Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Since its introduction in 1898 into South Africa, the Argentine ant, Linepithema humile [Mayr 1868 (Hymenoptera: Formicidae)], has invaded human-occupied areas (i.e. urban and agricultural areas) and natural areas characterised by few, if any, anthropogenic disturbances. However, compared to other countries in which the Argentine ant has been recorded, and until the past few decades, very little research had been done on this invasive ant in South Africa. Consequently, several issues concerning its ecological and social effects are still under-researched. The first of these issues concerns the lack of knowledge about the distribution of the Argentine ant in the natural areas, particularly the protected areas (PAs), of South Africa. In order to determine how many PAs are occupied by this invasive ant, a study was conducted in the Western Cape Province (WCP). It was found that, of the 614 PAs documented for WCP, ten have a known presence and nine known absence records of the Argentine ant. The remainder of the PAs have no known occupancy records for this ant. A second issue concerns the seasonal bait preference of the Argentine ant in a fynbos habitat. Six bait treatments (two carbohydrate and protein baits, a mixture of the carbohydrate and protein treatments, and a control) were applied in a fynbos habitat across a sampling grid in four different Latin Square designs, i.e. once for every season. Based on these experiments, it was determined that the Argentine ant prefers the mixture of carbohydrate and protein treatments, and that this preference does not change according to season. Furthermore, previous studies conducted in Jonkershoek Nature Reserve [JNR (in WCP)] determined the existence of a distribution boundary of Argentine ants in an area known as Swartboschkloof. Therefore, the third issue concerned the exact location of the distribution boundary and possible reasons for its establishment. This distribution boundary of the Argentine ant was found to be present 450 m from Swartboschkloof hiking trail. A combination of several explanatory variables may contribute to the maintenance of this boundary, i.e. a change in the horizontal and vertical vegetation distribution, as well as in the slope and aspect across the distribution boundary. With these explanatory variables, the increasing presence of an indigenous ant species, Anoplolepis custodiens, from this boundary may also have contributed to the distribution boundary. In addition, the short-term effect of a fire that swept through this area was also assessed, which revealed that Argentine ants are severely negatively affected by fire (at least over the short-term), i.e. their abundance decreased considerably after the fire and their local distribution range contracted. The final issue concerns the public perceptions of invasive alien species (IAS) in general and the Argentine ant specifically, at JNR. This study revealed that the majority of visitors to JNR were aware of the presence of IAS in South Africa and in its PAs, while very few visitors knew about the Argentine ant. This study also revealed that future research concerning South Africans perceptions of IAS might play a strong contributing role in conservation. / AFRIKAANSE OPSOMMING: Sedert die Argentynse mier, Linepithema humile [Mayr 1868 (Hymenoptera: Formicidae)], in 1898 in Suid-Afrika ingevoer is, het dié mier mens-bewoonde gebiede (soos stedelike en landbou gebiede) en natuurlike gebiede, gekenmerk deur min, indien enige, antropogeniese versteuringe, binnegedring. Nietemin, in vergelyking met ander lande waar die Argentynse mier opgeteken is, en tot die onlangse paar dekades, is min navorsing oor hierdie indringermier in Suid-Afrika onderneem. Gevolglik is daar verskeie kwessies rondom die mier se ekologiese en sosiale uitwerkinge wat nog nie nagevors is nie. Die eerste kwessie het betrekking op die gebrek aan kennis oor die Argentynse mier se verspreiding in die natuurlike gebiede, veral die beskermde gebiede (BG), van Suid-Afrika. Om te bepaal hoeveel BG deur hierdie indringermier beset word, is ʼn ondersoek in die Wes-Kaapprovinsie (WKP) uitgevoer. Daar is bevind dat, van die 614 BG gedokumenteerd in die WKP, het tien bevestigde aanwesigheid- en nege bevestigde afwesigheidrekords van hierdie mier. Die oorblywende BG het geen bekende besettingsrekords van hierdie mier nie. ʼn Tweede kwessie het betrekking op die seisoenale lokaasvoorkeur van die Argentynse mier in ʼn fynbos habitat. Ses lokaas-behandelings (twee koolhidraat en proteïen lokaas, ʼn mengsel van die koolhidraat en proteïen behandelings, en ʼn kontrole) is aangewend in ʼn fynbos habitat, oor ʼn steekproefruitgebied, in vier verskillende Latyns-kwadraatpatrone (“Latin Sqaure designs”), d.i. een vir elke seisoen. Op grond van hierdie eksperimente is vasgestel dat die Argentynse