in an Mlearning interaction. The development of the framework was facilitated by the exploration of: the Mobile User Experience factors and their impact, on the Mobile User Experience of learners participating in a goal-oriented Mlearning interaction. These critical factors were documented in terms of the Mobile User Experience components, and the relationships of these components to each other as well as the Mobile User Experience of an Mlearning interaction. The research, grounded in a phenomenological research philosophy, applied an inductive reasoning approach, and was operationalised through a single case study methodology. A qualitative research strategy was considered appropriate, as the phenomenon of User Experience is linked to the hedonistic attributes of the interaction. This study was conducted in four phases with focus on three embedded units of analysis. The three units of analysis were identified as: The learner as end user in an Mlearning interaction; The educator as designer of the Mlearning interaction; and The Mlearning interaction. The research revealed that the Mobile User Experience of an Mlearning interaction is affected by the mobile user, mobile use, mobile device, mobile business practices, mobile networks, mobile interaction and mobile context. Within the Mlearning interaction the significant components are the learners as mobile users, the enhance interactions, removal of barriers to the interaction, goal-oriented nature of the interaction and the ducational context. Identifying these components and their associated Mobile User Experience factors and impacts, present the main contribution of this thesis. In conclusion, the limitations of the study are documented and topics for future research are outlined.
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- Date Issued: 2011
An intervention for enhancing the mathematics teaching practices of grade four teachers in the Nelson Mandela Metropolitan area
- Authors: Botha, Adele
- Date: 2011
- Subjects: Mathematics -- Study and teaching , Mathematics , Mathematics -- Handbooks, manuals, etc , Mathematics teachers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9499 , http://hdl.handle.net/10948/d1008176 , Mathematics -- Study and teaching , Mathematics , Mathematics -- Handbooks, manuals, etc , Mathematics teachers
- Description: Mathematics is regarded as a driving force in economies worldwide. The performance of South African learners in mathematics over the past decade has highlighted that problems are being experienced across all grades. This situation needs to be addressed with urgency. The South African Department of Education stated that quality learning must be the objective for all grades. The implementation of good teaching practices plays a crucial role in improving the quality of education and in guiding learners towards quality learning. To achieve quality mathematics teaching and learning it is imperative to determine what good mathematics teaching practices are. The identification of good mathematic teaching practices will provide a yard stick to measure the mathematics teaching competency of teachers. This study identifies a set of good mathematics teaching practice indicators and evidences applicable to teachers in the Intermediate phase as a first contribution. These indicators and evidences frame the second research contribution: an assessment instrument entitled “A Classroom Observation Tool for Observing Mathematics Teaching Practices in Primary Schools”. As a third research contribution a generic profile of a Grade four mathematics teacher has been built. This generic profile has been built through an analysis of data gathered by means of self-assessment questionnaires completed by the research sample, as well as through applying the observation tool. The value of the generic profile lies in the identification of shared strengths and shared improvement opportunities in the mathematics teaching practice of the sample and as such, it forms the basis of a theory on Grade four mathematics teaching practice. The fourth research contribution is the design and application of an intervention that addresses the shared improvement opportunities. The research study concludes by comparing pre-intervention classroom observation data with post-intervention classroom observation data and reporting on the impact of the intervention.
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- Date Issued: 2011
Characterization and electrocatalytic applications of metallophthalocyanine-single walled carbon nanotube conjugates
- Authors: Mugadza, Tawanda
- Date: 2011 , 2011-03-30
- Subjects: Phthalocyanines Pesticides Nanotubes Electrocatalysis Electrochemistry Transmission electron microscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4419 , http://hdl.handle.net/10962/d1006855
- Description: Metallophthalocyanine-single walled carbon nanotube conjugates were successfully synthesized and applied in the electrochemical characterizations of pesticides (amitrole and diuron) and 2-mercaptoethanol (2-ME). The formation of conjugates was confirmed through the use of the following analytical techniques: UV-vis, FTIR, Raman and XRD spectroscopies, atomic force and transmission electron microscopies and voltammetry. Chemically linking SWCNT to MPcs created platforms that offered efficient transfer of electrons and this was confirmed through electrochemical impedance studies (EIS) and voltammetry as shown by lower ΔEp values observed in conjugates. Carboxy carrying MPcs have very poor electron transfer kinetics (both tetrasubstituted and low symmetry), but the presence of SWCNTs activates their catalysis. All electrochemical studies were done at pH 4. Cyclic voltammetry, rotating disk linear sweep voltammetry, chronoamperometry and EIS were used in the electrochemical characterization of 2-ME and the pesticides on poly-Ni(OH)TAPc and MPc-SWCNT modified glassy carbon electrodes (GCEs). High Tafel slopes were observed for the pesticides relative to 2-ME, an indication of the passivating nature of their oxidation products. However, conjugates showed very high resistances to passivation and were easily regenerated by shaking in methanol. Improved catalysis of the conjugates is also indicated by the high catalytic rate constants for the analytes, observed on these electrodes. Conjugates of low symmetry MPcs with SWCNTs gave the highest catalytic rate constants, confirming better catalysis on these electrode surfaces. The nature of SWCNT functionalization also affected catalysis, with amine functionalized SWCNTs inducing better catalytic properties into the MPcs than carboxylic acid terminated CNTs. The presence of amine functionalized SWCNTs activates the catalysis of non-catalytic carboxy-carrying MPcs and this is more pronounced in conjugates of tetrasubstituted MPcs relative to those of low symmetry Pcs. Ethylene amine (EA) functionalized SWCNTs reduced redox overpotentials of the MPcs more than the phenyl-amine (PA) functionalized counterparts. Poly-NiTAPc was successfully converted to poly-Ni(OH)TAPc through cyclisation in pH 4 buffer and showed very good catalytic properties towards diuron, relative to the former.
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- Date Issued: 2011
Comparative study of the feeding damage caused by the South African biotypes of the Russian wheat aphid (Diuraphis noxia Kurdjumov) on resistant and non-resistant lines of barley (Hordeum vulgare L.)
