Würzburg, University, Diss., 2002.

Würzburg, University, Diss., 2001. / Dateien im PDF-Format. - Erscheinungsjahr an der Haupttitelstelle: 2000.

Thesis (MA)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Pterocarpus angolensis is one of the timber tree species that regenerates naturally in the dry forest of Namibia, mainly assisted by the influence of forest fires. Tree development goes through a prolonged suffrutex stage to reach the sapling stage and then, finally, the bole tree stage. This study focused on assessing the main factors facilitating the development of Pterocarpus angolensis seedlings through the suffrutex stage to the sapling stage in Namibia dry forests. To achieve the study objectives three study locations (Okongo and Ncumcara Community Forests and Caprivi State Forest) were selected, representing a rainfall gradient. Within each study location, two different fire history treatments (recently burnt (RB) and recently unburnt (RU)) were selected, and four plots were randomly selected from each fire history treatment. Face to face individual interviews was conducted with community members surrounding the three forests to obtain indigenous knowledge information about Pterocarpus angolensis tree development. Seedlings and saplings found in all plots were counted and measured (tree height and diameter at breast height (DBH)) while trees more than 3 m high were only counted and measured for DBH. Laboratory analysis was performed to determine basic soil texture and nutrient status. In addition, destructive sampling was done on individual trees in the seedling and sapling stages at each study location. The destructive samples allowed for estimation of biomass in above and below ground components, determination of carbohydrate storage in the taproots and estimation of tree age by counting growth rings on the neck disc of the taproot sample. These measures could shed light on the tree development through the suffrutex stage. The main agents causing Pterocarpus angolensis tree damage and stand disturbances observed are drought, fires, insects, diseases, temperature, lightning, wind, animals and humans. Forest fires were found to be one of the major disturbances in all the study locations, particularly damaging to seedlings when fire intensity is high. Likewise, the most important factors influencing the tree development from seedlings to sapling and sapling to bole tree stages are soil water, soil fertility, plant competition, sunlight and fires. Through counting growth rings of taproot neck discs, it is estimated that the ages of seedlings most commonly range from 5 to 12 years in the dry forests of Okongo, Ncumcara and Caprivi. The soil texture in the three forests is dominated by sand, with the soil reaction usually being moderately acidic while the soils have low levels of organic carbon, phosphorus and exchangeable base cations. This study revealed that Caprivi State Forest (location with the highest rainfall) has the highest stand density followed by Okongo Community Forest and Ncumcara Community Forest with the lowest. Trees were grouped into different DBH and height classes. The highest numbers of trees are found in DBH class 0 – 10 cm and in height class 0.6 – 1.0 m at Okongo Community Forest but at Ncumcara and Caprivi many of the trees are in height class 1.1 – 1.5 m. The mean DBH difference is significant between locations but not significant between fire history treatments. A higher abundance of mature trees are found at Okongo Community Forest while a greater abundance of saplings occur at Ncumcara Community Forest which shows a significant difference between study locations. Seedling abundance is the same across study locations and fire history treatments. The difference in stand structure between study locations appears to be strongly influenced by different management regimes on the three locations. A majority of respondents from all the study locations alleged soil water followed by soil fertility as the main influential factors to Pterocarpus angolensis development. Again, most of the respondents revealed that seedling takes 4 – 7 years to reach sapling stage and their main environmental disturbance is fire. Tree cutting by members of the community was also perceived by the respondents as an important non-environmental disturbance. The most abundant tree development stage perceived by respondents was mature trees while seedlings rated the sparsest stage. Based on the respondents no silvicultural practices are performed to promote Pterocarpus angolensis growth. It follows that the Kiaat trees are currently growing without human intervention that might enhance their development. A combination of social survey (interview) and ecological survey provided reliable information on ecological processes. A weak positive significant correlation relationship existed between shoot mass (aboveground biomass) and taproot mass (belowground biomass), meaning