Dissertations / Theses on the topic 'Plant species – South Africa – Limpopo'

The study evaluated the extent and threat of bark harvesting of plant species for medicinal purposes in the Venda region and investigated possibilities of the sustainability of these practices. Approximately 30% of the woody plant species in Venda were found to have medicinal properties in their bark, but only about 12% of these species are commonly traded in muthi shops in the region. Fifty-eight medicinal plant species are commonly harvested for medicinal properties in their bark and found in muthi shops in the region. These 58 species were scored for the possible threat of bark harvesting to the species’ survival using 20 ecologically relevant plant population traits. The most vulnerable species were Adansonia digitata, Adenia spinosa, Albizia adianthifolia, Albizia versicolor, Brackenridgea zanguebarica, Croton megalobotrys, and Warburgia salutaris. Of these species Brackenridgea zanguebarica and Warburgia salutaris are amongst the ten most traded medicinal plant species in Venda region. Elaeodendron transvaalense and Brackenridgea zanguebarica, the two species investigated in detail in this study, were amongst the most commonly traded medicinal plant species in Venda region. Analysis of size class distributions showed that both species had growing and healthy populations, exhibiting J-shaped population curves, centroids left-skewed from the midpoint of the size class distribution, and a fine-grained status. However, size-class distributions in both species revealed certain classes that needed monitoring since they were negatively affected by bark harvesting. Adult individuals of B. zanguebarica showed a high degree of bark regeneration as a response to bark removal from medicine men. The crown health status of E. transvaalense was generally good although some individuals, contributing 9% of the sample, had dead crowns. A linear relationship was noticed between areas harvested and stem circumference, which is understandable considering the large surface area of harvestable bark on bigger individuals. Matrix modeling of E. transvaalense revealed that the vegetative stage should be targeted for management action. An assessment of the adequacy of the Brackenridgea Nature Reserve, an initiative aimed at protecting Brackenridgea zanguebarica, revealed that the reserve size is not enough for conservation of a viable population. The method flagged out potential growth habitat for B. zanguebarica around the current reserve, which could be incorporated to enlarge the conservation area, which could be incorporated to enlarge the conservation area. Four different scenarios were analysed on how best to conserve the species. Assuming a 50% reduction in human-related activities, such as cultivation, harvesting and livestock grazing, it is recommended that the reserve be enlarged from its current 110 ha to 366 ha to maintain a viable population into the future. Finally, the study recommended the adoption of an integrated approach to achieve sustainability of bark harvesting in the Venda region. Only by selecting best practices from both indigenous and conventional conservation techniques will the conservation of natural resources that are of important to local communities, be successful. An action plan that will involve the formation of an association by all stakeholders interested in the sustainable utilization of natural resources must be developed. The association must be governed by a constitution with a clear mission statement and the harvesting of natural resources should be done in line with a collection policy.
Thesis (PhD)--University of Pretoria, 2012.
Plant Science
unrestricted

South Africa generates more than 90 percent of its total energy capacity through non-renewable sources. With coal forming the predominant energy source, South Africa became the leading carbon emissive nation in Africa, emitting 450 million tonnes of CO2 in 2011. In an international effort to restrict global average temperature rise to 2° C above the average prior the industrial revolution, the Kyoto Protocol has been extended for another 8-year commitment period. This is complementary to an expected resolution of a new legally binding climate change policy in 2015. This policy will aim to introduce financial penalties for nations failing to meet ascribed GHG emission targets by 2020. In an attempt to meet these climate change resolutions South Africa will research and develop cleaner, alternative forms of energy, including hydro, wind, and biomass forms of renewable energy, in addition to designating stringent building regulations for the Incorporation of solar energy. These measures form part of an Integrated evelopment Plan that aims to generate a target of 10,000 GWh of renewable energy in 2013. South Africa is also investigating the possibilities of extracting its shale gas reserves and implementing it as a major energy source. This energy mix has given little attention to geothermal energy. The reasons for this omission appears to be the lack of active volcanism and previous research that suggests South Africa, largely underlain by the Kaapvaal Craton, has a relatively low heat Flow profile, deemed insufficient for harnessing geothermal energy.

Thesis (MSc)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The passive recovery of old fields in the Karoo is a slow process, hampered by low and erratic rainfall, poor seed germination due to limited availability of suitable micro sites for seedling establishment, competition from existing vegetation, altered soil properties and the reduction of key soil biotic processes. The objectives of the study were to investigate the role of seed banks in the recovery of old fields, and to identify possible plant species and methods of establishing these species with the primary aim of initiating the process of succession / recovery of old fields in the Little Karoo. The investigation of the seed bank addressed the following issues: the resemblance of the seed bank to the above-ground vegetation in an old field and the effect of disturbance on the seed bank. Furthermore, the role of propaguie migration was investigated to establish possible propaguie movement from undisturbed to disturbed areas was investigated. The study indicated that the perennial seed bank had a 31 % similarity to the above ground vegetation in the old field. The seed bank was dominated by annual species. In the above-ground vegetation perennial canopy cover was higher compared to annual cover. The perennials with the highest densities in the soil seed bank were disturbance-adapted species with little importance for grazing animals except perhaps in the short-term. Disturbance caused annual densities to increase and perennial densities to decrease. The investigation of propaguie migration compared adult canopy cover and seedling densities. The results show that perennial distribution was patchy and that propaguie migration is low to non-existent. This led to the conclusion that old fields require supplemental seed additions. A total of seven species were assessed for their restoration potential. The species used in the investigation were Tripteris sinuata, Ruschia spinose, Drosanthemum speciosum, Indigofera sessifolia, Pteronia incana, Ehrharfa calycina and Chaetobromus dregeanus. Seed viability was examined using one of two techniques ie. tetrazolium or a standard germination technique. The optimal temperature for germination was determined using the following temperature regimes: 15°C day / 1DoC night, 20°C day /1 DoC night and 30°C day / 15°C night. The temperature range with the best performance was 20°C day / 1DoC night indicating that species should be sown in autumn or early winter. This timing coincides with the onset of rains in this region. The field trial investigated the influence that various mechanical cultivation techniques (ploughing, disking, tilling and clearing) and soil amendments (seed, seed+aquasorb and seed+straw+branches) have on the establishment of the selected species. Seed germination and seedling survival was monitored. The influence of treatments on water infiltration and soil moisture was investigated. Only four of the seven species germinated (Tripteris sinuata, Ehrharta calycina, Chaetobromus dregeanus and Pteronia incana). As far as species performance was concerned, T. sinuata performed best followed by E. calycina and C. dregeanus, while P. incana failed to persist. The cultivation treatments that yielded the best results were tilling, disking and ploughing. Emergence success in cleared and untreated plots was relatively low. As far as seedling emergence was concerned the most appropriate soil amendments were seed+aquasorb, seed and seed+straw+branches. Although soil moisture was higher on-heuweltjies than offheuweltjies there was no significant difference in seedling emergence and survival between these localities. Even though soil moisture was higher in seed+straw+branches treatment than in seed+aquasorb and seed treatments, seedling emergence in this treatment were lower than in the two latter treatments. This clearly indicates that soil moisture is not the only factor that influences the establishment of species. In the trial a mixture of late successional and pioneer species were sown, primarily with the aim of initiating the process of succession! recovery of old fields. Contrary to what was expected the late successional species germinated first. This has led to the conclusion that these late successional species have no innate dormancy, further proved by the inability of species to germinate after the second season. It could thus be that these late successional species have a short live span, and that they germinate when conditions are favourable. It must also be kept in mind that the seed sown were freshly harvested, and it could be that the pioneer species needed an after-ripening period before they germinated.
AFRIKAANSE OPSOMMING: Die passiewe herstel van oulande in die Karoo is 'n tydrowende proses, wat vertraag word deur wisselvallige reënval, swak ontkieming as gevolg van 'n tekort aan geskikte mikro-habitatte vir saailingvestiging, kompetisie van bestaande plantegroei, veranderende grondeienskappe en die afname in sleutel biotiese prosesse. Die doel van hierdie studie was, om die rol van saadbank in die herstel van oulande te bepaal, sowel as om moontlike plantspesies te identifiseer en metodes van vestiging van hierdie spesies te bepaal met die primêre doelom die proses van suksessie / herstel van oulande in die Klein Karoo te inisieër. Met die saadbankstudie is die volgende punte aangespreek: die ooreenkoms tussen die meerjarige spesies in die saadbank en bogrondse plantegroei op ou lande, en die effek van versteuring op die saadbank. Verder is gekyk na die rol van voortplantingsmeganisme verspreiding om moontlike beweging vanaf onversteurde na versteurde areas te ondersoek. Die studie het aangedui dat daar 'n 31% ooreenkoms is tussen meerjarige spesies in die saadbank en die bogrondse plantegroei op ou lande areas. In die bogrondse plantegroei van die ou land was die kroonbedekking van meerjarige spesies hoër as die van eenjarige spesies. Die dominante meerjarige spesies in die saadbank was spesies wat aangepas is by versteurings, met min weidingswaarde, behalwe moontlik oor die kort termyn. Versteuring het In verhoging in eenjarige en In afname in meerjarige saailingdigthede veroorsaak. Resultate dui daarop dat meerjarige verspreiding onreëlmatig is in die versteurde area en dat die teenwoordigheid van voortplantingsmeganismes, baie laag is. Dit lei tot die gevolgtrekking dat oulande addisionele saad benodig vir hervestiging. 'n Totaal van sewe spesies is ge-evalueer vir hulle moontlike restorasie potensiaal. Die spesies wat in die ondersoek gebruik was, is Tripteris sinuata, Ruschia spinose, Orosanthemum speciosum, Indigofera sessitolie. Pteronia incana, Ehrharta calycina en Chaetobromus dregeanus. Die kiemkragtigheid van die spesies is bepaal deur gebruik te maak van een van twee tegnieke nl. die tetrazolium of 'n standaard ontkiemings tegniek. Die optimale temperature vir ontkieming is bepaal deur gebruik te maak van die volgende temperatuurreekse: 15°e dag / 1Qoe nag, 200e dag /10oe nag and 300e dag / 15°e nag. Die temperatuur reeks waarop spesies die beste presteer het, was 2DOC dag /1DOC nag. Dit dui daarop dat spesies tydens herfs en vroeë winter gesaai moet word. Dit is dan ook die tydperk vir die aanvangs van die reënseisoen in hierdie streek. In die veldproef is gekyk na die invloed van verskeie meganiese bewerkings - tegnieke (ploeg, dis, ghrop en plant verwydering) en grondverbeterings behandelings (saad, saad+aquasorb en saad+strooi+takke), op die vestiging van geselekteerde spesies. Saadontkieming en saailingoorlewing is gemonitor. Die invloed van die behandelings op waterinfiltrasie en grondvog is ook ondersoek. Slegs vier van die sewe spesies het ontkiem naamlik: Tripteris sinuata, Ehrharfa calycina, Chaetobromus dregeanus en Pteronia incana. Spesies wat die beste presteer het, was T. sinuata die gevolg deur E. calycina en C. dregeanus, terwyl P. incana nie oorleef het nie. Die bewerkingsbehandelings wat die beste vestiging van plante gegee het, was die ghrop en disbewerkings gevolg deur ploegbewerking. Ontkiemings sukses in areas waar plante verwyder is en onbehandelde persele was relatief laag. Die grondverbeterings behandeling wat die beste ontkieming gelewer het was saad+aquasorb gevolg deur saad en saad+strooi+takke. Alhoewel grondvog hoër was op heuweltjies as weg van heuweltjies, was daar geen betekenisvolle verskil in ontkieming en oorlewing tussen hierdie lokaliteite nie. Alhoewel grondvog hoër was in saad+strooi+takke behandelings as in saad+aquasorb en saad behandelings was ontkieming laer in hierdie behandeling as in die saad+aquasorb en saad behandelings. Dit dui dus daarop dat grondvog nie die enigste faktor is wat die vestiging van spesies beinvloed nie. In die veldproef is 'n mengsel van pionier en klimaks spesies gesaai, met die primêre doelom die proses van suksessie/herstel van oulande te inisieër. In teenstelling met wat verwag is het die meer klimaks spesies eerste ontkiem. Dit het gelei tot die gevolgtrekking dat hierdie spesies geen dormansie het nie, en dit is verder bewys deur 'n onvermoë om te ontkiem in die tweede seisoen. Dit mag wees dat die meer klimaks spesies 'n kort lewensduur het, en dat hulle ontkiem wanneer toestande gunstig is. Dit moet ingedagte gehou word dat die saad vars geoes was, en dit kon dus wees dat die pionier spesies 'n na-rypwordings periode benodig voordat hulle ontkiem.

Thesis (M.Sc. (Botany)) -- University of Limpopo, 2013
Traditional medicine plays a major role in the primary health care of many people residing in rural areas. People in these areas still consult traditional healers who utilise plants as medicine. Medicinal plants have come under increasing pressure due to a number of factors, which have resulted in the decline of certain species, extinction in others, and a general decrease in biodiversity of high use areas of South Africa, Blouberg Mountain included. To date there has been a lack of information on how traditional healers utilise the Blouberg Mountain with respect to amounts and species removed, or where the most important collecting sites are located. Thus, no conservation strategy exists for the Blouberg Mountain to ensure sustainable management of its natural resources. Furthermore, there is a perception amongst elders of this area that, as with indigenous knowledge around the world, the knowledge centered around Blouberg’s medicinal plants is declining, and little formal documentation of that knowledge has taken place. Consequently, this study investigated aspects related to medicinal plant use such as collection, patterns of collection, legislation, storage and packaging of medicinal plants by traditional healers around Blouberg Mountain. These were documented via a semi-structured questionnaire and a data collection sheet. Furthermore, traditional harvesting methods employed by traditional healers, and in situ conservation issues related to species removal from the mountain were investigated. Data was collected between September 2010 and September 2011. Sixteen villages in close proximity to the mountain, and 32 healers (two per village) were selected. In addition 16 consulting rooms were sampled (one per village) in order to gather information on the number of species collected from the mountain and stored in the consulting rooms. The 16 most used (indicated by village traditional healers) collection tracks, (one per village surrounding Blouberg Mountain), were travelled with traditional healers to record botanical and vernacular names of the medicinal plants, vegetation type, habitat, parts used, harvesting method, replacement value of plant species and perceived rarity of collected material. A Garmin GPS was used to record waypoints for the beginning and end of each track. Co-ordinates were logged automatically every 10 m. A map using Quantum GIS software to capture the position of the healers’ collection tracks, overlaid with topographical and vegetation information, and protected area information of the Blouberg Mountain, was generated. Geographic Information System software was used to geo-process the collection tracks of the healers with respect to where medicinal plants were collected relative to the various vegetation types. This gave information on vegetation types important to healers. The majority of traditional healers were females. Most of them had no formal education, with only a minority reaching secondary school. Due to their low level of literacy they tended to shy away from sources of written information, with the result that none of the questioned healers had any knowledge of the various national or provincial environmental legislations. The majority of them see between 15 and 20 patients per month. Most of the healers had more than 30 years of experience in traditional healing. The study found 64 plant species commonly used for medicinal purposes. Most of them were harvested for their roots and bark. According to the healers, Boophane disticha and Hypoxis hemerocallidea are declining in Blouberg Mountain, with Warburgia salutaris, endangered in South Africa, not perceived as rare or declining. However, a number of plant species recorded in the Red Data List as of least concern, or not threatened, are seen as rare by the healers. These include Clivia caulescens, Erythrina lysistemon, Lannea schweinfurthii and Maerua juncea. No exotic species were documented from the surveyed tracks. However, two naturalised exotics were collected from the mountain, namely Cassytha filiformis and Corchorus tridens. Cocculus hirsutus, a naturalised exotic and Abrus precatorius, an exotic species were found in one of the consulting rooms. Dichrostachys cinerea, Philenoptera violacea and Tarchonanthus camphoratus, which are indicators of bush encroachment, were identified on selected tracks. Tracks on which indicators of bush encroachment are present should be investigated more thoroughly to ascertain the extent and severity of such a threat. vii Investigations into healers’ collection tracks showed that the Soutpansberg Mountain Bushveld vegetation type is the most heavily utilised of the five vegetation types around Blouberg Mountain. This vegetation type is vulnerable to human population densities as most species were collected from it, therefore it should be conserved and managed if possible as it is targeted for plant species of medicinal value. The most travelled tracks were found in the Catha-Faurea Wooded Grassland community. Solutions to the problems of over harvesting of medicinal plants require local innovations and the full participation of traditional healers in resource management initiatives. The development of medicinal plant nurseries together with propagation of key species will be a crucial management tool, as this will reduce over harvesting of natural resources from the wild. In conclusion, it was found that although most species utilised around Blouberg Mountain are abundant and not threatened, healers are nevertheless concerned about dwindling medicinal plant supplies. They would welcome conservation initiatives and the use of GIS maps would be useful in prioritising conservation areas.

Quartz fields contribute significantly to plant diversity in the Succulent Karoo biome. They are distinctly different from surrounding habitats and have high levels of plant endemism. Biological soil crusts are features of quartz field soils and fulfill a vital function in that they stabilize soils. It is important for managers of nature reserves and agricultural rangelands to know what factors influence quartz field soils and vegetation. Both stakeholders could benefit from new information that would allow for informed decision-making regarding land-use on quartz fields. The present study took place in the Namaqua National Park that contains a significant proportion of the Riethuis-Wallekraal quartz fields phytochorion. The first part of the study aimed to understand whether certain land-use activities potentially destabilize quartz field soils, which might have possible ramifications for associated biological soil crusts and vegetation. It was followed by relating variation in soil stability with species richness, cover and species composition of quartz field vegetation. Overall, positions assumed to be impacted by land-use activities had less stable soils compared to positions assumed not be impacted. Soil stability had a significant influence on species richness and cover but to a lesser degree on species composition. Quartz field vegetation was significantly influenced by soil physical and chemical properties as well as location in the quartz fields landscape. The second part of the study aimed at understanding how species richness of isolated quartz outcrops is related to their size compared to that of a mainland body of quartz outcrops. No clear species-area relationships emerged from the study. There were significant differences between isolated outcrops and mainland outcrops in substrate and vegetation composition. Findings are discussed in relation to Island Biogeography Theory.