- Authors: Jimoh, Mahboob Adekilekun
- Date: 2011
- Subjects: Aphids Russian wheat aphid -- Research -- South Africa Barley -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4201 , http://hdl.handle.net/10962/d1003770
- Description: Cereal crop productivity is hampered when these plants are infested by phloem feeding aphids. A great deal of research has been carried out with the direct aim of a clearer understanding of the mechanism involved in the interaction between aphids and their host plants. Research has directly or indirectly been geared towards enhanced plant productivity and achieving sustainable agriculture. Barley (Hordeum vulgare L.) is an important small grain crop in South Africa, whose crop performance is negatively affected by fluctuations in weather patterns as well as by agricultural pests. One of the insect pests infesting barley is the Russian wheat aphid, Diuraphis noxia Kurdjumov (RWA), of which the two South African biotypes, codenamed RWASA1 and RWASA2, were studied in this thesis. During dry spells, RWA infestation becomes a more serious threat to barley productivity. Resistant plants have been used to combat RWA infestation of small grains. In South Africa, 27 RWA-resistant wheat cultivars are currently used in commercial cultivation, but no resistant barley lines have, unfortunately, been developed, in spite of this grain’s significant economic importance. This informed the study in this thesis, and this interest particularly focussed on three RWA-resistant lines developed by the USDA, testing their performance against South African RWA biotypes, for possible adaptation to South Africa. The aim was thus to examine the plant-aphid interactions, aphid breeding rates, plant damage and sustainability, evidence of resistance or tolerance and finally potential performance under elevated CO2 (a very real climate change threat). Two major avenues of research were undertaken. The first aspect involved examination of structural and functional damage caused by RWASA1 and RWASA2 on the three resistant and a non-resistant line. Aphid population growth and damage symptoms (chlorosis and leaf roll) of infestation by these aphid biotypes were evaluated. This was followed by a structural and functional approach in which the effects of feeding on the transport systems (phloem and xylem) of barley were investigated. Fluorescence microscopy techniques (using aniline blue fluorochrome, a specific stain for callose and 5,6-CFDA, a phloem-mobile probe) were applied to investigate the feeding-related damage caused by the aphids, through an examination of wound callose formation and related to this, the resultant reduction in phloem transport capacity. Transmission electron microscopy (TEM) techniques provided evidence of the extent of the feeding-related cell damage. The second aspect involved a study of the effect of changing CO2 concentrations ([CO2]) on the resistant and susceptible barley cultivars to feeding by the two RWA biotypes. Leaves of plants grown at ambient and two elevated levels of [CO2] were analysed to investigate the effect of changing [CO2] on biomass, leaf nitrogen content and C:N ratio of control (uninfested) and infested plants. The population growth studies showed that the populations of the two RWA biotypes as well as bird cherry-oat aphid (BCA, Rhopalosiphum padi L.) increased substantially on the four barley lines. BCA was included here, as it had been the subject of several previous studies. RWASA2 bred faster than RWASA1 on all lines. The breeding rates of the two RWA biotypes were both suppressed and at near-equivalent levels on the three resistant lines, compared to the non-resistant PUMA. This suggests that the resistant lines possessed an antibiosis resistance mechanism against the feeding aphids. Feeding by the aphids manifested in morphological damage symptoms of chlorosis and leaf roll. The two biotypes inflicted severe chlorosis and leaf roll on the non-resistant PUMA. In the resistant plants, leaf rolling was more severe because of RWASA2 feeding compared to RWASA1 feeding. In contrast, chlorosis symptoms were more severe during RWASA1 feeding than was the case with RWASA2 feeding. Investigation of the effect of aphid feeding on the plants showed that callose was deposited within 24h and that this increased with longer feeding exposure. Wound callose distribution is more extensive in the non-resistant PUMA than in the resistant plants. RWASA2 feeding on the resistant lines caused deposition of more callose than was evident with RWASA1 feeding. During long-term feeding, it was evident that variation in the intensity and amount of wound callose was visible in the longitudinal and transverse veins of the resistant plants. Of the three STARS plants, STARS-9301B had the least callose. Interestingly, wound callose occurred in both resistant and non-resistant plants, in sharp contrast to what has been reported on resistant wheat cultivars that were developed in South Africa. The relative reduction in the wound callose deposited in the resistant line, when compared to the non-resistant lines, suggests the presence of a mechanism in the resistant lines, which may prevent excessive callose formation. Alternatively, the mechanism may stimulate callose breakdown. RWASA2 feeding on the resistant lines deposited more wound callose than RWASA1 feeding. This evidence supports the hypothesis that RWASA2 is a resistance breaking and more aggressive feeder than RWASA1 is; and further underscores the urgent need for development of RWA-resistant barley cultivars. The ultrastructural investigation of the feeding damage showed that the two biotypes caused extensive vascular damage in non-resistant plants. There was extensive and severe cell disruption and often obliteration of cell structure of the vascular parenchyma, xylem and phloem elements. In sharp contrast, among the resistant plants, feeding-related cell damage appeared to be substantially reduced compared to the non-resistant PUMA. Low frequency of damaged cells indicated that majority of the cell components of the vascular tissues were intact and presumed functional. There was evidence of salivary material lining the secondary walls of the vascular tissue, which resulted in severe damage. Within xylem vessels, saliva material impregnated half-bordered pit pairs between the vessels and adjacent xylem parenchyma. This is believed to prevent solute exchange through this interface, thereby inducing leaf stress and vi leaf roll. A notable finding is that RWASA2 effectively induced more cell damage to vascular tissues in the resistant lines than did RWASA1. In general the experimental evidence (see Chapter 5) suggests that the resistant lines are possibly more tolerant (or able to cope with) to RWA feeding. Evidence for this is the reduction of wound callose and at the TEM level, a comparatively less obvious cell damage in the resistant lines, which suggests that they possess antibiosis and tolerance capacity. The apparent reduction of feeding-related cell damage from the TEM study confirmed the disruptive action of the feeding aphids in experiments using the phloem-mobile probe, 5,6-CF. Results showed that feeding by RWASA1 and RWASA2 reducedthe transport functionality of the phloem in all cases, but that RWASA2 feeding caused a more obvious reduction in the rate and distance that 5,6-carboxyfluorescein was transported, than did RWASA1. Investigation of the effect of changing [CO2] on the barley cultivars showed that in the absence of aphids and under elevated CO2 conditions, the plants grew more vigorously. In this series of experiments, the infested plants suffered significant reduction in biomass under ambient (as was expected) and under the two elevated CO2 regimes. Biomass loss was greater at elevated CO2 than under ambient [CO2]. The infested nonresistant PUMA plants showed a more significant biomass loss than did the resistant cultivars. Clearly, the benefits derived from elevated CO2 enrichment was thus redirected to the now-advantaged aphids. Uninfested vii plants showed an increase in leaf nitrogen under the experimental conditions. However, feeding aphids depleted leaf nitrogen content and this was more apparent on plants exposed to RWASA2 than was the case with RWASA1. The end result of this was that C:N ratio of infested plants were higher than uninfested plants. Clearly, the faster breeding rates of the aphids at elevated CO2 caused depletion of N and a resultant deficiency exacerbated chlorosis as well as leaf rolling due to the higher aphid population density under elevated CO2 than at ambient. By 28 days after infestation (DAI), majority of the plants exposed to enriched CO2 treatments had died. A major finding here was thus that although this study demonstrated that elevated CO2 resulted in an increase in biomass, this was detrimentally offset in plants infested by the aphids, with a decline in biomass and loss of functionality leading to plant death at 28DAI. The overriding conclusion from this study is a clear signal that the twin effects of CO2 enrichment (a feature of current climate change) and aphid infestations may precipitate potential grain shortages. A disastrous food security threat looms.