when the taproot mass increases the shoot mass also increases. Analysis of non-structural carbohydrates (NSC) storage in taproots showed that both sugar and starch contents in the taproots could facilitate the survival of the tree during suffrutex stages and its rapid growth thereafter. Based on this study Pterocarpus angolensis regeneration in these three dry forests is poor because seedling abundance is the lowest compared to saplings and mature trees. These study findings can be used as the basis for further studies to predict Pterocarpus angolensis natural regeneration in the dry forests, as well as input when management regimes are being developed for the dry forests of North Namibia. / AFRIKAANSE OPSOMMING: Pterocarpus angolensis (Kiaat) is een van die boomspesies wat natuurlik verjong in die droë bosveld van Namibië, met die hulp van bosbrande. Die boom ontwikkel deur ʼn lang semi-struik stadium waartydens die boompies as saailinge bekendstaan. Daarna ontwikkel dit deur die jongboom stadium tot dit uiteindelik die kroon stadium bereik. Hierdie studie fokus op die faktore bydra tot die ontwikkeling van Pterocarpus angolensis van die semi-struik stadium na die jongboom stadium in die droë bosveld van Namibië. Om die doelstellings van die tesis te bereik is drie studiegebiede gekies langs ʼn reënvalgradiënt (naamlik Okongo en Ncumcara gemeenskapsbosse asook Caprivi Staatsbos). Binne elke studiegebied is twee behandelings met verskillende brandgeskiedenis gekies (gebrand of nie-gebrand in die onlangse verlede). Vier persele is ewekansig uit elk van hierdie behandelings gekies vir eksperimentering. Persoonlike onderhoude is gevoer met gemeenskapslede wat in die omgewing woon ten einde inheemse kennis en inligting te versamel oor die ontwikkeling van die jong Pterocarpus angolensis bome. Alle saailinge en jongbome wat voorkom in die persele is getel en gemeet (boomhoogte en deursnee op borshoogte (DBH)) terwyl bome wat hoër as 3 m is, slegs getel en vir DBH gemeet is. Laboratoriumtoetse is gedoen op grondmonsters ten einde ‘n basiese beskrywing van die grondtekstuur en voedingstofstatus te verkry. Verder is destruktiewe bemonstering toegepas op bome in beide die saailing en jongboom stadium op elke studiegebied. Hierdie bemonstering het dit moontlik gemaak om bogrondse en ondergrondse biomassa te skat, om die opberging van koolhidrate in die penwortels te bepaal, en ook om die boom ouderdom te skat vanaf jaarringe in die nek van die penwortel monster. Hierdie metings kon lig werp op die boomontwikkeling deur die semi-struik stadium. Die faktore wat skade aan Pterocarpus angolensis bome veroorsaak asook versteuring van die opstande waarin die bome voorkom is droogte, brande, insekte, siektes, temperatuur uiterstes, weerlig, wind, diere en mense. Die bevindinge dui op bosbrande as een van die belangrikste versteuringsfaktor in al drie studiegebiede; dit is veral skadelik vir saailinge in die semi-struik stadium wanneer die vuurintensiteit hoog is. Die faktore wat die boomontwikkeling van saailing, na jongboom en kroonstadium beïnvloed is hoofsaaklik grondwater, grondvrugbaarheid, plantkompetisie, sonlig en brande. Die ouderdom van saailinge (bepaal vanaf jaarring tellings in die nek van penwortel monsters) van die meeste saailinge én jongbome is na raming tussen 5 en 12 jaar vir die droë bosse in die studiegebiede van Okongo, Ncumcara en Caprivi. Die grondtekstuur van hierdie studie se drie bosgebiede is hoofsaaklik sanderig, met ’n effens suur grondreaksie terwyl die gronde lae vlakke van organiese koolstof, fosfor, en uitruilbare basiese katione bevat. Die studie het aangedui dat Caprivi staatsbos (met die hoogste reënval) die digste opstande huisves, gevolg deur Okongo en dan Ncumcara gemeenskapsbos, met die laagste digtheid. Bome is gegroepeer in verskillende DBH en hoogte klasse. Die meeste bome kom voor in die DBH klas van 0-10 cm en in die hoogteklas van 0.6 – 1.0 m by Okongo, maar by Ncumcara en Caprivi is daar meer bome in die hoogteklas van 1.1 - 1.5 m. Die gemiddelde DBH verskil is betekenisvol tussen studiegebiede, maar is nie betekenisvol verskillend tussen brandgeskiedenis behandelings nie. ’n Hoër voorkoms van volwasse bome is by Okongo aangetref, terwyl ’n hoër voorkoms van jongbome by Ncumcara waargeneem is, en hierdie verskil was statisties betekenisvol. Die voorkoms van saailinge is soortgelyk oor alle studiegebiede en brandgeskiedenis behandelings heen. Die verskil in die struktuur van die opstande op die drie studiegebiede word skynbaar sterk beïnvloed deur verskillende bestuurspraktyke wat in elke gebied toegepas word. Die meerderheid van respondente van al drie studiegebiede beweer dat grondwater, gevolg deur grondvrugbaarheid die belangrikste faktore is wat P. angolensis ontwikkeling beïnvloed. Meeste van die respondente onthul dat saailinge 4 tot 7 jaar neem om die jongboom stadium te bereik en dat die belangrikste versteuringsagent bosbrande is. ʼn