mier die mengsel van koolhidrate en proteïne verkies, en dat hierdie voorkeur nie seisoenaal verander nie. Boonop, vorige ondersoeke wat in die Jonkershoek Natuurreservaat [JNR (in die WKP)] uitgevoer is, het ʼn verspreidings-grens van Argentynse miere ontdek in ʼn gebied bekend as Swartboschkloof. Gevolglik het die derde kwessie betrekking op die presiese ligging van hierdie grens en moontlike redes waarom dit gevestig het. Dié verspreidings-grens van die Argentynse mier is 450 m vanaf die Swartboschkloof voetslaanpad gevind. ʼn Kombinasie van verskeie verklarende veranderlikes kon tot hierdie grens bygedra het, d.i. ʼn verandering in die horisontale en vertikale plantegroeiverspreiding, sowel as in die helling en ligging oor die verspreidings-grens van die Argentynse mier. Tesame met hierdie verklarende veranderlikes, kon die toenemende teenwoordigheid van ʼn inheemse mier, Anoplolepis custodiens, vanaf hierdie grens ook tot die verspredings-grens bygedra het. Daarbenewens is die korttermyn-effek van ʼn vuur wat deur die area beweeg het, ook bestudeer. Die ondersoek het getoon dat die Argentynse mier (ten minste oor die korttermyn) erg negatief deur vuur beïnvloed is, d.i. hul volopheid het ná die vuur aansienlik verminder en hul plaaslike verspreidings-grens het gekrimp. Die finale kwessie het betrekking op openbare persepsie van uitheemse indringerspesies (UIS) oor die algemeen en spesifiek die Argentynse mier, by JNR. Hierdie ondersoek het aan die lig gebring dat die meerderheid van besoekers aan JNR bewus was van die teenwoordigheid van UIS in Suid-Afrika en in dié se BG, terwyl baie min egter van die Argentynse mier geweet het. Hierdie ondersoek het ook aan die lig gebring dat toekomstige navorsing rakende Suid-Afrikaners se persepsie van UIS ʼn sterk bydra tot bewaring kan maak.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Planococcus citri (Risso) (Hemiptera: Pseudococcidae), the citrus mealybug, is a highly destructive pest of citrus in South Africa. The ability of mealybugs to develop resistance to chemicals, as well as their cryptic nature and protective wax coverings, all individually and combined, impair the ability of insecticides to control them. Furthermore, chemicals deplete natural enemy populations that usually establish control over mealybug populations well before harvest in March to May. The inability of chemicals to control P. citri successfully and the growing public awareness of the detrimental environmental effects and health risks that are associated with pesticides are pressuring citrus growers to find alternative methods to chemical control. Entomopathogenic nematodes of the Rhabditida order, belonging either to the families Heterorhabditidae or Steinernematidae, have proven to be valuable biocontrol agents of a variety of insect pest species. These nematodes are, however, not yet commercially available in South Africa. Various laboratory bioassays were conducted to determine the potential of entomopathogenic nematodes to control P. citri. Adult female P. citri were screened for susceptibility to six indigenous nematode species. Planococcus citri was found to be most susceptible to Steinernema yirgalemense and Heterorhabditis zealandica, causing 97% and 91% mortality, respectively. Both H. zealandica and S. yirgalemense completed their life cycles inside adult female P. citri. Under optimal conditions, H. zealandica and S. yirgalemense, at an application rate of 170 infective juveniles (IJs) / insect (LD90), were able to control P. citri efficiently with a discriminating dosage of 11(LD50). The water activity (aw) bioassay indicated that S. yirgalemense was two times more tolerant to lower levels of free water than H. zealandica, with aw50 = 0.96 and aw90 = 0.99, compared to H. zealandica with aw50 = 0.98 and aw90 = 1.01. Furthermore, S. yirgalemense proved able to locate and infect P. citri at a faster rate than H. zealandica. Nematode activity was not significantly affected when exposed to 15°C, 20°C and 25°C. Results of the exposure trial also showed that the first 2−4 h post-application was the most decisive time for establishing successful infection of mealybugs. Further experiments were conducted to determine the ability of two polymer products, Zeba® and Xanthan gum, and a surfactant, Nu-Film-P®, to improve nematode application suspensions. Despite not being as effective as Xanthan gum, Zeba® still retarded sedimentation significantly. The addition of 0.02% Xanthan gum did not improve the ability of nematodes to control P. citri at 60% and 80% relative humidity containing H. zealandica and 0.03% Zeba® increased mortality by 14% at 60% RH and by 22% at 80% RH. The same polymer formulation was tested with S. yirgalemense, with mortality being found to have increased by 21% at 60% RH and by 27% at 80% RH. The combined addition of Nu-Film-P® and Zeba® was able to retard