Thesis (MScConEcol)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The role of mites as primary vectors of various fungi within Protea infructescences was recently confirmed and raised questions about their general diversity and their role within this unique niche. Although mites evidently form an integral part of Fynbos ecosystems and probably play a significant role in Protea population dynamics, there is a general void in our knowledge of mite diversity within the Cape Floristic Region. These organisms do not only affect ecological processes within the CFR, but also the economic value of Protea exports. This study sets out to describe mite communities within the infructescences of a variety Protea species. In the process, the role of various environmental variables and differences in host characteristics affecting these communities are also explored. A total of 24281 mite individuals, comprising of 36 morphospecies in 23 families, were collected from 16 surveyed Protea spp. Mite community structure and composition were significantly influenced by plant taxonomy, phenology and infructescence architecture in different Protea spp. At a temporal scale, infructescence age and season were influential factors on mite community structure. Collection locality significantly influenced mite communities within the infructescences of a single Protea sp. Host architecture had no influence on mite communities within a single host species. Geographic distance had no significant influence on mite community structure within Protea infructescences. This implies that factors particular to particular host species determine mite communities. These include factors such as the mode of pollination of the host plant, level of serotiny and plant life form. Numerous newly recorded mite species collected from Protea infructescences are also described in this study. An identification key to the Tydeidoidae of South Africa is provided here for the first time. This study forms a baseline dataset for future studies on the biodiversity of mites in this extremely diverse eco-region. / AFRIKAANSE OPSOMMING: Die rol van myte as primêre vektore van verskeie funguses binne Protea vrugtekoppe is onlangs bevestig, en het vrae laat ontstaan oor hulle algemene diversiteit en rol binne hierdie unieke nis. Alhoewel myte duidelik ‘n integrale deel vorm van Fynbos ekosisteme en waarskynlik ‘n belangrike rol speel in Protea populasie-dinamika, is daar ‘n algemene leemte in ons kennis van mytdiversiteit binne die Kaapse Floristiese Ryk (KFR). Hierdie organismes affekteer nie slegs ekologiese prosesse binne die KFR nie, maar ook die ekonomiese waarde van Protea-uitvoere. Hierdie studie mik as vertrekpunt om die verkillende myt-gemeenskappe binne die vrugtekoppe van verskeie Protea spesies te beskryf. In die proses is die rol van verskillende omgewingsveranderlikes en verskille in gasheer kenmerke wat hierdie gemeenskappe affekteer, ook ondersoek. ‘n Totaal van 24281 myt individue, saamgestel uit 36 morfspesies in 23 families, mytgemeenskappe is beduidende beinvloed deur die taksonomie van die plant, die fenologie en die vrugtekop-argitektuur van verskillende Protea spesies. Op ‘n temporale skaal is gevind dat vrugtekop-ouderdom en seisoen beduidende faktore is in die samestelling van mytgemeenskapstruktuur. Versamel-lokaliteit het verder mytgemeenskappe binne die vrugtekoppe mytgemeenskappe binne ‘n enkele gasheerspesie getoon nie. Geografiese afstand het geen beduidende invloed op mytgemeenskapstruktuur binne Protea vrugtekoppe getoon nie. Dit faktore in soos die metode van bestuiwing van die gasheer plant, die vlak van saadhoudendheid van die Protea koppe en plant-lewensvorm. Verskeie nuwe myt spesies wat uit Protea vrugtekoppe versamel is, word ook in hierdie studie beskryf. ‘n Identifikasie-sleutel vir die Tydeidoidae van Suid-Afrika word verder vir die eerste keer hier verskaf. Hierdie studie vorm die basis datastel vir toekomstige studies van die biodiversiteit van myte in hierdie besonder diverse eko-omgewing.

Thesis (MScConEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Invasive alien plants (IAPs) reduce streamflow and threaten the biodiversity of South Africa’s Cape Floristic Region. Up-to-date information on invasive vegetation is required for land management agencies to formulate policies and make appropriate resource management decisions. Invasion maps are typically not updated often enough because of the time and expenses required to do so. As a result, invasion maps for South Africa are limited to coarse resolution data or isolated small scale studies. Invasive alien plants change the landscape by destabilizing catchments and thereby increasing soil erosion, altering fire regimes and hydrology, as well as changing the physical and chemical composition of the soil. Information on IAPs is needed at a landscape scale. Remote sensing is a powerful tool that can be used to characterise landscapes in a biologically meaningful manner. The Normalised Difference Vegetation Index (NDVI) was used to create an up-to-date invasion map of the Agulhas Plain, lying at the heart of the species rich Cape Floristic Region. This information was combined with actual evapotranspiration data from the Surface Energy Balance Algorithm for Land (SEBAL) study done by Water Watch and the Council for Scientific and Industrial Research. The results showed that invasive vegetation uses more water than natural fynbos vegetation and that the greatest amount of water would be made available by clearing the invaded deep sands on the Agulhas Plain. These deep sand areas conflict with the priority areas of the Working for Water programme. This IAP eradication programme targets sparsely invaded upland areas for long-term sustainability. The recommendation of this study is to clear invaded wetland and riparian areas as these zones yield the greatest hydrological benefit per hectare and meet the priorities of Working for Water. Overall, 36 million cubic meters of water would be made available by clearing the Agulhas Plain. It can be concluded that there is a significant hydrological benefit to clearing invasive alien vegetation on the Agulhas Plain. / AFRIKAANSE OPSOMMING: Indringerplante (IP) verminder stroomvloei en bedreig die biodiversiteit van Suid-Afrika se Kaapse Floristiese Streek. Die nuutste inligting oor uitheemse plantegroei is nodig vir grondbestuuragentskappe om beleide te formuleer vir die neem van toepaslike hulpbronbestuur besluite. As gevolg van die tyd en uitgawes wat nodig is om indringingskaarte op te dateer, word dit gewoonlik nie dikwels genoeg gedoen nie. Dus is indringingskaarte vir Suid-Afrika beperk tot growwe resolusie data of geïsoleerde kleinskaal studies. Indringerplante verander die landskap deur opvangsgebiede te destabiliseer en sodoende te lei tot gronderosie, verandering van vuurregimes en hidrologie, sowel as die verandering in die fisiese en chemiese samestelling van die grond. Inligting oor IP is nodig op 'n landskapskaal. Afstandswaarneming is 'n kragtige tegniek wat gebruik kan word om landskappe op 'n biologies betekenisvolle manier te karakteriseer. Die Normalised Difference plantegroei-indeks (NDVI) is gebruik om 'n opgedateerde indringingskaart van die Agulhas-vlakte, wat in die hart van die spesiesryke Kaapse Floristiese Streek lê, te skep. Hierdie inligting is gekombineer met die werklike evapotranspirasie data vanaf die Surface Energy Balance Algorithm for Land (SEBAL) studie gedoen deur Water Watch en die Raad vir Wetenskaplike en Nywerheidnavorsing. Die resultate het getoon dat uitheemse plantegroei meer water gebruik as natuurlike fynbosplantegroei en dat die grootste hoeveelheid van hierdie water beskikbaar gestel sal word deur IP op diepsand op die Agulhas-vlakte skoonte maak. Hierdie diepsand areas is in konflik met die prioriteitsgebiede van die Werk vir Water-program. Hierdie IP uitroeiingsprogram fokus op yl ingedringde berggebiede vir langtermyn volhoubaarheid. Die aanbeveling van hierdie studie is om duidelik ingedringde vleilande en oewergebiede skoon te maak, siende dat hierdie sones die hoogste opbrengs en die grootste hidrologiese voordeel per hektaar bied, en voldoen aan die prioriteite van Werk vir Water. In totaal sou 36 miljoen kubieke meter water beskikbaar gestel word deur die skoonmaak van die Agulhas-vlakte. Dus kan dit afgelei word dat die verwydering van hidrologiese indringerplante op die Agulhas-vlakte 'n beduidende voordeel sal inhou.

