Thesis (MScConEcol )--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Over 70% of South Africa is too arid for crop farming and is used for commercial livestock ranching, communal livestock ranching, or game ranching. These management systems differ from each other in a number of aspects, e.g. herbivore species, stocking rate, grazing regime, and management structure. The main question addressed in this study is: to what extent do the three management systems affect rangeland condition? Following the equilibrium paradigm of vegetation dynamics, communal livestock ranches are expected to have a greater detrimental effect on rangeland condition than other management systems because stocking densities and, consequently, herbivore impacts, are usually far higher than under the other two management systems. However, recent nonequilibrium theories argue that vegetation dynamics in arid systems are mainly driven by rare and stochastic rainfall events. Biotic factors, such as grazing and herbivore diversity, are predicted to have little effect on rangeland condition. This leads to the prediction that herbivore impacts on arid ecosystems are not density-dependent and, consequently, the high stocking densities commonly recorded on communal livestock ranches will not cause more rangeland degradation than other management systems. Arid and semi-arid rangelands are characterised by high inherent spatial and temporal variation in vegetation and soil parameters. Hence, differentiating between the effects of grazing management systems and natural variability caused by abiotic factors, such as rainfall, is difficult. This problem can be circumvented by examining gradients of grazing intensity radiating from water-points (= piospheres). I examined changes in vegetation and soil parameters along 500 m-Iong grazing gradients on ranches in the semi-arid Northem Cape province, South Africa, with the three abovementioned management systems. Analysis of the vegetation on these ranches demonstrated the existence of grazing gradients around the water-points. Two characteristic zones described in other studies were identified, namely the sacrifice zone (almost complete denudation of the vegetation close to the water-point) and the dense shrub zone (distal to the sacrifice zone). Communal livestock ranching had a greater negative effect on rangeland vegetation than the two other ranching systems, particularly with regard to annual grass species diversity, percentage of bare soil, and shrub density. Within 100 m of the water-points, soil quality was negatively affected by commercial cattle ranching. Contrastingly, there were no significant effects of the other two management systems on soil quality in the piosphere. The feeding of supplemental forage and nutrients may explain the greater impact of commercial cattle farming on soil quality. The results of this study are consistent with the predictions of the equilibrium theory of vegetation dynamics because grazing impacts were density-dependent in these semi-arid rangelands. However, the results presented here also indicate that forage supplementation alters the spatial and temporal distribution of livestock in a manner that may have greater negative impacts on soil quality than density of livestock per se. / AFRIKAANSE OPSOMMING: Meer as 70% van Suid-Afrika is te droog vir gewasverbouing en word gebruik vir kommersiële veeboerdery, gemeenskaplike veeboerdery of wildboerdery. Die bestuur van dié verskillende boerderytipes verskil wesentlik van mekaar in verskeie opsigte, ondermeer herbivoorspesies, veeaanskaffingstempo, weidingstipe en bestuurstruktuur. Die belangrikste vraag wat aangespreek word in die studie is die volgende: Tot watter mate affekteer die drie verskillende boerderybestuurstipes die toestand van weivelde? Gesien teen die agtergrond van die ekwilibriumparadigma van plantedinamika, word verwag dat gemeenskaplike veeboerdery 'n groter impak op die toestand van weiveld sal hê as ander boerderytipes, omdat veedigtheid en gevolglik herbivoor-impak gewoonlik veel hoër is as met die ander twee boerderytipes. Onlangse nie-ekwilibria-teorië voer egter aan dat plantedinamika in ariede gebiede gedryf word deur seldsame en buitengewone reënvalgebeure. Biotiese faktore, soos weiding en herbivoor diversiteit sal na verwagting min effek hê op die toestand van weiveld. Hieruit volg die voorspelling dat herbivoorimpak op ariede ekosisteme nie afhanklik is van digtheid nie, en dat hoë veedigtheid algemeen aangeteken vir gemeenskaplike boerderye, nie rede sal wees vir groter ver1iese in weiveld nie. Ariede en semi-ariede weivelde word gekenmerk deur 'n hoë ruimtelike en tydelike veranderinge in plant- en grondparameters. Gevolglik is dit moeilik om te onderskei tussen die effekte van weidingsbestuur en natuur1ike veranderings wat veroorsaak word deur nie-biotiese faktore, soos reënval. Dié probleem kan oorbrug word deur gradiënte van weidingsintensiteit, wat vanaf waterpunte uitstraal, te ondersoek. Vervolgens het ek binne al drie bg. boerderybestuursisteme veranderinge in plant- en grondparameters langs SOOm-lange weidingsgradiënte ondersoek op plase in die semiariede Noord-Kaap provinsie van Suid-Afrika. Plantegroei-analise het getoon dat 'n weidingsgradiënt rondom waterpunte voorkom. Twee kenmerkende sones is in ander studies geïdentifiseer, nl., 'n opofferingsone (waar amper alle plantegroei naby waterpunte uitgetrap is) en die digte, struik-sone (distaal to die opofferingsone). Gemeenskapsveeboerdery het 'n groter negatiewe effek op plaasgewasse as die ander twee boerderytipes, veral waar dit betrekking het op grasspesie-diversiteit, persentasie grond sonder plantbedekking en struikdigtheid. Binne 100m vanaf waterpunte, is grondkwaliteit merkbaar negatief geaffekteer deur kommersiële veeboerdery. Daarteenoor, was daar geen merkbare effek op die grondkwaliteit naby waterpunte van die ander twee boerderytipes nie. Aanvullingsvoer kan moontlik die rede wees vir die waargenome, groter impak van kommersiële veeboerdery op grondkwaliteit. Die resultate van die studie strook met voorspellings van die ekwilibria-teorie van plante-dinamika, daarin dat weidingsimpak digtheidsafhanklik is in hierdie semiariede plaasgebiede. Die resultate toon ook egter, dat voedingsaanvullings die ruimtelike en tydelike verspreiding van vee in so 'n wyse verander, dat dit moontlik 'n veel groter negatiewe uitwerking op grondkwaliteit het as veedighteid per se.