sedimentation significantly, increasing the average number of nematodes deposited on 2-cm2 leaf discs. To illustrate those factors that should be taken into consideration before applying nematodes in an integrated pest management (IPM) programme for citrus, the compatibility of H. zealandica and S. yirgalemense with biological control agents and agrochemicals to which they are most likely to be exposed was determined. Bioassays showed the coccinellid beetle, Cryptolaemus montrouzieri, to be susceptible to both nematode species. Beetle larvae proved to be highly susceptible, with H. zealandica obtaining 80%, and S. yirgalemense obtaining 92% control. Adult beetles were found to be twice as susceptible to S. yirgalemense, with 64% mortality recorded, as to H. zealandica, with 30% mortality recorded. Tolerance of H. zealandica and S. yirgalemense infective juveniles to the affect of aqueous solutions of an insecticide (Cyperphos 500 E.C.®), two biopesticides (CryptogranTM and HelicovirTM), and two adjuvants (Nu-Film-P® and Zeba®) on the infectivity and survival of H. zealandica and S. yirgalemense was evaluated. Heterorhabditis zealandica proved to be highly compatible with all products tested. Significant increase in mortality of S. yirgalemense was recorded after 12 h exposure to CryptogranTM, HelicovirTM and Cyperphos 500 E.C.®, and after 6 h exposure to Nu-Film-P®. However, there was no decrease in the ability of S. yirgalemense to infect the insect hosts. Towards selecting the appropriate nematode species for field studies, the ability of S. yirgalemense and H. zealandica to control P. citri was first evaluated under less harsh simulated glasshouse conditions. The ability of both the above-mentioned nematode species to control P. citri, with and without the addition of 0.03% Zeba® and 0.06% Nu-Film-P®, was evaluated in a growth chamber at 75 ± 8% relative humidity and 22°C. All treatments resulted in significantly higher mortality of adult female P. citri than did the control. The addition of 0.03% Zeba® and 0.06% Nu-Film-P® to an H. zealandica and an S. yirgalemense suspension increased resultant mortality from 26% to 30%, and from 34% to 45%, respectively. This increase in mortality was, however, not significant. The ability of this formulation to prolong the ability of S. yirgalemense to infect P. citri and to prolong nematode survival was also evaluated under the same conditions and showed the formulation to improve both infectivity and survival for up to 2–3 h post-application. In the semi-field trial, S. yirgalemense was unable to obtain significant control of P. citri without the addition of 0.03% Zeba® to nematode application suspensions. However, with the addition of 0.03% Zeba® S. yirgalemnse was able to obtain up to 53% control. The study established that the polymer product Zeba® improves the ability of S. yirgalemense to infect P. citri by retarding desiccation and by buffering nematodes from suboptimal environmental conditions. / AFRIKAANSE OPSOMMING: Planococcus citri (Risso) (Hemiptera: Pseudococcidae), die sitrus witluis, is ʼn baie skadelike pes van sitrus in Suid Afrika. Die vermoë van witluise om weerstand teen chemiese middels te ontwikkel, hul kriptiese lewenswyse en die beskermende waslaag wat hul liggame omhul inhibeer gesamentlik en individueel die vermoë van insektisiede om witluis bevolkings te beheer. Chemiese middels verminder ook die natuurlike vyande wat gewoonlik witluis bevolkings beheer voor die sitrus oestydperk in Maart tot Mei. Die onvermoë van chemiese middels om P. citri suksesvol te beheer en verhoogde bewustheid van die publiek rond om die vernietigende omgewings impak en gesondheidsrisiko’s verbonde aan chemiese insek beheer, noodsaak sitrus produsente om alternatiewe beheermetodes te ontwikkel. Entomopatogeniese nematodes, van die orde Rhabditida wat aan die families Heterorhabditidae of Steinernematidae behoort, is bekend as effektiewe biologiese beheeragente van ʼn verskeidenheid insek pes spesies. Hierdie nematodes is egter tans nie kommersieel beskikbaar in Suid- Afrika nie. Om ten einde die vermoë van plaaslike nematode spesies te bepaal om P. citri te beheer, is verskeie biotoetse in die laboratorium uitgevoer. ʼn Vinnige siftings proses is uitgevoer om vas te stel watter plaaslike nematode spesies die hoogste persentasie mortaliteit van P. citri wyfies veroorsaak. Daar is bevind dat P. citri die mees vatbaarste is vir Steinernema yirgalemense en Heterorhabditis zealandica wat 97% en 91% mortaliteit respektiewelik veroorsaak het. Die ontwikkeling van beide H. zealandica en S. yirgalemense na die infektering van volwasse P. citri wyfies is gevolg en daar is bevind dat beide nematode spesies hul lewensiklusse kon voltooi in insek kadawers. Onder optimale toestande was H. zealandica en S. yirgalemense in staat om P. citri effektief te beheer, as hul teen ʼn