Thesis (MScConEcol)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Declines in natural capital, such as the degradation of ecosystems and loss of species, are the result of threats created by anthropogenic activities. The concept of sustainable development encompasses the economic and social growth of societies, with limited impacts on the natural environment. Sustainable development initiatives are being implemented in an attempt to mitigate the global decline in natural capital. Biosphere reserves, which are designated by the United Nations Educational, Scientific and Cultural Organisation’s (UNESCO) Man and the Biosphere Programme, aim to be landscape-scale examples of sustainable development. UNESCO requires biosphere reserves to submit a periodic review every ten years to ensure they are meeting their goals. This requires that that they monitor and evaluate their progress towards their sustainable development goals. Sustainability indicators are tools used to assess progress towards ecological, social and economic goals, and can thus be useful tools for biosphere reserves to ensure they are achieving their goals. The Kogelberg and Cape West Coast Biosphere Reserves are both situated within the Cape Floristic Region (CFR). The CFR, located in the South-West of South Africa, has been identified as a biodiversity hotspot owing to its high plant diversity. About a fifth of the CFR is formally protected, while about three quarters has been transformed, mainly by cultivated lands, urban areas and alien vegetation. The socio-economic dimensions of the region are also diverse. A high percentage of its inhabitants have low incomes and live in informal settlements, while a smaller percentage have high incomes and live in middle to upper-class urban areas. Biosphere reserves aim to encourage their diverse stakeholders to collaboratively develop and work towards sustainable development goals. This research project applied an action research approach. The research objectives were achieved through collaboration with biosphere reserve stakeholders. The first objective was to develop sustainability indicator sets for the Kogelberg and Cape West Coast Biosphere Reserves. Following the introduction to the research provided in Chapter 1, Chapters 2, 3 and 4 of this thesis describe the stages of the research process undertaken to achieve this objective. With the aim of investigating monitoring and evaluation within biosphere reserves, Chapter 2 presents a systematic review of the peer-reviewed and grey literature and Chapter 3 presents the results of interviews with managers of South African biosphere reserves and a web-based survey of the World Network of Biosphere Reserves. Chapter 4 describes the collaborative process of conducting local stakeholder workshops and specialist focus groups to develop sets of sustainability indicators; one set each for the Kogelberg and Cape West Coast Biosphere Reserves. The second objective was to formulate a national protocol for the development of sustainability indicators for South African biosphere reserves. This was developed through a synthesis of the results and lessons learnt in Chapters 2 to 4. This national protocol was designed to be flexible enough to be adapted to the local circumstances and needs of individual South African biosphere reserves. The global review of the peer-reviewed and grey literature revealed that monitoring and evaluation studies in biosphere reserves are mostly conducted in the developing world by authors from the developed world and many of the studies and indicators that were developed focused on ecological dimensions. These results show that biosphere reserves need to enhance their local capacity for the development and implementation of improved monitoring and evaluation methods and frameworks. The outcomes of the interviews with representatives of the management of South African biosphere reserves and a survey of the World Network of Biosphere Reserves found that many biosphere reserves identified in this survey are reportedly implementing monitoring and evaluation, but few have developed sustainability indicators. It was found that there are many similar challenges with regards to monitoring and evaluation in biosphere reserves, most notably the lack of capacity and funding Lastly, the collaborative process used to develop sustainability indicators for the Kogelberg and Cape West Coast Biosphere Reserves proved to be useful and produced the desired outcomes. The local stakeholder workshops produced large sustainability indicator sets, with many indicators that were immeasurable, but most were relevant to the biosphere reserves. The specialist focus groups produced more focused and feasible indicator sets. The local stakeholder and specialist indicator sets were integrated to produce a final set for each biosphere reserve that was relevant to the social-ecological systems of the biosphere reserves, with indicators that could feasibly be implemented. The action research approach applied in this study delivered a pragmatic set of sustainability indicators that can be implemented by both biosphere reserves. The National Department of Environmental Affairs, and the Kogelberg and Cape West Coast Biosphere Reserve co-ordinators have encouraged and supported the development of the sustainability indicator sets and the national protocol. Supporting these with a social learning institution within each biosphere reserve will be required for ensuring their on-going utility. / AFRIKAANSE OPSOMMING: Dalings in natuurlike kapitaal, soos die degradasie van ekosisteme en die verlies van spesies, is die gevolg van die bedreigings wat geskep word deur menslike aktiwiteite. Die konsep van volhoubare ontwikkeling behels die ekonomiese en sosiale ontwikkeling van samelewings, met beperkte impak op die natuurlike omgewing. Volhoubare ontwikkelings inisiatiewe word geïmplementeer in 'n poging om die afname in natuurlike kapitaal te verminder. Die doel van biosfeerreservate, wat aangewys is deur die Verenigde Nasies se Opvoedkundige, Wetenskaplike en Kulturele Organisasie (UNESCO) se Man en die Biosfeer-program, is om landskap-skaal voorbeelde van volhoubare ontwikkeling te wees. UNESCO vereis dat biosfeerreservate 'n periodieke hersiening elke tien jaar voor te lê om te verseker dat hulle op pad is om hul doelwitte te bereik. Dit vereis dat hulle moet hul vordering monitor en evalueer teenoor hul volhoubare ontwikkelingsdoelwitte. Volhoubaarheid aanwysers word gebruik om vordering ten opsigte van ekologiese, sosiale en ekonomiese doelwitte te bepaal, en kan dus nuttig wees vir biosfeerreservate om te verseker dat hulle hul doelwitte bereik. Die Kogelberg en Kaapse Weskus Biosfeerreservate is beide in die Kaapse Floristiese Omgewing (KFO) geleë. Die KFO, wat in die Suid-Wes van Suid-Afrika geleë is, is geïdentifiseer as 'n biodiversiteit-brandpunt as gevolg van sy hoë plant diversiteit. Oor 1/5 van die KFO is formeel beskerm terwyl ongeveer 3/4 omskep is, hoofsaaklik deur bewerkte landerye, stedelike gebiede en uitheemse plantegroei. Die sosio-ekonomiese aspekte van die omgewing is ook uiteenlopend. 