Belangrike nie-omgewingsfaktor wat verantwoordelik is vir versteuring in die bosse is mense wat bome, lote en/of takke afsaag. Respondente is van mening dat volwasse bome die grootteklas met die mees algemene voorkoms is, terwyl saailinge die skaarsste grootteklas uitmaak. Die respondente het aangedui dat geen boskultuurpraktyke toegepas word om die groei van P. angolensis aan te help nie. Die gevolgtrekking is dus dat die Kiaatbome tans groei sonder menslike ingryping om hul ontwikkeling te verbeter. Die kombinasie van persoonlike onderhoude en ʼn ekologiese opnames het betroubare inligting rakende ekologiese prosesse opgelewer. ’n Swak positiewe, maar betekenisvolle korrelasie bestaan tussen die massa van die bogrondse lote en die penwortelmassa, wat beteken dat die lote se massa toeneem met toenemende wortelmassa. Analise van opgebergde nie-strukturele koolhidraatreserwes in die penwortel toon dat beide suiker- én styselinhoud in die penwortels die oorlewing van die boom in die struikstadium aanhelp, asook sy vinnige groei na die struikstadium. Die feit dat die saailinge minder volop is as jongbome en volwasse bome in hierdie studie dui aan dat verjonging van Pterocarpus angolensis in hierdie droë bosse maar swak is. Die bevindinge van die studie bevat inligting wat gebruik kans word (a) as die grondslag van verdere studies op die natuurlike verjonging van Pterocarpus angolensis in droë bosse, en (b) as inset wanneer bestuursaanbevelings vir die droë bosse van Noord Namibië ontwikkel word.

Labour is a vital period for the labouring mothers, as it should bring with it the fulfilment of an expectation of having the baby that has been awaited. The health of the foetus which is to be born and that of the labouring mother are inextricably linked with each other which is why the labouring mother needs to be assessed and monitored carefully. The cardio-tocograph, which is a globally accepted method of diagnosis and assessment of the foetal status during labour is preferred to be used in monitoring labouring mothers, especially high- risk patients. Despite the evidence and information regarding the effectiveness of the use of the cardio-tocograph, midwives are still found not to be using it correctly, the reasons given that the women not always co-operate; do not keep the electrode and belt in place or cite the discomfort they experience from contraction. The objectives of this study were to: explore and describe the perceptions and current practice of Namibian midwives regarding the use of the cardio-tocograph as an informative labour- monitoring tool. Explore and describe how midwives working in labour wards in Namibia perceive informing laboring women of the use of the cardio-tocograph as an informative labour- monitoring tool and based on the results, develop an instruction guide for midwives working in the labour ward in intermediate hospital in Namibia that would serve as a guide on how to teach labouring women about the use of the cardio-tocograph as a labour- monitoring tool and enhance positive labor and delivery outcomes The study was conducted between May and June 2016, using a qualitative, explorative, descriptive and contextual design, following the necessary university approval and approval from other relevant authorities. The research population was midwives who work in labour wards at a public hospital in Namibia. Semi-structured interviews were used to collect data from purposively sampled participants using set criteria. A voice recorder was used to capture the interview with the permission of the participants. Seventeen midwives were interviewed of whom two were used for the pilot study. Data saturation determined the sufficient sample size. The collected data was analyzed using Tesch’s spiral method of data analysis with the assistance of an independent coder From the research findings, it emerged that midwives had varying perceptions regarding the use of the CTG machine. Midwives still perceive CTG interpretation as a challenge as a labour -monitoring tool and expressed a need for updates. Furthermore, midwives expressed the fact that they had limited communication with labouring women regarding the use of CTG. Based on the research findings and guided by Health Belief Model principles, three main guidelines were developed for midwives working in the labour ward in a public hospital in Namibia. These guidelines will serve as a tool to assist midwives in their teaching of labouring women about the use of the cardio-tocograph as a labour- monitoring tool, and the role to be played by labouring women during that monitoring period. Furthermore, recommendations for clinical nursing practice, nursing education and nursing research were developed. The researcher used literature control to ensure validation and integrity of the study. Trustworthiness, which was used to ensure rigour of the study, was guided by the principles of truth-value, transferability, dependability and confirmability. Ethical considerations were guided by the Belmont report adopting the principles of beneficence, respect for human dignity, justice and non-maleficence.