Includes bibliographies.
The unique vegetation in the lowlands of the fynbos biome is threatened by alien Acacia encroachment. The seed bank dynamics of the two most widespread invaders in the region, Acacia saligma and A. cyclops, was studied to elucidate those factors contributing most to their invasive success. This information was then used to assist in developing optimal control methods. On the basis of information available prior to this study, it was predicted that both species would have large, persistent seed banks in the so.il, and that seed bank processes would provide the - key to invasive success: namely, high seed longevity and heat-stimulated germination. Seed banks were monitored for several years following clearing of the parent stand, using either sites sampled in an earlier study, or sites providing chronosequences of clearing dates. Concurrently, a demographic study of the species' seed banks, including processes from seed rain through to seedling emergence and survival, was done in dense Acacia stands and in fynbos vegetation. Acacia saligma seed banks conformed to predictions, being large and persistent owing to high percentage viability and water-impermeable dormancy. Seed banks accumulate rapidly under dense stands and are "disturbance-coupled" as they have potentially high longevity unless stimulated to germinate by fire. Although A. cyclops seed banks also may be large and long-lived, they display variable percentage viability and dormancy, with the majority of a seed cohort surviving less than a year. Acacia cyclops seed banks do not respond to heat treatment and appear to be "disturbance-uncoupled".

In response to a growing concern over the rising rates of extinction of the world's plants and of habitat destruction, studies of Southern African threatened plants were initiated in the 1970's. These studies, which have largely concentrated on Western Cape flora, led to the publication of "Threatened Plants of Southern Africa" by Hall et al., 1980, which attempted to list as many threatened or possibly threatened species as possible. It was however marred by a lack of recent herbarium records and detailed studies from many parts of the region, the Eastern Cape being one of these. In order to extend these detailed studies to gain a clearer picture of the numbers of threatened species in the Eastern Cape and evaluate the conservation status of Eastern Cape vegetation this project was initiated. Initially lists of possibly threatened and endemic taxa of the Eastern Cape were compiled from various sources. These listed taxa were then checked against herbarium records, all available information being filled onto index cards for filing purposes. This paper-based filing system was then transferred into a computer-based data bank to facilitate the efficient storage and retrieval of information. Results from this data bank show that there are 662 variously threatened plant taxa in the Eastern Cape, many of which fall into temporary categories which need to be clarified by investigation in the field. Primarily based on the above results, a table ranking the various vegetation types into an order of priority for investigations about conservation requirement was developed.Subtropical Thicket was found to be the vegetation type in most need of investigation and so an extensive phytosociological survey was carried out in the Valley Bushveld which forms the major portion of Subtropical Thicket in the Eastern Cape. Twelve sites were sampled for floristic and environmental variables along a rainfall gradient of between 300 mm yr⁻¹ and 1 000 mm yr⁻¹ and along a longitudinal gradient from the Buffalo River in the east to the Gamtoos-Kromme complex in the west. Floristic data W(re analysed using multivariate techniques of classification and ordination. A classification by two-way species indicator analysis revealed the Valley Bushveld to consist of two orders of thicket, the Kaffrarian Succulent Thicket containing the two suborders, Inland Succulent Thicket and the Coastal Succulent Thicket and the Kaffrarian Thicket containing Coastal Kaffrarian Thicket and Inland Kaffrarian Thicket. Ordina tion by detrended correspondence analysis also grouped sites according to these vegetation categories in a sequence along one axis, to which the rainfall gradient could be related. Variables such as diversity indices, numbers of endemics, numbers of threatened taxa and structural features were also extracted from the data and these were correlated with environmental variables by multiple regression analysis. Species richness and the percent woody component w\!re positively correlated with rainfall while endemism and percent succulent component were strongly negatively correlated with rainfall. Most of the other relationships were explained by interrelationships with rainfall. Finally the sites were evaluated according to floristic criteria indicative of conservation value. The Coastal Succulent Thicket appeared to have the highest conservation value mainly owing to high endemism, while Inland Kaffrarian Thicket was also important as it supports a high number of species. The thickets with high conservation value are therefore the thickets of coastal areas in the western parts of the Eastern Cape which receive a low rainfall and the thickets which receive a rainfall in excess of 800 mm.
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Includes bibliographical references.
The Cape Floristic Region is one of the most species-rich regions of the world. Fynbos, the Mediterranean climate shrubland which comprises the largest part of this region, is characterized by high beta diversity and high edaphic endemism. However, very few quantitative studies of the factors controlling species turnover and community boundaries exist. I used an integrated approach of broad correlation techniques and detailed field experiments, to investigate this. The study site was a landscape on the southern slopes of the Soetanysberg hills, near Cape Agulhas. This area is exceptional in its floristic and edaphic complexity. The first part of this work involved an investigation of the patterns of soil characteristics and the relationship between these and the vegetation patterns. This showed a strong vegetation-environment correlation, particularly with regard to communities. Community boundaries were strongly related to patterns of soil nutrients and physical factors (relating to moisture availability). The second part consisted of detailed studies of the factors controlling the distribution of three pairs of key species (all Proteaceae). Each species is dominant in part of the landscape and, for each species pair, the replacement of one species by the other across the study site, is very distinct. Protea susannae and P. compacta occur in deep and shallow sands respectively. Root morphology, water relations and phenology of adult ( 15 yr-old) plants were studied over two years in the field. Differences between these species constituted habitat-specialization for soils of different depth. A laboratory study of seedling morphology and water-use showed that species differences also exist at the seedling stage and these would be important in determining distribution patterns. Very little is known about the importance of interspecific competition in fynbos communities. A three-year field experiment was set up to investigate its role in determining species distribution patterns across community boundaries and soil gradients. Each of the three pairs of Proteaceae species was grown from seed in cleared plots at three sites along a transect crossing a community boundary. Their growth and survival were studied in relation to site (soil factors), density and interspecific competition (monoculture/mixture). For all species, site factors had an overriding influence on survival. Average individual biomass was determined primarily by site for three species and, for the other species, by density (irrespective of monoculture or mixture). It was concluded that soil factors are a major influence on the distribution of these species and that, while competition has an important role in determining spacing patterns within communities, it has a minor role in determining species distributions.

Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2016.
This study focused on optimising four types of in-vitro conservation methods, namely: 1), micropropagation, 2) in-vitro slow growth, 3) seed germination and 4) cryopreservation for selected endangered plant species indigenous to the Cape Floristic Region. It is one of the targets set by United Nations millennium development goals, to integrate different conservation measures in order to preserve plant diversity and mitigate losses of genetic diversity. Therefore this study uses Phalaenopsis hybrids as a trial species that can be studied for the conservation of endangered Disa and Eulophia species through micropropagation and in vitro slow growth. Also conservation attempts on Leucadendron and Mimetes species that occur in the Cape Floristic Region were attemted to increase population densities by increasing germination percentages using smoke. Furthermore, the study attempted to store seeds by assessing different cooling rates for optimising cryopreservation measures for effective conservation. The use of tissue culture to increase propagules especially critically endangered species in South African has proven to be feasible. For the trial hybrids, shoot and protocorm explants of Phalaenopsis Psychosis Pink X P. No. 1; P. Large white X P. Large pink; P. No. 1 X P. Large pink; P. Mini pink X Brighton belle; and the P. aphrodite formed clusters of protocorms and shoots when cultured on ½ strength MS media supplemented with 10, 20 and 30gL-1 banana extract or ½ strength Murashige and Skoog, (1962) (MS) media supplemented with peptone. Continuous protocorms formation could therefore be obtained by culturing endangered Disa and Eulophia shoots and protocorms on banana containing media. Plantlet conversion from somatic embryos produced on 10gL-1 banana extract enriched media was successfully achieved on ½ strength MS supplemented with 20gL-1 sucrose and no plant growth regulators in the medium. However, optimum rooting was achieved on ½ strength MS supplemented with 30gL-1 of banana extract and this medium yielded the highest survival percentages for plantlet acclimatisation. Furthermore, ½ strength MS supplemented with 1gL-1 of peptone served as a stimulant for shoot development and protocorm formation. When coupled with banana extract at all stages of development, regeneration and rooting were enhanced.

The aim of this study is to gain a predictive understanding of the patterns and determinants of plant biodiversity in temperate, mesic grasslands of South Africa with a primary focus on the geographical area of the Eastern Cape. From a review of the literature on hypotheses explaining diversity (Chapter 2) it was possible to formulate a number of hypotheses that could be tested to explain species richness patterns in Eastern Cape grasslands. This thesis is organised so that each main chapter deals with a specific body of theory concerning the explanation of diversity patterns. A detailed description of the study area is provided (Chapter 3), including environmental variation and a description of major vegetation patterns. A summary is provided of grassland plant community patterns, as determined by phytosociological studies in the study area. A multivariate analysis of environmental variables was undertaken to determine which variables contributed the most towards explaining environmental variation in the study area and to determine whether any variables co-vary, a possible problem for any multivariate analysis in later chapters. Altitude produced one of the strongest gradients in the study area. There were a number of variables that were correlated with altitude, most notably temperature. Rainfall co-varied partially with altitude, but there was also a strong rainfall gradient perpendicular to the altitude gradient. A description of species richness, diversity and evenness patterns at the plot scale within different grassland plant communities of the Eastern Cape is provided in Chapter 4. To determine whether the environment acts differently on different growth forms, the contribution to species richness by different major growth forms is analysed. Furthermore, since the majority of literature attempts to explain diversity in terms of environmental factors, it was necessary to analyse the relationship between species richness and various environmental variables. The results indicate that there is high variation in species richness both within and among grassland communities. Forbs make the most significant contribution to overall species richness per 100 m2, followed by grasses. Variance in richness of all species together is not significantly related to environmental variables in mesic grasslands, but is significantly related to environmental variables in semi-arid grasslands. The result of greatest interest from this chapter is the fact that richness amongst different life-forms in the same place is explained by different environmental factors, indicating that the environmental factors that affect coexistence of species have a different effect on different life-forms. A classification of all the species of the dataset into plant functional types using a multivariate approach based on functional traits was conducted (Chapter 5). The grass species were classified into 16 functional types and the forbs into 14 functional types. The functional type classification provided the opportunity for undertaking analyses to develop an understanding of 8 the contribution by niche differentiation towards promoting species richness (Chapter 6). The results provide evidence of niche differentiation in the grasslands of the study area and also that niche differentiation promotes species richness in the grasslands of the study area. It was found that higher rainfall grasslands are less structured by niche differentiation than semi-arid grasslands. A regional / historical analysis is undertaken (Chapter 7) to investigate the relationship between the regional species pool and local richness, and the relationship between local richness and phytochorological diversity. Regional richness appears to have little effect in promoting local richness in grassland plant communities of the study area except at sites where there is high local richness. This provides an indication that regional richness only promotes local richness in the absence of local limiting factors. Phytochorological diversity promotes local richness, but mostly through diversity amongst species with narrow distribution ranges. Some theories ascertain that seasonal uncertainty may provide opportunities to species that would otherwise be outcompeted and thereby promote local richness. The degree to which seasonal uncertainty and seasonality promote local richness in the Eastern Cape grasslands was therefore investigated (Chapter 8). A weak relationship exists between these variables and local species richness in grassland communities of the study area, indicating that they do not promote niche differentiation to a significant degree in the study area. It is clear that in the grasslands of the Eastern Cape, environmental limiting factors are more important in semi-arid grasslands and species interactions are more important in mesic grasslands for structuring plant communities (Chapter 9, Discussion). Regional processes do not appear to be important in structuring local communities, but the analysis undertaken in this study shows that they may be significant when factors operating at the other two levels are overcome (species interactions and environmental limiting factors.

The project was initiated by Eastern Cape Parks (ECP) as a request for the construction of inventories of priority species and their population levels inside three nature reserves on the Eastern Cape Wild Coast, South Africa, and to develop a strategic management plan to manage these natural resources in each reserve. Thirty key species were identified by local communities in and around Dwesa-Cwebe, Silaka and Mkambati Nature Reserves through community workshops. For forested areas belt transects of 100 m x 6 m where used. The basal circumference of key tree species within the belt transect was measured as well as the height of saplings (height < 150 m). Tree species were categorized based on densities, size class distribution (SCD) curves and values, and spatial grain. For grassland areas straight transects of 200 m long were used, along which ten 3 m x 3 m quadrates were placed at 20 m intervals. Within each grassland transect the height of herbs or tuft diameter of grasses was recorded and percentage cover estimated. Grassland species were categorized based on density, SCD curves and percentage cover. All species were placed into harvesting categories based on analysed ecological data that was collected in the field. Category 1 species were very rare or not found in the reserve and it was recommended that species be conserved and monitored. Category 2 species had low densities in the reserve indicating declining populations and was suggested that these be monitored and not harvested. Category 3 species had high densities and have potential for harvesting with strict limitations. Category 4 species were most abundant with very high densities and can be harvested within management guidelines. These categories were grouped further using social and ecological data such as harvesting risk, frequency of collection, use value and number of uses. This highlighted which species have conservation priority within each category and a decision can be made as to how intense or limited extraction should be. By incorporating GIS the distribution of each species was looked at and harvesting and non-harvesting zones established to determine where species can be extracted. Monitoring plans must consider the quantity of plant material collected, fire regimes, optimal harvesting rates and harvesting zones, and be able to pick up changes in populations. Also, it is important that the community be involved in conserving and monitoring these species. Adaptive monitoring and management must be used to steer harvesting practices in the Wild Coast reserves. This allows for the development of harvesting practices through ‘learning by doing’, and the evolution of good questions to guide monitoring decisions

Thesis (MScAgric)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: Storing soil organic carbon (SOC) is a possible way of reducing atmospheric CO2 and potentially mitigating the effects of global warming. This study looks at soil carbon stocks, the sampling methodology and modelling of soil organic carbon in indigenous forests, wetlands, grasslands and pine plantations in Woodbush in the North-Eastern escarpment of Limpopo Province, South Africa. Dominant Pine species planted in Woodbush are Pinus patula, Pinus elliotti and Pinus taeda. Woodbush plantation was selected as study area because it provided easy access to all the ecosystems that were to be studied. All ecosystems in Woodbush are located in such a way that it was easy to compare them, as they existed under similar environmental and climatic conditions. The climatic conditions of Woodbush promote accumulation of SOC due to relatively higher precipitation and cooler temperatures than most parts of Limpopo Province. Five transects were made: two in indigenous forests and three in plantations. Only the surface (0-7 cm) layer was sampled with a distance of 20 m between sampling points. Transects were not made in grasslands and wetlands because of the patchy occurrence of these ecosystems. In addition to transects, eight 1ha plots, two in each ecosystem, were sampled. Surface (0- 7 cm depth) samples were collected on a grid of 20 x 20 m in each sampling plot. Two soil profile pits were sampled in each sampling plot, with samples being taken at 5, 10, 15, 20 30, 40, 50 60, 75 and 100 cm depth. The average carbon stocks per hectare of land to a soil depth of 100 cm were as follows: 71 t.ha-1 in wetlands, 28 t.ha-1 in grasslands, 64 t.ha-1in indigenous forests, and 46 t.ha-1 in pine plantations. Although wetlands sequestered large amounts of SOC per hectare, their relative contribution to carbon sequestration was low because of the relatively small area (87.2 ha) they occupy in the study area (and in South Africa). Prediction models for vertical distribution of SOC were developed using STATISTICA 6.0 for each ecosystem in order to estimate the carbon stocks to a depth of 100 cm based on SOC content and soil bulk density of the surface samples. These models were developed from observed values in soil profiles for each ecosystem. SOC content and carbon stocks were analyzed using GIS (ARCVIEW). The GIS analysis was aimed at assessing the effect of topography, elevation, soil type, and vegetation on accumulation and distribution of SOC stocks. Most shallow Inanda soils were distributed at elevations between 1545 m and 1777 m, and on a gentle slope in the Northern aspect of the mountain. Deep Inanda soils were found mostly in the lower elevation range of 967 m and 1545 m on moderate slopes. Deep and shallow Inanda soils were found on the southern aspect. Deep Kranskop soils are evenly distributed and mostly found at an elevation range of between 1080 and 1430 m on gentle slopes, while at an elevation range of between 1430 and 1780 m, they were found on moderate slopes. Deep soils had higher SOC stocks than shallow soils and soils in the southern aspects had higher SOC stocks than in the northern aspects.
AFRIKAANSE OPSOMMING: Die berging van grond organiese koolstof is ‘n moontlike manier om atmosferiese koolsuurgas (CO2) te verminder en dus om die invloed van globale verwarming te versag. In hierdie studie was die grond-koolstof voorraad bestudeer, asook die metodologie van die monsterneming en modellering van organiese grond-koolstof van inheemse woude, vleie, grasvelde en denneplantasies. Die studie was uitgevoer op Woodbush plantasie gele op die Noord-Oosterlike platorand van die Limpopo Provinsie, Suid-Afrika. Die algemeenste dennespesies in Woodbush is Pinus patula, Pinus elliotti en Pinus taeda. Die Woodbush plantasie was gekies as studiegebied omdat dit oor al die ekosisteme wat bestudeer moet word, beskik. Die ekosisteme in Woodbush is naby mekaar en dus maklik vergelykbaar want die omgewings- en klimaatstoestande is eenders. Die klimaatstoestande van Woodbush bevorder die akkumulasie van grond organiese koolstof omdat die reënval hoër en die temperature laer is as in die meeste ander dele van die Limpopo Provinsie. Vyf dwarssnitte was gemaak, twee in inheemse woude en drie in plantasies. Monsters was net uit die grondoppervlak laag geneem (7 cm) met 20 m tussen monsterpunte. Dwarssnitte was nie in grasvelde en vleie gemaak nie want hierdie sisteme is te gelokaliseerd. Monsters was ook geneem in agt 1 ha persele, twee in elke ekosisteem. Oppervlakmonsters (tot ‘n diepte van 7 cm) is op ‘n ruitnet van 20 x 20 m uit elke perseel versamel. Monsters was verder ook geneem uit twee profielgate per perseel, op dieptes 5, 10, 15, 20, 30, 40, 50, 60, 75 en 100 cm. Die gemiddelde koolstof voorraad per hektaar, op ‘n gronddiepte van 100 cm, was as volg: 71 t.ha –1 in vleie, 28 t.ha-1 in grasvelde, 64 t.ha-1 in inheemse woude en 46 t.ha-1 in denneplantasies. Alhoewel vleie groot hoeveelhede grond organiese koolstof akkumuleer, is hulle bydrae tot koolstof akkumulasie laag want hulle beslaan ‘n klein oppervlak binne die studiegebied (87.2 ha) asook klein oppervlaktes binne Suid-Afrika. Voorspellingsmodelle vir die vertikale verspreiding van grondkoolstof was met die gebruik van STATISTICA 6.0 ontwikkel ten einde te skat wat die koolstofvoorrraad op ‘n diepte van 100 cm was. Die skattings was gebaseer op organiese grondkoolstofinhoud en die gronddigtheid van oppervlakmonsters. Hierdie modelle was ontwikkel vanaf die waargenome waardes van grondprofiele vir elke ekosisteem. Die organiese koolstofinhoud van die grond en die koolstofvoorraad is ontleed met behulp van GIS (ARCVIEW). Die GIS ontleding was daarop gemik om die effek van topografie, hoogte bo seespiëel, grondtipe en plantegroei, op die akkumulasie en verspreiding van organiese grondkoolstof, te beraam. Die meeste vlak Inanda grondvorms kom voor tussen 1545 m en 1777 m bo seespiëel, asook op effens steil hellings op die Noordelike berghang. Die diep Inanda grondvorms is geleë op laer hoogtes bo seespiëel, gewoonlik tussen 967 en 1545 m, op effens steil hellings. Beide diep en vlak Inanda gronde word gevind op die suidelike berghang. Diep Kranskop gronde is eweredig versprei en word gewoonlik tussen 1080 en 1430 m bo seespiëel, op effens steil hellings, gevind. Dit kom ook voor op matig steil hellings, tussen 1430 en 1780 m bo seespiëel. Daar is meer organiese koolstof in diep grond as in vlak grond en meer in gronde teen die suidelike hang as op die noordelike hang.