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- Date Issued: 2011
Enhancing the role of the Kaizen suggestion tool in South African lean automotive companies of the Eastern Cape
- Authors: Adedeji, Adeyemi Charles
- Date: 2011
- Subjects: Lean manufacturing , Manufacturing processes , Production management -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:8644 , http://hdl.handle.net/10948/d1008157 , Lean manufacturing , Manufacturing processes , Production management -- Mathematical models
- Description: The Toyota manufacturing system, aptly referred to as Lean manufacturing, has received a reasonable appreciation and awareness over the past decade in South African industry. This production phenomenon constitutes an organizational culture that encourages world-class production success through the liberation of factory resources, while employees are empowered and encouraged to contribute ideas for the improvement of processes and products. However, despite lean awareness and the crucial role of employee participation in the suggestion of ideas in world-class organizations, the performance level of lean manufacturing in South African industry is largely devoid of the Kaizen suggestion tool, particularly in the automotive companies of the Eastern Cape. The aim of this research was to proffer appropriate recommendations, improved awareness, understanding and practice for the improvement of the Kaizen suggestion principle in the automotive companies of the Eastern Cape. The research primarily focused on the ‘management/employees’ paradigm within the organisational context. The methodology employed in the study included a thorough review of the relevant literature and a questionnaire, which was developed and administered to both the management and employees of the thirty automotive components suppliers in Eastern Cape. The target companies constituted the units of analyses and therefore provided the opportunity for a detailed investigation of the links between management and employees as well as a submission of ideas for operational and organisational processes as established in the literature review. Epistemologically, the research is objectivist and paradigmically, positivist. However, some qualitative aspects of the data were relevant to the study and, therefore, were used in a complementary manner. The case approach utilized mixed methods by applying a range of data collection techniques and evidence from multiple sources while the sampling technique was sequential, involving both purposive and stratified random sampling. The study reveals the apparent lack of a systematic mechanism for the practice and administration of the Kaizen suggestion tools in most Eastern Cape automotive companies. This demerit is found to have negatively affected maximum employee participation and involvement in organizational decision making within the Province. The study has established a basic level of awareness and understanding among employees / employers relations that the Kaizen suggestion scheme is a vital tool for delivering strategic objectives in the management of decision making and organizational growth. The study strongly advocates the inclusion of employee suggestion systems as part of the organizational process.
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- Date Issued: 2011
Identity, belonging and ecological crisis in South African speculative fiction
- Authors: Steenkamp, Elzette Lorna
- Date: 2011
- Subjects: South African fiction -- History and criticism Identity (Philosophical concept) in literature Group identity in literature Ecology in literature Science fiction, South African -- History and criticism Fantasy fiction, South African -- History and criticism Ecofiction -- History and criticism Ecocriticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2219 , http://hdl.handle.net/10962/d1002262
- Description: This study examines a range of South African speculative novels which situate their narratives in futuristic or ‘alternative’ milieus, exploring how these narratives not only address identity formation in a deeply divided and rapidly changing society, but also the ways in which human beings place themselves in relation to Nature and form notions of ‘ecological’ belonging. It offers close readings of these speculative narratives in order to investigate the ways in which they evince concerns which are rooted in the natural, social and political landscapes which inform them. Specific attention is paid to the texts’ treatment of the intertwined issues of identity, belonging and ecological crisis. This dissertation draws on the fields of Ecocriticism, Postcolonial Studies and Science Fiction Studies, and assumes a culturally specific approach to primary texts while investigating possible cross-cultural commonalities between Afrikaans and English speculative narratives, as well as the cross-fertilisation of global SF/speculative features. It is suggested that South African speculative fiction presents a socio-historically situated, rhizomatic approach to ecology – one that is attuned to the tension between humanistic- and ecological concerns.
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- Date Issued: 2011
Land use change, landslide occurrence and livelihood strategies on Mount Elgon Slopes, Eastern Uganda
- Authors: Mugagga, Frank
- Date: 2011
- Subjects: Land use -- Uganda -- Mount Elgon National Park , Landslides -- Uganda -- Mount Elgon National Park , Land degradation -- Uganda -- Mount Elgon National Park
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10646 , http://hdl.handle.net/10948/1468 , Land use -- Uganda -- Mount Elgon National Park , Landslides -- Uganda -- Mount Elgon National Park , Land degradation -- Uganda -- Mount Elgon National Park
- Description: An investigation of the relationship between the physical, pedological and anthropogenic influences on landslide occurrence on the midslopes within and outside Mt Elgon National Park was carried out. One of the landslides occurred in a protected pristine forest environment within the Park while the other two were located at sites deforested for cultivation within and outside the National Park. Field based surveys, GIS techniques and laboratory tests were used to collect and analyze the data. A household survey was undertaken to establish the main community livelihood strategies, the drivers of land use change and implications for land degradation on the mid slopes of Mt Elgon. Aerial photographs taken in 1960 and orthophoto maps formed the benchmark for the analysis of the respective land use changes between 1995 and 2006, using 30m Landsat TM and 20m SPOT MS images in IDRISI Andes GIS environment. Landslide sites were mapped using a Magellan Professional MobileMapperTMCX and terrain parameters were derived using a 15M Digital Elevation Model. A hybrid supervised/unsupervised classification approach was employed to generate land cover maps from which the areal extent of three land cover classes (agricultural fields, woodlands and forests) was calculated. Particle size distribution and atterberg limits were used to test the hypothesis that soils at the landslide sites are inherently ‘problem soils’ where slope failure can occur even without human intervention. Shear strength parameters (internal of friction and cohesion) were used calculate the slope factor of safety to ascertain slope stability at pristine and disturbed landslide sites. Results from the socio-economic survey revealed that smallholder subsistence agriculture and encroachment on the National Park resources are the main sources of livelihoods for the communities surrounding the Park. The communities also have a strong socio-cultural attachment to the National Park, as it is the source of items used during traditional rituals like circumcision. Encroachment is driven by the high population pressure and the prevalent political climate. Farmers mainly use slash and burn technique to prepare land for cultivation and those close to the National Park are reluctant to adopt appropriate farming and soil conservation practices due to the uncertainties surrounding their future on such plots. Slash and burn iii techniques were observed to accelerate various forms of erosion including rills, gullies and sheet. Soil and water conservation techniques were mainly practiced on privately owned farms. The period 1960 and 1995 was characterized by minimal land use changes and no encroachment into the designated Mount Elgon National Park. Conversely, the period 1995 – 2006 marked a significant loss of woodlands and forest cover particularly on steep concave slopes (36º – 58º) within the National Park. The land use change trends were attributed to the prevalent land politics and exponential population growth in the region. The encroachment onto the critical slopes was noted to have induced a series of shallow and deep landslides in the area. Deforestation on Mt Elgon was reported to have both onsite and offsite climate variability and implications in the form of drought, heat waves, flash floods, economic dislocation, crop failure and associated malnutrition in surrounding low lying areas. The soils on pristine and disturbed slopes contain high amount of clay (>10 percent), are fine textured (>50 percent of the material passing the 0.075mm sieve) and highly plastic. These soil attributes imply low permeability, excessive water retention and high susceptibility to expansion and sliding. The vertic nature of soils at Nametsi was confirmed by the extremely high plasticity indices (averaging 33percent), while, high liquid limits at Buwabwala (53 percent) and Kitati (59 percent) qualified the soils as vertisols which are associated with landslides. The results point to the fact that soils at landslide sites are inherently ‘problem soils’ where slope failure can occur even without human intervention. Therefore, the hypothesis that soils at three landslide sites are inherently ‘problem soils’ where slope failure can occur even without human intervention is accepted. Notwithstanding the fact that the study was focussed on mid-altitude slopes of Mt Elgon, the results are in tandem with investigations carried out earlier on the lower densely populated slopes, thus confirming the widespread nature of problem soils on Mt Elgon. There is an urgent need to control human population growth and restore forest cover on the heavily deforested steep slopes particularly within the National Park, and restrain communities from encroaching on the pristine slopes of Mt Elgon. This will be achieved if the politicians, Park Authorities and local communities jointly participate in the design and implementation of CFMs. Future research could focus on climate change implications of deforestation of Mt Elgon environments and quantification of carbon loss related to deforestation and soil degradation in the mountain environments.
