Thesis (MSc (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: During 2007, two evidence-based studies were undertaken in two catchment areas in South Africa. The first study ascertained the relationships between demographic attributes and general awareness, human impacts, attitudes and water use behaviour. The second study determined whether or not State-of-River (SoR) materials developed for foundation phase learners (grades 1 to 3) improved their understanding of and influenced their attitudes towards river conservation. Surveys were conducted amongst learners (n=1178) and parents (n=1144) from different cultures and socio-economic backgrounds. Questionnaires were available in three languages, namely English, isiXhosa and Afrikaans. The SoR reporting materials were not adequately distributed. The first study could therefore not ascertain whether increased awareness or attitudinal and behavioural changes could be ascribed to SoR reporting in the catchments. The majority of respondents (82%) indicated that there was a need for more information on rivers and 60% of the respondents indicated that they would participate in a follow-up survey. Thirty percent of respondents from the Buffalo catchment and 22% of respondents from the Hartenbos and Klein Brak catchment indicated that they use water very sparingly. Respondents from urban areas scored higher in their attitudes towards river conservation and were more aware of water issues than those from rural areas. Both attitudinal and awareness scores did not align with water use behaviour, with rural respondents using water more sparingly. Attitude and awareness improved with increased education levels. Respondents who indicated that they would rather pay more for water than change their water use behaviour showed the lowest score for attitude towards river conservation. Learners from the Buffalo rural area showed a significant increase in understanding the benefits that healthy rivers provide, and this can be ascribed to the distributed SoR activity book and poster. A survey consisting of quantitative and qualitative items, as well as participatory evaluations determined learners’ level of understanding of human impacts on rivers. The quantitative study showed learners from the Hartenbos and Klein Brak area as well as the Buffalo rural area improved the most over time. The qualitative items showed a 35% and 40% increase in the number of correctly listed items as either making a river happy (healthy) or sad (unhealthy) after exposure to SoR materials. Respondents from both catchments taking part in the participatory evaluations displayed an overall increase in their understanding of good practices, as well as the negative impact of human activities on rivers. Those learners that scored low in the participatory evaluations at time 1 showed the most improvement over time, concluding that those learners who knew the least at the start of the study, gained the most understanding of human impacts on rivers. All schools in the Hartenbos and Klein Brak catchment, with the exception of one, showed a slight increase in understanding of human impacts on rivers. Results from the schools in the Buffalo catchment were more variable. Data gathered demonstrated that the SoR materials helped learners to better understand benefits from clean rivers as well as human impact on rivers. Although the learners from urban areas had a better understanding of the concept of river conservation before contact with the SoR materials, learners from the rural areas showed the most improvement over time. There was an increase in the number of learners that showed a willingness to take responsibility for their actions that could impact on river health. Far more learners mentioned remediation types of actions than protection or preventative actions. A change in peoples’ attitudes and behaviour is needed to ensure adequate protection of South Africa’s natural water resources. Imprinting values and perceptions that would last into adulthood need intervention at an early age and throughout children’s’ formative years. / AFRIKAANSE OPSOMMING: Gedurende 2007, twee bewysgebaseerde ondersoeke is in twee wateropvangsgebiede in Suid Afrika gedoen. Die eerste studie was