Thesis (MScConsEcol (Conservation Ecology and Entomology)--University of Stellenbosch, 2007.
Understanding the drivers and mechanisms of changes in plant richness is a basis for making scientifically sound ecological predictions and land use decisions. Of the numerous factors affecting plant richness, soil has a particularly large influence on the composition and structure of terrestrial flora. Infiltrability is one of the most important factors determining soil moisture, and therefore is of particular interest in semi-arid ecosystems, where water is one of the most limiting resources. Other soil properties, such as clay + silt content, electrical conductivity (EC) and pH may also influence plants. Heterogeneity of these properties creates niches with specific conditions, which in turn affects spatial distribution of plants. An understanding of the relationships between plant richness and soil properties is, however, incomplete. The present study has two main foci. Firstly, relationships between plant richness and soil infiltrability, clay + silt, EC and pH (H2O) were investigated, and secondly, due to the strong influence of infiltrability on plant richness, further investigations were undertaken to improve the understanding of the role of particle size fractions, EC of the soil solution and exchangeable sodium percentage (ESP) on infiltrability. This study only concentrated on the surface 2 cm thick soil layer (known as pedoderm).

Includes bibliographical references (leaves 126-140).
In our search for new anti-tuberculosis lead molecules, five medicinal plant species, Olea capensis (L.l, Tulbaghia alliacea (L.), Inula graveolens (L.), Leyssera gnaphaloides (L.), and Buddleja saligna (L.) were collected in Cape Town and surrounding area and investigated for antimycobacterial activity following report of their therapeutic use in traditional medicine to treat infectious diseases such as tuberculosis. A bioassay guided fractionation of the acetone/water (4:1) crude extracts of O. capensis (leaves) and T. alliacea (rhizomes) showed no activity against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 252923, and Mycobacterium aurum A+. In contrast, the orgamc fractions (hexane, dichloromethane) of the acetone/water (4: 1) crude extracts of 1. graveolens, L. gnaphaloides, and B. saligna exhibited significant activity against M. tuberculosis H37Rv, M. avium 25291, M. microti ATCC 19422, and M. scrofulaceum ATCC 19987. The isolation and structure determination of the bioactive led to the identification of pentacyclic triterpenoids, ursolic acid (UA) and oleanolic acid as major antitubercular constituents of B. saligna, L. gnaphaloides, and 1. graveolens. The in vitro cytotoxicity assays of the isolated bioactive constituents showed no cytotoxicity against Chinese Hamster Ovarian (CHO) cells line. Subsequently, given the pharmaceutical value of the above finding, a survey on structure activity of pentacyclic triterpenoids was conducted. It was was found, for instance that selective substitutions at C-3 and/or C-28 and the double bond at UA, OA and betulinic and (1) BA) were made in order to improve anti-tumour and anti-HIV activity. However, thought a great number of modified bioactive pentacyclic triterpenoids is reported, none was tested against Mtb. Therefore, this study also explored a new synthetic route (scheme 1) toward a generation of (5), which may allow improving antitubercular, anti-HIV or anti-tumour activity, and/or specificity.

The Nama-Karoo biome is relatively understudied in terms of its baseline biodiversity. Apart from its rich agricultural land-use history, the region is also under pressure from the development of the Square Kilometre Array, an increased demand for cleaner energy from shale gas fracking and/or other renewable energy installations, and the overarching impacts of global climate change. A reliable baseline inventory of biodiversity for the region is essential if these impacts are to be monitored and managed effectively. The main aim of this study was to relate fine-scale patterns of plant diversity and community structure to broader-scale vegetation mapping in the Karoo regions. It also investigated the role of several environmental and climatic variables as drivers of species richness, relative cover, and growth form diversity in two habitat types (i.e. plains and rocky dolerite hillslopes), and along a longitudinal environmental gradient. A pairwise floristic survey approach was implemented, using modified Whittaker plots in each habitat type at 30 sites within the shale gas exploration area in the Upper Karoo bioregion. Data were collected on species richness, relative cover, and growth form diversity of the observed vegetation. Soil samples were collected from each Whittaker plot, and climate data were obtained by point sampling from raster layers using GIS. The results showed that mean species richness was significantly higher (p < 0.01) in slope habitats than in plains habitats across the environmental gradient. Trees and woody shrubs had significantly higher species richness (p < 0.001) and relative cover (p < 0.01) in slope habitats. Low woody shrubs comprised the greatest percentage of growth form diversity in both habitat types in terms of species richness and relative cover, and were the dominant growth form across the longitudinal gradient. At the arid western extent, leaf-succulent shrubs had slightly higher relative cover (~ 25%) in slope habitats compared to other growth forms, apart from low woody shrubs. In the central regions, perennial grasses were more abundant (25 – 60%) in slope habitats, while annual grasses were more abundant (25%) in plains habitats. At the more mesic eastern end of the longitudinal gradient, perennial grasses were dominant (> 50%) in plains habitats. Cluster analysis, based on species presence data in each habitat type, showed relatively strong correspondence between plant associations in slope habitats and their respective vegetation types as currently defined. These plant associations were spatially aggregated according to their position along the environmental gradient. Little to no correspondence was found between plant associations in plains habitats and their respective vegetation types. These plant associations were interspersed with each other when plotted spatially, and occurred in a repeating pattern in plains habitats across the study area. Multiple regression models indicated that a combination of climatic and environmental variables, and soil properties significantly predicted overall species richness and relative cover of the five dominant growth forms. Habitat type commonly emerged as a significant predictor for overall species richness and relative cover. Overall dissimilarity, and dissimilarity in the relative cover of five plant functional types between plains and slope habitats, were also predicted by a combination of climatic and environmental variables, and soil properties. These predictors varied greatly between the different response variables, suggesting that different plant functional types are influenced by different drivers, depending on the habitat in which they occur. Habitat heterogeneity, coupled with local and regional variation in prevailing climate and soils, has consistently emerged as an important driver of plant species richness and relative cover in global drylands research. Measuring richness and diversity within habitats requires a high sampling resolution in both plot size and number. This study has shown that sampling at the 0.1 ha scale (or larger) captures a representative sample of richness and diversity within a given habitat type in the Nama-Karoo biome, where low woody shrubs (< 60 cm tall) are the dominant growth form. In the current vegetation map of South Africa, the vegetation types for the Upper Karoo bioregion are coarse, and hence give the impression of homogeneity in what is in reality a relatively heterogenous landscape. Fine-scale baseline biodiversity data such as are presented in this study may improve the resolution of the existing vegetation map, as well as inform better conservation and management practices in economically important and biologically diverse rangelands in the Nama-Karoo biome, prior to future developments in the region.

Thesis (MSc (Plant Biotechnology))--University of Stellenbosch, 2006.
The development of a reliable and reproducible method for the genetic characterisation and identification of the commercially important Agathosma species was investigated. Previous research attempts aimed at developing a reliable and reproducible method of identifying these Agathosma species failed, mostly because these studies were based on phenotypic traits and these methods were therefore influenced by environmental factors. In this study amplified fragment length polymorphisms (AFLPs) were successfully used to quantify the genetic variation between the Agathosma species and as a result three distinct groups could be identified. The data obtained were elaborated with the Dice genetic similarity coefficient, and analysed using different clustering methods and Principle Coordinate Analysis (PCoA). Cluster analysis of the genotypes revealed an overall genetic similarity between the populations of between 0.85 and 0.99. The AFLP-based dendrogram divided the populations into three major groups: (1) the A. serratifolia and A. crenulata populations, (2) the putative hybrid, A. betulina X A crenulata populations, and (3) the A. betulina populations, confirming that this technique can be used to identify species. The question of hybridisation was also clarified by the results of the PCoA, confirming that the putative hybrid is not genetically intermediately spread between the A. crenulata and A. betulina populations, and that it is genetically very similar to A. betulina. The putative hybrid can therefore rather be viewed as a genetically distinct ecological variant of A. betulina. As the AFLP technique cannot be directly applied in large-scale, routine investigations due to its high cost and complicated technology, the development of polymerase chain reaction (PCR)-based molecular markers, able to accurately identify the species, was undertaken. Due to the superior quality of A. betulina oil, the development of such markers is especially critical for this species. Several species-specific AFLP markers were identified, converted to sequence characterised amplified regions (SCARs) and ultimately single nucleotide polymorphisms (SNPs) were characterised. The developed SCARs were unable to distinguish between the species. The conversion of AFLP fragments to SCARs is problematic due to multiple fragments being amplified with the AFLP fragment of interest. The diagnostic feature of the SNP-based markers was not sensitive enough, since this technique could not distinguish between the A. betulina and A. crenulata and/or the putative hybrid populations. The SNPs that were characterised were found not to be species-specific; they were only specific to the particular clone. Although a quick and robust marker specific for A. betulina has not yet been developed, this study sets the stage for future genetic studies on Agathosma species. Such a marker, or set of markers, would be an invaluable contribution to a blooming buchu oil industry.

Thesis (MTech (Horticulture)--Cape Peninsula University of Technology, 2017.
A study was conducted to investigate the effects of various media composition and wounding treating on the in vitro propagation of Argyroderma subalbum and A. testiculare explants derived from mature plants, antioxidants and plant growth regulators (PGR) concentrations. One experiment consisted of 3 medium types including Murashige and Skoog (MS) medium strength, vitamin supplement. Fifteen replicates were used for each treatment. The shoots were then sub-cultured to ten replicate regenerated medium consisting of varying levels and combination of indole-3-acetic acid (IAA) and 10 μM 6-Benzyladenine (BA) supplements. In another experiment consisted of varying levels of auxins with MS medium strength, activated charcoal (AC) and vitamin supplements ten replicates were used for each treatment. Results indicated the positive role of cytokinins types’ 6-Benzyladenine (BA), 2-isopentyladenine (2iP) and Kinetin in inducing callus formation from wounded explants. The highest rate of friable callus formation of wounded explants was observed in media containing vitamin supplementation with BA at 10 μM. Callus formation significantly increased with the addition of vitamins at 10 μM on BA, 2iP and kinetin. With regards to the effects of various media composition and wounding explants on in vitro growth and regeneration of A. subalbum and A. testiculare, significant results were achieved with BA, 2iP and kinetin concentrations on explants discoloration and callus formation. The antioxidant treatment, AC did not reduce explants discoloration, but the induction of the callus was developed furthermore, results showed that IAA with BA concentrations without addition of AC there was significantly difference on both species but A. subalbum dominated with browning intensity (Chapter 3). Only sub-culturing of the explants succeeded in preventing explants discoloration and subsequently increased the number of shoots. The interaction between Indole-3-acetic acid (IAA) concentrations combined with BA resulted in the most effective technique in reducing explants discoloration at the media contact point. This study provides an insight into the contributing factor and methods of overcoming the major problem of phenolic oxidation and promoting the in vitro growth and regeneration of A. subalbum and A. testiculare.

Although pharmaceutical industries have produced a number of new antibiotics in the last three decades, resistance to these drugs by infectious microorganisms has increased. For a long period of time, plants have been a valuable source of natural products for maintaining human and animal health. The use of plant compounds for pharmaceutical purposes has gradually increased worldwide. This is because there are many bioactive constituents in plants which hinder the growth or kill microbes. Plants could be considered a potential gold mine for therapeutic compounds for the development of new drugs. In this study, sixteen South African plant species were selected based on their antibacterial activity after a wide screening of leaf extracts of tree species undertaken in the Phytomedicine Programme, University of Pretoria. Literature search excluded eleven plants because of the work already performed on their antibacterial activities, while Pavetta schumaniana was found toxic and thus not included in the screening. The remaining four plants namely; Buxis natalensis, Macaranga capensis, Dracaena mannii and Garcinia livingstonei were screened for antibacterial activity by determining the minimum inhibitory concentrations (MIC) against 4 nosocomial bacterial pathogens Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa, and also by using bioautography. The extracts of Macaranga capensis, Garcinia livingstonei, Diospyros rotundifolia and Dichrostachys cinerea had good antibacterial activity with MIC values of 0.03, 0.04, 0.06 and 0.08 mg/ml against different pathogens. The average MIC values of the plant extracts against all the tested pathogens ranged from 0.23-1.77 mg/ml. S. aureus was the most susceptible bacterial pathogen with average MIC of 0.36 . The extract of Diospyros rotundifolia was the most active with an average MIC against all the organisms of 0.23 mg/ml. The extracts of Buxus natalensis, Dracaena mannii, and Pittosporum viridiflorum, Acacia sieberiana, Erythrina lattissima, Cassine papillosa and Pavetta schumanniana had lower antibacterial activity. G. livingstonei was selected for further work on the basis of its good activity. The bulk acetone extract of Garcinia livingstonei (20g) was subjected to solvent-solvent fractionation which yielded seven fractions. Only the chloroform and ethyl acetate fractions showed good bioactivity in the microdilution assay and bioautography. Column chromatography was used to isolate two bioactive biflavonoids from the ethyl acetate fraction. The structures of the two compounds were elucidated using nuclear magnetic resonance (NMR) spectroscopy, and were identified as amentoflavone (1) and 4′ monomethoxyamentoflavone (2). These two compounds have been previously isolated from plants that belong to the Clusiaceae. The two compounds were isolated in sufficient quantity with a percentage yield of 0.45% for amentoflavone and 0.55% for 4′ monomethoxyamentoflavone from 20 g crude acetone extract. The antibacterial activity was determined against four nosocomial bacterial pathogens (Escherichia coli, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa). The MIC values ranged from 8-100 μg/ml. Except for Staphylococcus aureus which showed resistance to amentoflavone at >100 μg/ml. All the other tested organisms were sensitive to both compounds. It has long been recognized that naturally occurring substances in higher plants have antioxidant activity. Based on this, the antioxidant activities of the two isolated compounds were tested using the Trolox assay. The two flavones had good antioxidant activity. Amentoflavone had a Trolox equivalent antioxidant capacity (TEAC) of 0.9. The second compound 4′ monomethoxyamentoflavone had a TEAC value of 2.2 which is more than double the antioxidant activity of Trolox, a vitamin E analogue. To assess the safety of the two compounds on cell systems, cytotoxicity was determined using a tetrazolium based colorimetric assay (MTT assay) using Vero monkey kidney cells. The compounds indicated little to low toxicity against the cell line with cytotoxic concentration (CC50) of 386 μg/ml and >600 μg/ml for compound 1 and 2 respectively. Berberine (used as the control toxic substance) had a CC50 of 170 μg/ml. The Ames genotoxicity assay is used to assess the mutagenic potential of drugs, extracts and phytocompounds. The compounds isolated in this study were assayed for genotoxicity using the Salmonella typhimurium TA98 strain. Amentoflavone was genotoxic at the concentration of 100 μg/plate, but 4′ monomethoxyamentoflavone was inactive at the highest concentration of 400 μg/plate tested. The results of the antibacterial, antioxidant and cytotoxicity testing were encouraging and indicated the potential usefulness of Garcinia livingstonei in traditional medicine and drug discovery. However, the genotoxicity assay revealed potential mutagenic effects of amentoflavone, a compound isolated from the plant. Therefore, it is suggested that application of Garcinia livingstonei extracts in the treatment of human and animal ailments be done with caution to avoid mutagenic effects on the treated subjects. A relatively small change in the structure of the two compounds by replacing an hydroxyl group with a methoxy group had a major effect in increasing antibacterial and antioxidant activity and in decreasing cellular and genotoxicity. This illustrates the potential value of modifying a molecule before its possible therapeutic use. Copyright
Dissertation (MSc (Veterinary Science))--University of Pretoria, 2009.
Paraclinical Sciences
unrestricted