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- Date Issued: 2011
Land use/cover change modelling and land degradation assessment in the Keiskamma catchment using remote sensing and GIS
- Authors: Mhangara, Paidamwoyo
- Date: 2011
- Subjects: Land use -- South Africa -- Eastern Cape , Land degradation -- South Africa -- Eastern Cape , Keiskamma River (South Africa)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10647 , http://hdl.handle.net/10948/1467 , Land use -- South Africa -- Eastern Cape , Land degradation -- South Africa -- Eastern Cape , Keiskamma River (South Africa)
- Description: Land degradation in most communal parts of the Keiskamma catchment has reached alarming proportions. The Keiskamma catchment is particularly predisposed to severe land degradation associated with soil erosion, thicket degradation and deteriorating riparian vegetation. There is a close coupling between land use/cover dynamics and degradation trends witnessed in the catchment. Soil erosion is prevalent in most of the communal areas in the catchment. The principal aim of this study was to investigate land use/cover trends, model the spatial patterns of soil loss and predict future land use/cover scenarios as a means of assessing land degradation in the Keiskamma catchment. Multi-temporal Landsat satellite imagery from 1972 to 2006 was used for land use/cover change analyses using object-oriented post-classification comparison. Fragmentation analysis was performed by computing and analyzing landscape metrics in the riparian and adjacent hillslope areas to determine the land cover structural changes that have occurred since 1972. The landscape function analysis was used to validate the current rangeland conditions in the communal areas and the former commercial farms. The current condition of the riparian zones and proximal hillslopes was assessed using the Rapid Appraisal of Riparian Condition and future land use/cover scenarios were simulated using the Markovcellular automata model. Spatial patterns of soil loss in the Keiskamma catchment were determined using the Sediment Assessment Tool for Effective Erosion Control (SATEEC), which is a GIS based RUSLE model that integrates sediment delivery ratios. Object oriented classification was used to map soil erosion surfaces and valley infill in ephemeral stream channels as a means of demonstrating the major sediment transfer processes operating in the Keiskamma catchment. The Mahalanobis distance method was used to compute the topographic thresholds for gully erosion. To understand the effect of soil characteristics in severe forms of erosion, laboratory analyses were undertaken to determine the physico-chemical soil properties. iv The temporal land use/cover analysis done using the post-classification change detection indicated that intact vegetation has undergone a significant decline from 1972 to 2006. The temporal changes within the intermediate years are characterized by cyclic transitions of decline and recovery of intact vegetation. An overall decline in intact vegetation cover, an increase in degraded vegetation and bare eroded soil was noted. Fragmentation analyses done in the communal villages of the central Keiskamma catchment indicated increasing vegetation fragmentation manifested by an increase in smaller and less connected vegetation patches, and a subsequent increase of bare and degraded soil patches which are much bigger and more connected. The Landscape Organisation Index revealed very low vegetation connectivity in the communal rangelands that have weak local traditional institutions. Fragmentation analyses in the riparian and proximal hillslopes revealed evidence of increasing vegetation fragmentation from 1972 to 2006. The Markov Cellular Automata simulation predicted a decline in intact vegetation and an increase in bare and degraded soil in 2019. The Keiskamma catchment was noted as experiencing high rates of soil loss that are above provincial and national averages. The classification of erosion features and valley infill showcased the vegetation enrichment in the ephemeral streams which is occurring at the expense of high soil losses from severe gully erosion on the hillslopes. This in turn has led to an inversion of grazing patterns within the catchment, such that grazing is now concentrated within the ephemeral stream channels. Soil chemical analyses revealed a high sodium content and low soluble salt concentration, which promote soil dispersion, piping and gully erosion. The presence of high amounts of illite-smectite in the catchment also accounts for the highly dispersive nature of the soil even at low SAR values. Significant amounts of swelling 2:1 silicate clays such as smectites cause cracking and contribute to the development of piping and gullying in the catchment. Given the worsening degradation trends in the communal areas, a systematic re-allocation of state land in sections of the catchment that belonged to the former commercial farms is recommended to alleviate anthropogenic pressure. Strengthening local institutions that effectively monitor and manage natural resources will be required in order to maintain v optimum flow regimes in rivers and curb thicket degradation. Measures to curb environmental degradation in the Keiskamma catchment should encompass suitable ecological interventions that are sensitive to the socio-economic challenges facing the people in communal areas.