gerig op die bepaling van die verband tussen demografiese kenmerke, algemene bewustheid, menslike impak, houdings en waterverbruik. Die tweede studie het bepaal of die Stand-van-Rivier (SvR) inligtingsmateriaal wat vir grondslagfase leerlinge (graad 1 tot 3) ontwikkel is, bygedra het tot hulle begrip van en houding jeens die bewaring van riviere. Steekproeftrekkings het leerlinge (n=1178) en ouers (n=1144) vanuit verskillende kultuur- en sosioekonomiese agtergronde betrek. Vraelyste was in drie landstale naamlik Engels, Xhosa en Afrikaans beskikbaar. Die SvR kommunikasie material is nie toereikend versprei nie. Die eerste studie kon derhalwe nie bepaal of groter bewustheid of veranderings in houding en gedrag in hierdie opvangsgebiede aan die SvR verslaggewing toegeskryf kon word nie. Die meerderheid respondente (82%) het aangedui dat daar ‘n tekort and rivierinligting is en 60% van die respondente het hulself bereidwillig verklaar om aan ’n opvolgstudie deel te neem. Dertig persent van die respondente uit die Buffels- en 22% uit die Hartenbos- en Klein Brak-opvangsgebiede het aangedui dat hulle water spaarsamig gebruik. Respondente afkomstig van stedelike gebiede het beter rivierbewaringshoudings getoon en was meer bewus van wateraangeleenthede as die van landelike gebiede. Houdings en bewustheids-vlakke het nie ooreengestem met waterverbruik nie – landelike respondente gebruik water meer spaarsamig. Beide houdings en algemene bewustheid het toegeneem met hoër onderwysvlakke. Respondente wat aangedui het dat hulle eerder meer vir water sal betaal as om hulle verbruik te verminder, het die swakste houding jeens die bewaring van riviere getoon. Leerlinge uit die landelike gebiede van die Buffels opvangsgebied het groter begrip getoon vir die voordele wat gesonde riviere inhou, en dit kan toegeskryf word aan die aktiwiteitsboek en SvR plakkaat wat onder hulle versprei is. ‘n Steekproef bestaande uit kwantitatiewe en kwalitatiewe items, sowel as deelnemende evaluasies is gebruik om leerlinge se vlak van begrip van menslike impak op riviere te bepaal. Die kwantitatiewe studie het aangedui dat die begrip van leerlinge van die Hartenbos en Klein Brak sowel as die van die landelike Buffelsrivieropvangsgebiede oor tyd die meeste toegeneem het. Op die vraag wat riviere gelukkig (gesond) of hartseer (ongesond) maak, het die kwalitatiewe items, na blootstelling van die leerders aan die SvR materiaal, ‘n toename van 35% en 40% in korrekte antwoorde getoon. In die deelnemende evaluasie het respondente van beide opvangsgebiede ‘n toename in begrip van goeie praktyke sowel as die negatiewe impak van menslike aktiwiteite op riviere getoon. Leerlinge wat swak gevaar het in die deelnemende evaluasie gedurende die eerste rondte het die meeste vordering getoon. Die gevolgtrekking is dus dat leerlinge wat die minste geweet het aan die begin van die studie, die meeste geleer het oor menslike impak op riviere. Op een na, het alle skole in die Hartenbos- en Klein Brakrivieropvangsgebied ‘n geringe verhoging in begrip van menslike impak op riviere getoon. Resultate van skole uit die Buffelsopvangsgebied het meer gevarieer. Data versamel het gedemonstreer dat die gebruik van die aktiwiteitsboek en plakkate gelei het tot ’n beter begrip by leerders van die voordele van skoon riviere asook van menslike impak op riviere. Alhoewel die leerlinge van stedelike gebiede beter begrip getoon het oor rivierbewaring voor kontak met die SvR material, het die landelike leerlinge die grootste toename in begrip oor die verloop van die studie getoon. Daar was ook ‘n toename in die aantal leerlinge wat bereid was om verantwoordelikheid vir hulle aktiwiteite wat ‘n impak op riviergesondheid kon hê, te aanvaar. Veel meer leerlinge het tydens die tweede fase verwys na herstel eerder as beskermings of voorkomende gedrag. ’n Verandering in mense se houdings en gedrag is noodsaaklik om genoegsame bewaring van Suid Afrika se natuurlike waterhulpbronne te verseker. Waarde sisteme en persepsies wat met volwassewording steeds geldig sal wees, word reeds teen ’n vroeë ouderdom, gedurende kinders se vormingsjare, vasgelê.

Thesis (MSc (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / Please refer to full text to view abstract.

