The temporal complexities of anthropogenic Global Climate Change (GCC) force us to extend our moral deliberations beyond what appear to be straightforward, contemporary issues to include the interests of future generations. The Karoo hydraulic fracturing debate is a case in point. The ethical debate thus far has focused on the present-day environmental aspects of Shell’s limited exploratory drilling proposal using hydraulic fracturing technology; but the shale-gas reserves that are believed to underlie the Karoo could assist in mitigating South Africa’s significant carbon emissions, the main contributor to anthropogenic GCC. Thus, I argue that the actual ethical debate is whether to allow gas exploration over the Karoo or to disallow the entire possibility of exploiting any gas reserves that may have been found. A consequentialist weighing up of the respective potential harms to all of the morally-considerable interests involved, including future generations, makes clear that not only is allowing exploration of the Karoo the morally correct decision, but it is ethically obligatory to do so.

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.

The aim of this thesis was to describe the structure and dynamics of ant and plant communities in the southern Karoo and to assess mechanisms of species coexistence in ant and plant communities. The role of species interactions in structuring natural communities was emphasised. Diversity indices were used to determine the importance of habitat in maintaining ant species diversity. Ant species diversity was not predicted by measurements of plant species diversity or vegetation structural diversity. Ant species richness was correlated with vegetation structural diversity but not with plant species diversity. Ant species appeared to respond to aspects of vegetation height. Although vegetation complexity influences ant species richness, competitive effects, particularly of dominant ant species, appear to suppress sub-ordinate ant species influencing measures of richness and diversity. Aggressive dominant ant species determine the distribution and abundance of sub-ordinate ant species. Interference competition for space was prevalent between dominant ant species and competitive success was a function of vegetation. It was not clear whether ants respond directly to physical conditions created by vegetation which then influences foraging activity or, alternatively, whether ants respond to productivity gradients which are affected by vegetation. Understanding vegetation dynamics is critical to interpreting patterns of ant species distribution and abundance. A patchy habitat disrupts the competitive dominance of aggressive dominant species, removing the potential towards habitat monopolisation, and therefore maintaining ant species diversity. In the Portulacaria afra rangeland, Pheidole sp. 2 was superior in well-shaded microhabitats but Messor capensis nested successfully under woody shrubs and several ant species (Tetramorium peringueyi, T. quadrispinosum, Monomorium alamarum, Ocymyrmex barbiger) persisted on bare nutrient-rich patches. Rangeland dominated by grass would favour Pheidole sp. 2 at the expense of other ant species which would be unable to establish successfully. There is no evidence supporting the notion that ant communities are at equilibrium. Rather, dominance hierarchies lead to the replacement of species over vegetation gradients with the tendency towards the aggressive acquisition and monopolisation of space. The coexistence of dominant ant species at study sites in the southern Karoo was a combination of territorial strategy and colonisation ability. In the P. afra rangeland most ant species escaped the severe competitive effect of Pheidole sp. 2 by persisting as fugitives on bare areas of local disturbance where Pheidole sp. 2 was less successful. At Tierberg, competitively inferior ant species with a decentralised territorial system coexisted with competitively superior ant species in an unstable equilibrium by pre-empting newly available space through the lateral expansion of territories. Competitively superior species, however, replace the inferior competitor (yet, superior coloniser) in time. Plant succession in the Portulacaria afra rangeland follows a deterministic pattern of cyclical replacement. No single mechanism adequately explains the coexistence of all plant species in this community. Nurse-plant effects were important for the establishment of P. afra and later-successional trees below woody shrubs and P. afra respectively. Soil moisture and nutrient levels below nurse plants were favourable for the successful establishment of seedlings but nurse plants also disrupt the inhibitory effect of grass on seedlings and young plants. Linked to the facilitative process is the directed dispersal of seeds by biotic vectors. Seed dispersal by ants and birds moves propagules away from the harsh competitive environment of established adult plants (particularly grass) to safe establishment sites below nurse plants. Complementary root systems of seedlings and nurse plants may facilitate the establishment of young plants but ultimately competition will reduce nurse plant vigour leading inevitably to the death of the nurse plant. At least two plant species (Lycium cinereum and Psilocaulon absimile) persist in the P. afra rangeland as fugitives on areas of local disturbance. The relatively cool and moist environment below P. afra clumps supports a variety of detritivorous taxa that enrich the soil. Once the P. afra clump collapses and dies, bare nutrient rich patches that favour the establishment of L. cinereum and P. absimile, ahead of the competitively superior grass component, remain. However, the replacement of the fugitive plant species by grass is inevitable as the soil nutrient levels decline. The competitive superiority