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- Date Issued: 2011
Macrophytes as indicators of physico-chemical factors in South African Estuaries
- Authors: Bezuidenhout, Chantel
- Date: 2011
- Subjects: Estuarine ecology -- South Africa , Aquatic plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10597 , http://hdl.handle.net/10948/1387 , Estuarine ecology -- South Africa , Aquatic plants -- South Africa
- Description: This study investigated the response of macrophytes to physico-chemical factors in seven South African estuaries and showed that dominant salt marsh species that occur in different estuaries respond to the same environmental factors. The most important variables influencing distribution were elevation, water level, sediment- and groundwater electrical conductivity and depth to the water table. In permanently open estuaries (Kromme and Olifants) transect surveys identified three distinct vegetation zones i.e. submerged macrophytes, intertidal salt marsh and supratidal salt marsh. In the Kromme Estuary intertidal salt marsh (81.2 ha) covered extensive areas, whereas supratidal (143 ha) and floodplain (797.1 ha) salt marsh were dominant in the Olifants Estuary. Transect surveys identified four distinct vegetation zones (submerged macrophytes, intertidal salt marsh, supratidal salt marsh and reeds and sedges) in the temporarily open/closed estuaries (Mngazi, Great Brak, East Kleinemonde and Seekoei estuaries), although all zones did not occur in all of the estuaries sampled. In the Mngazi Estuary reeds and sedges (1.09 ha) covered extensive areas (no submerged or salt marsh vegetation was present), whereas salt marsh (Great Brak 24.45 ha, East Kleinemonde 17.44 ha and Seekoei 12.9 ha) vegetation was dominant in the other estuaries. Despite the geographic differences, environmental factors influencing macrophyte distribution were similar in all estuaries. Canonical Correspondence Analysis showed that vegetation distribution was significantly affected by elevation, groundwater and sediment electrical conductivity and depth to groundwater. Supratidal species were associated with a greater depth to groundwater (1.2 ± 0.04 m; n = 153) compared to intertidal species (0.5 ± 0.01 m; n = 361). Correlation analysis showed that water level and rainfall were correlated with groundwater electrical conductivity in the lower and upper intertidal zones for all the estuaries sampled. These data indicate the influence of the estuary channel on the physico-chemical conditions of the salt marsh. Low rainfall (16 ± 3.3 mm per annum) in the Olifants Estuary (30-100 mS cm-1) and lack of freshwater flooding in the Kromme Estuary (42-115 mS cm-1) have resulted in high sediment electrical conductivity by comparison with the other estuaries sampled. In the Orange River Estuary approximately 70 ha of salt marsh have been lost through the building of a causeway and flood control levees. Even though salt marsh vegetation can tolerate hypersaline sediments by using the less saline water table, the groundwater at the Orange River Estuary was too saline (avg. of 90.3 ± 6.55 mS cm-1, n = 38) to be of use to the dominant floodplain species, Sarcocornia pillansii. Freshwater inflow to estuaries is important in maintaining longitudinal salinity gradients and reducing hypersaline conditions. In the Olifants Estuary and the Orange River Estuary where supratidal salt marsh is dominant, freshwater inflow is important in raising the water level and maintaining the depth to groundwater and salinity. Lack of freshwater inflow to the Kromme Estuary has highlighted the importance of rainfall in maintaining sediment salinity within acceptable ranges for the salt marsh. Macrophytes are relatively good indicators of physico-chemical factors in estuaries. From an understanding of the response of specific species to environmental variables, ecological water requirements can be set and sensitive areas can be rehabilitated.
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- Date Issued: 2011
My other - my self: post-Cartesian ontological possibilities in the fiction of J M Coetzee
- Authors: Mfune, Damazio Laston
- Date: 2011
- Subjects: Coetzee, J. M., 1940- -- Criticism and interpretation Self in literature Identity (Psychology) in literature Consciousness in literature Intersubjectivity in literature Ontology in literature Metaphysics in literature South African fiction (English) -- 20th century -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2246 , http://hdl.handle.net/10962/d1002289
- Description: The central argument of my study is that, among other matters, in his works, J.M. Coetzee could be said to demonstrate that the known Self is an embodied being and is not autonomous. With regard to the latter contention, Coetzee intimates that any two Subjects are implicated in each other’s subjectivities in a reciprocal process that involves what Derek Attridge has called “irruptions of otherness” (2005: xii) into the Subject’s subjectivity. These irruptions, which happen during the encounter, lead to a double loss of autonomy for each Subject and this phenomenon renders the relationship between Subjects non-dichotomus or non-binaric. In other words, the Subject does not produce the contents of his or her consciousness in a sui generis and ex nihilo fashion, and his or her ontological indebtedness to the Other constitutes his or her first loss of autonomy. As for those Others that do possess consciousness, the Subject is implicated in their consciousness and this constitutes the Subject’s second loss of autonomy. These losses counter the near solipsistic Nagelian neo-Cartesianism and paves the way for imagining both intra- and inter-species “intersubjectivity”. It is my view that this double loss of autonomy accounts for the sympathetic and empathetic imagination that we encounter in Coetzee’s fiction. Following Coetzee’s intimations of intersubjectivity through irruptions of otherness, what I see as my contribution to studies on this author’s work through this study is the link I have established between the physicalist strain within the philosophy of mind (whose central thesis is that consciousness is an embodied phenomenon) and a modified Kantian “metaphysics”, especially Immanuel Kant’s conception of concepts as comprising form and content. I have deployed this conception in demonstrating the Subject’s ontological indebtedness to external sources of the content part of consciousness. And, through the Husserlian concept of intentionality, and Kant’s (1929: 27) observation that we cannot have appearances without something that appears, I have linked the Subject to the sources of his or her content and thereby also demonstrated that the Subject is not eternally separated or alienated from those sources. Instead, the Subject is not simply contiguous but coterminous and co-extensive, albeit in a mediated way, with the external sources of the content part of his or her consciousness. Thus, while accepting the thesis of the Other’s radical otherness, I modify the thesis of the Other’s radical exteriority. Ultimately, then, ontologically speaking, the Coetzeean project could be described as one of embodying and grounding the supposedly autonomous, solipsistic and freefloating/disembodied Cartesian Subject. This he does by alerting this Subject, first and foremost, to its embodiedness and, further to that, pointing out its ontological indebtedness to its Others and its implication in the Others’s consciousnesses and so prevent it from continuing with its imperialistic and ecological barbarities. However, ethically speaking, beyond the reciprocal ethics that arises from mutual ontological indebtedness and implication, it is the selflessness that characterises a cruciform logic that comes across as the epitome of Coetzeean ethics.