konsentrasie van 170 infektiewe larwes (JIs) per insek (LD90) toegedien word, met ʼn diskriminerende toedienings dosis van 11 (LD50). ʼn Water aktiwiteit biotoets het gewys dat S. yirgalemense twee keer so verdraagsaam is teenoor laer vlakke van vrye water as wat H. zealandica is met aw50 = 0.96 en aw90 = 0.99, in vergelyking met H. zealandica met aw50 = 0.98 en aw90 = 1.01. Resultate van ʼn blootstellings toets het ook gewys dat S. yirgalemense die vermoë het om P. citri vinniger op te spoor en te infekteer as H. zealandica. Die blootstellings toets was uitgevoer teen 15°C, 20°C en 25°C en daar is bevind dat die aktiwiteit van H. zealandica nie beduidend verhoog het met ʼn verhoging in temperatuur nie. Resultate vir die blootstellings toets het ook gewys dat die eerste 2 tot 4 uur na toediening van nematodes die mees kritieke tyd is om suksesvolle infektering van witluise te bevestig. Verdere eksperimente is uitgevoer om te bepaal of die byvoeging van twee polimeer produkte nl. Zeba® en Xanthan gum en ʼn benatter Nu-Film-P®, nematode toedienings suspensies kan verbeter. Deur 0.02% Xanthan gum by nematode toedienings suspensies te voeg is die vermoë van nematodes om P. citri by 60% en 80% relatiewe humiditeit (RH) te beheer nie beduidend verhoog nie, terwyl die byvoeging van 0.03% Zeba® wel ʼn beduidende verhoging in mortaliteit veroorsaak het. ʼn Suspensie van H. zealandica en 0.03% Zeba® het beheer met 14% by 60% RH en met 22% by 80% RH verhoog. Die invloed van dieselfde polimeer formulasie was ook getoets op S. yirgalemense en mortaliteit het verhoog met 21% by 60% RH en met 27% by 80% RH. Ten spyte daarvan dat “Xanthan gum” nie so effektief was om afsakking van nematodes te verhoed nie, het die byvoeginging van 0.03% Zeba® by toedienings suspensies steeds ʼn beduidende invloed gehad. Die gekombineerde byvoeging Nu-Film-P® en Zeba® was in staat om die gemiddelde aantal nematodes gedeponeer op 2-cm2 blaar skyfies te verhoog. Om te wys watter faktore in ag geneem moet word voor EPNs as deel van ʼn geïntegreerde pes beheer program toegedien word, is die verenigbaarheid van H. zealandica en S. yirgalemense vir biologiese beheer agente en landbouchemikalieë, waaraan hulle heel waarskynlik blootgestel gaan word, bepaal. Biotoetse het gewys dat die liewenheersbesie, Cryptolaemus montrouzieri, vatbaar is vir beide nematode spesies. Die larwale fase was hoogs vatbaar met mortaliteit van 80% en 92% verkry deur die toedeining van H. zealandica en S. yirgalemense respektiewelik. Daar is ook bepaal dat volwasse besies twee maal so vatbaar is vir S. yirgalemense wat 64% mortaliteit veroorsaak het, as vir H. zealandica met 30% mortaliteit aangeteken. Verdraagsaamheid van IJs van H. zealandica en S. yirgalemense met oplossings van ʼn insektisied (Cyperphos 500 E.C.®), twee bio-plaagdoders (CryptogranTM en HelicovirTM), en twee byvoegmiddels (Nu-Film-P® en Zeba®), vir infektiwiteit en oorlewing is bepaal. Resultate het gewys dat H. zealandica hoogs verenigbaar is met alle produkte wat getoets is. ʼn Beduidende verhoging in mortaliteit van S. yirgalemense is aangeteken na 12 ure se blootstelling aan CryptogranTM, HelicovirTM en Cyperphos 500 E.C.®, en na 6 ure se blootstelling aan Nu-Film-P®. Resultate het egter ook gewys dat die vermoë van S. yirgalemense om om gashere te infekteer nie deur beinvloed word nie. Om ten einde te bepaal watter een van H. zealandica of S. yirgalemense die beter isolaat sou wees om te gebruik in veldproewe, is hul vermoë om P. citri te beheer eers evalueer onder minder ongunstige gesimuleerde glashuis toestande. Die vermoë van beide nematode spesies om P. citri te beheer is bepaal in ʼn groeikamer by 75 ± 8% (RH) met en sonder die byvoeging van 0.03% Zeba® en 0.06% Nu-Film-P®. Mortaliteit verkry deur alle behandelings was beduidend hoër as die kontrole. Deur 0.03% Zeba® en 0.06% Nu-Film-P® by toedienings suspensies van H. zealandica en S. yirgalemense te voeg is die gevolglike mortaliteit van P. citri verhoog van 26% na 30% en van 34% na 45%, respektiewelik. Hierdie verhoging in mortaliteit was egter nie beduidend nie. Die vermoë van die bo-genoemde formulasie om oorlewing van S. yirgalemense en infeksie tydperk van P. citri te verleng was bepaal onder dieselfde toestande en daar is gevind dat die formulasie beide die infektiwiteit en oorlewing van nematodes met 2 tot 3 uur na toediening verleng het. Tydens die semi-veldproef was S. yirgalemense nie in staat om beduidend hoër mortaliteit van P. citri te verkry, in vergelyking met die kontrole, sonder die byvoeging van 0.03% Zeba® by toedienings suspensies nie. Met die byvoeging van Zeba® is daar tot 53% beheer verkry. Die studie het onweerlegbaar gewys dat die polimeer produk Zeba® die vermoë van S. yirgalemense om P. citri te infekteer verbeter deur die uitdroging van nematodes te vertraag en deur hul te beskerm teen ongunstige omgewings toestande.