of grass controls the dynamics of the P. afra rangeland system. Disruption of the inhibitory effect of grasses by elevated nutrient levels (e.g. detritivore activity, ant nests) permits plant species to establish that would otherwise be unable to in the absence of disturbance. Degradation of the grass component by overgrazing at the P. afra rangeland site has the same effect as disturbance by soil-nutrient enrichment and results in an increase in plant species diversity. All stages of the cyclical process would be relatively uncommon in a grass dominated system because of the inability of plants to establish successfully in grass. Strong feedback links exist between the ant and plant communities studied. Habitat patchiness maintains ant species diversity by disrupting dominance hierarchies. Ants maintain plant species diversity by moving seeds out of competitively harsh microhabitats into safe sites (often below nurse plants) for establishment. Soil nutrient enrichment (ant nests and various detritivore taxa) create disturbances which also facilitates plant establishment. Overgrazing by domestic stock causes the replacement of palatable by unpalatable plant species. Unpalatable plant species, released of suppressive effects, develop into a monospecific stand that inhibits the further establishment of seedlings. Loss of habitat patchiness results in habitat monopolisation by one (or two) dominant ant species. Habitat degradation therefore severs the complex feedback links between the plant community and the important invertebrate component (dispersal agents and detritivores) which disrupts the dynamic processes driving the system. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1998.

The early efforts of Booth, Johnson, Rubidge, Catuneanu, de Wit, Chevallier, Stankiewicz, Weckmann and many other scientists in studying the Karoo Supergroup has led to comprehensive documentation of the geology on the main Karoo Basin with regards to understanding the age, sedimentology, sedimentary facies and depositional environments. In spite of these studies, the subsurface structure, variations in thickness of various formations in large parts of the basin, the location and orientation of subsurface dolerite intrusions, and the depth to magnetic and gravity sources remains poorly documented. A geological study with the aid of geophysical techniques, magnetic and gravity, was conducted in the southwestern part of the main Karoo Basin. The objectives of the study were to construct numerous models of the main basin that image the crust to a depth of 45 km, to determine thicknesses of various formations, to relate observed geophysical anomalies with geological bodies and lineaments, to estimate the depth of existing anomalous bodies, to determine densities and porosity of various formations, as well as to determine the mineralogy of various rocks in the Karoo Basin.

Ph.D (Geology) / The Karoo succession has economic significance through the exploitation of extensive coal deposits and in recent years has seen significant international interest due to potentially large shale gas resources. The thermal history of sedimentary basins affects the genesis of hydrocarbon deposits and it is therefore essential to model and reconstruct the geothermal variation across the Karoo Basin before evaluation of the hydrocarbon resources can take place. The main scientific questions related to the thermal history of the Karoo Basin are whether the emplacement of large volumes of magma was preceded by a large-scale lowgrade thermal doming as proposed for continental rift settings. Alternatively, was the Karoo thermal event restricted to the contact aureole of intrusives, as well as the question whether the intrusion of dolerite resulted in large-scale CO2 or CH4 degassing from coalbeds and carbonaceous shales based on similarities to other large igneous provinces? Magnetic techniques provide an alternative to more traditional methods to study the geothermal history of sedimentary basins (such as illite crystallinity and vitrinite reflectance), which are often associated with significant uncertainty. Three experiments using existing magnetic and palaeomagnetic methods were conducted to determine the peak temperatures reached by Karoo sedimentary rocks before and after the Karoo magmatic event. These experiments include the classic palaeomagnetic baked contact tests (magnetostratigraphy), analyses of the variation of magnetic susceptibility during repeated progressive heating (alteration index method) as well the variation of relative concentrations of fine grained pyrrhotite and magnetite in sedimentary strata relative to their distance from an intrusive (pyrrhotite/magnetite geothermometer). Additionally various magnetic fabric analyses were performed including a study of the variation in anisotropy of magnetic susceptibility (AMS). Although these techniques were successful in delineating the extent of the contact aureoles, only the alternating index (A40) had the ability to give estimated peak temperatures. Results indicate a general elevation of palaeotemperatures of the organic-rich sedimentary rocks of the Ecca Group to temperatures where hydrocarbons are normally converted into gas. Importantly, it is clear from this study that the greatest thermal effects of the sill intrusions on the sedimentary strata are limited to the contact aureoles, suggesting that there is an, as yet unquantified, potential for hydrocarbon resources remaining between these intrusions. A general increase in the palaeotemperatures from southwest to northeast across the basin was observed. This is mainly due to differences in thermal conductivity of the various lithologies across the basin from tight low porosity marine shales in the south and southwest towards more lacustrine mudstone and porous sandstone in the northeast.