This study was designed to provide the means for implementing formal scientific vegetation management 1n the succulent valley bushveld of the eastern Cape, South Africa. Nowhere in the world has a detailed, effective and practical veld management system being developed entirely from research, and even the most successful management systems rely heavily on the intuition of people. A process, formally called 'adaptive management', combines this intuition with scientific testing and the overall objective of this study was to provide a framework for formalized adaptive management in succulent valley bushveld. On analyzing the process of adaptive management, the following knowledge 'tools' were identified: (i) a management system for immediate implementation; (ii) a technique for vegetation assessment; (iii) a technique for monitoring vegetation change; (iv) a technique for monitoring forage use and recovery; (v) a list of key forage species; (vi) a model to set initial stocking rates; (vii) a method of recording essential information; and (viii) a database of ecological principles. Providing these 'tools' became the goals of this study. These topics covered almost all facets of rangeland science, and the approach was to address these in a 'top down' manner, rather than sub-optimize by specializing on anyone component. Most of the 'tools' were achieved to a greater or lesser extent and are presented as a series of publications. However, a central tool, that for monitoring vegetation change, remains outstanding despite comprehensive testing of a range of traditional botanical methods. Indeed, critical review revealed that this 'missing tool' is a problem which is common in all vegetation communities in South Africa - despite the impression created by vegetation researchers that adequate techniques are indeed available. This is serious because land managers are not able to evaluate the impact of their efforts and the government is unable to monitor the effectiveness of their research and extension services, costing millions of public monies annually. The implication also, is that vegetation cannot be managed scientifically (management implies monitoring). Either formal adaptive management is not practicable, or researchers are operating from an inappropriate paradigm; specifically that of providing techniques for their research projects and claiming that these (or derivatives of these) are adequate for farm or regional scale monitoring. More generally, research has often become an end in it's self, with research quality being judged by criteria which are of little significance to the real world and which damage efficiency. Perhaps, the real value of vegetation research lies in the experiential learning which the researcher gains not the inevitably parochial results. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1993.

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)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Arid lands comprise some 47.2 % of the world's land surface. Between 32 % and 35 % of these drylands are subject to some form of desertification and land degradation. South Africa is an arid country with water being a major limiting resource. The Nama-Karoo biome is an extensive tract of semi-arid vegetation comprising some 22.7 % of South Africa, characterised by low rainfall and high temperatures. Grazing is the most common form of land use in the country, and particularly in this biome. Aridity and grazing are two factors that make large areas of South Africa (including the Nama-karoo) susceptible to land degradation. The Nama-Karoo biome has been neglected in past research and is an understudied part of South Africa's vegetation. This study is a component of a bigger umbrella project entitled "Restoration of degraded Nama-karoo rangelands: the role of conservation islands". The aim of this project was to assess the role played by isolated hills and mountains (mesas, inselbergs, etc.) in conserving the remnant biological diversity of the Nama-karoo rangelands of Namibia and South Africa. Vegetation composition, seed banks, seedling recruitment, pollination and grazing patterns and intensity on and off isolated mesas in the eastern parts of the Nama-karoo were investigated in the South African component of this project. I report on patterns of 1) plant species diversity and 2) plant communities across the Middelburg District, Eastern Cape, South Africa. Three isolated mesas (Tafelberg, Folminkskop and Buffelskop) and their surrounding plains were selected for this study. Permanent plots were established in broad transects extending from the plains to southeastern slopes, plateaux, north-western slopes and north-western plains of each mesa. Plots were 25 m2 in size, and ten 1 m2 blocks within the 25 m2 plot were randomly selected and sampled. Species composition was recorded and cover values determined for all plants in every subplot. In the eastern Nama-karoo mesas were not found to be higher in Alpha Diversity than their surrounding plains. Plains habitats were mostly equally as diverse as mesa habitats, with some plains habitats being higher in diversity than mesa habitats. Greater differences between mesas and their surroundings were found in a parallel study in the northern parts of the Nama-karoo in Namibia, indicating that mesas are more distinct islands of diversity with an increase in aridity. In the Middelburg District, a greater presence of woody phanerophytes occurred on mesa habitats in comparison with plains habitats, a possible result of the more moist microhabitats on mesas. Cooler, moister conditions on the south-eastern slopes of the mesas led to higher Alpha Diversity there in comparison with the warmer and drier north-western slopes, a phenomenon commonly found in arid areas. In terms of Alpha Diversity, the largest mesa sampled, Tafelberg (450 m above surroundings), was not significantly more diverse than the two smaller mesas (Folminkskop and Buffelskop both being 200 m above surroundings). Tafelberg and Buffelskop were equally high in Beta Diversity, with Folminkskop being much less diverse. Increased Beta Diversity for Tafelberg was explained by the increased size of the mesa (providing a more diverse microhabitat) relative to Folminkskop, which has the same shape and geology but is much smaller in size. High Beta Diversity values for Buffelskop were explained by the presence of degraded communities on the northwestern slopes and plains, while the south-eastern slopes were some of the most diverse habitats sampled in the landscape. Mesas and plains shared few species. Proportionally fewer species were shared between the plateau and slopes of the larger Tafelberg in comparison with the smaller two mesas. Isolation of the plateau could possibly become more distinct with an increase in size of the mesa. However, Tafelberg had more species in common with the surrounding plains than did the smaller mesas. It is suggested that bigger mesas support a more diverse array of microhabitats enabling plains species to occupy selective sites on the slopes of the mesa. Average Shannon-Wiener Alpha Diversity Indices for Middelburg were higher than that of the Nama-karoo in general. This could be explained by the higher precipitation in the