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

Thesis (MScConsEcol (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / The widespread ecological impacts of overgrazing by livestock within the Succulent Karoo have received considerable attention. Literature shows communal and commercial rangelands have been thoroughly studied, and vegetation responses have been investigated in an attempt to understand the effects of overgrazing. Regarding animal species, literature is in short supply. In a one-year study of small mammal assemblages, the effect of the rangelands, and subsequently vegetation, on small mammal assemblages was examined, as well as the effects on number of occupied, unoccupied and collapsed burrows. This study shows that vegetation composition differs between rangelands, with a greater perennial shrub cover on the communal rangelands and a greater perennial succulent cover on commercial rangelands, consequently creating different habitats for animal assemblages. This study supports the notion of small mammal composition relating to vegetation structure, with certain species being impacted by heavy grazing. Four small mammal species were found in greater abundances on commercial rangelands, with one being exclusive, while communal rangelands were exclusively occupied by three nocturnal species. Diet and habitat requirements are the most important factors regarding species occurrence. With small mammal species composition differing between rangelands, and species richness not being affected by rangeland type, this study illustrates that the disappearance of certain species may arise without these different rangelands. This could result in reduced species richness, and thus diversity being lost. Regarding species present on both rangelands, no differences were observed in body mass, body size or body condition. Despite no differences found in body condition, calculating a body condition index is a good method for investigating how a species is coping within an environment. The proportion and number of occupied and collapsed burrows can be seen as a measure of trampling effect. It was expected for grazing intensity, as well as vegetation changes, to affect the occurrence of such burrows. This study showed differences between the communal and commercial rangelands as negligible. As expected, numbers of burrowing small mammal species were negatively correlated with numbers of collapsed burrows. However, a lack of consistency deemed this result unimportant. Results show that the effects of overgrazing on small mammal populations are complex and require more attention if to be fully explained. This study provides insights into the effects of land use on small mammals and burrow numbers, which have implications for the conservation of these species within arid regions.

Thesis (MScConsEcol (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / Medicinal plants represent an important asset to the livelihoods of many people in developing countries. This is the case for South Africa where most of the rural and also urban communities rely on medicinal plants for their primary healthcare needs and income generation. Harvesting for domestic usage is not generally detrimental to the wild populations of medicinal plants. However, the shift from subsistence to commercial harvesting is posing unprecedented extinction threat to the wild populations of medicinal plants. The purpose of this investigation was to: (1) document the most traded/used species of medicinal plants in the Cape Peninsula, including parts used, sourcing regions, harvesting frequencies and seasons as well as the conservation status of these species; (2) to profile and investigate the rationales for the involvement of stakeholders in medicinal plants related-activities; and to (3) assess constraints and opportunities for sustainable management of medicinal plants in the Cape Peninsula. Triangulation techniques such as semi-structured questionnaires, formal and informal interactions with key informants from the Cape Peninsula and surroundings, personal observations and field visits were used to gather relevant data for this investigation. Accordingly, about 170 medicinal plant species were found to be actively traded or used in the study area. These species were mostly traded/used for their underground parts; shoot, barks and in many cases the whole plant is uprooted. The bulk of traded/used species were from the wild populations, harvested on monthly basis and the Western and Eastern Cape provinces acted as the main source regions. Some of the traded/used species are rare, vulnerable, endangered, critically endangered and are declining from the wild. Nonetheless, there are subtitutes for some of these medicinal plant species. Traders and collectors were mainly men in the Cape Peninsula. Cultural considerations, economic conditions and the burden imposed by the number of dependents were the factors influencing local communities to engage in medicinal plants related-activities. Despite the fact that the majority of the informants acknowledged the decline of medicinal plants from wild stocks, an overwhelming number of them expected an upsurge in the future demand for natural remedy due to its popularity among South Africans. Similarly, the majority of the respondents were aware of the conservation status of the plants that they were using, but this did not prevent them from trading/using some protected species. Encouragingly, an overwhelming number of the informants were willing to use cultivated species and cultivate some of the most used medicinal plant species if seeds and land were freely provided. It is noteworthy that these results were influenced by the gender, age, category and time of involvement in medicinal plants, ethnicity and residence status of the respondents as well as the source of supply of medicinal plants. It is recommended that species that have been identified of concern should be prevented from further commercial harvesting. Competent conservation organizations like CapeNature should focus on practical skills development of people who have expressed willingness to cultivate medicinal plants or are already doing so, especially in plant propagation and basic gardening techniques.