Philosophiae Doctor - PhD
Diabetes mellitus (DM), being one of the most common metabolic disorders with an elevated morbidity and mortality rate around the world. It is characterised by deficiency in insulin secretion or degradation of secreted insulin. Many internal and external factors such as oxidative stress, obesity and sedentary lifestyle among others have been suggested as the major causes of these cell alterations. Diabetes I and II are the most common types of diabetes. Treatment of type I requires insulin injection, while type II can be managed using different synthetic antidiabetic agents. However, their effectiveness is limited as a result of low bioavailability, high cost of drug production, and unfavourable side effects. There is a great need to develop alternative and more active antidiabetic drugs from natural sources. Natural products are a well-known source for the discovery of new scaffold for drugs discovery, and South Africa is one of the most important megaflora with high percentage of endemism.
2023-12-01

Thesis (MScAgric)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: African Acacia species are often major contributors to the progressive increase in the woody component of savannas, a phenomenon commonly referred to as bush encroachment. In Hluhluwe- Umfolozi Park, the numbers of adult Acacia nilotica (L.) Willd. Ex Del. trees per hectare far exceed (by III) that of A. karroo Hayne adults. The relative dominance is reversed in the juvenile stage with A. karroo (725 ha') outnumbering A. nilotica (225 ha-I) threefold outside closed woodlands. African acacias produce large quantities of seed and may have large soil-stored seed banks. They suffer pre-dispersal predation by bruchid beetles and may be either wind or animal dispersed. Once dispersed they are vulnerable to post-dispersal attack. This study tested several hypotheses regarding various aspects of seed ecology of A. karroo and A. nilotica. The null hypothesis that seed ecology does not contribute to the success of A. karroo over A. nilotica, was tested. Acacia karroo trees were smaller (mean basal diameter: 7.8 cm) than A. ni/otica trees (mean basal diameter: 18.5 cm) on average, but produced more seeds (A. karroo mean: 1628; A. nilotica mean: 992) for a given basal diameter size class. It was found that A. karroo showed less bruchid infestation (mean: 1.36-3.81%) than A. nilotica (mean: 14.67-86.70%) at all stages of pod development with a proportion of A. karroo seeds (7.1 %) being able to germinate after bruchid attack. Bruchid attack rendered A. ni/otica seeds unviable. There was no difference between the two species with regards to the soil-stored seed bank and the viability of seeds found in the soil. Acacia karroo showed higher germination levels (5.1%) and better establishment (4.9%) than A. nilotica (1.5% and 0.4% respectively). On average, there was no difference in germination levels between burnt and unbumt seeds, but there was a significant difference in germination of burnt seeds in both burnt (4.5%) and unbumt (2.5%) sites and unbumt seeds in both burnt (2.8%) and unbumt (4.9%) sites when considered separately. Post-dispersal predation of A. karroo seeds (21.8%) was higher than that of A. nilotica (12.7%). There was more rodent predation in tall grass areas (26.0%) than short grass (10.7%) or canopy areas (15.2%), and most seeds were lost from unprotected control groups. Rodent presence was a significant factor in unexplained seed disappearance. The ability of A. karroo to germinate easily and the low levels of beetle predation experienced by this species seemed to be its main advantage over A. nilotica as an encroaching species in Hluhluwe-Umfolozi Park.
AFRIKAANSE OPSOMMING: Die Acacia spesies van Afrika is dikwels belangrike bydraers tot die progressiewe toename in die houtkomponent van savannas. Hierdie verskynsel word algemeen na verwys as bosindringing. In die Hluhluwe-Umfolozi Park is die aantal volwasse Acacia nilotica (L.) Willd. Ex Del. bome per hektaar aansienlik meer (l l l meer) as die aantal volwasse A. karroo Hayne bome. In die jong stadium is die oorheersing omgekeerd, met driekeer soveel A. karroo (725 ha-I) as A. nilotica (225 ha-I) bome buite beboste gedeeltes. Afrika se Acacia spesies produseer groot hoeveelhede saad en kan oor aansienlike grond-gebergde saadbanke beskik. Voor verspreiding word die saad aan predasie deur bruchid-kewers blootgestel. Die saad kan óf deur wind óf diere versprei word en na verspreiding word dit ook aan predasie blootgestel. Hierdie studie het verskillende hipoteses rakende verskeie aspekte van die saadekologie van A. karroo en A. nilotica getoets. Die nulhipotese dat saadekologie nie tot die groter sukses van A. karroo teenoor A. nilotica bydrae nie, is getoets. Acacia karroo bome was oor die algemeen kleiner (gemid. basale omtrek: 7.8 cm) as A. nilotica (gemid. basale omtrek: 18.5 cm) bome maar het meer saad (A. karroo gemid.: 1628; A. nilotica gemid.: 992) per gegewe basale diameter grootte klas gelewer. Daar is geen verskil tussen die twee spesies rakende grondgebergde saadbanke en die lewensvatbaarheid van hierdie saad gevind nie. Acacia karroo het hoër vlakke van ontkieming (5.1%) en beter vestiging (4.9%) as A. nilotica (l.5% en .4% respektiewelik) getoon. Daar was oor die algemeen geen verskil in die ontkiemingsvlakke van gebrande en ongebrande sade nie, maar wel 'n beduidende verskil in die ontkieming van gebrande sade in beide gebrande (4.5%) en ongebrande (2.5%) areas en ongebrande sade in gebrande (2.8%) en ongebrande (4.9%) areas as dit afsonderlik geëvalueer is. Die predasie van A. karroo saad na verspreiding (21.8%) was hoër as dié van A. nilotica (12.7%). Daar was meer knaagdier-predasie in gebiede met lang gras (26.0%) as dié met kort gras (10.7%) of boomryke gedeeltes (15.2%). Die meeste saad is in onbeskermde kontrolegroepe verloor. Die teenwoordigheid van knaagdiere het 'n belangrike rol in die onverklaarde verdwyning van saad gespeel. Dit is gevind dat A. karroo se vermoë om maklik te ontkiem, asook die lae vlakke van insek skade aan die saad, die belangrikste voorsprong is wat dié spesie oor A. nilotica as 'n indringer in Hluhluwe-Umfolozi Park het.

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2005.
Within the Table Mountain National Park (TMNP), Western Cape, South Africa, various management practices have been undertaken in the removal of alien vegetation. While considerable success in the control of alien plants is evident from the removal of standing plants, it is not known if this effort has actually made any long-term difference in the effort to eliminate alien vegetation from the TMNP. This is because no coordinated effort has been made to assess the extent of the alien seed bank, nor the effect that clearing (including the use of fire) has on this seed store. This study investigates the extent of pre- and post-fire Acacia saligna seed banks under differing stand ages, differing clearing techniques and different habitats in the Cape Peninsula National Park. Firstly, the focus is on two alien plant management techniques: The first technique involves clearing and stacking of biomass for burning during winter (stack burn technique), the second technique involves burning of standing alien plants (standing/block burn technique) to decrease heat release at the surface. Secondly, the extent of Acacia species seed banks along the Silvermine River is also investigated with the aim of determining the extent of alien seed stores in this habitat and therefore the long-term restoration potential of the riparian corridor. The primary question addressed in the first study is: “Under what clearing technique will most of the alien seed bank be reduced?” The secondary question reads: “Is seed bank density and distribution directly related to age of dense infestation of the alien vegetation stand and habitat?” The primary question addressed in the second study is: “What is the vertical, lateral and longitudinal distribution and density of Acacia species seed banks along the Silvermine River?” The secondary question reads: “Is seed density and distribution influenced by above ground density of alien vegetation?” In both riparian and terrestrial systems, alien soil seed banks accumulate in high densities where aboveground alien Acacia vegetation is dense. Most of the seed occurs in the upper soil layer, but seed density decreases with depth with an exception of a high seed density at a low depth in one of the samples in the riparian system. Intense fires are most effective in reducing seed stores and removing aboveground alien vegetation in both riparian and terrestrial fynbos systems. After burns, both stack and stand burns have shown a significant decrease in seed density especially in the upper layers but there is still much seed that remained in the matrix area between stacks. The cooler winter burns resulted in less destructive, lower temperatures that aided higher seedling recruitment. Mature stands of Acacia saligna tend to have greater seed stores than immature stands and habitats with deep colluvial soils have a greater density and also greater vertical distribution of seeds. The vertical distribution of the riparian system differed from the fynbos terrestrial system in that seeds were found down to lower depths. Along the river, seed density also increased laterally with more seeds occurring in the terrrestrial sections than in the channel. Seed density increased with longitudinal distribution with more seeds occurring at the sites in the lower catchment than upper catchment. Managers should be aware that fire is needed to reduce the seed bank in both riparian and terrestrial fynbos systems. The cooler winter stack burns is the best option as it results in less destructive, lower temperatures that aids higher seedling recruitment. It is important to know the site history as age of dense infestation, number of fires and geology of site could influence seed bank density. In riparian systems the vertical distribution of seed is deeper than in the fynbos area. In order for clearing to be effective it is imperative that follow-up takes place and should be done prior to flowering to stop reseeding.

Dissertation presented for the degree of Doctor of Philosophy (PhD) at Stellenbosch University.
Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The South African Cape lowlands have been severely transformed and reduced to fragments embedded in matrices of various activities. With the need to prioritise conservation efforts, information on the conservation worthiness and management of these fragments is required. This study aimed to better understand how fragmentation affects the Cape lowland vegetation patterns and dynamics and more specifically, to determine if, and if so to what extent these fragments contribute to regional plant diversity and more importantly their functionality. The novel approach adopted focused on plant functional traits, which are better predictors of ecosystem response to global change than individual species. Species were sampled at four scales in four sites of decreasing sizes, including: a mainland and three fragments of three Cape lowland vegetation types i.e. Atlantis Sand Fynbos (ASF), Swartland Shale Renosterveld (SSR) and Langebaan Dune Strandveld (LDS). Traits such as dispersal, pollination, breeding mode and longevity were selected based on relevance to species’ and plantfunctional types’ (PFTs) responses to fragmentation. The findings revealed different effects on species richness and PFTs. The effect of reduced patch size on species richness was more evident in ASF where fragments below 600 ha had significantly fewer species than the mainland. This effect was not unequivocal in SSR and LDS due to several confounding factors (notably the grazing history of the sites). The SSR fragment grazed by indigenous herbivores had significantly more species than the ungrazed sites. Also, the largest LDS fragment grazed by livestock had significantly more species than the ungrazed mainland, indicating that grazing rather than fragment size influences species richness, although the smallest fragments of these two vegetation types had significantly fewer species than the larger fragments. Species turnover and complementarity were high for all three vegetation types, reflecting the degree of habitat heterogeneity and high contribution of beta diversity to overall gama diversity. The effect of reduced patch size was higher on PFT diversity than on PFT richness, with Langebaan Dune Strandveld where habitat fragmentation was more recent being the least affected of the three vegetation types. This indicates a degree of functional redundancy in the Cape lowlands, which is important for ecosystem resistance and resilience. The ASF mainland and the largest fragment had higher PFT diversity than the medium-sized and the smallest fragments; the mainland had also higher PFT diversity than all the fragments combined. Similarly, the smallest SSR fragment had significantly lower PFT diversity and richness than the other sites. The grazed SSR fragment had higher PFT richness and diversity than the ungrazed mainland and smallest fragment, indicating the role of grazing in maintaining renosterveld vegetation. The PFTs absent from the different sites were mostly short-distance dispersed dioecious and non-dioecious species, and some with highly specialised pollination systems. This suggests that dispersal and pollination are vital functional attributes for the persistence of the studied fragmented ecosystems. Habitat fragmentation effects plant community composition and ecological functions in the Cape lowlands, a conclusion supported also by the revealed significant trait-convergence and divergence assembly patterns. These communities result from various fragmentation filters that operate at different spatial-temporal scales and selecting species with suitable responses. All three vegetation types are susceptible to fragmentation, albeit at varying degree. The fragmentation effect was confounded by the sampling and temporal scales, the nature of disturbance regime, and the traitmediated differences in species’ response. The role of the surrounding matrix on fragment connectivity and gene flow appears to be of crucial importance, hence mitigation measures focusing on improving connectivity between patches, monitoring threatened taxa, and promoting dispersal and pollination have been recommended.
AFRIKAANSE OPSOMMING: Suid-Afrika se Kaapse laagland het dramaties verander en weggekwyn tot fragmente wat in matrikse van verskeie bedrywighede veranker is. Gedagtig aan die voorkeuraandag wat bewaringspogings tans geniet, is inligting oor die bewaringswaardigheid en bestuur van hierdie fragmente nodig. Hierdie studie stel dit ten doel om beter begrip te vorm van hoe fragmentasie die plantegroeipatrone en -dinamiek in die Kaapse laagland raak, en meer bepaald om vas te stel óf, en indien wel, in watter mate, hierdie fragmente tot streeksplantdiversiteit en -funksionaliteit bydra. Die ongewone studiebenadering konsentreer op funksionele kenmerke van plante, wat beter aanwyser van ekosisteemreaksie op wêreldwye verandering is as individuele spesies. Spesiemonsters is op vier skale by vier terreine van wisselende grootte ingesamel, wat insluit moederstrook en drie fragmente van elk van drie plantegroeisoorte in die Kaapse laagland, naamlik Atlantis-sandfynbos (ASF), Swartland-skalierenosterveld (SSR) en Langebaan-duinestrandveld (LDS). Kenmerke soos verspreiding, bestuiwing, voortplantingsmetode en lewensduur is gekies op grond van die tersaaklikheid daarvan vir spesies en plantfunksionele tipes (PFT’s) se reaksie op fragmentasie. Die studie bring verskillende uitwerkings op spesie-oorvloed en PFT’s aan die lig. Wat spesie-oorvloed betref, was die uitwerking van kleiner strookgrootte (“patch size”)duideliker te sien by ASF, waar fragmente kleiner as 600 ha beduidend minder spesies as die moederstrook bevat het. Hierdie uitwerking kon nie so duidelik by SSR en LDS waargeneem word nie weens verskeie strengelingsfaktore, veral die weidingsgeskiedenis van die terreine. Die SSR-fragment waarop inheemse herbivore gewei het, het beduidend meer spesies as die onbeweide terreine bevat. Voorts het die grootste LDS-fragment waarop vee gewei het heelwat meer spesies as die onbeweide moederstrook gehad, wat daarop dui dat weiding eerder as fragmentgrootte spesie-oorvloed beïnvloed, hoewel die kleinste fragmente van hierdie twee plantsoorte steeds aansienlik minder spesies as die groter fragmente bevat het. Spesie-omset en -aanvullendheid was hoog vir ál drie plantsoorte, wat aanwyser is van die mate van habitat-heterogeniteit en die groot bydrae wat betadiversiteit tot algehele gammadiversiteit lewer. Die uitwerking van kleiner strookgrootte was duideliker te bespeur op PFT-diversiteit as PFT-oorvloed – in dié verband het LDS, waar habitatfragmentasie mees onlangs plaasgevind het, die ligste van die drie plantsoorte afgekom. Dít dui op mate van funksionele oorbodigheid in die Kaapse laagland wat belangrik is vir ekosisteemweerstandigheid en -gehardheid. Die ASF-moederstrook en die grootste ASF-fragment het hoër PFT-diversiteit getoon as die medium- en kleinste fragmente; die moederstrook het in werklikheid oor hoër PFT-diversiteit as ál die fragmente saam beskik. Insgelyks het die kleinste SSR-fragment beduidend minder PFT-diversiteit en -oorvloed as die ander terreine getoon. Die beweide SSR-fragment was hoër in PFT-oorvloed én -diversiteit as die onbeweide moederstrook en die kleinste fragment, wat die rol van weiding in die instandhouding van renosterveldplantegroei beklemtoon. Die PFT’s wat nié op die verskillende terreine voorgekom het nie, was meestal tweehuisige en nietweehuisige spesies wat oor kort afstande versprei, en sommige spesies met hoogs gespesialiseerde bestuiwingstelsels. Dít dui daarop dat verspreiding en bestuiwing noodsaaklike funksionele kenmerke vir die voortbestaan van die bestudeerde gefragmenteerde ekosisteme is. Habitatfragmentasie raak die samestelling en ekologiese funksies van plantgemeenskappe in die Kaapse laagland. Dié gevolgtrekking word ook gerugsteun deur die bewese patrone van beduidende kenmerkkonvergensie (“trait convergence”) en divergensiesamekoms (“divergence assembly”). Hierdie plantgemeenskappe spruit uit verskeie fragmentasiefilters wat op verskillende ruimte-tydskale funksioneer, en wat spesies met geskikte reaksies kies. Ál drie plantsoorte is ontvanklik vir fragmentasie, hoewel in wisselende mate. Die fragmentasie-uitwerking is beïnvloed deur monsterinsameling- en tydskale, die soort versteuringsbedeling, en die kenmerkbemiddelde (“traitmediated”) verskille in spesiereaksie. Die rol van die omringende matriks op fragmentverbondenheid en geenvloei blyk van die allergrootste belang te wees, en dus word temperingsmaatreëls aanbeveel wat daarop gemik is om verbondenheid tussen stroke te verbeter, bedreigde taksa te moniteer, en verspreiding en bestuiwing aan te help.