Due to overgrazing, mining and other anthropogenic disturbances, large sections of the Karoo region have been degraded, resulting in areas with low vegetation cover, where erosion rates are high and vegetation is dominated by unpalatable species. These areas have low and unpredictable rainfall, with slow to non-existent autogenic recovery, and this often forces landowners to implement reseeding rehabilitation in an attempt to increase both overall vegetation cover and the relative abundance of palatable plants. Landowners use soil preparation treatments, which include creating micro-catchments, ripping, mulching and brush packing, to supplement land rehabilitation. This study investigated the significance of initial rainfall, mean monthly rainfall, soil preparation techniques, slope, existing vegetation cover, litter, mulch and stone cover in determining the success of reseeding rehabilitation. Rainfall had the most significant influence, where long-lived shrubs established best under low initial rainfall and high mean monthly rainfall, and grasses established best after receiving high initial rainfall. Micro-catchments proved the most successful soil preparation technique for the establishment of long-lived shrubs, while ripping and mulching impacted negatively on grass establishment. A combination of mulch and micro-catchments aided Osteospermum sinuatum establishment in soils where soil shrinkage cracks occurred. Temperature influenced seed germination and drought tolerance of Lessertia annularis, Fingerhuthia africana and O. sinuatum, with higher germination success of O. sinuatum under temperatures simulating summer, and of F. africana under temperatures simulating winter. L. annularis germination had a faster growth rate and higher survival when germinated under autumn/spring temperatures. Landowners are advised to sow seeds of more than one species during rehabilitation, to include micro-catchments as soil preparation treatment, and to sow seeds during a time when rainfall is predicted to be high.

Thesis (MSc)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The composition and state of soil-stored seed banks on- and off the mesa Tafelberg, in the Nama Karoo rangelands of the Eastem Cape, South Africa, were investigated within the context of a broader restoration ecology project "Restoration of degraded Nama Karoo rangelands: the role of conservation islands'". The premise for this seed bank study was that restoration of degraded semi-arid rangelands is possible through applied management programs based on the methodology and practice of ecological restoration. Broadly acknowledged properties of non-equilibrium environments (e.g. unpredictable climates and varying degrees of disturbance) and soilstored seed banks (e.g. spatial and temporal distributions) formed the basis for investigating. the general environment and the properties.. of existing seed, banks, in the Tafelberg locality. The potential role of hills as refugia for palatable plant species was an under-lying element of the investigation. Following a brief investigation, of historical and contemporary research and policy on rangeland degradation in semi-arid regions of the world, the fundamental need for comprehensive and applied seed bank research in the Nama Karoo is emphasised. Within the framework of the umbrella project, the seed bank study examined local environmental criteria commencing with an investigation into seed bank- and vegetation habitats. Chemical and physical properties of soils from twenty two sites on- and off Tafelberg were described. Substantial soil habitat variation, between the top, the north west slopes and plains and the south east slopes and plains of Tafelberg, was identified. Micro-site variation between open-canopy (interplant spaces) and closed-canopy (under plant cover) microhabitats was found to be significant Primary soil habitat differences were linked to soil organic matter content which was found to be low on the plains relative to the top and slopes; and, low in open-canopy micro-sites relative to closed-canopy sites. Soil texture and nutrient composition on- and off Tafelberg was found to be highly variable with significant differences between the top and the plains as well as between the north west and south east plains. The slopes were found to be intermediate (showing some level of gradient) between the top and the plains. Soil nutrient variation was interpreted as a function of textural and parent-material properties of soils. Anthropogenic factors for accelerated erosion, deposition, leaching and salt-crust formation were also considered. It was concluded that while properties of soils on- and off Tafelberg