Thesis (MScConsEcol (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / This thesis examines the role of agricultural activity in the process of invasion of west coast renosterveld fragments by annual alien grass species. This highly endangered vegetation type has less than 5% remaining, it is vital to understand the mechanisms allowing invasion of annual alien grasses in order to effectively prevent the loss of the many rare and endemic species found in west coast renosterveld. This study was divided into three major components. Firstly the distribution of indigenous and alien plant species in relation to fence lines, separating active agricultural fields from untransformed vegetation, was described. Regression analysis was used to test for relationships between distances from agricultural fields and soil physical and chemical characteristics in natural vegetation. Cover by annual alien invasive grasses in untransformed vegetation decreased significantly with distance away from agricultural land. Secondly alien and indigenous grass seed banks were sampled along the transects, at the same sites, in order to establish whether the seed banks correlated with above ground cover. Results varied among sites and seed banks were correlated with the vegetation cover at only one site. It appears that there are a multitude of factors determining the distribution of annual alien grass cover. Thirdly a greenhouse experiment established the role that nitrogen plays in the success of the alien grass Avena fatua. This species was grown in competition with three indigenous species, an annual forb (Dimorphotheca pluvialis), a geophyte (Oxalis purpurea) and an indigenous perennial grass (Tribolium uniolae) at three levels of soil nitrogen. The geophyte was largely unaffected, while growth of the annual and indigenous perennial grasses was negatively affected by competition with A. fatua. Nitrogen did not seem to affect competitive interactions. Management of these renosterveld patches, in order to conserve them effectively, will require a multi-faceted approach, including prevention of further invasion and removal of invasive grasses already present.

Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Riparian ecosystems of the Mediterranean south-western Cape region are projected to experience significant decreases in streamflow due to climate change and increased demands for water associated with human demographic trends and increasing living standards. Aggravating this problem are woody invasive alien plants, such as Acacia mearnsii, whose impacts, including those on catchment water yields, have justified extensive eradication programmes such as Working for Water (WfW). WfW has been highly successful in managing invasive alien species in some areas, while at the same time enhancing the quality of life of poor South Africans. Unfortunately, the managers of these eradication initiatives often experience a lack of information on the species- and site-specific ecological properties that may aid in prioritising sites more prone to invasion, essentially inhibiting accurate management output. Knowledge, such as that associated with the possible future distribution of invasive species in a changing environment, may help to optimise eradication initiatives. I therefore determined whether woody plants portray different physiological (vulnerability to cavitation) and wood anatomical traits (wood density, vessel resistance to implosion, vessel lumen and wall diameters) across three prominent riparian zones in the south-western Cape that each differ in streamflow quantity – to gain a mechanistic understanding of how woody species, especially invasive species, adapt their hydraulic strategy across this proxy for water availability. Using factorial ANOVA’s, to distinguish any differences in plant physiological and wood anatomical responses to water availability within and between species, showed Acacia mearnsii having consistently higher drought-tolerance (lower P50 values and denser wood) compared to native species under reduced water availability. These results supported the significant variation in drought-tolerance strategies that exist within and between taxonomically different species across different environments. Water availability thus has a strong selective effect on functional traits of species; however, minimum water potentials were more useful in describing in situ hydrological conditions than streamflow. Additionally, a non-causal relationship between wood anatomical traits and drought-induced cavitation was observed. Therefore, using only wood anatomical measurements to assess drought-tolerance of species might not be accurate across all species. This mechanistic approach to assess the invasive potential of species under projected drier conditions has great practical value. It can be used to improve species selection for restoration initiatives, and is of great value for future use in prioritizing eradication programmes. / AFRIKAANSE OPSOMMING: Rivieroewer ekosisteme in die Mediterreense Suidwes-Kaap streek kan groot afnames in stroomvloei verwag, wat meestal toegeskryf kan word aan klimaatsverandering en die verhoogde aanvraag na water geassosieerd met stygende