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- Date Issued: 2011
Sedimentology of plio-pleistocene gravel barrier deposits in the palaeo-Orange River mouth, Namibia : depositional history and diamond mineralisation
- Authors: Spaggiari, Renato Igino
- Date: 2011 , 2013-08-19
- Subjects: Diamond mines and mining -- Namibia Sediments (Geology) -- South Africa and Namibia -- Orange River Estuary Diamond deposits -- Namibia Orange River Estuary (Namibia and South Africa)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4927 , http://hdl.handle.net/10962/d1004636
- Description: The largest known marine diamond placer, the Namibian mega-placer, lies along the Atlantic coast of south-western Africa from the Orange River mouth 1,000 km northwards to the Namibian-Angolan border. The most economically viable portion of the Namibian mega-placer (>75 million carats recovered at >95% gem quality) comprises onshore and offshore marine deposits that are developed within ∼100km of the Orange River outfall. For much of the Cainozoic, this long-lived fluvial system has been the main conduit transporting diamonds from kimberlitic and secondary sources in the cratonic hinterland of southern Africa to the Atlantic shelf that has been neutrally buoyant over this period. Highly energetic marine processes, driven in part, by southerly winds with an attendant northward-directed longshore drift, have generated terminal placers that are preserved both onshore and offshore. This study, through detailed field sedimentological and diamond analyses, investigates the development and mineralisation of gravel barrier deposits within the ancestral Orange River mouth area during a major ∼30 m regional transgression ('30 m Package') in the Late Pliocene. At that time, diamond supply from this fluvial conduit was minimal, yet the corresponding onshore marine deposits to the north of the Orange River mouth were significantly diamond enriched, enabling large-scale alluvial diamond mining to take place for over 75 years. Of the entire coastline of south-western Africa, the most complete accumulation of the '30 m Package' is preserved within the palaeo-Orange River mouth as barrier spit and barrier beach deposits. Arranged vertically and laterally in a 16m thick succession, these are deposits of: (1) intertidal beach, (2) lagoon and washover, (3) tidal inlet and spit recurve and (4) storm-dominated subtidal settings. These were parts of larger barrier features, the bulk of which are preserved as highstand deposits that are diamond-bearing with varying, but generally low grades (<13 stones (diamonds) per hundred tons, spht). Intertidal beach and spit recurve deposits have higher economic grades (12-13 spht) due to the energetic sieving and mobile trapping mechanisms associated with their emplacement. In contrast, the less reworked and more sandy subtidal, tidal inlet and washover deposits have un-economic grades (<2 spht). Despite these low grades, the barrier deposits have the largest average stone (diamond) size (1-2 carats/stone, cts/stn) of the entire Namibian mega-placer, given their proximity to the ancestral Orange River outfall. This study demonstrates that barrier shoreline evolution at the fluvial/marine interface was controlled by: (1) a strong and coarse fluvial sediment supply that sustained shoreline growth on a highly energetic coast, (2) accommodation space facilitating sediment preservation and (3) short-duration, high-frequency sea-level cycles superimposed on the∼30 m regional transgression, promoting hierarchal stacking of progradational deposits. During these sea-level fluctuations, diamonds were 'farmed' from older, shelf sequences in the offshore and driven landward to accumulate in '30 m Package' highstand barrier deposits. In spite of the large supply of diamonds, their retention in these deposits was poor due to an incompetent footwall of ancestral Orange River mouth sediment and the inherent cobble-boulder size of the barrier gravels. Thus the principal process controlling diamond entrapment in these barrier deposits was kinetic sieving in a coarse-grained framework. Consequently, at the marine/fluvial interface and down-drift for ∼5 km, larger diamonds (1-2 cts/stn) were retained in low-grade (<2 spht), coarse-gravel barrier shorelines. Smaller diamonds (mostly < I cts/stn) were rejected into the northward-driven littoral sediments and further size-sorted along ∼95 km of Namibian coast to accumulate in finer, high-grade beach placers (> 100 spht) where bedrock footwall promoted such high concentrations. The gravel-dominated palaeo-Orange River mouth is considered to be the ' heart' of the Namibian mega-placer, controlling sediment and diamond supply to the littoral zone further north. Although coarse gravel is retained at the river mouth, the incompetence of this highly energetic setting to trap diamonds renders it sub-economic. This ineffectiveness at the fluvial/marine interface is thus fundamental in enriching the coastal tract farther down-drift and developing highly economic coastal placers along the Atlantic coast of south-western Africa. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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- Date Issued: 2011
Systematics, morphology, phylogeny and historical biogeography of the Mayfly family Prosopistomatidae (Ephemeroptera: Insecta) of the world
- Authors: Barber-James, Helen Margaret
- Date: 2011
- Subjects: Mayflies Mayflies -- Classification Mayflies -- Morphology Mayflies -- Phylogeny Mayflies -- Geographical distribution Ephemeridae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5785 , http://hdl.handle.net/10962/d1005473
- Description: The diversity, classification and historical biogeography of the mayfly family Prosopistomatidae are explored. First, the higher classification of the Ephemeroptera is reviewed, focussing on the phylogenetic placement of the Prosopistomatidae relative to other mayfly families. All relevant literature from 1762 to 2010 is synthesized. Baetiscidae are established as the probable sister lineage of Prosopistomatidae, the two constituting the superfamily Baetiscoidea. Next, qualitative morphological variation within the Prosopistomatidae is reviewed and revised, emphasizing nymphs because imaginal specimens are few. The labium and associated structures and the hypopharynx of nymphs, and the highly-derived wing venation of the imaginal stages, are re-interpreted. The structure of the male tarsal claws changes considerably between subimago and imago, which, together with deeply scalloped ridges on male imaginal forelegs and unusual pits on the female thorax, are interpreted as providing an unusual mating mechanism. These structures provide morphological characters for species definition and phylogenetic analyses. Two approaches to species delimitation are explored. First, morphometric variation is analysed using Principal Component Analysis, revealing groupings that can be interpreted as species, although there is some overlap between them. Discriminant Function Analysis shows that head width and carapace shape have the most value in identifying nymphs of different species. The carapace of Prosopistoma nymphs is shown to grow allometrically and gradually, in contrast with that of Baetisca, indicating a difference in early ontogeny. Second, an Artificial Neural Network algorithm applied to nymphal morphological characters accurately identified species. This computer-driven artificial intelligence method has power to provide future easy-to-use electronic identification aids. Phylogenetic analysis of nymphal morphology using the parsimony method shows two clades of Prosopistomatidae, one sharing characters with the type species, Prosopistoma variegatum and the other predominating in Africa, although also occurring in Asia; these clades are named the “P. variegatum” and “African” clades, respectively. Parsimony analysis of adult morphology supports these two clades, but supertree analysis obscures the relationships, nesting the “P. variegatum” lineage within the other clade. Preliminary molecular phylogenetic analysis of the 16S rRNA, (mitochondrial) 18S rRNA and Histone-3 genes using Bayesian Inference methods does not support the two clades shown by morphology. Instead, there is a strong relationship between the European species and one African species, with the single Asian representative being most distantly related. These results are limited by lack of fresh material, patchy taxon sampling, and problems with finding suitable primers. A molecular clock program, BEAST, calibrated using fossils, suggests divergence times for the oldest crown-group Prosopistoma clade, represented by the Asian P. wouterae, of about 131 Ma, with the youngest species, the African P. crassi, of 1.21 Ma. Stem-group relationships are analysed using parsimony analysis, focussing on wing characters of the Baetiscoidea, other extant mayfly lineages, and extinct stem-group lineages. This suggests that the Baetiscoidea diverged from main-line Ephemeroptera earlier than any other extant mayfly lineage. This approach expands upon ideas hinted at by earlier scientists. Finally, historical biogeographical analysis of the distribution of known Baetiscoidea s.s. stem-group fossils implies a once Pangean distribution of the lineage. Changing palaeo-climate, catastrophic extinction events and plate tectonic movements in relation to the distribution of crown-group species are reviewed. Other approaches to historical biogeography that build on both morphological and molecular phylogenies are used to interpret disperalist and vacarianist arguments. Distribution patterns of eight unrelated freshwater organisms which share a similar distribution pattern are compared, assuming that shared patterns indicate similar historic biogeographic processes. The distribution of recent Prosopistoma species is seen to be the product of evolution resulting from both vicariance and dispersal. In conclusion, this thesis encompasses a variety of disciplines. It successfully recognises new characters and distinguishes previously unknown species. It uses new approaches to delimiting species and known methods to determine phylogeny from several angles. The analysis of stem-group relationships offers an insight into possible early lineage splitting within Ephemeroptera. Interpretation of historical biogeography allows for both a Gondwanan origin of Prosopistomatidae, with rafting of species on the Deccan plate to Asia, and for subsequent dispersal from Asia down to Australia and across to Europe, and possibly back to Africa.