are inherently related to parent soils, changes to textural and nutrient properties may be occurring and these changes may have been exacerbated by high levels of grazing. An investigation (focusing on small shrubs) of plant phenological response, in relation to rainfall and grazing gradients, identified trends of peak budding- and flowering seasons following rainfall during summer and autumn respectively. A continuum of seeding activity, with peaks in late autumn and early winter, was construed from quarterly data. Flush vegetative growth was noted for most small shrubs during spring, autumn and summer surveys. Since some form of activity related to reproductive output (flush growth, budding, flowering or seeding) was apparent at almost all times of the year, it is argued that high intensity disturbance (including grazing) might impact negatively on plant survival, leading to reduced reproductive input (i.e. seeds) into future generations. Plant communities on the top and plains are described noting significant differences between vegetation on top of Tafelberg (comprising primarily high production, palatable grass and shrub species) and that on the plains (comprising mainly spinescent, ephemeral, toxic and low production species). Given the high grazing pressure on the plains (relative to the less utilised slopes and top of Tafelberg), differences in vegetation composition are discussed in relation to studies elsewhere that describe degraded rangelands. It is concluded firstly that the plains surrounding Tafelberg are degraded, secondty that long term over-utilisation has altered vegetation composition and finally that inter-grazing rest periods of three- or six months alone may not restore vegetation diversity nor desirable plant species to the plains. Results of germination trials (investigating soil-stored seed banks) from two sampling episodes (spring and autumn 1998) revealed that seed banks in soils removed from the plains, slopes and top of Tafelberg followed distribution patterns observed in above-ground vegetation. Species-specific data was not finalised for this thesis since not all seedlings matured and flowered within given time constraints. In order to compare seedling emergence data, plant categories were developed that distinguished ephemerals versus persistent (perennial) species and dicotyledonous species versus grasses and other monocotyledonous plants. Samples from the top and the middle to upper slopes showed a high percentage of palatable and persistent grass and shrub species present in soil-stored seed banks while over twothirds of plants germinating from plains' soil samples were ephemeral species and most of these were both tiny «Scm) and short-lived «3 months). Most of the perennial species germinating from plains' samples were seedlings of Pentzia incana, Chrysocoma ciliata and succulents (mostly Mesembryanthemaceae) but few perennial grasses were present. On the other hand, roughly 94% of seedlings germinating from samples from the top and 63% of seedlings germinating from two slopes of Tafelberg respectively were persistent- grass or shrubby species. Roughly 89% of ephemeral species recorded from slopes' samples germinated from the lowest footslope sites. Seed densities were closely linked to micro-habitats with roughly three-fold differences between open- (lower seed density) and closed-canopy (higher seed density) micro-sites. Multivariate analysis of variance (MANOVA) indicated that most of the variation in seed density data was explained at the micro-habitat level. Seasonality played a secondary role with significant twoway interaction between the two effects. It is concluded that both factors must be considered when developing restoration programmes that aim to improve both overall plant cover and improved plant species diversity. While the original or "pristine" state of vegetation composition and seed banks on the plains is unknown, concems were raised regarding the apparently degraded state of total above- and below-ground plant diversity on these plains. A likely consequence of habitat degradation is that species with specific soil-, nutrient ratio-, aspect- and altitudinal requirements from the top and slopes of Tafelberg (as well as from nearby plains' refugia) may not be able to establish in degraded habitats on the plains. The identification of pioneer plant species (tolerant of habitat degradation) that allow increased vegetation cover and safe-sites for seedling germination of desirable plant species is recommended. Restoration programmes will need to be coupled with strict grazing management principles that allow seedling germination. establishment and successful reproductive