Thesis (M.Dev.) --University of Limpopo, 2012
The main aim or purpose of this study was to look at the ways and the strategies of minimizing\ mitigating the over-harvesting of indigenous medicinal plants in order to use them sustainably. The task of identifying and assessing challenges facing local communities in utilizing and sustaining indigenous medicinal plants in Thengwe village and their implications on environmental conservation and management of natural resources was done during the pilot survey. The environmental field survey was conducted after gaining permission to enter into the identified study areas including the Mutavhatsindi Nature Reserve. The result revealed that most of the indigenous medicinal plants are used for healing, religious, economical and for protection purposes. Most of the indigenous medicinal plants in the study area are depleted and many of them are facing extinction. The study was qualitative in design. Semi-structured interviews and a questionnaire were used. The questionnaire had both open-ended and closed questions. The study area was Thengwe Village in the Mutale Municipality. The existence of medicinal plants is threatened by people `s perceptions and attitudes towards them. For some indigenous medicinal plants, depletion is at a high rate due to over-harvesting and because the plants when traded by herbalists they have a premium price attached to them. Interestingly, perhaps surprisingly, the majority of young people hold negative attitudes towards the indigenous medicinal plants due to poor knowledge of the value of indigenous medicinal plants, in contrast to the elders who appreciate their role and consider them as part of their culture, economy and religion. One of the findings is that medicinal plants were found to be important to the community members as the source of income and creation of jobs for the medicinal collectors who sell the species to traditional healers. For the reason of preserving indigenous medicinal plants and others as the environmental resources, this study recommends that there should be strong intergovernmental relationships between the National, Provincial and Local governments in order to prevent over-harvesting of the medicinal plants. The indigenous medicinal plants are equally important to biodiversity students and researchers who want to study and research indigenous medicinal plants which play an important role in the improvement of the livelihoods of community members. Furthermore, education campaigns within the communities and school learners are recommended to encourage the prevention, sustainability and utilization of the indigenous medicinal plants. Additionally, the legal authorities should be empowered to prosecute all people who may be found illegally in possession of indigenous medicinal plants, as well as endangered and protected species. Heavy fines and charges should be imposed on such culprits. Of importance is the fact that the results and recommendations of this study may facilitate the teaching of environmental education and management of natural resources as well as boost the local economy of the Vhembe district Municipality by showing that medicinal plants in the area can be seen as a viable tourist attraction.

Magister Scientiae (Biodiversity and Conservation Biology)
The spread of invasive species is one of the greatest threats to global biodiversity. Alien plant invasions also have serious economic impact in terms of the delivery of ecosystem goods and services. Studies of biological invasions in southern Africa have tended to overlook grasses (family Poaceae), although there are many naturalised species in the region. Only a few of these, all perennials, have been officially categorised as invasive in South Africa, but in the winter rainfall region of the Western Cape, grass invasion especially by Mediterranean European annuals have also been noted. These grasses can be difficult to identify. DNA barcoding has been suggested as an alternative method of identifying grasses in the hope of facilitating identification of existing invaders and preventing future invasions. In this study a list of all known naturalised grasses in South Africa was compiled, and a DNA barcoding reference database was assembled for these naturalised grass species as well as for native southern African grass species. The two official markers for plant DNA barcoding (rbcLa + matK) were used in barcoding and phylogenetic analyses, both individually and in combination. The barcoding data was assessed for identification efficacy using three distance-based metrics and one tree-based metric in the R package SPIDER, both including and excluding singleton data. This study lists 128 naturalised grass species and subspecies found in South Africa. In the DNA barcoding analyses, matK was found to perform better as a single barcode than rbcLa, with identification success rates of up to 84% for matK and 76% for rbcLa, using the most successful metric which was the Nearest Neighbour criterion for both of these markers in the data sets without singletons. The combined rbcLa + matK data set performed better than either of the two individual markers, with identification success rates of up to 91% in the data without singletons, with the most successful metric again being the Nearest Neighbour criterion. The combined rbcLa + matK data would therefore be the recommended DNA barcode for southern African grasses of the three data sets tested, based on the results of this study. Phylogenetic trees were constructed with the DNA barcoding data using Bayesian Inference (BI) and Maximum Parsimony (MP) to assess the usefulness of the data in phylogenetic studies and to confirm the efficacy of this grass DNA barcoding data when using tree-based methods of identification. Both the matK and combined datasets resolved all of the grass tribes represented in this study as monophyletic, but the rbcLa data did not.

Thesis (M. Tech. (Agriculture)) -- Central University of Technology, Free State, 2013
ntroduction: Good quality Eucalyptus is of importance to South Africa’s pulp and paper industry. Limited land is available for forestry, therefore Eucalyptus with genotypes for good pulp and paper qualities, particularly hybrids, are bred and cloned via cuttings. Although these Eucalyptus clones keep the favourable genotypes in the population, many have difficulty with rooting. Research has shown that rhizobacteria can improve rooting. Thus, one strategy to enhance the rooting of cuttings is to use rhizobacterial preparations. The aim of this study was to characterise rhizobacterial communities of Eucalyptus hybrid and species and identify possible plant-growth promoting rhizobacteria (PGPR). Materials and methods: Rhizospheric samples were collected from Eucalyptus hybrids and species. The rhizobacterial communities were characterised using fatty acid methyl esters (FAME) analysis and denaturing gradient gel electrophoresis (DGGE). DGGE fragments were further sequenced to identify rhizobacteria. Results and discussion: FAME analysis successfully achieved a broad characterisation of the Eucalyptus hybrid and species rhizobacterial communities based on their fatty acid composition. Myristic acid (C14:0) was the most abundant fatty acid. DGGE profiles gave a molecular profile of the Eucalyptus hybrid and species rhizobacterial communities based on their DNA composition. Nitrosomona eutropha was present in all samples which illustrates a nitrogen-rich environment. Adhaenbacter aquaticus was unique to the better rooting Eucalyptus hybrid GU111. Conclusion: This study provided some insight into the diversity of rhizobacterial communities of Eucalyptus hybrids and species. Possible PGPR were identified and the observation made that the nature of the soil environment changes with the aging of the associated host. These findings allow further investigation into the formulation of potential rhizobacterial preparations for rooting enhancement of Eucalyptus cuttings.

Includes abstract
Includes bibliographical references (leaves 124-133).
Spontaneous succession, as a method to restore degraded riverine habitats, was assessed for three different components of the Silvermine River ecosystem over one year. These were the state of the physical habitats (biotopes) available to aquatic organisms, changes in the community composition of riparian vegetation, and changes to aquatic macroinvertebrate assemblages present in the river. Data were collected during two successive summer-sampling periods (200 I and 2002) at three study sites along the river. Site I was situated in the mountain stream zone, while Sites 2 and 3 were situated in the foothills. Changes in the riverine ecosystem and its associated habitats were compared to reference condition data for each of the three components from each study site. There were no large changes to the macro-channel banks of the river over the one year study, other than where a meander cut-off occurred at Site 2. Changes over the year in the proportions of flow at the three sites revealed a lack of faster-flow types, which would normally characterise mountain stream and foothill reaches, at all three study sites. Measurements of the proportions of substratum types at the three sites revealed there was an unusually high proportion of fine substratum types present. In the foothills, this was attributed to erosion of the unstable bank at Site 2, which continued to deposit an excess of fine sediment that was transported downstream. In the vegetation study, most species that came to dominate the mountain stream (Site I) and the foothill (Sites 2 and 3) riparian communities emerged from the seed bank within the first two years after the fire. Thus, using the presence or absence of characteristic riparian vegetation species it is possible to determine whether there is a need to augment the recovery process after two years. The aquatic macroinvertebrate communities of the mountain stream differed clearly from those in the foothill. The differences were attributed to a combination of the channel type and the longitudinal position of the sites along the river, both of which dictated the physical habitats available. There were clear differences in the potential for recovery at each of the three study sites. It was shown that non-intervention will not support successful recovery in the short to medium term for any of the measured three components of this river. A blanket policy of non-intervention cannot address site-specific differences, be they natural or artificial, which pose different challenges to restoration. There were zonal differences in the availability of substrata and flow types. There were also other differences that were attributed to water abstraction and the presence of different woody exotic trees. Recovery of the mountain stream was being hampered by the presence of the reservoir and the history of water abstraction while recovery of the foothill was being retarded by erosion from the massive sediment deposit at Site 2. Plans to restore the river, that took into account these inter-site differences, were proposed.

Thesis (M.Sc. (Physiology)) --University of Limpopo, 2015
Water is an essential and yet scarce resource, which has a vital role for human use and also serve as a habitat for numerous organisms in aquatic environments. Despite its scarcity there have been many reports indicating that it is continually polluted by domestic, agricultural, mining and other anthropogenic activities; subsequently affecting the health of organisms residing in such water bodies. Fish have been selected as the bio-monitoring species due to its direct interaction with the environment; thereby making it an appropriate model to monitor and evaluate the health status of the environment. The feral population of the alien species, Hypopthalmichtys molitrix (Valenciennes, 1844) commonly known as the silver carp in Flag Boshielo Dam has been considered a healthy population. However, this perception changed considerably after reports of lethargic, dying fish were first noted in 2011. Currently the sporadic deaths amongst mature specimens (>0.7m) persist; and the reason(s) for their demise remains unclear. Therefore, the aim was to employ a seasonal study design to investigate the health status of selected fish species such as H. molitrix in Flag Boshielo Dam by evaluating haematological parameters, oxidative stress biomarkers and bio-accumulation levels of particular transition metals. Seasonal surveys were carried out from February 2012 to January 2013 at Flag Boshielo Dam, Olifants River System, Limpopo Province. The locality surrounding the dam is known to be in an agriculture and mining catchment. Hypopthalmichtys molitrix and Labeo rosae (Steindachner, 1894) commonly known as the rednose labeo were collected with the use of scoop nets, conventional angling gear and gill nets. Following collection, morphometric measurements were taken and blood was collected. The blood samples required for further analysis at the Medical Science Department, University of Limpopo were kept on ice (4˚C). After the collection of all blood samples the specific fish was sacrificed and muscle samples were collected for bio-accumulation analysis and gills and liver samples were collected for the measurement of oxidative stress biomarkers. These tissue samples were rapidly frozen and kept frozen (-85˚C) until further analysis. Haematological parameters from the study reflected a variation amongst comparison of the inter- and intra-species. It was observed that mature H. molitrix suffered from anaemia. The response of glutathione-S-transferase (GST) and thiobarbituric acid reactive substances (TBARS) was relatively constant throughout all seasons when the young (<0.5m) and mature H. molitrix (0.6 – 0.90m) specimens were compared. However, the catalase (CAT) response of mature H. molitrix was dramatically impaired. This would increase their vulnerability to oxidative stress. Bioaccumulation levels of the eleven selected transition elements exhibited various trends. Metals such as Molybdenum (Mo), Vanadium (V), (Chromium) Cr, Cobalt (Co), Zinc (Zn), Cadmium (Cd) and Mercury (Hg) exhibited seasonal bio-accumulation levels that were in support of the various feeding behaviours of the fish species in this study. On the other hand, metals such as Manganese (Mn), Iron (Fe), Copper (Cu), Zinc (Zn), Cadmium (Cd) and Mercury (Hg) also illustrated the potential to be contributing factors in the death of the mature specimens. In conclusion, the findings from this study illustrate the complex nature of metabolic disturbances resulting in the death of mature H. molitrix specimens. It is clear that no single aspect investigated in this study could be solely implicated as the major cause of death. This multifactorial presentation necessitates further haematological assessment focussing on blood cell morphology and pathology, as well as investigations into other oxidative stress biomarkers in liver and gill tissue. In addition, identifying the most appropriate tissue type for future bio-accumulation measurements of transition metals in this feral population is necessitated. It is further suggested that neuro-muscular assessments, focussing on neurotransmitters such as γ-aminobutyric acid (GABA) and acetylcholine (Ach), form part of the investigation into the lethargic behaviour of the mature fish.

Thesis (MSc)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Invasive alien plant species have devastating effects on the environments that they invade. Australian Acacias, a group of plants that has been planted globally for a range of uses, but has escape plantation areas and became invasive in many countries, are particularly problematic. Acacia mearnsii is one of these invasive alien plant species and in South Africa it is also an important forestry species. It is currently the fifth most widespread invasive alien plant in South Africa, only restricted by the very arid Karoo, thus it is important to assess the different habitats that it enters. The Afromontane forest complex in South Africa is highly fragmented and is one of the most threatened Biomes in the country. The widespread forest margin tree Virgilia divaricata occurs within these forest margins. It is ecologically similar to A. mearnsii as these two species share many characteristics (nodulating legumes, forest pioneer species, fast growing and fire adapted). These species occur sympatrically within invaded forest margins and within these sites, there is a potential for biological exchanges of associated pests and pathogens in the form of arthropods and fungal species. We hypothesize that these two species have different interactions with their pests and pathogens in accordance with the Enemy Release Hypothesis (ERH) and the Biotic Resistance Hypothesis (BRH), respectively. We first compared arthropod associates between these two tree species and found that they share many arthropod species. The native tree did, however, have much higher abundances of herbivores and overall arthropod associates than the invasive tree species, which supports the predictions of the ERH. The distribution of these two species also had an effect on their arthropod assemblages. We assessed their ophiostomatoid fungal associates and herbivore loads and then determined how these pests and pathogens were influenced by environmental conditions along a water gradient. We also compared the effect of plant nutrient content of the two tree species on pest and pathogen loads. A. mearnsii was unaffected by water limitation along this gradient, while δ12C/ δ13C analyses showed that V. divaricata trees experienced drought within drier sites. V. divaricata also had higher herbivore loads in drier sites. A. mearnsii had higher herbivore loads on nutrient deficient trees and higher disease development in trees with sufficient nutrient levels. Comparisons of the nutrient economies of the two legume trees showed that they had similar leaf nutrient contents and resorption efficiencies, but they differed in the use of Biological Nitrogen Fixation (BNF). The native tree utilized BNF more than the invasive. We also tested the physiological effects of a native fungal species on the two tree species. We found the infection elicited more response from the invasive, while the native plant was almost non-responsive. Both plants had significantly longer lesions on infected seedlings than on control plants after inoculation with this pathogen. This difference in response offers a measure of support to the BRH, as the invasive may be more vulnerable to infection. The importance of using related, ecologically similar species in the assessment of the impacts of invasive alien plants is highlighted here. This may provide more information on the actual ecological interaction between native and invasive species within invaded ranges. Forest margins are very vulnerable and dynamic habitats. The influx of a new species into this habitat in the form of an invasive alien plant may therefore have much negative effects. We found support for the exchange of pest and pathogens where these two tree species co-occur. The two host species were very similar in their nutrient economies, creating a potential for competition for similar resources between A. mearnsii and V. divaricata. The environment had an influence on how these plants responded to pest and pathogens and this may be important under the predicted scenario of future climate change.
AFRIKAANSE OPSOMMING: Uitheemse indringer plant spesies het vernietigende effekte op die omgewings waarbinne hulle indring. Australiese Acacias, ‗n groep plante wat reg oor die wêreld aangeplant is vir ‗n reeks gebruike, maar wat uit plantasie areas ontsnap het en indringers geword het in baie lande, is besonder problematies. Acacia mearnsii is een van hierdie indringer uitheemse plant spesies, en in Suid Afrika is ook ‗n belangrike bosbou spesie. Dit is tans die vyfde mees wydverspreide uitheemse indringer plant in Suid Afrika, en word slegs beperk deur die baie droë Karoo, so dit is belangrik om die verskillende habitatte wat dit binnedring te ondersoek. Woudrandte, the grense van die Afromontane woudkompleks in Suid Afrika, is hoogs gefragmenteerd en is dus een van die mees bedreigde Biome in die land. Die wydverspreide woudrand boom Virgilia divaricata kom in hierdie woudrandte voor. Dit is ekologies eenders aan A. mearnsii, aangesien hierdie twee spesies baie kenmerke deel (wortelknop-vormende peulplante, woudpionier spesies, vining groeiend, aangepas tot brande). Hierdie spesies kom simpatries voor binne woudrandte wat deur A. mearnsii ingedring is, en in hierdie lokaliteite bestaan daar die potensiaal vir biologiese uitruiling van geassosieerde peste en patogene in die vorm van geleedpotiges en fungi spesies. Ons stel die hipotese dat hierdie twee spesies verkillende interaksies met hulle peste en patogene het, in ooreenstemming met die Vyand-Vrystellingshipotese (VVH) en die Biologiese-Weerstandshipotese (BWH), onderskeidelik. Ons het eers die geleedpotige assosieasie tussen hierdie twee boom spesies vergelyk en het bevind dat hulle baie geleedpotige spesies deel. Die inheemse boom het egter baie hoër getalle herbivore en algehele geleedpotige-assosiasies gehad as die indringer boom spesie, wat die voorspellings van die VVH ondersteun. Die verspreiding van hierdie twee spesies het ook ‗n effek gehad op hulle geleedpotige samestellings. Ons het ook hulle geassosieerde ophiostomatiede fungus assosiate en hulle herbivoor ladings bestudeer, en het bepaal hoe hierdie peste en patogene deur omgewingstoestande beinvloed is langs ‗n water gradient. Ons het ook die effek van hierdie peste en patogene op die voedingstof-inhoud van hierdie twee spesies vergelyk. A. meansii is nie geaffekteer deur waterbeperkings langs hierdie gradient nie, terwyl δ12C/ δ13C analises aangedui het dat V. divaricata bome droogte stres in droër lokaliteite ervaar het. V. divaricata het ook hoër herbivoorladings gehad in die droër lokaliteite. A. meanrsii het hoër herbivoorladings gehad op voedingstof-beperkte bome, en daar was verhoogde siekte-ontwikkeling in bome met genoegsame voiding. Vergelykings van die voedingstof-ekonomië van die twee peulplant bome het aangedui dat hulle eenderse blaarvoedingstof-inhoude en resorpsie effektiwiteite het, maar het verskil in die gebruik van Biologiese Stikstof Fiksasie (BSF). Die inheemse boom het meer van BSF gebruik gemaak as die indringer. Ons het ook die fisiologiese effekte van ‗n inheemse fungus spesie op die twee boomspesies getoets. Ons het bevind dat infeksie ‗n sterker reaksie in die indringer ontlok het, terwyl die inheemse plant feitlik glad nie op infeksie gereageer het nie. Beide plante het beduidend langer wondmerke in geinfekteerde saailinge ontwikkel as in kontrole plante na innokulasie met die patogeen. Hierdie verskil in reaksie verleen ‗n mate van ondersteuning aan die BWH, aangesien die indringer meer vatbaar mag wees teen infeksie. Die belang daarvan om verwante, ekologies soortgelyke spesies te gebruik in die bepaling van die effekte van uitheemse indringer spesies word hier beklemtoon. Dit mag meer inligting verskaf oor die werklike ekologiese interaksie tussen inheemse en indringer spesies binne verspreidings wat binnegedring is. Woudrandte is baie weerlose en dinamiese habitatte. Die invoer van nuwe spesies in hierdie habitat in die vorm van ‗n uitheemse indringer plant mag daarom baie negatiewe effekte hê. Ons het ondersteuning gevind vir die uitruiling van peste en patogene waar hierdie twee spesies saam voorkom. Hierdie spesies was baie eenders in terme van hulle voedingstof-ekonomië, wat die potensiaal skep vir kompetisie tussen A. mearnsii en V. divaricata. Die omgewing het ‗n effek gehad op hoe hierdie plante gereageer het op peste en patogene, en dit mag belangrik wees onder die huidig voorspelde senarios van toekomstige klimaatsverandering.