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, 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 (MScConEcol)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The fire-prone mediterranean-type climate regions of the world are immensely biodiverse. Changes in fire frequency due to anthropogenic ignitions and climate change are one of the factors threatening the plant diversity of these regions. Many postfire regeneration studies have focused on seedling recruitment, whereas much can still be learned about regeneration through resprouting. This project focused on resprouters after a fire and assessed if there are differences between the obligate (OS) and facultative (FS) resprouting life history types. OS species have to resprout after fire, as their seeds are not fire resistant and seedling recruitment takes place in fire-free periods, whereas FS species have the ability to resprout and recruit seedlings after a fire. My analyses found a significant difference in postfire resprout success between OS species and FS species, supporting the division of woody resprouting shrubs into these two life history types. OS species had minimal fire-related mortality and this was related to their ability to resprout early and vigorously after fire. OS species had no postfire mortality, which points to traits that enable them to endure the hot and dry summer months. The FS species varied in their response to fire and had greater fire induced mortality than the OS species. Postfire mortality (post-sprouting) was also greater compared to OS species, especially towards the end of the long dry summer suggesting a link to water stress. A postfire seedling survey of target FS, OS and non-sprouters (NS), revealed that NS species had seedling/adult ratios that were orders of magnitude higher ranging between 40-200 seedlings per adult against less than 1-10 seedlings per adults for FS, with OS species recruiting no seedlings directly postfire, as is consistent with their life history type. Although the NS species do not sprout and the FS species had some mortality, the population was at or above replacement two-year postfire on account of seedling recruitment. OS species maintained their pre-fire population by successfully resprouting and by experiencing almost no postfire mortality. These results provide strong justification for grouping woody resprouters into OS and FS species in future studies seeking to understand the underlying differences in postfire recovery. Postfire flowering phenology was also observed during the two year study period. Geophytes, mostly belonging to the Iridaceae and Orchidaceae were overrepresented within the first year postfire, many displaying fire-stimulated flowering. This suggests that some geophytes limit their reproductive cycle to the immediate postfire environment, when nutrients and light are abundant. Smaller resprouting shrubs generally flowered earlier than larger resprouting shrubs. Many non-sprouting shrubs did not reach maturity within the study period and those that did mostly belonged to the Fabaceae and Asteraceae families. This study added 71 species to the existing Paarl Mountain species list, including eight new red listed species, highlighting the importance of early postfire field surveys. / AFRIKAANSE OPSOMMING: Veldbrande is ‘n natuurlike verskynsel in die meditereense klimaatstreke van die wereld. Hierdie areas is ook bekend vir hulle ryk biodiversiteit. Veranderinge in die vuur frekwensie as gevolg van klimaatsverandering en veldbrande wat deur mense veroorsaak word, bedreig die plantdiversiteit van hierdie streke. Vorige veldbrandstudies het meestal gefokus op saailinge en daar bestaan ‘n groot leemte om regenerasie deur herspruiting beter te verstaan. Hierdie navorsingsprojek fokus op herspruiting van fynbos plante as ‘n oorlewingstrategie na ‘n veldbrand. Spesifiek word daar gekyk na verskille tussen verpligte (VH) en nie-verpligte (fakultatiewe) herspruiters (FH). VH spesies moet herspruit na vuur om hulle populasie stabiel te hou, aangesien hulle saad nie vuurbestand is nie. FH spesies het die vermoë om te herspruit sowel as saailinge te werf na ‘n brand. Die studie bevindinge dui op betekenisvolle verskille tussen hierdie twee lewensgeskiedenistipes en regverdig die groepering van houtagtige herspruiter spesies as VH of FH. VH het minimale mortaliteit getoon na die veldbrand. Bykans alle plante het vinnig en kragtig herspruit. VH besit ook eienskappe wat hulle in staat stel om die warm, droeë somers te oorleef. Die oorlewing van FH was wisselvallig, met mortaliteit as gevolg van direkte vuurskade en verdere mortaliteit gedurende die lang somermaande, moonlik as gevolg van water stress. ‘n Saailingstudie van VH, FH en ook nie-spruiters (NS) het getoon dat die saailing/volwasse verhoudings van NS ordes hoër is as die van FH. VH het geen saailinge direk na die vuur geproduseer nie. Twee jaar na die vuur was FH en NS saailing getalle steeds heelwat meer as die aantal volwasse plante wat dood is in die veldbrand. VH het hul populasie stabiliteit gehandhaaf deurdat alle volwasse plante suksesvol herspruit het. Hierdie bevindinge regverdig die verdeling van herspruitende fynbos spesies as VH of FH. Verdere studies is belangrik om die onderliggende ekofisiologiese verskille tussen die twee lewensgeskiedenistipes beter te verstaan. Die blompatrone van verskillende spesies is ook aangeteken tydens die tweejaar studieperiode. Bolplante, veral in die iris- (Iridaceae) en orgidee (Orchidaceae) families het oorheers gedurende die eerste jaar na die brand, aanduidend van ‘n vuur-gestimuleerde blompatroon. Sommige bolplante mag hul voorplantingssiklus beperk tot die periode direk na veldbrand, terwyl daar genoeg lig is en die grond verryk is met voedingsstowwe. Kleiner herspruitende struike het in die algemeen vroeër geblom as groter struike. Nieherspruitende struike het meestal nie seksuele volwassenheid bereik binne twee jaar na die veldbrand nie, buiten sommige in die ertjie- (Fabaceae) en asterfamilies (Asteraceae). Die studie het 71 nuwe spesies tot die bestaande Paarlberg spesielys gevoeg, waarvan agt rooidataspesies was, wat die waarde van plantopnames direk na ‘n veldbrand beklemtoon.