output of desirable plants for future rangeland regeneration. Common and salient features of the soil habitat, plant pbenological response and germination trial studies are brought together in an examination of habitats and related seed bank diversity on- and off Tafelberg. Acknowledging the brevity of this research study, but utilising case studies from elsewhere and integrating both lines of questioning, the conclusion is again reached that the plains surrounding Tafelberg are degraded through decades and probably centuries of grazing by domestic livestock. It is considered crucial that restoration through improvement (or rehabilitation) of habitats and increased seedling safe-sites be considered. Both climate and grazing management appear to play an irrevocably linked role in shaping vegetation composition in rangelands. While rangelands are intrinsiCalfy adapted to surviving extremes of climatic variability found in non-equilibrium regions it is argued that the impacts of grazing, particularly during times of drought and climate change, are slowly reducing the intrinsic "buffer-capacity" of rangelands to withstand these changes and extremes. It seems apparent from research elsewhere that restoration through passive management is slow and probably not economically achievable within a viable time frame. The instifution and promotion of integrated and strategic programmes that identify and address issues of land degradation and land use change in semi-arid rangelands is recommended. The input and endeavours of different authorities, ministries and a broad public participation incentive are encouraged in these proposed programmes in order to ensure broadly-based input into long term sustainability and conservation of the considerable biological diversity of these regions. Seed bank assessment is considered to be a valuable means of indicating restoration potential and ranqeland condition with potential for the identification of both degraded and conservationworthy areas. Finally, some limitations and challenges of this study are examined through a process of firstly identifying alternative approaches to research methodologies and secondly through proposing recommendations for future research projects. While alternative methods could have been applied for the purposes of accomplishing this study it is concluded that, within the given time- and other constraints, the appropriate methods were applied. / AFRIKAANSE OPSOMMING: Die samestelling entoestand van groncbbewaarde saadbanke.op en van die mesa Tafelberg af, in die Nama Karoo weiveld van die Oos-Kaap, Suid-Afrika, is ondersoek binne die konteks van 'n wyer herstelekologieprojek: "Restourasie van oorbeweide Nama Karoo weiveld: die rol van bewannqseilande'". Die uitqanqspunt van hierdie saadbankondersoek was dat dit moontlik is om beskadigde semidroë weiveld te herstel deur middel van toegepaste bestuursprogramme wat gebaseer is op die metodologie en praktyk van ekologiese herstel. Algemeen erkende eienskappe van nieekwilibrium- omgewings (byvoorbeeld onvoorspelbare klimate en wisselende mates van versteuring) en grond-bewaarde saadbanke (byvoorbeeld ruimtelike en temporale verspreidings), het die basis gevorm vir die ondersoek van die algemene omgewing en die eienskappe van bestaande saadbanke in die Tafelberg omgewing. Die potensiële rol van heuwels as skuilplek vir aanvaarbare plantspesies was 'n onder1iggende element van die ondersoek. Na 'n kort ondersoek van historiese ~n kontemporêre navorsing en beleid oor weiveldbeskadiging in semi-droë streke van die wêreld, is die fundamentele behoefte aan omvattende en toegepaste saadbanknavorsing in die Nama Karoo beklemtoon. Binne die raamwerk van die oorkoepelende projek het die saadbankondersoek plaaslike omgewingskriteria bestudeer, beginnende met 'n ondersoek na saadbank- en plantegroeihabitats. Chemiese en fisiese eienskappe van grond vanaf twee en twintig terreine op en van Tafelberg af is beskryf. Omvattende grondhabitatwisseling tussen die kruin, die noordwestelike hange en die vlaktes en die suidoostelike hange en vlaktes van Tafelberg is geïdentifiseer. Mikroterreinwisseling tussen die oop-dak (tussenplantruimtes) en toe-dak (onderplantdekking) -mikrohabitats is as beduidend bevind. Primêre grondhabitatverskille is gekoppel aan die inhoud van die grond se organiese materiaal, wat op die vlaktes as laag bevind is vergeleke met die kruin en hange; en laag bevind is in oop-dak-mikroterreine vergeleke met toe-dak-terreine, Daar is gevind dat die grondtekstuur en voedingstofsamestelling op en van Tafelberg af aansienlik varieer, met beduidende verskille tussen die kruin en die vlaktes, en ook tussen die noordwestelike en suidoostelike vlaktes. Daar is gevind dat die hange intermediêr is (toon 'n mate van gradiënt) tussen die kruin en die vlaktes. Die wisseling in grondvoedingstowwe is vertolk as 'n funksie van teksturele en ouermateriaaleienskappe van grond. Antropogeniese faktore vir versnelde erosie, neerslag, loging en soutkorsvorming is ook oorweeg. Die gevolgtrekking is gemaak dat terwyl die eienskappe van grond op en van Tafelberg af inherent aan ouergrond verwant is, kan veranderinge aan tekstuur en voedingstofeienskappe voorkom, en hierdie veranderinge kon deur hoë vlakke van weiding vererger gewees het. 