eastern parts of the Nama-karoo relative to the rest. Diversity in Middelburg compared favourably with that in other arid lands of North America and Australia and was found to be similar in patterns and determinants of diversity compared to arid lands such as those of the New World. Regarding plant community composition, mesas were found to be distinctly different from their surrounding plains, with no shared communities between mesas and plains. The distribution of communities across the landscape was mainly attributed to a soilmoisture gradient. Mesas, compared to plains, have shallower, rockier soils coupled with very little run-off and naturally higher precipitation due to elevation. This results in a more mesic habitat. Plains, compared with mesas, have little rock cover, high percentages of bare soil and higher run-off rates than mesas, resulting in a more xeric habitat. Habitat differences such as these probably existed before the impact of domestic livestock but overgrazing has probably exacerbated the differences. The dominance structure of plant communities on the plains has probably changed in favour of toxic, spinescent or unpalatable plant species due to selective grazing by livestock. For the two dolerite-capped mesas (Tafelberg and Folminkskop) aspect and the expected cooler, moister conditions on south-eastern slopes as factors determining community composition were overridden by soil type and associated nutrient status. On Buffelskop (sandstone mesa), aspect and slope overrode soil type and associated nutrient status as determinants of community compositions. The potential to use mesas as a source of seeds and propagules to restore degraded plains habitats is low. Approximately 28 % of species were shared between mesas and their surroundings, and not all of these species could be regarded as good colonisers. Generalist, palatable species occurring across the landscape, such as Eragrostis obtusa, Felicia muricata, F. ovata, Fingerhuthia africana, Jamesbrittenia tysonii, Limeum aethiopicum, Pentzia incana and Selago albida could have some potential for future restoration attempts. Mesas are distinct in composition and can be regarded as islands of one vegetation type (mesas) in a sea of a different vegetation type (plains). Mesa habitats are not generally used for grazing by livestock, due to their general inaccessibility, and are not threatened by development. Plant communities in the Middelburg area were very similar In composition to communities identified in other parts of the Nama-karoo. Results from this study suggest that the plains are at present more degraded than the mesa habitats, but it is impossible to conclude whether or not these rangelands have stabilised given current stocking rates and climatic conditions. The Braun-Blanquet classification system proved an effective method to describe plant communities in the semi-arid Nama-karoo. All the plots used during the duration of the study were marked by metal stakes and are therefore of a permanent nature, so that they can be resampled in future. This might possibly shed some light on questions related to resilience, stability and degradation of the karoo. Restoring rangeland in the future is an important option, however, few farmers would, in the short term, be able to afford costly restoration techniques. It is recommended that farmers inspect the condition of their veld on a regular basis, and adjust stocking rates accordingly. Veld should be rested on a regular basis, and assessment should precede the movement of stock to a camp. Most farmers plough denuded areas of veld to encourage restoration, and it is recommended that this practice be combined with reseeding, followed by rest during and shortly after germination of the seed. / AFRIKAANSE OPSOMMING: Ariede areas beslaan tans 47 % van die aarde se land oppervlak. Tussen 32 % en 35 % van hierdie areas is onderworpe aan een of ander vorm van land degredasie. Die Nama- Karoo bioom is 'n ekstensiewe semi-ariede area wat naastenby 47 % van Suid-Afrika beslaan. Die karoo word gekenmerk deur hoë temperature en lae reënval. Suid-Afrika is 'n ariede land en water is 'n beperkende faktor. Weiding is die algemeenste boerderypraktyk, en meer so in ariede areas soos bv. in die karoo. Die droë klimaat en hoë voorkoms van weiding as boerderypraktyk maak ekstensiewe areas (insluitende die karoo) van Suid-Afrika vatbaar vir land degredasie. Hierdie studie is deel van 'n breër projek genaamd: "Restorasie van gedegradeerde Nama-karoo veld: Die rol van bewaringseilande". Die doel van hierdie projek was om die rol te bepaal van ge-isoleerde koppies en berge (mesas, inselberge, ens.) in die bewaring van biologiese diversiteit in die Nama-karoo van Suid-Afrika en Namibië. Plantegroeisamestelling, saadbanke, saailing oorlewing, bestuiwing en weidingsintensiteitlpatrone op koppies en hulle omringende vlaktes in die oostelike dele van die Nama-karoo is ondersoek in die Suid-Afrikaanse komponent van die studie. Ek rapporteer oor patrone van 1) plant diversiteit en 2) plantegroeigemeenskappe in die Middelburg Distrik, Oos-Kaap, Suid-Afrika. Drie ge-isoleerde koppies (Tafelberg, Folminkskop en Buffelskop) en hulle omliggende vlaktes is geselekteeer vir die doel van die studie. Permanente persele is uitgelê in 'n breë lyn vanaf die suid-oostelike vlaktes na die suid-oostelike hang, oor die plato's, noord-westelike hange en noord-westelike vlaktes vir al drie koppies. Persele was 25 m2 in grootte, waarvan tien 1 m2 sub-persele geselekteer is binne die groter 25 m2 blok. Spesies samestelling en bedekkingswaardes is bepaal vir alle plante in al die sub-persele. Mesas was nie hoër in Alpha Diversiteit as hulle omringende vlaktes nie. Vlaktes was meestal net so hoog in diversiteit as die mesas, en somtyds selfs hoër. Groter verskille in diversiteit is gevind in 'n paralelle studie in die noordelike dele van die Nama-karoo in Namibië. Dit dui aan dat mesas moontlik meer definitiewe eilande van diversiteit is in droër gebiede. Meer houtagtige fanerofiete het voorgekom op die mesas in vergelyking met die omliggende vlaktes, 'n moontlike gevolg van 'n natter habitat op die mesas. Suid-oostelike hange was hoër in alfa-diversiteit in vergelyking met noord-westelike hange. Dit is toegeskryf aan die koeler, natter mikrohabitat van die suid-oostelike hange. Die groter mesa (Tafelberg - 450 m bo die vlakte), was nie meer divers as die twee kleiner mesas nie (Folminkskop en Buffelskop is sowat 200 m bo die vlakte). Tafelberg en Buffelskop was ewe hoog in Beta Diversiteit, terwyl Folminkskop heelwat laer was. Hoër Beta Diversiteit vir Tafelberg kan verklaar word deur die groter oppervlak en hoogte van die mesa (voorsien 'n meer diverse mikrohabitat) in vergelyking met Folminkskop. Folminkskop het dieselfde vorm en geologiese geskiedenis as Tafelberg, maar is veel kleiner. Buffelskop was hoog in Beta Diversiteit as gevolg van 'n gedegradeerde gemeenskap op die noord-westelike hang en vlaktes, terwyl die suidoostelike hang baie hoog was in diversiteit. Min spesies kom op beide mesas en vlaktes voor. Minder spesies is gedeel deur die plato en hange van Tafelberg in vergelyking met die plato's en hange van Folminkskop en Buffelskop. Isolasie van die plato kan moontlik hoër wees in groter