'n Hoë persentasie van die bevolking het 'n lae inkomste en woon in informele nedersettings, terwyl 'n kleiner persentasie het 'n hoë inkomste en woon in middel tot bo-klas stedelike gebiede. Biosfeerreservate streef daarna om hul diverse rolspelers aan te moedig om saam volhoubare ontwikkelingsdoelwitte te ontwikkel. Hierdie navorsingsprojek het 'n aksie-navorsing nadering toegepas. Die navorsing doelwitte is bereik deur middel van samewerking met biosfeerreservaat rolspelers. Die eerste doelwit was om volhoubaarheid aanwyser stelle vir die Kogelberg en Kaapse Weskus Biosfeerreservate te ontwikkel. Na aanleiding van die Inleiding tot die navorsing wat in Hoofstuk 1, Hoofstuk 2, 3 en 4 van hierdie tesis beskryf die fases van die navorsing wat onderneem is om hierdie doelwit te bereik. Met die doel van die ondersoek van monitering en evaluering binne biosfeerreservate, Hoofstuk 2 bied 'n sistematiese hersiening van die eweknie-geëvalueerde en grys literatuur aan en Hoofstuk 3 bied die resultate van onderhoude met bestuurders van Suid-Afrikaanse biosfeerreservate en 'n web-gebaseerde ondersoek van die wêreld Netwerk van Biosfeerreservate aan. Hoofstuk 4 beskryf die saamwerkende proses van die uitvoer van plaaslike rolspeler werkswinkels en spesialis fokusgroepe stelle van volhoubaarheid aanwysers te ontwikkel; een stel elk vir die Kogelberg en Kaapse Weskus Biosfeerreservate. Die tweede doelwit is om 'n nasionale protokol vir die ontwikkeling van volhoubaarheid aanwysers vir Suid-Afrikaanse biosfeerreservate te formuleer. Dit is ontwikkel deur middel van 'n sintese van die resultate en lesse wat geleer is in Hoofstukke 2 tot 4. Hierdie nasionale protokol is ontwerp om buigsaam genoeg te wees om aangepas te word by die plaaslike omstandighede en behoeftes van individuele Suid-Afrikaanse biosfeerreservate. Die globale oorsig van die eweknie-geëvalueerde en grys literatuur het gewys dat monitering en evaluering studies in biosfeerreservate word meestal in die ontwikkelende wêreld uitgevoer deur die skrywers van die ontwikkelde wêreld en baie van die studies en aanwysers wat ontwikkel word is gefokus op ekologiese dimensies. Hierdie resultate dui aan dat biosfeerreservate hul plaaslike kapasiteit vir die ontwikkeling en implementering van monitering en evaluering metodes en raamwerke moet verbeter. Die uitkomste van die onderhoude met verteenwoordigers van die bestuur van die Suid-Afrikaanse biosfeerreservate en 'n ondersoek van die Wêreld Netwerk van Biosfeerreservate dui aan dat baie van die biosfeerreservate wat in hierdie ondersoek na berig word implementeer monitering en evaluering, maar min het volhoubaarheid aanwysers ontwikkel. Daar is gevind dat daar baie soortgelyke uitdagings met betrekking tot monitering en evaluering in biosfeerreservate, veral die gebrek aan kapasiteit en befondsing Ten slotte, die gesamentlike proses wat gebruik is om die volhoubaarheid aanwysers vir die Kogelberg en Kaapse Weskus Biosfeerreservate te ontwikkel het bewys om nuttig te wees en het die verlangde uitkomste gelewer. Die plaaslike rolspeler werkswinkels het groot volhoubaarheid aanwyser stelle geproduseer, met baie onmeetbare aanwysers, maar meeste van die aanysers was relevant tot die biosfeer-reservate. Die spesialis fokusgroepe het meer gefokusde en uitvoerbaar aanwyser stelle geproduseer. Die plaaslike rolspeler en spesialis aanwyser stelle is geïntegreer in 'n finale stel vir elke biosfeerreservaat wat relevant is tot die sosiaal-ekologiese stelsels van die biosfeer-reservate, met aanwysers wat uitvoerbaar is. Die aksie-navorsing benadering wat in hierdie studie toegepas is het 'n pragmatiese stel van volhoubaarheid aanwysers afgelewer wat sal deur beide biosfeerreservate geïmplementeer word. Die Nasionale Departement van Omgewingsake, en die Kogelberg en Kaapse Weskus Biosfeer Reservaat koördineerders het die ontwikkeling van die volhoubaarheid aanwyser stelle en die Nasionale Protokol aangemoedig en ondersteun. Ondersteuning van hierdie uitsette met 'n sosiale leer instelling binne elke biosfeerreservaat sal vereis wees om hul deurlopende nut te verseker.

Thesis (MScConEcol)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The aim of the research presented in this dissertation was to investigate localised acridid outbreaks causing damage to sugarcane in Empangeni, Kwazulu-Natal, South Africa. Reports of outbreaks with increasing severity have occurred for the last six or seven years, which prompted this research. In general, little is known about acridid outbreaks in sugarcane due to their sporadic nature, therefore this project set out to identify morphologically and molecularly, all species associated with Empangeni sugarcane and to determine the ecology and population dynamics of the most important species, to provide baseline data for the development of an integrated pest management (IPM) plan against these crop pests. A year-long population survey was conducted on a number of affected farms and adjacent grassland sites to determine the life cycles, population density and composition of this acridid complex on these farms. Surveys showed that this complex comprised five species: Nomadacris septemfasciata, Petamella prosternalis, Ornithacris cyanea, Cyrtacanthacris aeruginosa and Cataloipus zuluensis. Observed damage was recorded throughout the year in order to correlate with species densities. It was found that damage was closely associated with two species, namely Petamella prosternalis and Nomadacris septemfasciata, therefore these two species are of particular concern due to their higher densities and large body size resulting in them being the biggest threat to Empangeni sugarcane. All five species are univoltine but two different life cycle strategies were discovered, 3 species exhibit a winter egg diapause while 2 species exhibit a winter adult reproductive diapause, an important finding considering the knowledge intensive method of control which has been proposed. Population surveys revealed a large difference in species composition among farms (sugarcane sites) and among grassland sites. Nomadacris septemfasciata and Petamella prosternalis showed a significant preference for sugarcane while species such as Cyrtacanthacris aeruginosa, Zonocerus elegans and Orthocta sp. seemed to prefer grassland sites. Feeding potential trials were completed on the two most economically important species, Nomadacris septemfasciata and Petamella prosternalis. The results showed that Petamella prosternalis has a significantly higher feeding potential (% leaf damage) compared to Nomadacris septemfasciata even though in terms of dry weight and length, it is a smaller specimen. Feeding data were used to determine the voracity of these two species under laboratory conditions. Petamella prosternalis eats roughly 1.83 grams of fresh sugarcane per day while Nomadacris septemfasciata eats approximately 1.16 grams per day. These results were then compared to observed field damage data in order to gauge their accuracy and applicability within a field setting, which showed that although sugarcane field damage is significantly correlated with the population fluctuations of both these species, it is more closely associated with Petamella prosternalis resulting in a correlation coefficient of 0.429143 while Nomadacris septemfasciata had a correlation coefficient of 0.250. Phase polyphenism in the red locust Nomadacris septemfasciata was investigated using three methods including traditional morphometrics (Elytra/Femur (E/F) ratio), hopper colouration and eye stripe data. The E/F ratio indicated that the majority of the Empangeni population sampled is in the transiens and gregarious phase with a mean E/F ratio of 2.0063 and that they seem to be becoming more gregarious over time, with