'n Ondersoek (wat op klein struike gefokus het) van plantfenologiese reaksie met betrekking tot reënval en weidingsgradiënte het tendense van piekbot- en blomseisoene na reënval gedurende die somer en herfs onderskeidelik geïdentifiseer. 'n Kontinuum van saadskietaktiwiteit, met piektye in laat herfs en vroeë winter, is van kwartaallikse data saamgestel. Groeistuwing is vir die meeste klein struike waargeneem gedurende lente-, herfs- en someropnames. Aangesien die een of ander vorm van aktiwiteit met betrekking tot voortplantingsgroei (groeistuwing, bot, blom of saadskiet) op feitlik al die tye van die jaar sigbaar was, word daar geredeneer dat hoëintensiteitversteuring (ook weiding) 'n negatiewe impak op plantoorlewing kan hê, wat sal lei tot verminderde voortplantingsinset (m.a.w. sade) in toekomstige geslagte. Plantgemeenskappe op die kruin en vlaktes word beskryf met beduidende verskille tussen plantegroei op die kruin van Tafelberg (wat hoofsaaklik bestaan uit hoëproduksie, smaaklike gras- en struikspesies) en dié ap die vlaktes (wat bestaan uit hoofsaaklik doringagtige, efemere, toksiese en laeproduksie-spesies). Gegee die hoë weidingsdruk op die vlaktes (vergeleke met die minder benutte hange en kruin van Tafelberg), word verskille in die samestelling van plantegroei bespreek met betrekking tot studies elders wat beskadigde weiveld beskryf. Die gevolgtrekking word eerstens gemaak dat die vlaktes om Tafelberg beskadig is, tweedens dat langtermyn-oorbenutting die samestelling van die plantegroei verander het, en laastens dat interweiding-rusperiodes van drie tot ses maande alleen dalk nie die diversiteit van plantegroei of die verlangde plantspesies op die vlaktes kan herstel nie. Die uitslae van kiemingstoetse (wat ondersoek ingestel het na grond-bewaarde saadbanke) van twee steekproefepisodes (lente en herfs 1'998)het getoon dat saadbanke in grond wat van die vlaktes, hange en kruin van Tafelberg verwyder is, die verspreidingspatrone volg wat in bogrondse plantegroei waargeneem is. Spesie-spesifieke data is nie vir hierdie tesis gefinaliseer nie, aangesien nie alle saailinge binne die gegewe tydsbeperkinge gegroei en geblom het nie. Ten einde saailing-verskyningsdata te vergelyk, is plantkategorieë ontwikkel wat efemere en langdurige (meerjarige) spesies en dikotiele spesies en grassoorte en ander monokotiele plante onderskei. Steekproewe van die kruin en teen die middelste en boonste hange het 'n hoë persentasie van aanvaarbare en standhoudende gras- en struikspesies getoon wat in grond-bewaarde saadbanke teenwoordig is, terwyl meer as twee derdes van plante wat in die vlaktes se grondmonsters ontkiem het, efemere spesies was, en die meeste daarvan was klein «5cm) en met 'n kort leeftyd «3 maande). Die meeste van die meerjarige spesies wat van die vlaktes se steekproewe kom, was saailinge van Pentzia incana, Chrysocoma ciliata en vetplante (hoofsaaklik Mesembryanthemaceae), maar min meerjarige grasse was teenwoordig. Daarenteen was onderskeidelik ongeveer 94% van saailinge wat van monsters van die kruin en 63% van saailinge wat van twee van die hange van Tafelberg ontkiem het, langdurige gras- of struikspesies. Ongeveer 89% van die efemere spesies wat van die hange se steekproewe aangeteken is, het op die laagste voethang-terreine ontkiem. Saaddigthede toon 'n noue verband met mikrohabitats, met ongeveer drievoudige verskille tussen oop- (laer saaddigtheid) en toe-dak (hoër saaddigtheid) -mikroterreine. 'n Multivariaatontleding van variansie (MANOVA) het aangedui dat die meeste van die variasie in saaddigtheidsdata op die mikrohabitat-vlak verduidelik is. Seisoenaliteit het 'n sekondêre rol gespeel, met beduidende tweerigting-interaksie tussen die twee uitwerkings. Die gevolgtrekking word gemaak dat albei faktore oorweeg moet word wanneer herstelprogramme ontwikkel word wat ten doel het om algehele plantbedekking en die diversiteit van verbeterde plantspesies te verhoog. Terwyl die oorspronklike of "ongerepte" toestand van die plantegroei se samestelling en saadbanke op die vlaktes onbekend is, is kommer uitgespreek oor die klaarblyklik beskadigde toestand van die totale bo- en ondergrondse plantdiversiteit op hierdie vlaktes. 