Rural schools are faced with numerous challenges and are often perceived to be academically unsuccessful. However, in spite of this perception there are some which manage to beat the odds by being academically successful year after year. This peculiar phenomenon of ‘unequal performance’ among rural schools struck my interest; hence my decision to investigate what it is that successful rural schools do to keep afloat in a turbulent environment where others around them collapsed. As the literature suggests that leadership play a key role in the success of an organisation, I focused my study on how the leadership role of the principal makes a rural school thrive. The study is situated in the interpretive paradigm and attempts to reveal participants’ perceptions and experiences of the principal’s leadership. My participants were the principal, circuit inspector, the School Board Chairperson, a Head of Department and the LRC president. These people were purposefully selected; the principal was selected because he is the one executing the roles hence he would be better informed about them while the others due to the positions they occupy, work closely with the principal. The research is a case study as it focused on a single case, and for data generation I employed semi-structured interviews, observation and document analysis. The study revealed various characteristics that describe the leadership role of the principal. An overarching characteristic that emerged is that the principal is a balanced leader - he focuses on both task completion and consideration for people. Different characteristics that emerged from this balance leadership portrayed the principal of Ruacana Senior Secondary School to be a transformational and an instructional leader who believes that teaching and learning are the central activities of a school. Moreover he has been painted to be a team player and a servant leader who holds and practices the principle of ubuntu. The principal has also been described as a strategic and exemplary leader. It emerged that his exemplary leadership has moulded the practices of teachers and learners into a shared culture that supports academic excellence. The findings also depicted a paradoxical picture of the principal in that while he exhibits democratic procedures he is also perceived to be autocratic.

Empowerment of women in leadership and in particular, school leadership has been the focus of the Namibian government and the country since independence in 1990. Different policies and laws, post‐independence, make provision for women empowerment and leadership in a range of organisations and institutions throughout the country. However, reports on gender equity in leadership positions suggest that Namibia is not really moving towards these policy goals at a sufficiently quick pace. A lot still needs to be achieved in terms of transforming the gender stereotyping in Namibia, which still suffers from the legacy of gender discrimination of the apartheid era. Modern‐day academic authors and journalists portray an increasing interest in an awareness of the advantages of women leadership. Women are increasingly perceived to have leadership styles more suitable for contemporary conditions than men. It is against this backdrop that this study sought to investigate women leadership in the Otjiwarongo circuit in the Otjozondjupa educational region in Namibia. The study used a qualitative, interpretive research paradigm. It adopted a case study approach. The primary participants consisted of four women principals in the Otjiwarongo circuit and the secondary participants included four women education officers from the same circuit. Semi‐structured interviews, a focus group interview and observation were applied as methods for collecting data and the data collection period was just over six weeks. Data analysis was done through coding and identification of categories. The findings revealed that women principals possessed the qualities of commitment, good communication and are passionate about their work, which are qualities normally associated with effective leadership. In terms of their role in their schools, they emerged as democratic leaders who involved all stakeholders in the decision making process through consensus. In addition, they demonstrated distributive and servant leadership in their interactions with stakeholders. The main challenge to the leadership position of these women principals seemed to be the stereotypical view held, that as women, they had to work twice as hard as men at leading schools. The study recommended that people oriented leadership styles, such as the ones enacted by the women principals in this study, are highly recommended for effective leadership in the 21st century.