mesas. Tafelberg (slegs mesa) het meer spesies in gemeen met sy omliggende vlakte as die ander twee mesas. Groter mesas soos Tafelberg kan moontlik 'n meer diverse spektrum van mikrohabitatte bevat, wat sekere vlakte spesies in staat stel om te oorleef op mesa hange. Gemiddelde alfa diversiteit vir die Middelburg Distrik was hoër as die van die res van die karoo. Dit kan verklaar word deur die hoër reënval in die oostelike dele van die karoo relatief tot die meer westelike dele. Diversiteit in Middelburg vergelyk goed met die van ander ariede lande in Noord-Amerika en Australie, terwyl patrone en faktore wat diversiteit bepaal soortgelyk was aan die van gemeenskappe in ariede lande van die Nuwe Wêreld. Mesas en vlaktes het drasties verskil in die samestelling van hulle onderskeie plantegroeigemeenskappe, alhoewel hulle soortgelyk was in diversiteit. Geen plantegroeigemeenskappe het voorgekom op beide mesas en vlaktes nie (gedeelde plantegroeigemeenskappe). Die verspreiding van plantegroeigemeenskappe oor die landskap was toegeskryf aan 'n grond-water gradient. Mesas het, oor die algemeen, vlakker, meer rotsagtige grond en 'n hoër reënval met minder afloop as vlaktes. Vlaktes het minder rotse, 'n hoër persentasies kaal grond en vinniger afloop tempo's na reën as mesas. Hierdie faktore het tot gevolg dat mesas 'n natter habitat verteenwoordig in vergelyking met die meer ariede vlaktes. Habitatsverskille soos dié het heel moontlik klaar bestaan voor die aankoms van vee, maar oorbeweiding het die verskille in habitat tussen mesas en vlaktes groter gemaak. Selektiewe beweiding deur vee het waarskynlik tot gevolg gehad dat plante wat giftig, doringagtig of onsmaaklik is, toegeneem het in plantegroeigemeenskappe, ten koste van meer smaaklike spesies. Grondtipe en grondsamestelling het aspek en verwagte koeler kondisies op die suidoostelike hange onderdruk as bepalende faktore vir plantegroeigemeenskap samestelling op Tafelberg en Folminkskop (beide bedek met 'n doleriet laag). Aspek en steilte van die hange het grondtipe en grondsamestelling onderdruk as bepalende faktore vir plantegroeigemeenskappe op Buffelskop. Die potensiaal om mesas te gebruik as bronne van saad vir die rehabilitasie van die vlaktes was laag. Mesas en hulle omliggende vlaktes het naastenby 28 % van spesies in gemeen gehad, maar nie al hierdie spesies was goeie koloniseerders nie. Sekere smaaklike plante wat op beide mesas en vlaktes voorgekom het, kan potensiaal hê vir toekomstige restorasie doeleindes, bv. Eragrostis obtusa, Felicia muricata, F. ovata, Fingerhuthia Africana, Jamesbrittenia tysonii, Limeum aethiopicum, Pentzia incana en Selago albida. Mesas is uniek in samestelling en kan beskou word as een plantegroeitipe in 'n see van 'n ander tipe (vlaktes). Mesas word nie oor die algemeen bewei nie (as gevolg van hulle steil hange en bergagtigheid) en word gevolglik nie bedreig deur huidige ontwikkeling nie. Plantegroeigemeenskappe in Middelburg is soortgelyk aan die van ander dele van die Nama-Karoo bioom. Resultate van die studie dui aan dat die vlaktes huidiglik meer gedegradeer is as mesas, maar dit is onbekend of die veld gestabiliseer het of steeds besig is om verder te degradeer in huidige weidings- en klimaatskondisies. Die Braun-Blanquet klassifikasiemetode IS effektief vir die beskrywing van plantegroeigemeenskappe in ariede areas. Al die persele in die studie area is gemerk met metaal paaltjies en is dus permanent. Dit maak dit moontlik om in die toekoms die persele weer te ondersoek. 'n Langtermyn datastel kan moontlik lig werp op die stabiliteit en degredasie van karoo veld. Restorasie van veld is 'n moontlikheid vir die toekoms, maar min boere kan duur restorasie metodes bekostig in die kort termyn. Boere moet hulle lande gereeld ondersoek en drakrag aanpas by die kondisie van die veld. Baie boere ploeg kaal kolle in die veld op 'n gereelde basis, en daar word voorgestel dat die praktyk gekombineer word met die saai van geskikte saad, gevolg deur 'n rusperiode tydens en na ontkieming daarvan.

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Arid and semi-arid rangelands of the Nama-Karoo Biome are believed to have changed considerably since the arrival of domestic livestock in the veld. Severe grazing pressure is considered to be one of the prime factors responsible for the perceived degradation of vegetation and concurrent soil degradation. To understand the process of degradation and to make further recommendations for future veld restoration, a large-scale project was undertaken in the Eastern Cape. This project focused on the role that landscape heterogeneity plays in providing refuges for plant species. The key question asked in this project was: What role do these hypothetically less grazed mesas play in the conservation of rangelands in the Nama-Karoo of the Eastern Cape? This study, a component of the larger project, investigated grazing and soil landscape gradients on- and off- the three mesas (Tafelberg, Folminkskop and Buffelskop) in the Middelburg District of the Eastern Cape, South Africa and the possible influences that they might have on the veld. The flats surrounding the mesas were mostly used as grazing camps in contrast to the plateaux of the mesas, which had varied levels of accessibility. In the absence of direct observations, the primary objective of the study was to test the differential dung pellet abundance and impact of animals on different parts of the landscape. As such, dung pellet counts in this study were correlated with surrogates of soil physical properties including bare ground, trampling and litter cover. Variation in dung pellet density was found at the different habitats (flats, slopes and plateaux) of all mesas. The flats to the north-eastern and south-western of Tafelberg mesa were found to be more heavily utilized by livestock and herbivores, while the plateaux and southeastern slopes of Folminkskop and Buffelskop were also utilized by grazers. The Tafelberg mesa was the only study site that was consistent with the hypothesis which stated that grazers would be less concentrated on the plateau compared to the surrounding flats due to its inaccessibility, whilst the high mean dung pellet density on the plateaux of the smaller Folminkskop and Buffelskop mesas due to easier access contradicted the original hypothesis. It appeared that dung pellet density did not clearly turn out to be an indicator of habitat use in this study, but showed where slopes and plateaux were accessible to herbivores, as in the case for the Buffelskop mesa, a higher abundance of dung pellets were found suggesting that higher intensities of habitat use took place. During this study a strong pattern was observed of bare soil patches on the flats surrounding the mesas. There was a decrease in percentage of bare soil along the gradient of the three mesas with a high percentage of bare soil on the plateaux of the mesas. A significant correlation was found between bare soil and dung pellet density. However, the plateaux of Folminkskop and Buffelskop had a high percentage of bare soil compared to the plateau of Tafelberg mesa. Farmers mainly used these smaller mesas as grazing camps for their livestock and herbivores. A positive correlation between bare soil and litter cover of