populasiegrootte. Uitheemse indringerplante soos Acacia mearnsii vererger hierdie probleem. Laasgenoemde spesies plaas groot druk op opvanggebiede se water opbrengs, en vorm grootliks die rede waarom uitroeiing programme soos Werk vir Water (WfW) gestig is. WfW het al groot suksesse behaal in die bestuur van uitheemse indringerplante, en terselfdertyd die lewenskwaliteit van arm Suid-Afrikaners verhoog. Ongelukkig sukkel hierdie indringer uitroeiing inisiatiewe telkens met ongenoegsame bewyse wat kan help om leiding te verskaf by die prioritisering van areas meer geneig tot indringing. Die gevolg is dat onvoldoende bestuurs besluite gemaak kan word. Gevolglik sal kennis geassosieerd met die moontlike toekomstige verspreiding van hierdie indringerplant in ʼn veranderlike omgewing help om uitroeiing programme meer akkuraat te stel en gevolglik waardevol wees t.o.v. prioritisering van kwesbare areas. Die doel van hierdie studie was om die kwesbaarheid van sleutel inheemse houtagtige rivier spesies en veral die dreigende indringerplant Acacia mearnsii, te bestudeer in terme van verlaagde stroomvloei soos voorspel vir die Wes-Kaap fynbos ekosisteem. Deur te bepaal of houtagtige plante verskillende fisiologiese (kwesbaarheid teen xileem blokkasie) en anatomiese (hout digtheid, vat weerstandbiedendheid teen inmekaarkolking, vat holte en wand deursnee) hidrologiese eienskappe tentoonstel gemeet tussen drie prominente rivieroewer sones in die suidwes Kaap wat variëer in stroomvloei kwantiteit, verskaf ʼn meganistiese begrip van hoe spesies, veral die indringerplante, hul hidrologiese strategieë ten opsigte van droogtes kan aanpas. Faktoriële ANOVAS’s tussen spesies en liggings het getoon dat beide plant fisiologiese en hout anatomiese data beduidend variëer tussen taksonomies verskillende spesies. Veral Acacia mearnsii het deurgaans laer P50 waardes asook hoër houtdigtheid getoon, ‘n teken van hierdie spesies se verhoogde droogte toleransie in vergelyking met die inheemse spesies. Wat beduidend is is dat spesies-spesifieke lewensstrategieë ten opsigte van droogte toleransie in hierdie rivieroewer sones voorkom. Resultate het bevestig dat water beskikbaarheid ʼn groot rol speel in die seleksie van funksionele karaktereienskappe in plante, maar, dat minimum water potensiaal meer akkuraat was om in situ hidrologiese toestande te beskryf as wat stroomvloei kon. Die verhouding tussen plant fisiologiese en hout anatomiese karaktereienskappe was indirek as gevolg van spesies-spesifieke lewensstrategieë. Gevolglik sal die allenige gebruik van hout anatomiese eienskappe om droogte toleransie in plante te assesseer onakkuraat wees omdat daar ʼn swak verhouding tussen hout anatomie en droogte-geïnduseerde xileem blokkasie bestaan. ʼn Meganistiese benadering om die indringing potensiaal van spesies onder voorspelde droër kondisies te assesseer, asook om spesies seleksie vir restourasie doeleindes op te skerp, is prakties uitvoerbaar, en van groot waarde vir toekomstige gebruik in uitroeiing en restourasie inisiatiewe.

Thesis (MSc (Conservation Ecology)--University of Stellenbosch, 2004. / 89 leaves single sided printed, preliminary pages i-xiv and numbered pages 1-89. Includes bibliography. List of tables, figures used. / Scanned with a Hp Scanjet 8250 Scanner to pdf format (OCR). / ENGLISH ABSTRACT: The main aim of an old field rehabilitation trial initiated in 2000 was to find a solution to the rehabilitation process for approximately 90 000 ha of unutilised land in the Little Karoo, South Africa. Depending only on a natural succession process to restore unutilised old fields would mean that the period of recovery would be longer than the life span of an average farmer. The trial, initiated by Witbooi in 2000 aimed to see how human intervention can facilitate the process of rehabilitation of old-fields. Three years later, the trial was again monitored to evaluate the success of reseeded indigenous species and method of cultivation in the rehabilitation process. A second objective was based on a result of Witbooi (2002) who showed that there was a tendency of 0. pes-caprae to invade disturbed areas, and aimed to evaluate the effect of this species on the rehabilitation process. Seven indigenous species were reseeded in 2000, of which only four species germinated and survived to the present. These surviving species are Pteronia incana Burm Dc., Tripteris sinuata DC., Ehrharta calycina SM and Chaetobromus dregeanus Nees. The highest level of recruitment in 2001 was recorded for T sinuata followed by P. incana, E. calycina and C. dregeanus. In September 2003, three years after the trial was initiated, the highest number of surviving seedlings were of T sinuata followed by E. calycina, C. dregeanus and P. incana. Five different cultivation methods were used to enhance the germination rate and survival of seedlings. The number of seedlings that survived differs according to the cultivation methods and soil type. Tripteris sinuata had the highest number of surviving seedlings in all cultivation methods off-heuweltjies. Tripteris sinuata was therefore selected to analyse the effect of various cultivation methods. The second objective was to study the impact of Oxalis pes-caprae on