High structural diversity amongst plant species in the arid winter rainfall region of southern Africa is common to other arid regions of the world. Details of the range and combinations of structural attributes in species, and within plant communities, are not widely known for southern African arid ecosystems. Hence little is known of how plant-form distributions vary within and between arid ecosystems. and of the environmental factors that may be responsible for any variations found. Nor is much information available on how phenological behaviour relates to the structural attributes of plant species. This study examined structural attributes of perennial plant species on the Worcester Veld Reserve, southwestern Cape. in relation to their distribution and phenology. Species were grouped on the basis of above ground structural and anatomical criteria. The distribution of species and plant-forms was assessed through a phytosociological survey along an environmental gradient in the area, and their phenology determined through qualitative and quantitative monitoring of species phenophases over a two year period. The results show that species of the predefined structural groups i) Co-occur throughout the area. but relative abundances vary from site to site and in relation to topography. aspect and the presence of Mirna-like mounds; ii) Phenological patterns for the flora overall are strongly seasonal, but the timing and periods of phenophases differ between, but are relatively uniform within, the defined structural plant groups. Since phenological patterns are indicative of resource-use patterns. these results indicate that the different plant-forms have different functional responses to the conditions of limited water availability and summer drought. This conceivably facilitates the co-existence of species in this water-limited environment. Habitat variability. which can be related to land-form patterns. is also implicated as a factor facilitating the co-existence of a diversity of species and plant-forms. Structural functional relationships known for arid region plants help to explain the relative uniformity of behaviour within plantform groups. and aid in understanding the ecological significance of distribution patterns of plant-forms in the arid landscape. The conclusion is reached that because of the close coupling between photosynthesis and water-use. the water storage potential and photosynthetic organ type are plant attributes which can serve as useful criteria by which arid region species can be grouped into ecologically meaningful categories or functional guilds. The formulation of a practical and meaningful functional classification is necessary to facilitate the understanding of complex vegetation patterns and processes within arid ecosystems. and allow for meaningful inter-ecosystem comparisons.

Thesis (MScFor)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Several studies have shown that stands of invasive alien plants in the natural forest environment can facilitate the rehabilitation and recovery of such forests and challenged the general and global perception that such invasive species threaten the biodiversity and functioning of natural vegetation systems. The aim of this study was to develop an understanding of the dynamics of the spread and establishment of natural forest species in a large stand of the invasive alien plant species Acacia mearnsii (Black wattle) along the Buffeljagsrivier, Western Cape, South Africa. Several patches of Moist forest, Dry forest and Riparian forest occur along the Buffeljagsrivier, above the Buffeljagsrivier dam. The stand of Black wattle consists of 90 ha for a distance of 3.12 km. The main objective was pursued through four specific objectives: (i) to map and assess the patterns in the distribution, size and species composition of the natural forest clusters within the Black wattle stand; (ii) to determine the relationship between natural forest clusters establishing within the Black wattle stand and the neighboring natural forest patches as potential seed sources for the developing forest clusters; (iii) to determine the subsequent spread of natural forest species from the developing forest clusters into the rest of the Black wattle stand; and (iv) to synthesize the information on the dynamics of the spread and establishment of natural forest species into the Black wattle stand as a basis for developing general guidelines for the conversion of invasive alien plant stands in the forest environment towards regrowing natural forest. In total, 329 clusters of natural forest species were GPS recorded and mapped (Arc-GIS) in three zones (Proximal, Intermediate and Distant in relation to the forest patches) within the Black wattle stand: 266 small clusters (one to three reproductively mature trees), 36 medium sized clusters (four to nine trees) and 27 large clusters (more than 10 trees). Large clusters were abundant in the zone close to the natural forest patches and the number of small clusters increased with increasing distance from the forest patches. A total of 28 species of 20 families were recorded. Natural forest species are therefore able to establish within a Black wattle stand. The relationship between natural forest clusters establishing within the Black wattle stand and the natural forest patches as potential seed sources was studied by sampling the stand composition along transects through the stands. A total of 55 rectangular plots (20 m x 10 m, 200 m2) were sampled across forest patches and forest clusters. Hierarchical clustering analysis, using number of stems of a species per plot, identified three main groups and 10 sub-groups. All the sampled forest clusters were included in four of the five Riparian forest sub-groups. Most Moist and Dry forest species were absent from the forest clusters. The three main forest types differed in their general characteristics and site conditions, and this was supported by the ordination analyses: aspect, slope and canopy closure. The developing forest clusters within the Black wattle stand related more to the Riparian forest in terms of similar very gentle south-westerly slope and mean stem diameter. This suggested Riparian forest to be the primary seed source of the establishing forest clusters within the Black wattle stand. However, the large-sized stems of common species were not significantly different between Riparian forest patches and forest clusters, suggesting that large-sized stems in the forest clusters could be part of remnant forest patches, which could act as local seed sources. Detailed evaluation of species importance values and stem diameter distributions showed that some important Moist and Dry forest species are present in the forest clusters. The conclusion was that every type of forest patch contributes to a greater or lesser degree to the development of forest clusters within the Black wattle stand. Seven large clusters were selected to sample the regeneration of natural forest species within 18 m from the forest cluster boundary. Two species lists were generated; one of species from adjacent natural forest patches, and another from 59 forest clusters of all sizes sampled throughout the wattle stand. The results indicated that (1) Mature trees of well-established forest clusters were the main seed sources for the cluster expansion in all directions; (2) Three different patterns were observed in terms of the distance of expansion of regeneration from the clusters: a decrease in regeneration with increasing distance from the cluster margin; increasing regeneration with increasing distance from the cluster; and no distinct pattern with a lack of regeneration of the dominant species of a forest cluster. The 40 species recorded within the Buffeljagsrivier site include a wide range of fruit and seed characteristics. Four main groups of woody species were identified, based on their presence/absence in forest patches and forest clusters. The presence/absence of most species can be explained in terms of their fruit/seed characteristics and dispersal mechanisms. The majority of recorded woody species were most likely dispersed by birds and mammal, particularly Rameron pigeons and baboons. In conclusion, a conceptual framework was developed to guide the rehabilitation of stands of light demanding invasive stands in the forest environment. Several topics for further research were identified.
AFRIKAANSE OPSOMMING: Verskeie studies het gewys dat opstande van uitheemse indringerplante in die woudomgewing kan die rehabilitasie en herstel van sulke woude fasiliteer, en daag die algemene en globale persepsie uit dat sulke indringerplantspecies die biodiversiteit en funksionering van natuurlike plantegroeisisteme bedreig. Die doel van hierdie studie was om ‘n beter begrip te ontwikkel van die dinamika vir die verspreiding en vestiging van inheemse woudspesies binne ‘n omvangryke opstand van die uitheemse indringerplant, Acacia mearnsii (swartwattel), langs die Buffeljagsrivier, Wes-Kaap, Suid Afrika. Verskeie kolle (‘patches’) van Vogtige, Droë- en Oewerwoud kom langs die Buffeljagsrivier voor. Die swartwattel opstand van ongeveer 90 ha groei langs die Buffeljagsrivier oor ‘n afstand van 3.12 km, tussen die dam en die woudkolle aan die stroom-op kant van die swartwattelopstand. Die hoofdoel is nagevolg deur vier spesifieke doelwitte: (i) om die groepies (‘clusters’) vestigende inheemse houtagtige plantsoorte binne die swartwattelbos te karteer en die patrone in hul verspreiding, grootte en spesies samestelling binne die swartwattelopstand te evalueer; (ii) om die verwantskap tussen natuurlike woudgroepies wat binne die swartwattelopstand vestig en die aangrensende woudkolle as potensiële saadbronne vir die ontwikkelende woudgroepies te bepaal; (iii) om die daaropvolgende verspreiding van inheemse woudspesies vanaf die ontwikkelende woudgroepies binne die res van die swartwattelopstand te bepaal; en (iv) om die inligting oor die dinamika van die verspreiding en vestiging van die woudspesies binne-in die swartwattelopstand saam te vat as ‘n basis vir die ontwikkeling van algemene riglyne vir die omskepping van uitheemse indringerplantopstande in die woudomgewing na hergroeiende inheemse woud. In totaal is 329 groepies van inheemse woudspesies aangeteken (via GPS) en gekarteer (Arc-GIS) in drie sones (nabygeleë, intermediêre en afgeleë) binne die swartwattel opstand: 266 klein groepies (een tot drie voortplantingsvolwasse bome), 36 medium-grootte groepies (vier tot nege bome) en 27 groot groepies (10 of meer bome). Groot groepies was volop in die sone naby aan die woudkolle en die aantal klein groepies het toegeneem met toenemende afstand vanaf die woudkolle. ‘n Totaal van 28 species van 20 families is aangeteken, en spesies soos Canthium inerme, Celtis africana, Gymnosporia buxifolia, Rapanea melanophloeos en Vepris lanceolata was algemeen binne die swartwattelopstand. Dit is daarom moontlik vir inheemse woudspesies om binne die swartwattelopstand te vestig. Die verhouding tussen inheemse woudgroepies wat binne die swartwattelopstand vestig en die woudkolle as potensiële saadbronne is bestudeer deur die opstandsamestelling langs transekte deur die opstande te bemonster. ‘n Totaal van 55 reghoekige persele (20 x 10 m, 200 m2) is opgemeet: nege in Droeëwoudkolle, 17 in Vogtige woudkolle, 20 in Oewerwoudkolle, en nege in die woudgroepies binne the swartwattelopstand. Hiërargiese Groeperingsanalise, gebaseer op aantal stamme van ‘n spesies per plot, het drie hoofgroepe en 10 sub-groepe ge-identifiseer: Vogtige woud met drie sub-groepe, Oewerwoud met vyf sub-groepe, en Droeëwoud met twee sub-groepe. Al die gemete woudgroepies is in vier van die Oewerwoud sub-groepe ingesluit. Die meeste Vogtige en Droeëwoud spesies was afwesig van die woudgroepies. Die hoof woudtipes (Droog, Vogtig, Oewer) verskil in hul algemene eienskappe en groeiplektoestande, en dis ondersteun deur die ordinasie-analises: aspek, helling en kroonsluiting. Die ontwikkelende woudgroepies binne die swartwattelopstand was nouer verbonde met Oewerwoud in terme van soortglyke baie geleidelike suid-westelike helling en gemiddelde stamdeursneë. Dit veronderstel dat Oewerwoud is die primêre saadbron van die vestigende woudgroepies binne die swartwattelopstand. Baie inheemse woudspesies kom egter oor die verskillende groepe en sub-groepe voor, met goeie verjonging oor die gemeenskappe. Die stamdeursneë van goter stamme van algemene spesies was niebeduidend verskillend tussen die Oewerwoudkolle en die woudgroepies, en dit veronderstel dat die groter stamme in die woudgroepies kan deel wees van oorblywende woudkolle, wat as plaaslike saadbronne kan dien. Gedetaileerde ontleding van spesies belangrikheidswaardes en stamdeursneëklasverdelings het getoon dat sommige belangrike Vogtige en Droeëwoud spesies is wel teenwoordig in die woudgroepies. Die gevolgtrekking was dat elke tipe woudkol in a mindere of meerdere mate bydra tot die ontwikkeling van die woudgroepies binne die swartwattelopstand. Sewe groot woudgroepies is geselekteer om die woudverjonging binne 18 m vanaf die woudgroepierand te bemonster. Twee spesieslyste is saamgestel; een van spesies van die aangrensende woudkolle, en een van spesies van 59 woudgroepies van alle groottes wat deur die hele swartwattelopstand aangeteken is. Die resultate het aangetoon dat (1) volwasse bome van goed-gevestigde woudgroepies was die hoof saadbronne vir die uitbreiding van die woudgroepies in all rigtings; (2) drie verskillende patrone is waargeneem in terme van die afstand van uitbreiding van verjonging weg vanaf die woudgroepies: ‘n afname in verjonging met toenemende afstand vanaf die groepierand; toenemende verjonging met toenemende afstand vanaf die woudgroepie; en geen beduidende patroon met ‘n gebrek aan verjonging van die dominante spesies van die woudgroepie. Die 40 spesies wat binne die Buffeljagsrivierstudiegebied aangeteken is het ‘n wye reeks vrug- en saadeienskappe ingesluit. Vier hoofgroepe van houtagtige spesies is geïdentifiseer, gebaseer op hul aan- of afwesigheid in die woudgroepies and woudkolle: spesies algemeen in die woudkolle en teenwoordig in die woudgroepies; spesies spesifiek to bepaalde woudkolle en teenwoordig in die woudgroepies; spesies teenwoordig in die woudkolle maar afwesig van die woudgroepies; en spesies afwesig van die woudkolle maar teenwoordig in die woudgroepies. Die aan- of afwesigheid van die meeste spesies kan verduidelik word in terme van hul vrug/saadeienskappe en verspreidingsmeganismes. Die meerderheid van aangetekende houtagtige spesies was meeswaarskynlik deur voëls en soogdiere versprei, veral Geelbekbosduiwe en Bobbejane. Ten slotte, ‘n konsepsuele raamwerk is ontwikkel om die rehabilitasie van opstande van ligafhanklike indringerspesies in die woudomgewing te rig. Verskeie onderwerpe vir verdere navorsing is geïdentifiseer.
RESUME: Plusieurs études ont montré que les peuplements de plantes exotiques envahissantes dans le milieu de forêt naturelle peuvent favoriser la réhabilitation de ces forêts contestant par-là, la perception générale et globale que ces espèces envahissantes menacent la biodiversité et le fonctionnement des systèmes de végétation naturelle. L’objective de cet étude était de mieux comprendre le dynamisme d’établissement et de propagation dans une forêt naturelle des espèces forestières au sein d’un large peuplement de l'espèce de plantes exotiques envahissantes Acacia mearnsii (acacia noir) le long de Buffeljagsrivier, Western Cape, en Afrique du Sud afin d’élaborer des axes directives de réhabilitation relative aux recouvrements d’espèces invasive. La forêt de Buffeljagsrivier s’étale sur un gradient de petites parcelles de forêt allant de forêt sèche, humide et marécageux. Au milieu de ces parcelles de Buffeljagsrivier, on circonscrit un peuplement d’acacia noir estimé à 90 ha sur une distance de 3,12 km. L’objective principal s’est poursuit à travers quatre sous objectives à savoir: (i) cartographier et évaluer les formes d’ invasions dans la distribution, la taille et la composition des recouvrements des espèces de forêt naturelle à l’intérieur du recouvrement d’acacia noir servant comme preuve possible de l’existence et établissement des espèces de forêt naturelle sous un recouvrement d'une espèces invasive; (ii) de déterminer la relation entre les recouvrements de forêt naturelle s’établissant á l’intérieur du peuplement d’acacia noir et ceux de la forêt naturelle avoisinante humide, sèche et marécageuse pouvant être considéré comme sources potentiel de semences conduisant au développement des premiers recouvrement cités; (iii) de déterminer l’étalement subséquent des espèces de la forêt naturelle à partir des recouvrements d’ acacia noir se développant à l’intérieur du reste du peuplement de l’Acacia noir; (iv) Synthétiser les informations sur la dynamique de la propagation et l'établissement d'espèces forestières naturelles dans l’acacia noir comme une base pour l'élaboration des lignes directrices générales pour la conversion de peuplements de plantes exotiques envahissantes se trouvant dans l'environnement de la forêt vers des repousses des forêts naturelles. Au total, 329 recouvrements d'espèces forestières naturelles ont été GPS enregistrées et cartographiées (Arc -GIS) dans trois zones (Proximale, Intermédiaire et Eloignée par rapport aux parcelles de forêt avoisinantes) dans le peuplement de l'acacia noir: 266 petits recouvrements avaient un à trois arbres matures, 36 recouvrements de taille moyenne avaient quatre à neuf arbres matures et 27 larges recouvrements avaient plus de 10 arbres matures. La visualisation de la carte a révélé que les larges recouvrements de forêt mature étaient abondant dans la zone proche des parcelles de forêt naturelle avoisinantes et que de petits recouvrements de jeunes arbres de forêt naturelles croissaient en nombre à mesure que la distance depuis les parcelles de forêts naturelles adjacentes s’élargissait. Un total de 28 espèces appartenant à 20 familles a été répertorié. Deux familles, Rubiaceae suivit de Anacardiaceae ont dominé l’echantillon. Les espèces forestières naturelles sont donc en mesure de s’établir dans un peuplement d'acacia noir. L’échantillon qui a servi à l’évaluation des sources de semences pour le développement des recouvrements de forêt naturelle à travers l’investigation de la relation entre les recouvrements de forêt naturels qui s’établissent à l’intérieur du peuplement d’acacia noir et les parcelles de forêt avoisinantes humide, sèche et marécageuse était constitué de 55 placettes rectangulaires de 200m2 le long de layons à travers le site d’étude. Une analyse hiérarchique des recouvrements réalisée sur la composition des espèces de l’échantillon a révèle que la forêt marécageuse concentre les espèces les plus fréquentes des recouvrements de forêts, et que la majorité des espèces présentes sur les parcelles des forêts sèches et humides étaient absente dans l’ensemble des recouvrements des forêts de l’acaci noir. Les trois principaux types de forêts différaient dans leurs caractéristiques générales et les conditions du site, et cela a été appuyé par l’analyse d’ordinants à partir de trois facteurs environnementaux, la pente, l’angle d’inclinaison par rapport au soleil, et la fermeture de la canopée. Les recouvrements de foret en développement au sein de l'acacia noir se sont trouvés davantage liés à la forêt marécageuse en termes de pente plate orientée sud-ouest et en diamètre moyen des arbres. Ces résultats ont désigné la forêt marécageuse comme la première source potentielle de semences permettant l’établissement des recouvrements de forêt à l’intérieur des peuplements d’acacia noir. Cependant, les souches d’arbres de grande taille des espèces communes entre les parcelles de forêts marécageuses et les recouvrements de forêt dans l’acaci noir n'étaient pas significativement différents, suggérant ainsi que ces arbres de grande taille trouves dans les recouvrements de foret pourraient faire parties des parcelles de forêt subsistantes de la dernière turbulence. Elles pourraient constituer des sources locales de semences. Par ailleurs, une évaluation détaillée des valeurs d'importance des espèces et des distributions des diamètres des souches d’arbres a montré que certaines espèces importantes de forêts humides et sèches sont présentes dans les recouvrements de foret. Finalement l’on conclue que chaque type de parcelles de forêt contribue plus ou moins à l’établissement des recouvrements de forêt dans le peuplement de l'acacia noir. Sept grands recouvrements de foret ont été sélectionnés pour étudier la régénération des espèces forestières naturelles sur un rayon de 18 m depuis la limite du recouvrement de foret. Deux listes d'espèces ont été générées, l'une des espèces de parcelles de forêt naturelle adjacentes, et une autre venant des 59 recouvrements de foret, toutes tailles confondues le long de l'acacia noir. Les résultats ont indiqué que (1) Les recouvrements de forêts, lorsque bien matures et bien établies devenaient les principales sources de semences pour leur expansion sur toutes les directions; (2) Trois allures différentes ont été observées en fonction de la distance de l'expansion de la régénération autour des recouvrements: une diminution de la régénération avec l'augmentation de la distance; une croissance de la régénération avec une distance croissante depuis les revcouvrements de foret, et pas d’allure particulaire voire une absence de régénération de certaines especes pourtant dominant dans les recouvrements de foret. Les 40 espèces recensées sur le site deBuffeljagsrivier comprennent un large éventail de caractéristiques de fruits et de graines. Quatre principaux groupes d'espèces ligneuses ont été identifiées, en fonction de leur présence / absence dans des parcelles de forêt et les recouvrements de forêt. De façon générale, la présence / absence de la plupart des espèces a pu être expliquée en termes de caractéristiques de leur fruits/graines et les mécanismes de dispersion. La majorité des espèces ligneuses enregistrées sont susceptibles d’être dispersées par les oiseaux et les mammifères, en particulier les pigeons rameron et les babouins vues sur le terrain. En conclusion, un cadre conceptuel a été élaboré pour guider la réhabilitation de peuplements envahissants de lumière en milieu forestier. Plusieurs sujets pour des recherches plus poussées ont été identifiés.