the different habitats was evident in this study. A lower percentage of litter cover at these sites was associated with a high percentage of bare soil. Litter is very important in a healthy vegetation community in terms of nutrient cycling and fertile patches. A detailed assessment of soil chemical and physical properties would reveal, firstly, if vegetation change is better explained by soil or grazing effects and, secondly, if changes in soil have resulted from land use. Differences in macro- and micro-site variations between open-canopy (between shrubs) and closed-canopy (under shrubs) sites for each habitat were determined to differentiate between local scales due to land use and landscape scales due to geomorphology. The results suggested that carbon, phosphorus, calcium, magnesium, copper and manganese levels in soils at landscape scale better explain vegetation changes between habitats. At a local scale (open- and closed-canopy sites) land use was responsible for little changes in soils. Changes in only soil potassium, zinc and boron elements were actually a consequence of local scales due to land use. The soil nutrient content on the slopes appeared to be intermediate between the flats and plateaux of all three mesas. It appeared that dolerite capped Tafelberg and Folminkskop mesas had high silt and clay content, while Buffelskop (sandstone) mesa had a lower silt and clay content. Consequently, the texture and parent material of the soils contributed to the variations in soil nutrient composition between these mesas. High infiltration rate together with low nutrient content on the flats clearly showed that these flats, surrounding the mesas were degraded. The high infiltration rates were caused by high activity by livestock and other indigenous animals on the flats which breaks the surface crusting of bare soil and improve infiltration. It was concluded that high levels of grazing at these sites have also altered the textural and soil properties. Endozoochory dispersal and the deposition of dung pellets in areas of small patch disturbances play an important role in veld regeneration in degraded areas. Dung pellets collected from permanent study sites on the southeastern and northwestern flats and slopes, and all the study sites on the plateau of Tafelberg mesa, was sown in seedling trays, watered and monitored for seedling germination. Species list were then compared to below-ground soil seed bank data and above-ground vegetation data collected by other researchers at the same permanent study sites. Higher seedling percentages were recorded from dung pellets collected on the flats than on the plateau. A total of sixteen species were found to germinate in dung pellets collected on the flats compared to ten species germinating in dung pellets collected on the slopes and two species on the plateau of Tafelberg mesa. The seeds that germinated represent a variety of palatable grasses and shrub species. Aristida sp., Eragrostis bicolor, Eragrostis ch/orome/as and Eragrostis obtusa were palatable grasses recorded for dung pellets collected on the flats. Of the species recorded, Aristida sp., Chenopodium sp. and Pentzia sp. were found in dung pellets but were not recorded in parallel soil seedbank and vegetation studies. Successful restoration of veld conditions requires strict grazing management practices. Germination of seed in dung pellets might be considered to be a valuable means of indicating restoration potential and rangeland conditions for the identification of both degraded and conservation worthy areas. With appropriate land management skills and restoration measures, these challenges can be constructively and creatively faced. / AFRIKAANSE OPSOMMING: Daar word geglo dat die ariede en sernl-arlede weivelde van die Nama-Karoo bioom aansienlik verander het sedert die aankoms van mak lewende hawe in die veld. Swaar weidingsdruk word beskou as een van die vernaamste faktore verantwoordelik vir die waarneembare oorbeweiding van plantegroei en die gelyktydige grond agteruitgang (degradasie). Ten einde die proses van degradasie beter te verstaan, en om verdere aanbevelings te kan maak vir toekomstige veld herstel, is huidiglik 'n grootskaalse projek in die Oos-Kaap aan die gang oor die rol wat landskap ongelyksoortigheid speel in die voorsiening van skuiling aan plant spesies. Hierdie studie ondersoek weiding en grondlandskap gradiënte (op en af) van die drie mesas (Tafelberg, Folminkskop en Buffelskop) in die Middelburg streek van die Oos- Kaap, Suid-Afrika en die moontlike invloed wat hierdie gradiënte op die veld het. Die vlaktes was meestal gebruik vir weidingskampe in teenstelling met die kruin van die mesas. Hierdie studie het duidelike patrone vir habitat-gebruik op die vlaktes, hange en kruine van al die mesas aangetoon. Die vraag wat gestel was, was watter rol speel hierdie hipoteties minder beweide mesas in die bewaring van weivelde in die Nama- Karoo van die Oos-Kaap? Hierdie studie toets nie direk vir mis verspreiding as 'n plaasvervanger vir dier verspreiding in die landskap sedert werklike dier getalle nie oorweeg was nie. In die awesigheid van direkte waarneming, die primêre doelwit was om te toets die differensiaal misdigtheid en die impak van diere op verskillende dele van die landskap. Mis getalle in hierdie studie was gekorreleer met plaasvervangers van fisiese eienskappe insluitent onbedekte grond, vertrapping en droë plant material decking. Variasie in misdigtheid was gevind by die verskillende habitate (vlaktes, hange en kruine) van all die mesas. Die vlaktes aan die noord-oostelike en suid-westelike kante van die Tafelberg mesa was meer hewig benut deur lewende hawe en hêrbivore, terwyl die kruine en suid-oostelike hange van Folminkskop en Buffelskop ook gebruik was deur weidende diere. Die Tafelberg mesa was die enigste studie area wat konsekwent was met die hipotese, terwyl die hoë gemiddeld misdigtheid op die kruine van die kleiner Folminkskop en Buffelskop mesas, as gevolg van makliker toegang weerspreek die oorspronklike hipotese. Dit blyk dat misdigtheid duidelik opkom as 'n nie aanwyser habitat-gebruik in hierdie studie, maar wys well waar hange en kruine toeganklik was vir herbivore, soos in die geval van Buffelskop mesa, oorvloed van mis was gevind wat voorstel dat hoer intensiteit van habitat-gebruik voorgekom het. 'n Duidelike patroon is waargeneem tydens hierdie studie van onbedekte grond areas op die vlaktes rondom mesas. Daar was 'n afname in persentasie onbedekte grond langs die gradiënt van die drie mesas. Die kruine van Folminkskop en Buffelskop toon hoër persentasies onbedekte grond in vergelyking met die kruin van die Tafelberg mesa. Daar is 'n betekenisvolle korrelasie tussen onbedekte grond en misdigtheid gevind. Boere gebruik hierdie kleiner mesas hoofsaaklik as weidingskampe vir hulle lewende hawe en hêrbivore. In hierdie studie is daar 'n positiewe korrelasie gevind tussen onbedekte grond en droë plant material decking van die verskillende habitatte. Droë plantmateriaal bedekking speel 'n baie belangrik rol in 'n gesonde plant gemeenskap in terme van voedingsirkulering en vrugbare kolle. 