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- Date Issued: 2011
The discoursal construction of female physical identity in selected works in children's literature
- Authors: Hunt, Sally Ann
- Date: 2011 , 2013-09-20
- Subjects: Rowling, J K -- Criticism and interpretation Lewis, C S (Clive Staples), 1898-1963 -- Criticism and interpretation Girls in literature Girls -- Identity Human body in literature Gender identity in literature Sex role in literature Children's stories, English -- History and criticism Young women in literature Women in literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2377 , http://hdl.handle.net/10962/d1005965
- Description: This thesis reports on an analysis of the discursive construction of female and male physical identity in children’s literature and explicitly combines corpus linguistic methods with a critical discourse approach. Based on three novels from each of the Chronicles of Narnia and the Harry Potter series, it shows clear gendering of body parts, not only in terms of the purely quantitative preferences for certain body parts to be associated with one or other gender, but in terms of discourse prosody, or the uses to which the body parts are put. Human body parts in these series are mostly used in the following four ways, all of which show differences in realisation in terms of gender: · to describe individuals, physically, in order to distinguish one from the other; · to convey emotion, unintentionally as well as consciously; · for physical interaction between people and · for interaction with the world more broadly: responses to danger and agency, i.e. the ability to act on the world and the nature of what is achieved. The use of body parts by characters to express emotion and act agentively on the world is revealed to be strongly gendered in the two series. I characterise the most prominent patterns in terms of the bodily products blood, sweat and tears, of which the last is strongly connected to female characters, who are generally associated with emotion. The other two, referring to active participation in fighting and injury, as well as agency, are almost exclusively reserved for males, with female characters rendered unable to act on the physical world as a result of overwhelming feelings. The females’ response to danger suggests stereotyped discourses of inequality which see women and girls as requiring protection and being physically incapable. Thus gender is still a particularly salient aspect in these widely-read examples of children’s literature, despite plots which appear to be fairly positive towards women. The strength of the inclusion of a corpus approach in this study lies in its capacity to reveal objective, and often fairly covert, trends in language use. These in turn enrich the critical analysis of discourses in these influential texts, which facilitates social change through linguistic analysis.
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- Date Issued: 2011
The role of small antelope in ecosystem functioning in the Matobo Hills, Zimbabwe
- Authors: Lunt, Nicola
- Date: 2011
- Subjects: Antelopes -- Zimbabwe -- Rhodes Matopos National Park Ecosystem health -- Zimbabwe -- Rhodes Matopos National Park Forest ecology -- Zimbabwe -- Rhodes Matopos National Park Savanna ecology -- Zimbabwe -- Rhodes Matopos National Park Woody plants -- Effect of fires on -- Zimbabwe -- Rhodes Matopos National Park Duikers -- Zimbabwe -- Rhodes Matopos National Park Bushbuck -- Zimbabwe -- Rhodes Matopos National Park Greater kudu -- Zimbabwe -- Rhodes Matopos National Park
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5760 , http://hdl.handle.net/10962/d1005448
- Description: The 28-month study assessed the impacts of five syntopic medium-sized mammalian browsers and one fire event in a woodland savanna in the Matobo Hills, Zimbabwe. Aspects of herbivory, mechanical pressures, seed dispersal and nutrient cycling were investigated for three species of small antelope (common duiker [Sylvicapra grimmia]1, klipspringer [Oreotragus oreotragus] and steenbok [Raphicerus campestris]) and two medium-sized species (bushbuck [Tragelaphus scriptus] and greater kudu [T. strepsiceros]). Focusing on Burkea africana2 woodland, in a system that does not include elephant (Loxodonta africana), effects of browsing antelope on woody and herbaceous vegetation development were investigated using exclusion plots. Browsers regulated woody plant cover (measured as basal stem area), with smaller antelope having a greater impact than larger species. This was linked to feeding height, feeding selectivity and mechanical pressures (e.g. twig breakage and trampling). Fire caused an initial reduction in above-ground standing biomass, but in the presence of fauna, pre-fire equilibria were attained within 15 months. In antelope exclosures, herbaceous biomass increased and woody biomass decreased following fire. Responses by woody vegetation to browsing varied among species, with highly palatable species typically exhibiting compensatory regrowth. Woody species richness and abundance (especially of palatable species) increased in the absence of browsers, but species richness of the herbaceous layer was promoted by moderate disturbance (trampling or fire). Faecal deposition behaviour, primarily the use of latrines by small antelope, resulted in localised soil enrichment within defended territories. Decomposition rates (and therefore return of nutrients to the soil) varied among species and seasons, due to defecation site selection, accessibility to decomposers and desiccation rates of faecal pellets. Controlled seed germination experiments indicated that ingestion by small antelope enhances germination rates of large, hard-seeded fruits such as Sclerocarya birrea. However, germination of savanna seeds may require multiple cues. This study demonstrated the critical roles of small antelope in ecosystem functioning, and highlights the importance of the less visible impacts of frequently overlooked smaller mammalian herbivores. Perturbations to the faunal community, especially small antelope, are predicted to have substantial impacts on woody plant cover.