populations in 2012 having a mean E/F ratio of 1.9973 and in 2013 a mean E/F ratio of 2.01315. Hopper colouration also indicates that populations are generally showing gregarious tendencies with the majority of hoppers exhibiting gregarious type colouration. Eye stripe data showed that the majority of adult specimens observed had seven eye stripes, an indication of gregarious individuals. Geometric morphometrics, a relatively new, software based technique which has not been used in phase polyphenism studies before was used as a means to accurately measure variations among populations of N. septemfasciata by measuring the variation in forewing shape according to allocated landmarks. The resulting shape variation were compared to traditional morphometrics in an attempt to relate the two techniques so that geometric morphometrics can possibly be used as a tool to study phase polyphenism in locusts in the future. The results indicate that similarities in terms of location and gender exist between the two methods, however the exact same individuals should be used for both methods which will improve the accuracy of comparisons. This study, for the first time identified the acridid complex causing damage to Empangeni sugarcane and provided a broad summary of the potential impact the complex has on the crop as well as what may be causing them to occur in this area such as optimal habitat conditions and sugarcane as a preferable host plant being two factors which are likely to be having an influence. The findings of this study provide the baseline data needed in order to develop a more integrated and sustainable approach to controlling these acridids pests. Understanding the biology of the species enables practitioners to make more effective management decisions which is clearly needed as the current techniques being used have not solved the ‘grasshopper problem’. / AFRIKAANSE OPSOMMING: Die doel van die navorsing wat in hierdie verhandeling was om ondersoek in te gelokaliseerde acridid uitbrekings veroorsaak skade aan suikerriet in Empangeni, KwaZulu-Natal, Suid-Afrika. Verslae van die uitbreek met toenemende erns plaasgevind het vir die laaste 6-7 jaar, wat gelei het tot hierdie navorsing. In die algemeen, is min bekend oor acridid uitbreek in suikerriet as gevolg van hul sporadiese aard, daarom is hierdie projek uiteengesit morfologies en molekulêre identifiseer, al die spesies wat verband hou met Empangeni suikerriet en die ekologie en bevolkingsdinamika van die belangrikste spesies te bepaal, te voorsien basislyn data vir die ontwikkeling van 'n geïntegreerde plaagbestuur (GPB) plan teen hierdie oes peste. 'N jaar lank bevolking opname is uitgevoer op 'n aantal plase wat geraak is en aangrensende grasveld plekke om die lewensiklus te bepaal, bevolkingsdigtheid en samestelling van hierdie acridid kompleks op die plase . Opnames het getoon dat hierdie komplekse bestaan uit vyf spesies: Nomadacris septemfasciata, Petamella prosternalis, Ornithacris Cyanea, Cyrtacanthacris aeruginosa en Cataloipus zuluensis Waargeneem skade is aangeteken deur die jaar ten einde te ooreenstem met spesie digtheid. Daar is gevind dat die skade was nou verbind met twee spesies, naamlik P. prosternalis en N. septemfasciata, dus is die twee spesies van besondere belang as gevolg van hul hoër digtheid en 'n groot liggaam grootte lei daartoe dat hulle die grootste bedreiging vir die Empangeni suikerriet. Al vyf spesies is univoltine maar twee verskillende lewensiklus strategieë ontdek, 3 spesies toon 'n winter eier diapouse terwyl 2 spesies toon 'n winter volwasse reproduktiewe diapouse, 'n belangrike bevinding oorweging van die kennis intensiewe metode van beheer wat is voorgestel. Bevolking opnames openbaar 'n groot verskil in spesies samestelling onder plase (suikerriet webwerwe) en onder grasveld webwerwe. Nomadacris septemfasciata en Petamella prosternalis het 'n beduidende voorkeur vir suikerriet, terwyl spesies soos Cyrtacanthacris aeruginosa, Zonocerus elegans en Orthocta SP. gelyk grasveld webwerwe te verkies. Voeding potensiaal proewe is op die twee mees ekonomies belangrike spesies voltooi, Nomadacris septemfasciata en Petamella prosternalis Die resultate het getoon dat Petamella prosternalis het 'n aansienlik hoër voeding potensiaal(% blaarskade) in vergelyking met Nomadacris septemfasciata selfs al in terme van droë gewig en lengte, is dit is 'n kleiner model. Voeding data is gebruik om die gulzig van hierdie twee spesies onder laboratorium toestande te bepaal. Petamella prosternalis eet ongeveer 1.83 gram vars suikerriet per dag, terwyl Nomadacris septemfasciata eet ongeveer 1,16 gram per dag. Hierdie resultate is dan in vergelyking met waargeneem veld skade data om die akkuraatheid en toepaslikheid in 'n veld omgewing, wat getoon het dat hoewel suikerriet veld skade beduidend gekorreleer met die bevolking skommelinge van beide hierdie spesies, is nouer dit verband hou met Petamella prosternalis te meet lei tot 'n korrelasie koëffisiënt van 0.429143 terwyl Nomadacris septemfasciata het 'n korrelasie koëffisiënt van 0.250408 Fase polyphenism in die rooisprinkaan Nomadacris septemfasciata is ondersoek met behulp van drie metodes, insluitend tradisionele Morphometricsveld (Elytra/Femur (E/F) verhouding), hopper kleur en oog streep data. Die Elytra te Femur verhouding (E/F -verhouding) het aangedui dat die meerderheid van die bevolking is Empangeni in die transiens en gesellige fase met 'n gemiddelde E/F verhouding van 2,0063 en dat dit lyk asof hulle meer kuddedier met verloop van tyd, met bevolkings in 2012 met 'n gemiddelde E/F verhouding van 1,9973 en in 2013 'n gemiddelde E/F verhouding van 2,01315 . Hopper kleur dui ook aan dat die bevolking in die algemeen toon kuddedier neigings Thye meerderheid van hoppers uitstal gesellige tipe kleur. Oog streep het getoon dat die meerderheid van die volwasse eksemplare waargeneem het sewe oog strepe: 'n aanduiding van die gesellige individue. Geometriese Morphometricsveld, 'n relatief nuwe, sagteware gebaseer tegniek wat nie gebruik is in fase polyphenism studies voor was gebruik as 'n middel tot verskille tussen bevolkings van die rooisprinkaan akkuraat te meet deur die variasie meet in voorvlerk vorm volgens toegeken landmerke Die gevolglike vorm variasie is in vergelyking met die tradisionele Morphometricsveld in 'n poging om die twee tegnieke in verband te bring , sodat meetkundige Morphometricsveld kan moontlik as 'n instrument fase polyphenism om te studeer in sprinkane in die toekoms gebruik kan word. Die resultate dui daarop dat die ooreenkomste in terme van ligging en geslag bestaan tussen die twee metodes is egter presies dieselfde individue moet gebruik word vir beide metodes wat die akkuraatheid van vergelykings verbeter. Hierdie studie, wat vir die eerste keer geïdentifiseer die acridid kompleks om skade aan Empangeni suikerriet en verskaf 'n breë opsomming van die potensiële impak van die kompleks het op die gewas sowel as wat kan veroorsaak word om hulle te kom in hierdie gebied soos optimale habitat toestande en suikerriet as 'n beter gasheer plant. Die bevindinge van hierdie studie verskaf die basislyn data wat nodig is om 'n meer geïntegreerde en volhoubare benadering tot die beheer van hulle as die begrip van die biologie van die spesie in staat stel om praktisyns meer effektiewe bestuur besluite wat duidelik nodig is as 'n die huidige tegnieke gebruik moet maak om te ontwikkel nie opgelos die "sprinkaan probleem".