'n Breedvoerige skatting van grond chemise en fisiese eienskappe wou openbaar eerstens of plantegroei verandering beter verklaar word deur grond of weiding effekte en tweedens, of verandering in grond veroorsaak was deur land-gebruik. Verskille in makro- en mikroterrein-wisseling tussen oop-blaredak (tussenplantruimtes) en toeblaredak (onderplantdekking) terreine vir elke habitat was bepaal om te onderskei tussen lokaal effek as gevolg van land-gebruik en landskap effek as gevolg van geomorfologie. Die resultate stel voor dat koolstof, fosfor, kalsium, magnesium, koper en mangaan vlakke in die grond by landskap effek beter plantegroei verandering tussen habitate verduidelik. By 'n lokaal effek (oop-en toe-blaredak terreine) land-gebruik was verantwoordelik vir min veranderinge in grond. Verandering in grond kalium, sink en baron elemente was werklik 'n gevolg van lokaal effek as gevolg van land-gebruik. Die nutrient inhoud van grond op die hange blyk intermediêr te wees tussen die van die vlaktes en kruine van al drie mesas. Hierdie studie toon ook dat die geologie en topografie van hierdie mesas die grond tekstuur en nutrient samestelling op en af van die mesas beinvloed. Dit wil voorkom asof die dolerite bedekte Tafelberg en Folminkskop mesas, hoë slik en klei materiaal bevat, terwyl Buffelskop (sandsteen) mesa 'n laer slik en klei inhoud het. Gevolglik, tekstueel en ouer materiaal grond dra by tot die variasie in grond nutrient samestelling tussen hierdie mesas. Hoë infiltrasie tempo tesame met lae voedingstof van die vlaktes dui daarop dat die vlaktes rondom die mesas oorbewei was. Hierdie hoë infiltrasie tempo word veroorsaak deur hoë dierlike aktiwieteite op die vlaktes deur lewende hawe en ander inheemse diere wat die oppervlakke van onbedekte grond versteur en infiltrasie verbeter. Die gevolgtrekking word gemaak dat die hoë weidingsvlakke van hierdie terreine ook die tekstuur en ander grond eienskappe verander het. Endozoochoreeuse verspreiding en die mis-afsetting in gebiede van klein areaversteurings, speel 'n belangrike rol in veld herlewing in oorbeweide gebiede. Mis versamel by permanente studie terreine op die SO en NW vlaktes en hange, as ook al die studie terreine op die kruin van die Tafelberg mesa, is gesaai in saailing bakke, besproei en gekontroleer vir saailing ontkieming. 'n Lys van spesies is vergelyk met onder-grondse saadbank gegewens en bo-grondse plantegroei gegewens wat deur ander navorsers by dieselfde studie terreine versamel was. Hoër saailing persentasies is gevind vir mis wat op die vlaktes versamel is as op die kruine. 'n Totaal van sestien geidentifiseerde spesies het uit die mis op die vlaktes ontkiem in vergelyking met die tien spesies wat ontkiem het uit die mis van die hange en twee spesies iut die mis van die kruin van Tafelberg mesa. Die ontkiemde saad verteenwoordig 'n verskeidenheid van vreetbare gras en struik spesies. Aristide sp., Eragrostis bicolor, Eragrostis chloromelas en Eragrostis obtusa is vreetbare grasse wat gevind was in die mis versamelop die vlaktes. Die spesies opname wys dat Aristida sp., Chenopodium sp. en Pentzia sp. Gevind was in die mis, maar nie in die parallelle grond saadbank en plantegroei studies nie. Die suksesvolle herstel van veldtoestande vereis "n streng weidingsbestuur toepassing. Die ontkieming van saad in mis kan beskou word as "n bekostigbare manier om veld herstel potentiaal te bepaal, asook weiveld toestande vir die indentifiseering van beide degradasie en bewaring van waardevolle areas. Met gepaste veldbestuur vaardighede en herstel maatreels, kan hierdie uitdagings konstruktief en kreatief aangespreek word.

Communal rangelands occupy 13 percent of the agricultural land in South Africa, and these rangelands serve as a source of feed to livestock. These areas are threatened by bush encroachment due to poor rangeland management. This study was conducted in Alice (Sheshegu communal area) and the objective was to assess farmers' perceptions and the impact of bush encroachment on herbaceous vegetation and soil nutrients. Structured questionnaires were used to assess indigenous knowledge of communal farmers on the impact of bush encroachment on rangelands. Fourty (40) respondents from households who owned livestock were randomly selected and interviewed at Sheshegu village. About 89 percent of communal farmers perceived that change of their grasslands to encroached savannas was caused by unreliable rainfall, prolonged drought, and poor rangeland management. Rangeland assessment was performed at four sites (Scattered, Moderate, Mixed and Dense bushland. 100mx50m were demarcated per site, and four 100m transects were laid parallel to each other, 30m apart. The step point method was used to determine both species composition and basal cover. Biomass production was determined by harvesting forage within randomly-paced a 0.25m2 quadrats. Aristada congesta and Eragrostis obtuse were the most dominating grass species in dense, mixed and moderate bushland. Scattered bushland was dominated by Themeda triandra. Biomass production increases with increase in bush density and basal cover improved from winter to summer season. Increaser grass species increase with the increase in bush density, this indicated that the rangeland was poorly managed and palatable species were being replaced by less palatable ones. Species composition of woody plants was determined within a 200m2 belt transect in all sites. Maytenus polycantha, Aloe ferox, Erehia rigida and lucas capensis were the most dominant woody species in Mixed bushland while Acacia karroo was most dominated in Scattered, Moderate and Dense bushland. Woody density showed no significant differences (P> 0.05) between Dense, Mixed and Moderate bushland. Woody plant density in all these sites exceed 2500 plants/ha, which showed that the rangeland was encroached with woody plants. Soil nutrient content was determined for each site. Five samples of soil were collected per site to test the effect of bush encroachment on soil nutrient composition. The concentration of nitrogen and soil pH increased with increase in bush density, while that of potassium, phosphorous, magnesium, sodium and sulphur showed no significant differences (P>0.05) across all homogenous vegetation units. The study revealed that Sheshegu communal farmers are aware of both negative and positive effects of encroachment on their community, and also argue that the government is not willing to support communal farmers in the process of reducing the spread of bush encroachment. It was concluded that the concentration of nitrogen and soil pH increased with increasing bush density and that bush encroachment had negative effects on herbaceous species. It was recommended that communal farmers should be formulating rangeland rules and regulations to manage rangeland resources. Rangeland rules and regulations should be based on the management of livestock management during grazing and harvesting of rangeland resources. The harvesting of woody and good timing of application of fire can also reduce the spread of bush encroachment. Veld resting and rotational grazing can also improve fuel load which is required for burning of woody plants. Furthermore, Department of agriculture should also provide workshops or training to communal farmers use different approaches or cheap ways of reducing bush encroachment and conserving rangeland resources.