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- Date Issued: 2011
Trials and triumphs in public office: the life and work of E J N Mabuza
- Authors: Sarimana, Ashley
- Date: 2011
- Subjects: Mabuza, E J (Enos John), 1939- Public officers -- South Africa South Africa -- Politics and government -- 20th century South Africa -- History -- 20th century South Africa -- Social conditions -- 20th century Homelands (South Africa) -- Politics and government -- 20th century Homelands (South Africa) -- History -- 20th century Homelands (South Africa) -- Social conditions -- 20th century Apartheid -- South Africa South Africa -- Race relations Actor-network theory
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3305 , http://hdl.handle.net/10962/d1003093
- Description: Enos John Nganani Mabuza's life and work is used as a case study to highlight the conceptual and methodological theories and challenges in academic biographical writing regarding history, memory and legacies. This thesis answers the question: Who was Mabuza and what is his place or relevance in South Africa's history? We over-simplify and stereotype people because it is convenient. We judge others but there is no saint without a past or a sinner without a future. Mabuza reconciled with the main liberation movements and moved from a maligned position on the political fringes to a respectable one within the emerging black economic elite. History, like reference systems and values is not calcified or static. It is prone to interpretation, adaptation, modification, invention, manipulation, decomposition and re-composition. Bourdieu's habitus-field analysis, theory or logic of practice, notions of capital (symbolic, political, social, cultural and economic) is used together with Latour's actor-network theory as the basis of analysis of the social contracts and trust bonds that Mabuza was able to create and which enabled him to navigate South Africa's socio-political and economic milieus during apartheid and the transition in the early 1990s. As people or actors, we believe in the mantra, nothing ventured, nothing gained. We exercise agency and take risks every day. We make choices and those choices have consequences. Mabuza's choices in the fields of education, politics and business had implications for how he is perceived or has been written into history. His choices put notions of identity, citizenship, power, legitimacy, ambition, elite accommodation, class, personal and professional networks, popular struggles, agency and structure under the spotlight. Mabuza's involvement in Bantustan politics, for instance, is contextualised in terms of a historical overview of the unpopular role played by traditional authorities in South Africa before and during colonialism and apartheid. His later foray into the world of business, however, was facilitated in part, by the personal and professional contacts that he made whilst he was in politics and the opportunities which opened up during the country's political transition. Mabuza adapted to changing circumstances and demonstrated a level of versatility which other Bantustan functionaries did not or could not exercise.
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- Date Issued: 2011
Trophodynamics of the benthic and hyperbenthic communities inhabiting the Sub-Antarctic Prince Edward Islands : stable isotope and fatty acid signatures
- Authors: Allan, Elizabeth Louise
- Date: 2011
- Subjects: Benthos -- Prince Edward Islands Benthos -- Feeding and feeds -- Prince Edward Islands Benthos -- Nutrition -- Prince Edward Islands Prince Edward Islands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5806 , http://hdl.handle.net/10962/d1006350
- Description: The aim of this study was to investigate spatial changes in the trophic and energy pathways of the benthic community in the shallow shelf waters of the sub-Antarctic Prince Edward Islands (PEI). A combination of stable isotope and fatty acid analyses were used to provide a time-integrated view of the assimilated feeding history of selected components of the PEI benthic community. This study forms part of the larger project entitled “Variability in the Southern Ocean ecosystems” and is a contribution to the South African National Antarctic Programme (SANAP). During austral autumn 2009, benthic specimens were collected from 10 stations (from depths of 70 to 295 m) in different regions around the PEI: inter-island shelf (upstream, between and downstream of the islands) and nearshore. Historical data were combined with new data collected during 2009 to assess the long-term trends in the feeding ecology of the benthos in the region of the islands. The stable isotope and fatty acid signatures of the benthic suspension- and deposit-feeding organisms generated during this study suggested that these two communities incorporated both phytoplankton and kelp in their diets. Stable isotope, and to a lesser extent fatty acid signatures, indicated that kelp contributed more to the diets of those organisms in close proximity to the kelp beds (nearshore stations) than those from the inter-island region. Overall, however, pelagic phytoplankton was the dominant food source in the diets of all organisms, even for those living near the kelp beds. Notable exceptions were the sponges and bryozoans, in which kelp and phytoplankton contributed similar proportions to their diets, most likely resulting from a size restricted feeding mode. There were, therefore, no distinct spatial differences in the importance of the various food sources. However, fatty acid compositional data indicated increased food quality between and within the lee of the islands compared to upstream. The organisms collected upstream of the PEI had substantially lower quantities of total fatty acids (TFAs) than organisms of the same species collected from nearshore, open shelf or downstream stations. The increased food quality between and within the lee of the islands was likely a result of the “island mass effect”, which reflects increased phytoplankton concentrations at the PEI. The fatty acid profiles of hyperbenthic shrimp Nauticaris marionis, a key species in the PEI ecosystem, revealed no distinct ontogenetic or spatial patterns. This result is in contrast to the stable isotope analyses, which detected both spatial and ontogenetic differences in the diet of the shrimp. Nearshore shrimp were more ₁₃C-enriched than those from the inter-island region, suggesting increased kelp entering the food web within these regions. In addition, the shrimps demonstrated enrichment in δ₁₃C and δ₁₅N signatures with an increase in size, resulting in a relatively distinct separation of size classes, thus reflecting niche separation through their diets. The fatty acid profiles revealed that the shrimp all contained large proportions of polyunsaturated fatty acids (PUFAs) and essential fatty acids (EFAs), indicating that the quality of food consumed was similar among size class and region despite the niche separation and variation in carbon sources utilised. In addition, diatom and dinoflagellate fatty acids (20:5ω3 and 22:6ω3, respectively) occurred in the highest proportions in N. marionis, highlighting the importance of phytoplankton (indirectly) in their diet. These results represent strong evidence that phytoplankton is an importance food source in the PEI ecosystem. The temporal investigation of isotope signatures in the benthos at the PEI indicated that N. marionis demonstrated an overall depletion in δ₁₃C signatures over the period of 1984 to 2009 (nearshore: -2.55 ‰, inter-island: -2.32 ‰). Overall, the benthic community showed similar depletions in δ13C signatures (from -1.96 to -4.70 ‰), suggesting that shifts have occurred in the carbon signatures at the base of the food web. The depletion in δ₁₃C signatures of the benthos at the PEI most likely reflects increased contributions of smaller slow growing phytoplankton cells (more depleted signatures than large fast growing cells) in the diets of these organisms over time. These diet shifts, in turn, suggest a decrease in productivity has occurred at the islands, likely due to a decreased frequency and intensity of the “island mass effect”. Decreased phytoplankton productivity at the PEI likely results from the southward shift in the average position of the sub-Antarctic Front (SAF), most likely in response to climate change, which in turn promotes flow-through conditions rather than retention at the PEI.
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- Date Issued: 2011