Thesis (MScConEcol)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Restoration practices commonly make use of a reference condition in order to restore a site to a better ecological state than it is currently in. The selection process and relevance of the reference condition has not yet been tested in upland Western Cape rivers especially with relation to spatial and temporal scales. This thesis sought to evaluate whether space (longitudinal) and time (temporal) influence riparian plant community composition (laterally), how it influences the community composition and whether these differences impacts the selection of a reference condition used in restoration practices. In order to investigate the role longitudinal position, sites were selected across three longitudinal zones: mountain stream, transitional and upper foothills. Historic sites used in a previous study on riparian vegetation of upland rivers were resampled and datasets used for temporal comparisons between undisturbed sites, sites recovering after clearing of invasive alien plants and sites affected by fire. Riparian vegetation communities showed differences between longitudinal zones, basins and rivers. The species responsible for marginal zone identity (plants in close proximity to the active channel), determined using relative cover abundance varied, with Isolepis prolifera responsible for the group identity in the mountain stream and transitional sites but in the foothills Calopsis paniculata, Drosera capensis and Metrosideros angustifolia saplings were responsible for lateral zone identity. The lower dynamic (transitional between wet and drybank) had no similarities between different longitudinal zones across rivers. In the lower zone Pteridium aqualinum was mostly responsible for the identity. The upper bank had no single species responsible for group identity. The species described to be typical for the reference condition on these particular rivers by other studies were mostly present in the comparable lateral zone but it was however not always responsible for the identity of the specific lateral zone. By comparing selected environmental variables such as horizontal distance from active channel, elevation and substrate calibre with different longitudinal zones’ riparian vegetation species distribution, different combinations were produced. The mountain streams showed the strongest relationship with horizontal distance and elevation in combination to one another and the upper foothills horizontal distance from the active channel was linked most strongly to vegetation positioning. These results confirm the importance of space when attempting to assess, study or restore riparian communities. Temporally, sites had stronger similarity to data collected during the same sampling period than with historic data. Also, the overall relative species abundance did not show significant change to be present at a site scale. The changes in community composition were found to be due to a lateral zone scale variation in species abundance. As expected the undisturbed rivers showed less variation in species responsible for temporal changes than the recovering and fire-exposed rivers. Species responsible for changes in relative abundance at a lateral zone scale were Metrosideros angustifolia, Morella serrata, Brabejum stellatifolium, Isolepis prolifera, Elegia capensis, Prionium serratum and Calopsis paniculata. Due to the species diversity not changing much temporally but the relative abundance of specific species showing much variation over time it can be concluded that the changes are not diversity based but instead driven by changes in relative abundances of species typical for a lateral zone. The spatial and temporal variation in riparian vegetation community composition was found to be significant enough to suggest that the use of a fixed reference condition for all Western Cape rivers would not be feasible due to clear differences between basins. Secondly when selecting a reference site the spatial location of this site should be within the same longitudinal zone since bank shape does influence riparian plant species distribution. Finally the temporal comparison between sites showed high diversity in species abundances but small differences in diversity overall. This would suggest that a general community description specific to 1) where the site is situated and 2) based on the present riparian vegetation community composition within a specific basin may be more realistic and achievable for restoration and environmental management purposes as opposed to using site descriptions from the past and reference sites too far upstream or downstream from the restoration site. / AFRIKAANSE OPSOMMING: Herstel praktyke maak algemeen gebruik van 'n verwysing toestand om 'n terrein te herstel na 'n beter ekologiese toestand as wat dit tans is. Die keuringsproses en relevansie van die verwysing toestand is nog nie in die boonste gedeeltes van Wes-Kaap Riviere getoets nie, veral met betrekking tot ruimtelike en tydskale nie. Hierdie tesis het gesoek om te evalueer of ruimte (longitudinaal) en tyd (temporaal) rivieroewers plant gemeenskap samestelling (lateraal) beïnvloed en of hierdie verskille die keuse van 'n verwysing toestand in die herstel praktyke beïnvloed. Ondersoek terreine was oor drie longitudinale sones geselekteer: berg stroom, oorgangs en boonste hange terreine. Historiese terreine was weer ondersoek en die datastelle was gebruik vir die temporale vergelykings tussen onversteurde terreine, terreine wat herstel na die skoonmaak van indringer spesies en wat geraak was deur 'n brand. Oewerplantegroei gemeenskappe het verskille tussen longitudinale sones, rivier-kom en rivier takke gewys. Die spesies wat verantwoordelik was vir marginale zone (plante in nabye afstand met die aktiewe rivier kanaal) identiteit, bepaal met behulp van relatiewe dekking hoeveelheid, het gevarieer met Isolepis prolifera verantwoordelik vir die groep identiteit in die berg stroom en oorgangs trerreine, maar in die boonste hange was dit Calopsis paniculata, Drossera capensis en Metrosideros angustifolia boompies wat verantwoordelik was vir die laterale sone identiteit. Die laer dinamiese area het geen ooreenkomste tussen marginale gebiede van verskillende longitudinale sones gehad nie. In die onderste sone was Pteridium aqualinum meestal verantwoordelik vir die groepering se identiteit. Die boonste bank het nie 'n enkele spesie wat verantwoordelik was vir die groep identiteit gehad nie. Die spesies beskryf as tipies vir die laterale sone deur Reinecke et al. (2007) was meestal teenwoordig in die beskryfde laterale sone van hierdie studie, maar dit was egter nie altyd verantwoordelik vir die identiteit van die laterale sone gemeenskap nie. Verskillende lengte sones het gekorreleer met verskillende omgewingsveranderlikes wat sterkste gekoppel kon word aan die verspreiding van spesies. Die bergstrome het die sterkste verhouding met horisontale afstand en hoogte in kombinasie met mekaar gehad en in die boonste hange was horisontale afstand van die aktiewe kanaal die sterkste gekoppel aan plantegroei posisie. Die belangrikheid van ruimte is onmiskenbaar ten opsigte van evaluering, bestudering en die herstel van rivieroewers gemeenskappe. Terreine het sterker ooreenkoms met data gehad wat tydens dieselfde tydperk versamel was, as met historiese data. Die algehele relatiewe spesies hoeveelheid het egter nie beduidende verandering getoon op 'n terrein skaal nie. Soos verwag was het die onversteurde riviere minder temporale variasie in spesies getoon as die herstellende en brand blootgestelde riviere. Spesies wat verantwoordelik was vir die verandering in relatiewe hoeveelhede op 'n laterale sone skaal was M. angustifolia, Morella serrata, Brabejum stellatifolium, I. prolifera, Elegia capensis, Prionium serratum en C. paniculata. As gevolg van die diversiteit van spesies wat nie baie verander het tydelik nie, maar die relatiewe hoeveelheid van spesifieke spesies wat heelwat variasie oor tyd getoon het, kan dit afgelei word dat die veranderinge nie diversiteit gebaseerd was nie, maar eerder gedryf was deur veranderinge in relatiewe hoeveelhede van tipiese spesies in 'n laterale sone. Die ruimtelike en tydelike variasie in oewerplantegroei gemeenskap samestelling was beduidende genoeg om voor te stel dat die gebruik van 'n vaste verwysing toestand vir alle Wes-Kaapse riviere nie haalbaar sou wees nie as gevolg van duidelike verskille tussen riviere. Tweedens, by die kies van 'n verwysing terrein moet die ruimtelike plek van hierdie terrein in dieselfde lengte sone wees aangesien bank vorm 'n invloed op rivieroewer plant verspreiding het. Laaastens, het die tydelike vergelyking tussen terreine hoë diversiteit in spesies verspreidings maar klein verskille in algehele diversiteit gehad. Dit stel voor dat 'n algemene beskrywing van die gemeenskap wat spesifiek op 1) waar die terrein geleë is en 2) gebaseer op die huidige oewerplantegroei gemeenskap samestelling binne 'n spesifieke rivier netwerk dalk meer realisties en haalbaar vir hersteel en bestuurs doeleindes sou wees. Hierdie benadering word verkies bo die gebruik van n terrein beskrywings uit die verlede en verwysing terreine te ver stroomop of stroomaf van die herstel gebied.