Bibliography: leaves 148-160.
The effects on birds of fine-scale differences in plant species assemblage and vegetation structure, and of two major disturbance factors (woody alien plant infestation and fire), were investigated in Mountain Fynbos at two sites in the southwestern Cape Province, South Africa. Three associated processes were also studied. These were the relative importance of three animal taxa as seed predators following fire, the extent to which an indigenous bird species ate alien Acacia cyclops fruits, and potentially dispersed its seeds, and the number of nectarivorous birds which visited an isolated nectar resource. Avian responses to fire in Mountain Fynbos varied according to season, locality and burning regime. Recently and cleanly burnt fynbos at a flat, low altitude, coastal site supported a distinctly non-fynbos avifauna, characterized by relatively large-bodied, ground-feeding, opportunistic species.

Oldenburgia grandis is a rare, long-lived woody paleoendemic of the Fynbos Biome of South Africa. Confined to quartzite outcrops, it has a small geographic range and narrow habitat specificity. O. grandis responds to its fire-prone environment by resprouting. Elasticity analysis of O. grandis reveals that growth and fecundity were traded off for persistence of adult, mature and sapling stages. Morphological adaptations such as a corky fire-resistant bark and the ability to resprout after fire are traits that O. grandis have evolved to persist in a frequently disturbed environment. Population growth rate for sites undisturbed by fire for a number of years (l = 1.01) and sites at various stages of recovery after fire (l = 1.00) were very similar. The highest variation in transition probabilities for all sites was seen in the persistence of the seedling stage and growth from seedling to sapling. Observed population structure and stable stage distribution determined by the matrix model show that sites recently undisturbed by fire had high abundances of the adult and sapling stages. A peak in sapling stages was seen for the stable stage distribution where similar peak in sapling numbers were seen for population structures of sites at various stages of recoveryafter fire. Favourable environmental conditions for the persistence of O. grandis populations include no fire with transition probabilities between the observed minimum and maximum and fire frequency at a 10 year interval where seedling protection from the fire is high and adult and mature mortalities during the fire are low. Stochastic environmental events that could put populations (particularly small populations) at an increased risk of extinction include high to moderate fire intensities where seedling protection from the fire is low and adult and mature mortalities are high as a result of the fire.

Thesis (MSc. (Zoology)) -- University of Limpopo, 2014
The Olifants River is presently one of the most threatened river systems in South Africa. The Upper and Middle catchments are heavily impacted by anthropogenic activities, however little is known of the status of the river in the Lower catchment in the Limpopo Province. Thus the aim of this study was to evaluate the impact of water quality on the health of Oreochromis mossambicus and Schilbe intermedius at the Phalaborwa Barrage. This was achieved through assessing the water (seasonally) and sediment quality (bi-annually) at three sites in the Phalaborwa Barrage (inflow, middle and the wall). Ten specimens of each of the two selected fish species were seasonally collected using gill nets of different mesh sizes from May 2010 to January 2011. The water, sediment and the dorsal muscle tissues from both fish species were analysed for selected metals at an accredited laboratory by means of ICP-OES spectrometry and the human health risk factor upon consumption of fish contaminated with metals was assessed. Fish health was determined at the field laboratory by applying the HAI, PI and IPI. In addition, the condition factor (CF) was determined for the selected fish species during all seasons. All water constituents with the exception of turbidity during spring (wall), anions (Cl, F and SO4) and cations (Ca, K, Mg and Na) fell within the target water quality range (TWQR) for aquatic ecosystems throughout the study. Inorganic nitrogen concentrations showed eutrophic (spring) and oligotrophic conditions (autumn, winter and summer), while phosphorus indicated eutrophic (autumn, winter and spring) and hypertrophic (summer) conditions throughout the study. There was no significant difference in anions (F=0.07; df=3; p=0.97), cations (F=0.57; df=3; p=0.64) and nutrients (F=0.79; df=3; p=0.56) detected in water. The metals that were detectable in the water samples were: Al, Fe, Sn, B, Sr, Se, Ba, Mn, Sb and As, while in sediment all metals (Fe, Al, Ti, Mn, Ba, B, Zn, Ag, V, Cr, Ni, Sr, Sn, Co, Cu, Cd, Pb, As and Sb) were detected with the exception of Se. The average metal concentrations detected above the TWQR are; Al, Fe, Se, Sn, Sb and As, in the sediment only Cr and Cd were above suggested quality guidelines. There was no significant difference in metals detected in water (F=0.05; i df=3; p=0.98) and sediment (F=1.62; df=1; p=0.21). Higher HAI values were recorded for S. intermedius than O. mossambicus, indicating that O. mossambicus was in better health than S. intermedius. For S. intermedius, parasites contributed the most to the total HAI followed by abnormal liver conditions, haematocrit levels (internal variables) and abnormal gills (external variable). While for O. mossambicus, parasites, liver, haematocrit (internal variables), gills, eyes, fins and skin (external variables) contributed to the HAI values. There was no significant difference in HAI values for O. mossambicus (F=1.9; df=3; p=0.15) and S. intermedius (F=2.58; df=3; p=0.66) throughout the study. The PI and IPI for ectoparasites for both fish species, were higher than the PI for endoparasites. There was a significant difference for PI values of O. mossambicus (F=0.07; df=3; p=0.041) and S. intermedius (F=3.65; df=3; p=0.019) during the study. Oreochromis mossambicus had higher CF values than S. intermedius and both fish species had values that indicated good fish. Metals that were detectable in O. mossambicus muscle tissue included: Ba, B, Zn, Fe, Sr, Al, Mn, Cr, Ag, Pb, Ni, Cu, Se, V, Sb, Ti, Sn and Co, while for S. intermedius Ba, B, Zn, Fe, Al, Cr, Sr, Mn, Cu, As, Pb, Se, Sn, Ag, Ti, Ni, Sb and Co were recorded. There was no significant difference in bioaccumulation levels between the two fish species (F=1.412; df=3; p=0.250). The human health risk assessment indicated that fish muscle tissues are unsuitable for continuous (weekly/daily) consumption. As some carcinogenic metals i.e. Pb, Cr and Sb for O. mossambicus and Pb, As and Cr for S. intermedius were detected at HQ levels of more than 50 times the recommended value of one. In conclusion, the Phalaborwa Barrage is impacted by metals (Al, Fe, Se, Sn, Sb and As) and occasionally with nutrients. The water and sediment quality and metal bioaccumulation have confirmed the latter statement and to a lesser extent the HAI, PI and IPI. The human risk assessment done indicated that continuous consumption of fish by humans, especially O. mossambicus may have adverse effects on the health of humans.

The Southern Ground Hornbill (SGH) (Bucorvus leadbeateri) has recently been listed globally by the IUCN Red list as Endangered or Critically Endangered. In South Africa, the declining population of the SGH has led it to be listed nationally as Vulnerable and falls under the “Protected Species” legislation. Research into the habitat preferences and identification of suitable reintroduction areas have been few since the initiation of reintroduction attempts, therefore resulting in mixed outcomes of previously-reintroduced SGH. The aim of this study was to identify and verify optimal reintroduction sites for the SGH, in the Musina area in the Limpopo Province. Five main objectives were determined, namely: to identify optimal reintroduction areas; to develop a habitat profile of the designated area; to determine the availability of prey items; to determine the availability of large trees needed for nesting and roosting; to evaluate pre-release sites by involving a number of stakeholders. Three study sites were selected on the farm Greyghost Safaris (Ludwigslust), each made up of a different plant community. Sampling was carried out a total of four times during the year: one sampling bout in each season. A niche-based modelling technique was used to describe the suitability of a particular habitat (“ecological space”) then used to project it onto another geographical space. Floristic and faunal surveys were conducted to determine the species composition of prey items and composition and frequency of the herbaceous and woody layer. High-resolution, natural-colour aerial imagery was used in order to determine the availability of trees for nesting and roosting. Pre-release site evaluations and stakeholder engagements were conducted by means of interviews with landowners on and around the study sites. The Limpopo River Valley and across to the KNP on the eastern border of the Limpopo Province, is suitable re-introduction sites for the SGH. This study site provided a good opportunity to explore what an optimal site for reintroduction should resemble.
Thesis (MSc (Zoology))--North-West University, Potchefstroom Campus, 2012.

In most rural areas, reliance on traditional medicine and food is high and this is attributed to both economic and cultural factors. The edible stink-bug (Encosternum delegorgueiSpinola), local name “thongolifha” is consumed by the Venda tribe in Limpopo Province of South Africa. Thongolifha is important to the Venda tribe in terms of culture, nutrition and economical value. They eat it raw or cooked with porridge or as a snack. The edible stink-bug is sold at the Thoyandou open market and provides valuable income for the harvesters. Many insects have been reported to contain good source of proteins minerals and vitamins. In terms of medicinal value, insects have also been used in folk medicine in the past by various cultures to treat many ailments such as stroke, asthma, cold, etc. Some insects are also known to sequester compounds from their host plant and use them for its defensive mechanism. The host plant for thongolifha was identified as Dodonaea viscosa Jacq. var. angustifolia which has been reported to have antibacterial activity. The aim of this study was to investigate the possible interaction between the thongolifha and its host plant Dodonaea viscosa. Since thongolifha is so important to the Venda tribe and its nutritional value was never analysed before it was also relevant to determine its nutritional composition. Nutritional components of thongolifha such as the proteins, fats, amino acids and carbohydrates contents were detected by using standardized methods. Thongolifha contained 35.2% protein, 50.6% fat and 7.63 g/100 g carbohydrate with an energy content of 2599 kJ/100 g. These results compare well to nutritional values of other edible insects such as termites (41.8% protein and 44.3% fat) and wasps (31% protein and 62% fat).The mopane worm has higher protein content (63.5%) and a lower fat content of (18%). Mineral content of thongolifha (1.2 g/100 g) was found to be at a comparable level to other bugs such as the Acantocepphala declivis (1.0 g/100g). Analysis of essential amino acids varied from 0.82 mg/100 g (threonine) and 1.32 mg/100 g (valine). The nutritional composition of thongolifha is acceptable and thongolifha is not just a traditional delicacy but also contributes as a diet supplement of the Venda tribe. Between 680 and 3400 of thongolifha will however have to be consumed to supply the daily nutritional needs for the essential amino acids phenylalanine and methionine. Analysis for antibacterial activity of thongolifha was carried out after extracting with solvents of varying polarities, separation by thin layer chromatography (TLC) and bioautography against four nosocomial bacteria; Gram-negative; Escherichia coli and Pseudomonas aeruginosa; Gram positive; Staphylococcus aureus and Enterococcus faecalis. Bioautography results of the thongolifha extracts revealed some activity against S. aureus and E. faecalis. Evaluation of the minimal inhibitory concentration (MIC) by using a serial dilution microplate method indicated low antibacterial activity (MIC > 2.5 mg/ml). Thongolifha therefore does not contain antibacterial compounds but there may be present in a low concentration or the serial dilution microplate method does not work well with insects extracts. Some insects contain peptides as antibacterial compounds. Spraying thongolifha extracts chromatograms with several spraying reagents indicated that these antibacterial compounds were not peptides Methanol crude leaf extracts of D. viscosa was reported in the literature to have antibacterial activity against S. aureus however the results were obtained by using the agar diffusion method which does not provide convincing quantitative results. In our study we extracted components from D. viscosa using solvents of varied polarities to evaluate its antibacterial and antioxidant activities. Dichloromethane and acetone extracted more compounds with good antibacterial activity against S. aureus, E. faecalis, E. coli and P. aeruginosa. The average MIC values varied from 0.04 to 0.28 mg/ml, indicating excellent to good antibacterial activity. The antioxidant activity using the DPPH Spectrophotometric assay gave the EC50 of the extracts of 212 ± 4 to 469 ± 9 µg/ml. As expected, the more polar crude extracts, ethyl acetate and acetone demonstrated higher activity compared to other extracts. This was supported by the TLC qualitative assay showing more yellow bands in these extract on TLC chromatograms after spraying with 0.2% DPPH in methanol. To determine whether thongolifha has sequestered compounds from the host plant, D. viscosa, a serial exhaustive extraction was performed in order to extract components from the crude extracts of both insect and the host plant by using various solvents and separating the extracts on TLC plates by using various eluant systems. After the TLC chromatograms were sprayed with vanillin-sulphuric acid to reveal separated components, there were few similarities of components from both insect and host plant. This could mean that either a sequestered plant compounds are present in low quantities in the insect extract, that insect may have metabolized the sequestered compounds or alternatively that the insect might not have sequestered the compounds from the host plant at all. It should be kept in mind that the stink-bugs feed by sucking sap from the host plant. By using bioassay-guided fractionation based mainly on silica gel chromatography, four compounds (5-hydroxy-3,74’-trimethoxyflavone (1); 5,7-dihydroxy-3,6,4’-trimethoxyflavone (2); 5,7,4’-trihydroxy-3,6-dimethoxyflavone (3); and 4’-O-methylkaempferol (4) where isolated from dichloromethane fraction of a crude D. viscosa leaf extract, acetone crude leaf extract yielded only one compound, Kaempferol (5). Compounds 1, 2, 3 and 5 where previously isolated from D. viscosa whereas compound 4 was isolated for the first time from D. viscosa. Compounds 4 is not a novel compound because it was previously isolated from other plants species such as the Lens culinaris. Compounds 3, 4 and 5 have good antibacterial activity against E. coli and E. faecalisat MIC values of 15.63 µg/ml and 31.25 µg/ml respectively. In addition, the DPPH quantitative assay has demonstrated that Compounds 4 and 5 have strong antioxidant activities (EC50 = 35.1 ± 0.85 and 75.5 ± 1.76 µM respectively) but lower than L-ascorbic acid (EC50 = 13.5 ± 0.28 µM) used as a standard antioxidant agent. The antibacterial and antioxidant activity of most of the isolated compounds were not known previously. Investigation of structure antibacterial-activity relationship in the isolated compounds did not yield a clear correlation. When investigating the possible interaction between the insect and the host plant, bioautography assay has shown compounds with antibacterial activity against S. aureus (Rf 0.79) E. faecalis (Rf 0.66) when separated with CEF eluent system. Some of the isolated compounds from D. viscosa leaf extracts had an Rf of 0.79 (5, 7-dihydroxy-3, 6, 4’-trimethoxyflavone) and Rf 0.61 (5, 7, 4’-trimethoxxyflavone) when separated with CEF eluent system. These findings indicate that thongolifha may have sequestered the two compounds from D. viscosa leaves, but this possibility has to be confirmed. This study has indicated that thongolifha is good source of protein, vitamins, minerals and amino acids; however we have not found evidence of significant antibacterial activity of thongolifha. If fresh material of thongolifha can be analysed in future work the probability of finding medicinal properties may be greater. On the other hand, D.viscosa. crude leaf extracts have demonstrated strong antibacterial and antioxidant activities; although isolated compounds have shown moderate level of activities. Because practically all antibacterial compounds based on bioautography have been isolated, it is clear that in the crude dichloromethane extract some synergism must have taken place because the antibacterial activity on a mass basis was nearly as good as the isolated compound without removing >90% of non active compounds.
Thesis (PhD (Paraclinical Science))--University of Pretoria, 2006.
Paraclinical Sciences
PhD
unrestricted