The investigation covering 1500 square kilometres within the central granite zone of the Damara belt, South West Africa, revealed Pre - Damara (Abbabis) basement unconformably overlain by metasediments of the Damara Supergroup. The term Leeukop member is proposed for basal metaconglomerates of the Nosib Group that immediately overlie the basement augen-gneisses. Augen-gneiss clasts are present within the Leeukop metaconglomerates. The Damara orogeny has only partly affected the Abbabis rocks of the Tumas River Inlier but further to the west the Husab suite of red granites and granite-gneisses, as field and geochemical evidence suggest, were derived syntectonically during the Damara orogeny by reactivation of the pre- Damara basement. Rõssing alaskitic granites represent late stage melts, that were also derived from Pre- Damara basement rocks during orogenesis, which accumulated post-tectonically in structural traps at the base of the Khomas Subgroup. Salem granitoids are present in synclinal structures associated with metasediments of the Khomas Subgroup and syntectonic derivation by anatexis during the Damara orogeny is suggested. In the east the differentiated Gawib granitoid stock was emplaced post- tectonically through basement rocks into the Damara metasediments. A deep seated origin is indicated by high crystallisation temperatures (>8500°) obtained from quarternary Qz-An-Ab-Or- H₂0 plots. The metamorphic grade increases westwards from medium grade to high grade. In the east, the metapelites contain andalusite, and coexisting muscovite and quartz. This indicates that temperatures of 6000° at 3,5- 4 kb pressure were attained. In the west, coexisting wollastonite and anorthite in the Khan gneisses indicate pressure- temperature conditions of 720° at 4,5-5 kb. Two tectonic events were responsible for the regional structure. An early F₁ episode produced east- west oriented overturned folds and was followed by an intense F₂ episode of isoclinal folding which is responsible for the dominant northeast - southwest regional fabric. The interference of these folds in the proximity of the underlying basement produced the complex dome and basin structures seen in the central and western parts of the area. An F₃ episode of minor importance was also recognized. The presence of continental basement rocks in this central part of the Damara belt is evidence for formation of the orogen by in-situ deformation rather than continental collision.

No description available.

Two monkfish species are caught off the coast of Namibia. These are Lophius vomerinus Valenciennes (1837) and L. vaillanti Regan (1903). L. vomerinus is the more abundant of the two and contributes approximately 99% to the total Namibian monkfish landings. The Namibian monkfish fishery is one of the largest and most valuable of its kind in the world. Two fishing fleets harvest the resource, viz. the monkfish and sole fleet and the hake directed fleet. In 1998 and 1999, monkfish were also harvested by one gillnet vessel that had an experimental right. In this study, the biology, abundance and exploitation patterns of monkfish were investigated and used as inputs into a stock assessment framework as a contribution towards the development of a management procedure for this species. Ground and sectioned otoliths and sectioned illicia were used to age Lophius vomerinus. The illicia provided more precise estimates of age, and growth was subsequently modelled using these age estimates. Growth in length and weight was best described by the threeparameter specialised von Bertalanffy model as Lt (cm TL) = 72.29 (1-e⁻°·¹⁴⁽t⁺°·³°⁾) and Wt (kg) = 3.96 (1-e⁻°·¹⁸⁽t⁺°·¹°⁾)²·⁹⁹ for males, and Lt (cm TL) = 111.98 (1-e⁻°·°⁸⁽t⁺°·³⁶⁾) and Wt (kg) = 6.92 (1-e⁻°·¹⁸⁽t⁻°·⁶⁴⁾)³·°³ for females. L. vomerinus is a slow-growing species with a life span in excess of 10 years. Reproductive activity was shown to occur throughout the year, with a slight peak during the winter months. The adult sex ratio of fish > 37 cm TL was biased towards females. Length-at-50% sexual maturity was attained at 32.1 cm TL