Thesis (PhD (Agric) (Conservation Ecology and Entomology))--University of Stellenbosch, 2006. / A study was performed to develop a generic pest monitoring system for sampling the main table grape pests in vineyards in the Hex River Valley, Western Cape Province of South Africa. The presence of phytophagous and predatory mites on cover crop plants was also investigated as this may contribute to biological control of the phytophagous mites in vines. Life table studies for Epichoristodes acerbella (Walker), an important phytosanitary pest, were conducted to determine whether or not this pest was sensitive to high temperatures. Information gained from the latter can also be used for breeding purposes in the possible future development of a sterile insect technique (SIT) programme to control this pest. The sampling system consisted of inspecting 20 plots of five vines per plot per one to two hectares. The top fork of each of the five vines per plot was examined for Planococcus ficus (Signoret) to a distance of within 30 cm of the stem, as well as the distal 15 cm of one cane per vine for the presence of P. ficus and damage caused by Phlyctinus callosus Boh. One bunch per vine was examined for insect damage or presence, and one leaf per vine for the presence of leaf infesting arthropods, such as Tetranychus urticae Koch, P. ficus and Frankliniella occidentalis (Pergande). Corrugated cardboard bands, tied around the stem of one vine per plot, were used to monitor activity of P. callosus. Blue sticky traps, at a density of four to five traps per one to two hectares, were used to monitor activity of F. occidentalis. Pheromone traps, at a density of one trap per one to two hectares, were used to monitor activity of P. ficus, E. acerbella and Helicoverpa armigera (Hübner). All the above-mentioned inspections were done at two-weekly intervals, except traps for E. acerbella and H. armigera, which were inspected weekly. In each of the rows in which the sample plots were situated, one leaf of each of the cover crop plant species was examined for the presence of phytophagous mites and their predators. The abundance and distribution of cover crop plants were determined using a co-ordinate sampling system. Cover crop sampling was done at monthly intervals. The current threshold for P. ficus is 2% stem infestation, which is reached when more than 65 males per pheromone trap are recorded. Counting mealybugs on the sticky pads in the pheromone traps is time consuming. However, the number of grid blocks on the sticky pad with males present can be counted. When P. ficus males are found in 27 blocks on the sticky pad, stem inspections should commence. Due to the spatial association between P. ficus bunch and stem infestation, stem infestation could give an indication of where bunch infestation could be expected. The use of blue sticky traps for predicting halo spot damage, caused by F. occidentalis, is not recommended. The presence of thrips on the vine leaves could not give an indication of where to expect bunch damage, since thrips on the leaves and halo spot damage were not spatially associated. A suitable sampling method for F. occidentalis still needs to be developed. The monitoring system described here can only provide information on the infestation status of the vineyard. For E. acerbella, H. armigera and P. callosus, the traps and cardboard bands could be used to identify vineyards where these pests are present and therefore, where phytosanitary problems may arise. The presence of P. callosus under the bands was spatially associated with P. callosus damage and could be used as an indicator of the latter. The presence of drosophilid flies in the bunches could not be used as an indicator of the presence of E. acerbella in the bunches. If 5% bunch damage is used as an economic threshold for E. acerbella and P. callosus, there will be a good chance of not under spraying if control measures are applied at 1% bunch damage. Epichoristodes acerbella favoured more moderate constant temperatures, with constant temperatures of 28°C and above being unfavourable for development. The economic threshold for Tetranychus urticae Koch is six mites per leaf, or if presence-absence sampling is used, 11 to 29% leaf infestation. Three important predatory mites, that kept T. urticae under control, were found in the Hex River Valley, namely Euseius addoensis (Van der Merwe & Ryke), Neoseiulus californicus (McGregor) and an undescribed phytoseiid in the genus Typhlodromus. Various cover crop plants served as hosts for T. urticae and predatory mites. The presence of these plants created suitable conditions for the survival of these mites and may have influenced their presence on the vine leaves. In the case of phytosanitary pests, both field and pack shed inspections can be used to conclude with a 99% degree of certainty that infestation levels in the pack shed will be 10% or less, since similar results for both methods were obtained. However, more than 20 plots will have to be inspected.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This study tested the proposal that fleshy-fruited alien shrubs competed more effectively for avian dispersal services than indigenous shrubs. Several different quantitative measures of increasing complexity were applied to test bird foraging preferences for fruits of two established alien shrubs (Lantana camara, Solanum mauritianum), two emergent alien shrubs (Myoporum tenuifolium, Pittisporum undulatum) and two indigenous shrubs (Chrysanthemoides monilifera, Olea europaea subsp. africana). Overall the simplest quantitative measure, namely that of bird visitation frequency identified foraging preferences of individual bird species for fruits of alien and indigenous shrubs. Moreover, even the more complex measures of numbers of foraging birds, foraging times and products of these in the computed consumption intensity and seed dispersal efficiency were positively correlated to visitation frequency. There was a distinct preference of several, especially heavily fugivorous, bird species for fruits of established alien than indigenous shrubs and several moderately fugivorous bird species preferred fruits of emergent than established alien shrubs. Intricate photographic and experimental approaches were applied to obtain precise numerical data on seed removal rates by birds from the alien and indigenous shrubs. Deficiencies associated with the experimental approach included its inability to discriminate between asynchronous fruit production and fruit ripening, individual foraging bird species, and fruit consumption by other fruit foraging vertebrates. The advantages of the photographic approach were in its provision of a detailed permanent record of individual foraging bird species, their total numbers and precise foraging times and the proportions of whole fruits consumed, as well as other behavioural foraging traits. Tested also was the proposal that frugivorous birds remove larger amounts of fruits from plants with high fruit production and nutritional contents and that the germination of the bird-ingested seeds is enhanced. In compliance with this proposal, canopy fruit mass and monosaccharide content were all positively correlated with the total numbers of seeds removed by birds and viable seeds excreted by birds. Only defecated seeds of the indigenous C. monilifera and alien L. camara displayed enhanced germination following their ingestion by birds Seed dispersal distances of alien and indigenous shrubs by birds were estimated from published records of bird body masses, gut retention times of consumed seed and flight speeds. Estimated seed dispersal distances ranged between 0.41 and 0.81 km for the subset of heavily and moderately frugivorous bird species examined. However, their foraging distances derived from birdring recapture records were much greater, these peaking between 2.5 and 50 km in some heavily frugivorous bird species. It is concluded 1. that bird visitation frequency be applied as the most efficient and practical quantitative measure for gauging bird foraging preferences in future surveys which should involve large complements of indigenous, emergent and established alien species, 2. that flight speeds and gut passage times of ingested alien and indigenous seeds need to be measured in local bird species so long distance seed dispersal potentials can be more precisely determined and 3. that control measures should be focused on eradicating especially emergent alien species with fleshy fruits from urban environments to prevent their transport by birds into adjacent natural areas. / AFRIKAANSE OPSOMMING: Hierdie studie het die voorstel getoets dat uitheemse vlesige-vrug struike meer effektief kompeteer vir voël verspreidingsdienste as inheemse vlesige-vrug struike. Verskeie kwantitatiewe maatstawwe van toenemende kompleksiteit was toegepas om die voedingsvoorkeure van voëls vir vrugte van twee gevestigde uitheemse struike (Lantana camara, Solanum mauritianum), twee ontluikende uitheemse struike (Myoporum tenuifolium, Pittisporum undulatum) en twee inheemse struike (Chrysanthemoides monilifera, Olea europaea subsp. africana) te toets. Algeheel het die eenvoudigste kwantitatiewe maatstaf, naamlik voël besoek frekwensie, voedingsvoorkeure van individuele voël spesies vir vrugte van uitheemse en inheemse struike geïdentifiseer. Addisioneel het die meer komplekse maatstawwe soos voël getalle, voedings tye, asook produkte hiervan in die berekende verbruiks intensiteit en saadverspreiding effektiwiteit almal positiewe korrelasies met besoek frekwensie. Predominant