The dynamics and complexities of climate-soil-vegetation relations in the Kruger National Park are poorly known. Although primary production and composition of the grass layer are very important components of the Park's ecosystem, equally little is known about the determinants of these parameters. A better understanding of these processes and relations will be of value to the management of this Park, as well as providing a better insight into these complex dynamics. A study was consequently undertaken covering a 14-year period to identify the most important determinants of above-ground grass production and composition. At the core of the study is the soil water balance. The use of evapotranspiration data in a study of this nature is however not absolutely essential, provided a variety of rainfall parameters are used, though it has the important advantage of providing a much more detailed and more complete insight into the relations of the grass sward with its environment. Stepwise and tree regression procedures were used to identify the important factors. It is concluded that rainfall in its various forms is the primary determinant of grass production, standing crop, and composition, the latter either as perennials or Decreasers. Secondary determinants, in varying degrees of importance, are the thickness and base status of the A horizon, distance to permanent drinking water, and competition by woody plants. Herbivore utilization is insignificant or at most, plays a relatively minor role. Herbivores appear to exert a negative influence on Decreaser abundance only when soil moisture stress exceeds a threshold level. When this is exceeded, relatively low herbivore densities are apparently sufficient to reduce Decreaser abundance. The definitions of Decreasers and Increasers consequently require revision to take into account the overriding influence of environmental factors, particularly those of soil moisture stress. The calibration of the disc pasture meter was re-evaluated. The relation between mean disc height and standing crop is non-linear. Up to a mean disc pasture meter height of 260 mm, the correlation between this parameter and above-ground standing crop is very strong (r2 = 0.95; P<0.0005). Beyond this height, the correlation is very poor (r2 =0.09; P<0.0005), apparently being strongly influenced by the structure of the grass plant, with tall grasses, or grasses with highly lignified culms resulting in a weaker correlation. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

This study was conducted to determine livestock production, rangeland management and the mineral levels of soils, grass and cattle blood serum in two communal areas (Kwezana and Dikidikana). A total of 77 farmers from both Kwezana and Dikidikana were interviewed to determine farmers’ perceptions. Soil and grass sampling was done at three sites in each communal area. Soil and grass samples were analysed for N, Ca, Mg, K, P, Fe, Cu, Zn, Mn and Bo. Three, two and half year old Nguni heifers were randomly selected from each communal area and blood samples were collected for the analysis of Ca, Mg, K, Cu and Fe. Soil, grass and blood samples were all collected in two seasons (winter and summer). The results of the study revealed that feed availability was the major constraint in livestock production as indicated by 83 percent of thefarmers at Kwezana and 88 percent at Dikidikana. At both villages less than 20 percent practiced supplementation and grazing management. From both villages, 83 percent of the farmers did not know the forage species preferred by their cattle. The second study revealed significant seasonal variations in soil N in both study areas while forage N exhibited seasonal variations (P<0.05) only at Dikidikana. Spatial variation (P<0.05) in soil Mn was apparent in both seasons at Dikidikana and in summer at Kwezana. At Dikidikana forage P varied (P<0.05) both seasonally and spatially. In both study areas, there was a positive correlation (P<0.05) between soil and forage levels of Cu and Zn. The blood serum of animals from both study areas had higher (P<0.05) K and Na in winter than in summer. Farmers do not understand the composition of their rangelands but are concerned about cattle nutrition during winter. Indeed the mineral status of soils, forages and Nguni cattle blood serum tend to vary not only seasonally but also spatially. There is need therefore to assist the farmers to understand these changes in order to find ways of managing the rangelands in a way that will manipulate both seasonal and spatial variations in soil nutrients for the benefit of the grazing livestock. Further research is required to determine the digestibility of the forages and the amount of energy available from these forages for the grazing livestock.