for females and 23.7 cm TL for males. The rate of natural mortality was estimated at 0.15 year⁻¹, while fishing mortality rates during the 1970s, 1980s and 1990s were estimated at 0.01 year⁻¹, 0.04 year⁻¹ and 0.14 year⁻¹, respectively. Gillnetting for monkfish (300 mm stretched mesh) was highly efficient with a moderate bycatch of around 20% during the two years of operation. The main bycatch species were red crab, spider crab, squalid sharks, rays and Cape and Deep-water hake. The mean length of the monkfish caught in gillnets (67 cm TL) was significantly larger than the monkfish landed by the trawlers (38 cm TL) and less than 1% of immature fish were landed. Gillnet catch-per-unit-effort for monkfish fluctuated between 0.03 and 0.67 kg.day⁻¹.50 m net panel⁻¹, with a soak time of between one and sixteen days. More than 50% (by weight) of monkfish landed by monkfish and sole trawlers, consisted of fish below 36 cm TL. There was a significant increase in catches of juvenile monkfish during 1997 and 1998 in comparison to the period 1994 to 1996. Various types of rigid sorting grids were tested to release juvenile monkfish below 32 cm TL. Five grid designs were tested. These included an “Ex-it” grid with horizontal bars spaced at 55 mm, single grids with vertical and horizontal bars spaced at 55 mm and grids with circular openings of 110 and 168 mm in diameter. The most efficient design was the grid with circular openings of 110 cm in diameter, which ensured the escape of 66% of monkfish smaller than 31 cm TL. However, studies need to be undertaken to quantify the survival of released fish and to test the feasibility of using grid sorters on commercial monkfish and sole trawling gear. The monkfish resource was assessed by means of length cohort analyses, the Thompson and Bell predictive model and by way of a deterministic age-structured production modelling approach. The length cohort analysis models were sensitive to the rate of natural mortality and insensitive to changes in the terminal fishing mortality rate. These biases may, however, not be serious provided that estimates of abundance are used to reflect relative changes. Fish ranging between 26 and 59 cm TL are the most heavily exploited. The Thompson and Bell model predicted that the monkfish resource is exploited above MSY -levels and a reduction of approximately 40% in fishing effort would provide a higher yield. Yield-per-recruit ranged between 10 000 and 14 000 tonnes. Results should, however, be treated with caution, as the condition of steady state was not satisfied. The age-structured production model was tuned using trends in catch-per-unit-effort data, estimated by Generalised Linear Modeling, as well as relative abundance indices calculated from hake biomass surveys. The model was found to be sensitive to both the ‘steepness’ parameter h and estimates of natural mortality. The ‘depletion’ level of the monkfish resource is currently estimated to be 49%. Estimated coefficients of variation were high (> 63%) due to the lack of a consistent trend within the abundance indices to tune the model. Overall productivity of the monkfish resource was estimated to be approximately 16%, similar to other southern African demersal resources. Results of the risk analyses suggest that catches in excess of 7 000 tonnes may be unsustainable and that catches of 5 000 or 6 000 tonnes would decrease the risk of stock collapse and possibly lead to a recovery in the stock. Monkfish management strategies were reviewed and these were considered in relation to the results of this study. The following management recommendations were made: to follow the precautionary approach and implement a total allowable catch for monkfish; to implement rigid sorting grids as these would be the most appropriate way in which to reduce catches of juvenile monkfish; to restrict soak time, depth of operation and implement means to reduce ‘ghost fishing’ by gillnetting and finally, to develop a management procedure for Namibian monkfish with the main objective being the sustainable exploitation of the resource.