'n Waarskynlike gevolg van habitatbeskadiging is dat spesies met spesifieke grond-, voedingstofverhouding-, aspek- en seevlak-vereistes van die kruin en hange van Tafelberg (asook van nabygeleë vlakteskuilings) nie in staat sal wees om in beskadigde habitats op die vlaktes te vestig nie. Die identifikasie van pionierplantspesies (verdraagsaam vir habitatbeskadiging) wat verhoogde plantegroeidekking en veilige terreine vir saailingontkieming van verlangde plantspesies toelaat, word aanbeveel. Herstelprogramme sal gekoppel moet word aan streng weidingsbeginsels wat saailingontkieming, die vestiging en suksesvolle voortplantingsproduksie van gewenste plante vir toekomstige weiveldherstel moontlik maak. Algemene en belangrike eienskappe van die grondhabitat, plantfenologiereaksie en kiemingsproefondersoeke word saamgevoeg in 'n ondersoek van habitats en verwante saadbankdiversiteit op en van Tafelberg af. Met erkenning van die kortstondigheid van hierdie navorsingsondersoek, maar met benutting van gevallestudies van elders en die integrasie van albei vraaglyne, word daarweertot die slotsom gekom dat die vlaktes om Tafelberg beskadig is deur dekades en waarskynlik eeue se beweiding deur mak lewende hawe. Dit word as uiters belangrik beskou dat herstel deur verbetering (of rehabilitasie) van habitats en 'n groter aantal saailing beveiligingsterreine oorweeg moet word. Dit lyk asof klimaat sowel as weidingsbestuur 'n onherroeplik gekoppelde rol speel in die vorming van die samestelling van plantegroei op weiveld. Terwyl weiveld intrinsiek aangepas is by die oorlewing van uiterste klimaatswisseling wat in nie-ekwilibriese streke aangetref word, word daar geredeneer dat die impak van beweiding, veral gedurende droogtetye en klimaatsverandering, stadigaan die intrinsieke "buffervermoë" van weiveld verminder om hierdie veranderinge en uiterstes te weerstaan. Dit blyk uit navorsing elders dat herstel deur passiewe bestuur stadig en waarskynlik nie ekonomies haalbaar is binne 'n lewensvatbare tydsraamwerk nie. Die instelling en bevordering van geïntegreerde en strategiese programme wat kwessies van grondbeskadiging en verandering van grondgebruik in semi-droë gebiede identifiseer en oplos, word aanbeveel. Die insette en pogings van verskillende owerhede en ministeries en deelname deur die breë publiek word aangemoedig in hierdie voorgestelde programme ten einde insette met 'n breë basis in die langtermyn~volhoubaarheid en bewaring van die aansienlike biologiese diversiteit van hierdie streke te verseker. Saadbankbeoordeling word beskou as 'n waardevolle manier om die herstelpotensiaal en weiveldtoestande met die potensiaal vir die identifisering van beskadigde sowel as bewaringswaardige gebiede aan te dui. Laastens word 'n paar beperkings en uitdagings van hierdie studie ondersoek deur 'n proses van eerstens die identifisering van alternatiewe benaderings tot navorsingsmetodologieë, en tweedens deur die voorstel van aanbevelings vir toekomstige navorsingsprojekte. Terwyl alternatiewe metodes toegepas kon gewees het ten einde hierdie studie af te handel, is die gevolgtrekking dat die toepaslike metodes binne die gegewe tyd5- en ander beperkings toegepas is.

Thesis (MSc (Earth Sciences))—University of Stellenbosch, 2005. / The integration of whole-rock chemistry, heavy mineral chemistry, detrital zircon morphology and age dating has enabled high-resolution characterization of the Permian Laingsburg and Tanqua submarine fan provenance in the Karoo Basin, upper Ecca Group, South Africa. Geochemically, the Laingsburg and Tanqua sandstones are classified as greywacke and litharenite. The chemical index of alteration values for these sandstones suggest low to moderately weathered sources and a relatively cold climate. Abundant angular clastic grains and lithic fragments as well as the predominance of pristine zircons indicate a near provenance and a first cycle derivation. The investigated sandstones originated from a continental island arc and an active continental margin. The source is dominantly intermediate to felsic and includes tonalites, granodiorites, and adamellites or their volcanic equivalents.

This aim of this study was to improve the understanding and functioning of the Table Mountain Group aquifer system and contribute to the sustainable development of this potential source for water supply in the Montagu area.

This aim of this study was to improve the understanding and functioning of the Table Mountain Group aquifer system and contribute to the sustainable development of this potential source for water supply in the Montagu area.