vrugtevretende voël spesies het ‘n duidelike voorkeur getoon vir vrugte van gevestigde uitheemse eerder as inheemse struike. Verskeie meer gematigde vrugtevretende voël spesies het egter vrugte van ontluikende eerder as gevestigde uitheemse struike verkies. Ingewikkelde fotografiese en eksperimentele benaderings was gebruik om presiese numeriese data van saad verwyderingstempo’s deur voëls vanaf die bestudeerde struike te bekom. Tekortkominge geassosieerd met dié eksperimentele benadering sluit in die onvermoë om te onderskei tussen asinkrone vrug produksie en vrug rypwording, individuele kos soekende voël spesies, asook vrug verbruik deur ander vrugvretende werweldiere. Die voordele van die fotografiese benadering was die verskaffing van ‘n gedetailleerde permanente rekord van individuele kos soekende voël spesies, hul totale getalle, presiese voedingstye, proporsie heel vrugte verbruik, asook ander voedingsgedrag eienskappe. Ook getoets was die voorstel dat vrugtevretende voëls groter hoeveelhede vrugte verwyder van plante met hoë vrugproduksie en hoë nutriënt inhoud, en dat ontkieming van voëlingeneemde sade verhoogd is. In nakoming met die voorstel, was blaredak vrugte massa en monosakkaried inhoud albei positief gekorreleer met totale aantal sade verwyder deur voëls en lewensvatbare sade uitgeskei deur voëls. Slegs sade van die inheemse C. monilifera en die uitheemse L. camara het verhoogde ontkieming gewys na inname deur voëls. Saadverspreiding afstande van uitheemse asook inheemse struike deur voëls was bepaal vanaf gepubliseerde rekords van liggaams massa, saad behoud tye in die maag na inname, en vliegspoed. Beraamde saadverspreiding afstande het gestrek tussen 0.41 en 0.81 km vir dié subgroep van predominant en gematigde vrugtevretende voël spesies bestudeer. Nogtans was voedings afstande, afgelei van geringde voël hervangs rekords, veel groter, en het gepiek tussen 2.5 en 50 km vir sommige predominant vrugtevretende spesies. Gevolglik weet ons nou dat 1) voël besoek frekwensie toegepas kan word as die mees effektiewe en praktiese kwantitatiewe maatstaf vir die bepaling van voël voedings voorkeure in toekomstige opnames waar komplementêre groepe inheemse, ontluikende en gevestigde uitheemse spesies bestudeer word; 2) vliegspoed en maag passeer tye van ingeneemde uitheemse en inheemse sade gemeet moet word in plaaslike voël spesies sodat langafstand saadverspreiding potensiaal meer presies bepaal kan word; en 3) beheer maatstawwe moet fokus op die verwydering van spesifiek ontluikende uitheemse vlesige-vrug spesies vanuit stedelike omgewings, om sodoende saad vervoer deur voëls na naasliggende natuurlike areas the verhoed.

Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The spatial distribution of animals and plants at different scales is a central theme in ecology. Knowledge of biodiversity distribution is essential, especially with the current threat of climate change and invasion by alien species. Since the impact of climate change and alien species will be, and has already been pronounced in polar regions, information on the current spatial distributions of biota in these regions is critical to predict the consequences of climate change and alien species on the future survival, distribution and abundance of indigenous biota. This study was conducted on the sub- Antarctic Prince Edward Islands (consisting of Marion Island and Prince Edward Island), which have experienced rapid climate changes over the past 50 years. Additionally, a number of alien plant, vertebrate and invertebrate (also microarthropod) species have been introduced to these islands. Since microarthropods (mites and springtails) play an essential role in decomposition and mineralization of plant material on the islands, the loss of microarthropods from decomposer communities might have disastrous results for ecosystem processes. Therefore it is essential to know the current distributions of microarthropods in order to predict future distributions patterns in reaction to climate change and invasive species. In this study, the spatial distribution of mites and springtails inhabiting the cushion plant Azorella selago Hook, were examined at different scales of observation. Firstly, the microarthropod community was examined at a fine scale. The relationship between microarthropod species richness and abundance and plant size, isolation, within-plant variability, grass cover and microclimate variables were investigated. Thereafter, the spatial variability of microarthropod abundances was examined within stands of plants, with statistical methods using varying degrees of locational information to determine if microarthropod abundance is random, regular or aggregated at this scale. Further, the spatial variability of microarthropod communities in A. selago at different altitudes and on different sides of Marion Island, i.e. island-wide scale, was examined. The last scale of observation was the island-wide scale, in which microarthropod assemblages were compared between Marion Island and Prince Edward Island, as well as in different plant species. Microarthropods showed spatial heterogeneity within A. selago plants (higher abundances in eastern and southern sides of plants), island-wide (lower springtail abundance on the eastern side of the island and at high altitudes) and between islands (more alien species on Marion Island). In contrast, microarthropod abundance was not spatially heterogeneous within a stand of plants, i.e. mostly randomly distributed. The possible mechanisms responsible for these patterns differ between scales, and range from temperature and nutrient availability at the within plant and island wide scale to alien species between islands. Climate change is likely to alter these distribution patterns of microarthropods, either directly (unfavourable climate for indigenous species growth, development and dispersal) or indirectly (favouring alien microarthropod species; increase in grass cover on A. selago plants may alter community structure). The information presented here, is essential for predicting the possible impacts of climate change on microarthropods in fellfield ecosystems on sub-Antarctic islands. / AFRIKAANSE OPSOMMING: Die ruimtelike verspreiding van diere en plante op verskillende skale is ‘n sentrale tema in ekologie. Kennis van die verspreiding van biodiversiteit is belangrik, veral met die huidige bedreiging van klimaatsverandering en indringerspesies. Omdat die impak van klimaatsverandering en indringerspesies in die poolstreke alreeds duidelik is en nog meer so sal word, is inligting oor die huidige ruimtelike verspreiding van biota in hierdie streke noodsaaklik. Hierdie studie is op die sub-Antarktiese Prins Edward-eilande (bestaande uit Marion Eiland en Prins Edward Eiland) uitgevoer, waar die klimaat vinnig verander het oor die afeglope 50 jaar. Bykomend is ‘n aantal indringer plant, vertebraat en invertebraat (ook mikroartropood) spesies op die eilande ingebring. Omdat mikroartropoda (myte en springsterte) ‘n baie belangrike rol in ontbinding en mineralisering van plantmateriaal op hierdie eilande speel, sal die verlies van mikroartropoda uit die ontbindingsgemeenskap rampspoedige gevolge vir die prosesse in die ekosisteem hê. Kennis van die huidige verpreiding van mikroartropoda is dus noodsaaklik om die toekomstige verspreidingspatrone, asook oorlewing en volopheid van inheemse spesies in reaksie op klimaatsveranding en indringerspesies, te voorspel. In hierdie studie is die ruimtelike verspreiding van myte en springsterte wat in die kussingplant Azorella selago Hook voorkom, op verskillende ruimtelike skale ondersoek. Eerstens is die mikroartropood gemeenskap op ‘n klein skaal ondersoek. Die verwantskap tussen mikroartropood spesies rykheid en volopheid en plantgrootte, isolasie, binne-plant variasie, gras bedekking en mikroklimaat faktore is ondersoek. Daarna is die ruimtelike variasie van mikroartropood volopheid binne in ‘n plantstand ondersoek deur gebruik te maak van metodes wat verskillende grade van ligging data gebruik. Dit is gedoen om uit te vind of mikroartropood volopheid lukraak, reëlmatig of versameld verspreid is. Verder is die ruimtelike verspreiding van mikroartropood gemeenskappe in A. selago op verskillende hoogtes bo seespieël en op verskillende kante van Marion Eiland ondersoek. Laastens is die mikroartropood gemeenskap op Marion Eiland en Prins Edward Eiland, asook die gemeenskap in verskillende plant spesies vergelyk. Mikroartropoda is ruimtelik heterogeen verspreid binne-in A. selago (meer individue in die oostelike en suidelike kante van plante), asook regoor Marion Eiland (minder springstert individue aan die ooste kant van die eiland asook minder op hoë hoogtes bo seespieël) en tussen eilande (meer indringerspesies op Marion Eiland). In teenstelling hiermee is mikroartropood volopheid ruimtelik homogeen oor ‘n plantstand, dus meestal lukraak verspreid. Die meganismes wat moontlik vir hierdie patrone verantwoordelik is wissel van temperatuur en voedselbeskikbaarheid op die binne-plant en oor die eiland skaal tot indringerspesies op die tussen-eiland skaal. Klimaatsverandering mag waarskynlik mikroartropood verspreidingspatrone direk (ongunstige klimaat vir inheemse spesies se groei, ontwikkeling en verspreiding), of indirek verander (indringer spesies word begunstig; toename in grasbedekking bo-op A. selago mag die gemeenskapstruktuur van mikroartropoda verander). Hierdie inligting is belangrik vir die voorspelling van die moontlike impak van klimaatsverandering op mikroartropoda in klipveld ekosisteme op sub-Antarktiese eilande.