Thesis (MScConsEcol)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Wetland systems provide vital hydrological ecosystem goods and services to mankind. When wetlands are transformed, through invasion by alien plants or replaced with agriculture, natural capital is lost, and the system is no longer able to provide the same quality of hydrological ecosystem services. Natural capital can be restored, but it involves substantial financial investment, and there is no guarantee that these hydrological ecosystem services will be fully recovered. This thesis aimed to investigate the hydrological impact of the land-cover changes in the Kromme River Catchment over the last 50 years, by using a combination of mapping and hydrological modelling techniques. We hypothesized that wetland loss in the Kromme has resulted in a shift in the flow regime, greater responsiveness to floods as a result of less storage, lower baseflow, and reduced water quality. We also hypothesised that the riparian invasion by Acacia mearnsii has caused flow reductions as a result of increased evaporation relative to the wetlands. Modelling results predict that over the past 50 years, the transformation of the floodplain wetlands in the Kromme River has shifted the flow regime, reducing baseflows and increasing the responsiveness of the catchment to extreme rainfall events. The invasion of A. mearnsii over time has also been predicted to have caused a reduction in river flow. Various restoration scenarios were considered, however if the Kromme were to be restored back to a land-cover state comparable to the 1950’s, 26.9 km2 (65.1%) of A. mearnsii would have to be cleared, and 5.2 km2 (34.2%) of the wetlands would have to be restored. The hydrological benefits would include a predicted increase in riverflow (42 mm/a), baseflow (2.9 mm/a), an increase in flood protection and improved water quality. This restoration strategy could be regarded as a type of insurance plan, and the benefits gained in terms of increased ecosystem service delivery would be the insurance premium. In conclusion it appears that restoration, insuring natural capital in the Kromme River, would provide significant economic returns on investment. / AFRIKAANSE OPSOMMING: Moeraslandstelsels voorsien die mens van noodsaaklike hidrologiese ekosisteemgoedere en -dienste. Wanneer moeraslande verander word, hetsy deur die indringing van uitheemse plante of vervanging met landboubedrywighede, gaan natuurlike kapitaal verlore en kan die stelsel nie meer dieselfde gehalte hidrologiese ekosisteemdienste lewer nie. Hoewel natuurlike kapitaal herwin kan word, behels dit beduidende finansiële belegging, en is daar boonop geen waarborg dat die hidrologiese ekosisteemdienste ten volle sal herstel nie. Hierdie tesis het ten doel gehad om die hidrologiese impak van die grondbedekkingsveranderinge in die Krommerivier-toeloopgebied oor die afgelope 50 jaar met behulp van ’n kombinasie van karterings- en hidrologiese modelleringstegnieke te ondersoek. Die hipotese was dat moeraslandverlies in die Kromme tot ’n verandering in die vloei-regime, hoër responsiwiteit op erge reënval as gevolg van minder bergingsruimte, ’n laer basisvloei en swakker watergehalte gelei het. Daar is voorts gehipoteseer dat die oewerindringing deur Acacia mearnsii ’n verlaging in vloei veroorsaak het weens ’n toename in verdamping uit die moeraslande. Modelleringsresultate dui daarop dat die transformasie van die vloedvlakte-moeraslande in die Krommerivier oor die afgelope 50 jaar die vloei-regime verander het, basisvloei verminder het en die toeloopgebied se responsiwiteit op erge reënval verhoog het. Die indringing van A. mearnsii het ook volgens aanduidings mettertyd ’n vermindering in riviervloei tot gevolg gehad. Verskeie herstelscenario’s is oorweeg. Om die grondbedekking in die Kromme te herstel tot wat dit in die 1950’s was, moet 26,9 km2 (65,1%) van die A. mearnsii verwyder en 5,2 km2 (34,2%) van die moerasland herwin word. Die hidrologiese voordele kan ’n verwagte toename in riviervloei (42 mm/a) en basisvloei (2,9 mm/a), ’n toename in vloedbeskerming sowel as beter watergehalte insluit. Hierdie herstelstrategie kan as ’n soort versekeringspolis beskou word, en die voordele verbonde aan beter ekosisteemdienslewering as die versekeringsuitbetalung. Ten slotte blyk dit dat die herstel van die Kromme, en die gepaardgaande versekering van natuurlike kapitaal, beduidende ekonomiese opbrengste op belegging sal meebring.

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.