Thesis (Ph.D. (Agriculture)) --University of Limpopo, 2015
The ability to utilise dietary components differs between fish species. Digestive enzymes may be used to determine the efficiency of the digestive process. In this study, the activities of the digestive enzymes in Tilapia rendalli, Oreochromis mossambicus and Clarias gariepinus were explored. Protease, amylase, lipase and cellulase activities were measured in different parts of the digestive tract of the three fish species. The pH dynamics along the digestive tract were monitored. In all fish species, the presence of food led to a reduction in stomach pH. pH values of 1.54, 1.58 and 2.01 were recorded 12 hours after feeding in Oreochromis mossambicus, Tilapia rendalli and Clarias gariepinus respectively. Protease and amylase activities were significantly higher (P<0.05, ANOVA) in the tilapias than in Clarias gariepinus. The tilapias may be pre-adapted to produce more protease and amylase to digest plant material which is more difficult to digest compared to animal matter. In all species amylase activity was significantly higher in the proximal intestine than in the other parts of the digestive tract (P<0.05, ANOVA). The highest proteolytic activity was recorded in the distal intestines. This is because of the alkaline pH recorded in the proximal and distal intestines which favours for amylase and protease activity respectively. Lipase activities were not significantly different (P>0.05) in all species. Marginal cellulase activities were recorded in all species. It is inferred here that phylogeny and not diet may be the main factor influencing enzyme activities as all fish were fed a similar diet. Two locally available plant diets, kikuyu grass and moringa leaves, were tested as protein sources in the diet of a macrophagous fish, Tilapia rendalli (11.5±1 g). Nine diets (30% CP: 20 MJ/kg) were formulated by substituting fishmeal for kikuyu leaf meal (KLM) and moringa leaf meal (MLM). A control diet contained 10% fishmeal and no leaf meal. Fishmeal was replaced at 25, 50, 75 and 100% by KLM in diets: KLM 25, KLM 50, KLM 75 and KLM 100; then by MLM in diets MLM 25, MLM 50, MLM 75 and MLM 100. Each diet was fed to triplicate groups of fish for 60 days. The best growth (SGR, TGC) was in the control group. There was no significant (P>0.05) decrease in SGR and TGC when KLM replaced up to 50% fishmeal. There was a significant (P<0.05) decrease when MLM replaced >25% fishmeal. Kikuyu diets had no effect on villi height. A trend towards shorter villi was evident with increasing MLM. Digestive enzyme activities also decreased with increasing KLM and MLM vii levels in the diet. Hepatocyte degradation was higher in fish fed moringa-based diets. Anti-nutrients (polyphenols, tannins, saponins and phytate) in moringa may have contributed to the poor growth, irritation of the enterocytes and hepatotoxic effects. These results show that replacing up to 25% fishmeal with KLM is effective in reducing the costs without negatively affecting the growth performance or health of Tilapia rendalli. Adding MLM, even at the lowest level (25%) was expensive and resulted in compromised growth and health. The efficacy of KLM and MLM was also tested as alternative protein sources for Oreochromis mossambicus (12.5±1 g) a microphagous herbivore. The same diets used for Tilapia rendalli were fed to triplicate groups of twenty fish for 60 days. Linear regressions of feed intake, SGR, PER and protein ADC with increasing levels of leaf meal were significant (P<0.05). Superior growth performance, protein ADC and feed utilisation were also recorded in fish fed KLM-based diets than those fed MLM diets. When compared to Tilapia rendalli, Oreochromis mossambicus had superior growth performance and feed utilisation when fed the control diets and the lowest level of KLM. This was attributed to phylogeny. Protease, amylase and lipase decreased with increasing leaf meal levels and were higher in the intestine of fish fed KLMbased diets than those fed MLM-based diets. Fish fed MLM-based diets had higher number of goblet cells in the enterocytes, higher hepatocyte degradation and poor haematological parameters than those fed KLM diets. These adverse alterations were more pronounced in Oreochromis mossambicus compared to those observed in Tilapia rendalli feeding of the same diets. Cost benefit analysis also indicated that substitution fishmeal with KLM is a cheaper protein source in Oreochromis mossambicus diets. Kikuyu leaf meal may be used to replace up to 25% fishmeal without compromising the growth performance and health of Oreochromis mossambicus. Reduced growth and poor health was evident even at the lowest inclusion level of MLM. The effects of replacing fishmeal with KLM and MLM in the diets of a predatory omnivore, Clarias gariepinus were also investigated. The same KLM and MLMbased diets used in the previous experiments were used. Each diet was randomly assigned to triplicate groups of Clarias gariepinus (30.5±2 g) and fed to apparent satiation for 60 days. Significantly higher (P<0.05) growth performance, feed and viii protein utilisation was observed in Clarias gariepinus fed KLM diets compared to those fed MLM. Protein digestibility was higher in Clarias gariepinus fed the control diet than in both tilapias. However, in the treatment diets protein ADC was lower in Clarias gariepinus than in the tilapias. A decrease in the activity of digestive enzymes was also observed with increasing leaf meal level in the diet. This was attributed to the natural feeding habits and digestive adaptations of the different fish species. No histological alterations were found in liver of fish fed the control diet. Increased hepatocyte degradation was seen in fish fed higher levels of KLM and MLM in the diet. The enterocytes showed a significant increase in the number of goblet cells with increasing levels of MLM. Villi height decreased significantly (P<0.05) when MLM replaced >75 fishmeal. The damage to the hepatocytes and enterocytes as well as the poor health condition shown by haematological parameters was more pronounced in Clarias gariepinus than in the tilapias. This suggests that the predatory fish is not equipped to utilise high levels of leaf meals in its diet. The results of this study indicate that KLM can replace up to 25% fishmeal and that adding MLM resulted in reduced performance. Higher profit index and lower incidence cost was observed KLM diets than in MLM diets. Anti-nutrients in the leaf meals were the main factors leading to reduced feed intake and poor growth in fish fed the plant-based diet. Therefore, a subsequent study was undertaken to determine the efficacy of exogenous enzyme supplementation to reduce the negative effects of anti-nutrients and improve fish growth. A commercial multi-enzyme Natuzyme50® was supplemented at a rate of 0 (control), 0.25, 0.5, 0.75 and 1.00 g/kg DM feed in the best performing diet (KLM 25). These diets were tested in Oreochromis mossambicus. Natuzyme50® supplementation led to improved growth performance. Fish fed the diet containing 0.50 g/kg had the best growth performance and protein ADC and highest levels of digestive enzyme activities. At higher (>0.50 g/kg) enzyme supplementation levels, growth performance decreased. The improved growth performance with enzyme supplementation was attributed to the presence of enzymes such as cellulase and xylanase in the cocktail that are not naturally produced by fish. In addition, the activities of endogenous enzymes were enhanced. The optimal Natuzyme50® dietary level for optimal growth performance in Oreochromis mossambicus was 0.62 g/kg DM feed.

Includes bibliographical references.
Several cochineal species have been used with great success for biological control of invasive cactus species, both in South Africa and elsewhere. Although most cochineal species are oligophagous, they are all exclusively associated with opuntioid cacti and therefore pose minimal risk of non-target effects in the Old World where there are no native Cactaceae. However, the ability of cochineal to use more than one host plant species has validated reports of inadvertent displacement of Dactylopius ceylonicus (the original agent released in 1913) by D. opuntiae (which was originally released on Opuntia ficus-indica in 1938) on O. monacantha in South Africa. There are also reports that the two cactus hosts, O. monacantha and O. ficus-indica, have hybridized in South Africa, but there are uncertainties as to which of the two cochineal species is associated with the alleged hybrid. The primary aim of this study was to determine the present status of D. ceylonicus and D. opuntiae on O. monacantha and on the possible hybrid. Cochineal samples were collected off cactus plants from sites in the Eastern Cape and Western Cape and identified using bioassays and morphological features. The performance of each cochineal species on each of the three cactus hosts (O. monacantha, O. ficus-indica and the hybrid) was determined through measures of female developmental rates, survival and mass at reproductive maturity. Results showed that D. ceylonicus remains present on O. monacantha at each of seven study sites, while D. opuntiae did not occur on O. monacantha at any of the sites. However, D. opuntiae is capable of establishing on O. monacantha, O. ficus-indica and the possible hybrid cactus under laboratory conditions. Dactylopius ceylonicus is also compatible with both O. monacantha and the possible hybrid, although it did not establish on O. ficus-indica. These findings showed that D. ceylonicus has not been displaced by D. opuntiae on O. monacantha in South Africa and it is expected that O. monacantha will continue to be kept under excellent biological control into the future. Results also indicated that possible hybridisation between the two Opuntia species has not produced a new taxon that is immune to either of the two control agents. However, further research is required to improve our understanding of this new plant taxon and confirm it will be suppressed by one or both of the cochineal species.

The fire-prone mountain fynbos of the southwestern Cape Province of South Africa has been severely invaded by introduced trees and shrubs. These invasions have transformed fynbos shrublands to dense thickets of trees and shrubs in many parts of the region, thus disrupting various natural ecosystem processes. The ecology of invasions by species of Pinus and Hakea (the most successful genera) was studied using a series of natural experiments in conjunction with autecological studies. The study was divided into main four parts: (i) case studies to elucidate major patterns and processes of invasion; (ii) studies of the life history and population ecology of selected invaders; (iii) studies of the determinants of invasibility; and (iv) assessments of the consequences of invasion and of control programmes. Bibliography: pages 235-272.

MESMEG
Department of Ecology and Resource Management
Invasive alien plants refer to plant species that show a tendency to escape from human control, go beyond the intended physical boundaries and cause environmental damage. The issue of letting the Invasive alien plant species grow and spread, with no attempts made to control the spread of the species beyond the limits of plantations, is not sustainable. All the attempted methods that the Department of Environmental Affairs used seemed to have failed in yielding the expected results. The main objective of the study was to determine the Wolkberg Working for Water programme’s level of success in terms of clearing invasive alien plant species. Wolkberg Project was used as a case study as it is one of the Working for Water Programme. The data were collected using random sampling methods on the worked areas, where work is in progress and those where no work has been done. Primary data were collected from land owners through field observations and questionnaires from the participants whilst secondary data were collected from the Department of Environmental Affairs. The study adopted a mixed methods approach which is both quantitative and qualitative. The data were analyzed using Statistical Package for the Social Sciences (SPSS) package. The research determined the level of success in terms of clearing invasive alien plant species, employment opportunities, tools/materials that have been used to clear the plants and the advice on the possible strategies that can be employed in the invasive alien plant species management. It was found out that the Invasive alien plant species require constant maintenance in order for them to be controlled. The Wolkberg project is mainly dominated by male workers compared to females. Each team comprised 3% underage workers. The study recommends that the project should make sure that the follow-ups are done at the correct time and stage. Looking at the statistics of males and females, the study revealed that transformation is not adhered to in this project.
NRF

MSc (Botany)
Department of Botany
Invasive alien plants (IAPs) are non-native species that have spread beyond the introduction site; become abundant to an extent that they serve as agents of change that also threaten native biological diversity (Garcia-Berthou, 2007). IAPs have medicinal applications for the treatment of various aliments in humans (Jäger et al., 1996). In this study, an ethnomedicinal survey was conducted on medicinal uses of invasive alien plant species in order to identify and investigate the various disease treatment methods employed by Bapedi traditional health practitioners within Capricorn District. Six traditional health practitioners were randomly selected, via the snowball method from each of the five local municipalities namely: Aganang, Blouberg, Lepelle-Nkupi, Molomole and Polokwane. The whole survey included 30 traditional health practitioners. A semi structured questionnaire was administered to document information about the medicinal uses of IAPs from participants. The collected data from the questionnaire was captured in Microsoft Excel 2010 and analyzed using descriptive statistics. The study recorded 22 IAPs belonging to 14 plant families. Records or data collected show invasive alien plants species to have been used for treatment of different alignments amongst Bapedi traditional health practitioners. Plant families with the most recorded species include: Solanaceae and Myrtaceae with 18.2% for both of them. The plant parts most frequently used in descending order were as follows: roots vii (40%), followed by the leaves (39%), fruits (7%), thorns (6%), bark (4%), seeds (2%) and lastly stems (2%). Decoction was recorded as the most dominant method used during medicinal preparations (n = 176) and flu was recorded as the most treated ailment amongst traditional health practitioners (n = 29). Apart from clearing IAPs as part of management strategy by South African government, there are other alternative innovative ways that can be employed to ensure that the number of IAPs introduced does not exceed beyond measure.This could be achieved by encouraging local people to use them as either medicinal sources or by incorporating them into any other local ethnobotanical use. The new innovative ways (such as traditional health practitioners utilizing the IAPs instead of endangered plants or indigenous plants species) can bring in some form of relief to the already declining indigenous species populations. Research scholars from different research institutes and higher education research centres can regard IAPs used medicinally as source of new pharmaceutical leads to create new medications. With such attention turned to alien invasive species, their survival as well as their spread will be kept on check at the same time creating a control measure to their spread with little effort. Further laboratory-based studies are needed to determine efficiency and safety of the IAPs used by traditional health practitioners in this study.
NRF

MSc (Botanty)
Department of Botany
Background: Problem plants and alien invasive weed species are part of today‟s ecological transformation. Ethnobotanical literature on ecological prominence and ethical values of problem alien weeds is scant and should be documented to avoid loss of valuable species. Aim: The study was aimed at documenting problem weeds and alien invasive plant species considered to be beneficial in deep rural communities. Materials and method: Purposeful triangulation research methods were used to ensure the proper gathering of both qualitative and quantitative data sets. Results and conclusion: Some problem weeds and alien invasive plant species are being utilized by local people to maintain their livelihood. A total of 78 plant species from 33 families were recorded. These plant species belonged to diverse growth habits, namely: climbers, herbaceous, succulents, shrubs, trees as well as creepers. Recorded problem weeds and alien invasive plant species were contributing towards ecological, medicinal and social values. These included being utilized as a source of food (14), fruits (4), medicinal (31), ornamentals (7), firewood (3), social (2) and multiple purposes (17). The main utilized families were Asteraceae (14.1%) and Solanaceae (14.1%). These families were mostly utilized for the purpose of medicinal and food. Plant species that were widely used are as follows: Achyrathes aspera L., Agave sisalana L., Amaranthus spinosus L., Anredera cordifolia L., Canna indica L., Centella asiatica L., Chenopodium album L., Chenopodium ambrosioides L. and Chromolaena odorata (L.) R. M. King and H. Rob. The dominant category for problem weeds and alien invasive plant species was 1b (44%) followed by weeds (35%), category 2 (9%), invaders (5%), category 3 (4%) and 1% for both category 1, 1a as well as X3. The results revealed that the legislative listing of plant species as problem weeds and alien invasive species was based on single knowledge basis system, rather than on multi-dimensional knowledge systems. Therefore, this study recommended that for judgment to be considered in decision-making, it should be based on species-specificity as well as multi-dimensional-knowledge basis. The reconciliation of inherent grapples among scientific and indigenous knowledge systems could possibly be underpinned by equal legislative consideration for the aforementioned knowledge systems especially in the establishment and implementation of environmental regulations. This could also aid with the provision to support transformation in South Africa and worldwide.