Thesis (PhD(Agric) (Conservation Ecology and Entomology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: See full text document for abstract / AFRIKAANSE OPSOMMING: sien volteks dokument vir die opsomming

Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Invasive alien trees (IATs) and agriculture are rapidly altering the capacity of ecosystems to provide a variety of essential services, with decreasing habitat quality having an adverse effect on arthropod biodiversity. Although both agricultural intensification and IATs have an impact on ecosystems, it is unclear which of these two is currently the most severe. Here I compare the influences of vineyards and IATs on arthropod diversity in the Cape Floristic Region (CFR) from two perspectives. Firstly, insect diversity from four different vegetation types (native fynbos, IATs, cleared invasive alien trees (CIATs) and vineyards), and their ecotones were assessed. Secondly, soil compaction in the different vegetation types was assessed and compared to determine how soil compaction relates to arthropod species richness and abundance. Surface-active arthropods were used for these evaluations, as they were considered to be the most abundant, yet sensitive groups for these comparative assessments. Pitfall trapping, which has been widely used for such comparative studies, was the method of choice. Additionally, as a result of incidental wildfires at some of the study sites (IATs and fynbos vegetation), it was decided opportunistically to assess recovery of arthropod diversity following the impact of fire. The results categorically indicate that IATs had by far the most significant impact, in comparison with vineyards, in reducing arthropod diversity and changing assemblage composition. Both IATs and vineyards, not surprisingly, supported lower arthropod diversity compared to fynbos, while CIATs supported arthropod species richness comparable to that of fynbos. However, different invertebrate species responded differently to IAT invasion, with some species even adapted to conditions in IAT patches. Environmental factors such as leaf litter and soil compaction were strongly correlated with arthropod species richness. However, other factors, such as soil moisture content, were not correlated with species richness, despite varying significantly between different vegetation types. IATs were found to reduce soil compaction, while vineyards increased soil compaction. The ecotone between adjacent land-use types was important for sustaining high arthropod species richness, particularly for the CIATs/fynbos ecotone, followed by the interface between CIATs/vineyard and vineyard/fynbos. Some species even preferred ecotones. Surface-active invertebrate species richness declined substantially immediately after fire in both IATs and fynbos. Nevertheless, recovery was rapid, with some species recolonizing or re-establishing within three months. Indeed, both species richness and abundance were high following fire. Fire had no significant impact on arthropod assemblage within IATs, despite having a serious impact in the fynbos where a different arthropod assemblage was observed after fire. The recovery of the historic assemblages may be dependent on both the pre-fire composition of the habitat and its adjacent vegetation. Effective co-operation among conservation biologists, farmers, and landowners to actively plan the future of CFR landscape biodiversity is required. / AFRIKAANSE OPSOMMING: Indringer uitheemse bome (IUB) en landbou bedrywighede is vinnig besig om die kapasiteit van ekosisteme vir die voorsiening van „n verskeidenheid van noodsaaklike dienste, met „n afname in habitatkwaliteit en „n nadelige uitwerking op artropood biodiversiteit, te verander. Alhoewel beide, landbou intensifikasie en IUB‟s, ‟n impak op ekosisteme uitoefen, is dit onduidelik watter van hierdie twee huidig die mees ernstige een is. In hierdie studie vergelyk ek die invloed van wingerde en IUB‟s op artropood diversiteit in die Kaapse Floristiese Streek (KFS) vanuit twee perspektiewe. Eerstens, insekdiversiteit van vier verskillende vegetasietipes (natuurlike fynbos, IUB‟s, verwyderde indringer uitheemse bome (VIUB‟s) en wingerde) en hulle ekotone is bepaal. Tweedens, is grondverdigting in en van die verskillende vegetasietipes ondersoek en vergelyk om te bepaal hoe grondverdigting verband hou met artropood spesies rykheid en volopheid. Oppervlak-aktiewe artropode is vir hierdie bepalings gebruik aangesien hulle beskou word as die mees volopste, maar ook mees sensitiewe groepe vir hierdie vergelykende bepalings. Pitvalvangste, wat alom gebruik word vir sulke vergelykende studies, was die verkose werkswyse. Bykomend, as gevolg van onbeplande veldbrande in sommige studie gebiede (IUB‟s en fynbos plantegroei), is oppertunisties van die geleentheid gebruik gemaak om die herstel van artropood diversiteit na die impak van brand te bepaal. Die resultate toon duidelik aan dat IUB‟s, in vergelyking met wingerde, by verre die mees beduidende impak gehad het deur ‟n verlaging van artropood diversiteit en veranderende groeperingssamestellings. Beide, IUB‟s en wingerde, het, nie onverwags nie, in vergelyking met fynbos, laer artropood diversiteit ondersteun, terwyl VIUB‟s artropood spesies verskeidenheid, vergelykbaar met dié van fynbos, ondersteun het. Verskillende invertebrate spesies het egter verskillend gereageer op IUB indringing, en sommige spesies het selfs by toestande in IUB kolle aangepas. Omgewingsfaktore soos blaarafval en grondverdigting was sterk gekorrelleer met artropood spesies rykheid. Ander faktore, soos grondvoginhoud, was egter nie in ooreenstemming met spesies rykheid nie, ten spyte van ‟n beduidende wisseling tussen verskillende vegetasietipes. IUB‟s het grondverdigting verminder, terwyl by wingerde grondverdigting toegeneem het. Die ekotone tussen aanliggende grondgebruike was belangrik om hoë artropood spesies rykheid, veral by die VIUB‟s/fynbos ekotoon, gevolg deur die kontaksones tussen VIUB‟s/wingerd en wingerd/fynbos, te onderhou. Sommige spesies het selfs ekotone verkies. Oppervlak-aktiewe invertebraat spesies rykheid het onmiddelik na brand in beide, IUB‟s en fynbos, wesenlik afgeneem. Tog was herstel vinnig, met sekere spesies wat binne drie maande teruggekeer of hulle hervestig het. Inderdaad was beide, spesies rykheid en volopheid, hoog na ‟n brand. Brand het geen noemenswaardige invloed op artropood groeperings binne IUB‟s gehad nie, ten spyte van ‟n ernstige impak in fynbos waar ‟n verskillende artropood groepering na ‟n brand waargeneem is. Die herstel van die historiese groeperings van beide, die voor-brand samestelling van die habitat en sy aangrensende plantegroei, mag afhanklik wees. Effektiewe en aktiewe samewerking tussen bewaringsbioloë, boere, en grondeienaars om die toekoms van KFS landskap biodiversiteit te beplan, word benodig.