In South Africa, communal and/or emerging farmers’ rangeland condition and grazing capacities deteriorate, because grazing capacity is usually over-estimated due to lack of knowledge on veld and livestock production system by the farmers. Woody plants has encroached in the arid and semi-arid savannas and grasslands biomes many parts of world, including in southern Africa. This causes challenges to farm owners due to its negative effects on the herbaceous plant material, which offers a substantial part of forage for livestock production. Although the consequences of deteriorating rangeland condition on livestock production is understood, there is limited research on the impact of land ownership on rangeland condition. Furthermore, knowledge on how farmers manages their livestock and rangelands. The objectives were to document the knowledge of emerging livestock farmers on livestock-rangeland management practices, and to determine the effects of land ownership and practices on rangeland condition. Firstly, we hypothesize that, emerging livestock farmers unknowingly manages livestock in isolation from their rangelands, and secondly, rangeland in private owned lands are relatively in good conditions compared to communal and leased lands. Fifty (50) emerging livestock farmers (i.e. ruminants) in different vegetation types and district municipalities of the Gauteng province were selected using a snowball procedure. To investigate the knowledge of emerging farmers on livestock - rangeland management practices, the farmers were asked questions about their 1) demographic information, 2) livestock management practices and 3) rangeland management practices. To test the differences in farmers’ demographic profiles, Chi-square statistics was employed. To determine the effects of land ownership on rangeland condition of the selected farms, rangeland condition among three land ownership types was compared using ANOVA, and the relations between veld condition score (%) and herbaceous biomass production (kg DM/ha) was tested using Pearson’s correlation analysis The results revealed that, the emerging livestock farmer are dominated by males (68 %) compared to female (32%). Majority (66%) of the farmers are old aged (> 50 years) compared to middle aged (30% (31 – 50 years)) and young (< 30 years) farmers (4%). Farmers who did not receive any agricultural training were higher (74%) than farmers who had prior training (26%). Sixty-three percent of the farmers had knowledge and understanding of breeding and calving seasons of their livestock, with only 27% having no knowledge and understanding of breeding and calving seasons of their animals. Eighty-three percent of the farmers keep mixed livestock (cattle, sheep and goats) species and 17% only keep cattle. The mean cattle herd sizes were significantly lower 8.2 ± 7.16 compared to goats and sheep (15.5 ±11.2). Feed shortage was the major constrain to livestock production (46%) compared to diseases (26%), marketing (14%), stock theft (8%) and other (6%) constrains. Sixty-three percent of the farmers had knowledge and understanding of breeding and calving seasons of their livestock, with only 27% having no knowledge and understanding. Eighty-three percent of the farmers keep mixed livestock (cattle, sheep and goats) species and 17% only keep cattle. All of the farmers indicated that they did not conduct rangeland condition assessment (mainly due to lack of knowledge). All farmers did not have fodder conservation plan for their farms and highlighted that during dry season, forage is scarce for their animals. Majority (58%) of the farmers relay on government-drought relief programme compared to those who were supplementing (20%), selling their animals (14%) and those with no drought coping strategy (8%). v Vegetation was assessed using nearest plant technique. In total, 28 grass species were identified during field survey, of which n=23, n=4 and n=2 were perennials, annuals and short-lived perennial, respectively. The most commonly observed and very palatable grass species, Digitaria eriantha had the highest frequency on private lands (n=92 and the lowest on communal lands (n=51). There were no significance difference in grass species richness and basal cover among land ownership types (P > 0.05). There were significant differences in veld condition score, large stock units, grazing capacity and herbaceous biomass production among land ownership types (P < 0.05). Private lands had a significantly higher veld condition score (69.63%) than leased (56.07%) and communal lands (52.55%). The herbaceous biomass production was positively correlated to the veld condition score (r = 0.159; P<0.005). The outcomes of this study show that emerging livestock farmers in Gauteng province have little understanding of rangeland-livestock management practices. The current results further indicated that poor grazing practices such as overgrazing might be common on leased and communal lands due to farmers’ lack of knowledge on rangeland management practices. This may lead to rangeland degradation thus negatively affecting livestock production and the livelihood of farmers who rely on farming as a source of income. / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)

South African rangelands in combination with their surrounding homesteads occupy 13% of the entire land surface in South Africa. These rangelands are a source of forage for communal livestock. The rangelands in communal tenure system are degraded due to high human population and livestock numbers. The rangeland of Peddie was never evaluated since the introduction of Nguni Cattle Empowerment Project. Therefore, socio-ecological evaluation was conducted in order to interlink farmer‟s perceptions and scientific data to recommend appropriate rangeland management and restoration programme. Two structured questionnaires consisting of close and open ended questions were used to investigate farmer‟s perceptions on rangeland condition, dynamics, and their causes. Sixty households were randomly selected on the bases of livestock ownership and the membership in Nguni Cattle Project. In each household, any respondent of 20 years or greater, and a key informant of age greater than 40 years were selected. For scientific assessment of range condition, three homogenous vegetation units namely grassland, scattered and dense bushland were demarcated into four 100m x 50m replicates. In each replicate, two 100m transects were laid parallel to each other with 30m equidistant apart. The step point and harvesting method along each transect were employed for herbaceous species composition and biomass production. The point-to-tuft distance was also determined as a proxy for basal cover. Woody density, species composition and tree equivalents were determined in 200m2 belt transects in each HVU replicates. The germination method for soil seed bank evaluation was also employed to find plant species composition and density. The soil nutrients (OC, N, P, K, Na, Ca, Mg, Zn, Cu and Mn) and pH were analysed through solution preparation and observation under photospectrometer to determine functional capacity of the soil of Peddie rangeland. The farmer‟s perceptions comprised of 63% females and 37% males (n = 120) with a mean household of 8 people, 5 adults and 3 children. It was perceived by 93.3% respondents that the rangeland of Peddie have undergone changes over two decades. These changes were perceived by 83% respondents to be accompanied by decline in livestock numbers. Woody encroachment and overgrazing were perceived to be the major attributes of these vegetation changes. The scientific rangeland condition assessment confirmed that these changes were more pronounced as bush density increases. Dense bushland had a significantly high (p<0.05) encroached condition with 6650 trees ha-1 and 4909.5 TE ha-1 beyond the recommended thresholds of 2400 trees ha-1 and 2500 TE ha-1 respectively. Scattered bushland had a fair condition of 1950 trees ha-1 and 1198.1TE ha-1. Themeda triandra as a key species was significantly higher (p<0.05) in grassland (31.1%) than scattered (15.6%) and dense bushland (6.1%). There was a declining trend in biomass production from grassland to dense bushland. The summer biomass production was significantly higher (p<0.05) in grassland than scattered and dense bushland but winter biomass was not significantly different (p>0.05) from all homogenous vegetation units of Peddie rangeland. However, the soil fertility increased with an increase in bush density except organic carbon (OC) which was 1.61% in grassland, 1.46% in scattered and 1.53% in dense bushland respectively. Soil N, K, P, Mg2+ Na+, Ca2+, Cu, Zn, Mn and pH were significantly higher (p<0.05) in dense bushland than grassland and scattered bushland. High soil fertility in dense bushland may be attributed to by abscission of woody plants and litter decomposition. In the soil seed bank, the abundances of forbs were significantly higher than sedges (χ2 = 12, df = 1, p = 0.001) and grasses (χ2 = 8.333, df = 1, p = 0.004) in all homogenous vegetation units while sedges were not significantly different (χ2 = 3, df = 1, p = 0.083) from grasses. The Sorensen‟s index indicated that soil seed bank and extant vegetation were significantly different (p<0.05). Annual and biennial forbs and sedges had high abundances while perennial grasses formed a bulk in above ground vegetation. This provided an insight that a reliance on soil seed bank for restoration of Peddie rangeland would not be advisable because it can result in retrogression. The communal rangeland assessment provided clear qualitative and quantitative data when the combination of indigenous knowledge and scientific assessments was done. The rationale is that conclusions and recommendations of range assessment are relient on the farmer‟s perceptions pertinent to their livestock production systems and their rangeland management objectives. This study has shown that inclusion of communal farmers in policy making can provide better insight because those are the people experiencing the consequences of range degradation.