species diversity in restored old fields by assessing its ability to disperse in old fields under different cultivation methods. The multivariate ANOVA results showed that there was a significant difference in the density of O. pes-caprae between on and off heuweltjies (sites) and treatments (cultivation methods). There was a significant difference in the density of O. pes-caprae between cultivation methods. A Post Hoc LSD test showed a significant difference in the density of aboveground O. pes-caprae plants between control sites (no disturbance) compared to those sites that underwent some sort of soil disturbance. There was, however, no significant difference in the abundance of O. pes-caprae on plots that underwent some sort of disturbance (i.e Cleared vs Tilled vs Disked vs Ploughed sites) on heuweltjies. There was a significant difference in the number of O. pes-caprae bulbs collected between blocks (on and off-heuweltjie) and significant differences between cultivation methods. There was also a significant difference in bulb diameter between cultivation methods when compared between on and off-heuweltjie sites. The bulbs were classified into four measurement classes. The highest number of small (2-5 mm diameter) and medium (5-8 mm diameter) sized bulbs were found in the Tilled cultivation method. In contrast the Control treatment (uncultivated) had the highest number of large sized bulbs (14-17 mm diameter) and medium bulbs size categories. In conclusion, T. sinuafa has the potential to be used for rehabilitation of old fields in combination with Tilled cultivation method. Attention should be paid to the effect of O. pes-caprae especially on heuweltjies where this species showed a complete dominance in the rehabilitation trial. / AFRIKAANSE OPSOMMING: Die hoof doel van 'n ou veld rehabilitasie eksperiment wat in 2000 geinisieer is was om 'n oplossing te vind vir die rehabilitasie proses vir ongeveer 90 000 ha onbenutte land in die Klein Karoo, Suid-Afrika. Indien daar slegs op natuurlike suksessie prosesse staatgemaak word om die onbenutte ou lande te restoreer, sou dit beteken dat die periode van herstel langer sou wees as die lewensverwagting van die gemiddelde boer. Hierdie eksperiment, wat in 2000 deur Witbooi geinisieer is, het gepoog om te bepaal hoe menslike inmenging die proses van rehabilitasie van ou velde kan fasiliteer. Drie jaar later is die eksperiment weer gemonitor om die sukses van die teruggesaaide inheemse spesies en bewerkings-metodes in die rehabilitasie proses te evalueer. 'n Tweede doelwit is gebaseer op 'n resultaat van Witbooi (2002) wat aangetoon het dat daar 'n neiging was vir O. pes-caprae om versteurde areas binne te dring, en het dus gemik om die effek van hierdie spesie op die rehabilitasie proses te evalueer. Sewe inheemse spesies is in 2000 teruggesaai, waarvan slegs 4 spesies ontkiem en oorleef het tot die hede. Hierdie oorlewende spesies is Pteronia incana Burm Dc., Tripteris sinuata DC., Ehrharta calycina SM en Chaetobromus dregeanus Nees. Die hoogste vlak van werwing in 2001 is vir T sinuata aangeteken, gevolg deur P. incana, E. calycina en C. dregeanus. In September 2003, drie jaar na die aanvang van die eksperiment, was die hoogste getal oorlewende saailinge die van T sinuata, gevolg deur E. calycina, C. dregeanus en P. incana. Vyf verskillende bewerkings-metodes is gebruik om ontkiemingstempo en saailing oorlewing aan te help. Die aantal saailinge wat oorleef het varieer volgens die bewerkings-metode wat gevolge is en die grondtipe. Tripteris sinuata het die grootste aantal oorlewende saailinge gehad in al die bewerkings-metodes af van heuweltjies. Tripteris sinuata is daarom geselekteer om te analiseer vir die effek van verskillende bewerkings-metodes. Die tweede doelwit was om die inpak van Oxalis pes-caprae op spesie-diversiteit in die gerestoreerde ou land te bepaal deur die vermoë van hierdie spesie om in ou velde te versprei onder verskillende bewerkings-metodes te evalueer. Die multi-veranderlike ANOVA resultate het aangetoon dat daar 'n beduidende verskil in O. pes-caprae digtheid tussen heuweltjie en nie-heuweltjie (persele) en verskillende bewerkings-metodes was. Daar was 'n beduidende verskil in die digtheid van o. pes-caprae tussen verskillende bewerkingsmetodes. 'n Post Hoc LSD toets het 'n beduidende verkil in die digtheid van bogrondse O. pes-caprae plante tussen kontrole terreine (geen versteuring) vergeleke met persele wat een of ander vorm van grondversteuring ondergaan het aangedui. Daar was egter geen beduidende verskil in die volopheid van 0. pes-caprae op persele wat een of ander vorm van versteuring ondergaan het (i.e Skoongemaakte vs Getilde vs Geskottelde vs Geploegde persele) op heuweltjies nie. Daar was 'n beduidende verskil in die aantal O. pes-caprae bolle wat versamel is tussen blokke (op en af van heuweltjies) en beduidende verskille tussen die bewerkings-metodes. Daar was ook 'n beduidende verskil in bol-deursnitte tussen bewerkings-metodes wanneer dit tussen heuweltjie en nie-heuweltjie persele vergelyk is. Die bolle is in vier metingsklasse verdeel. Die grootste aantal klein (2-5 mm deursnit) en medium (5-8 mm deursnit) bolle is in die Getilde bewerkings-metode gevind. In kontras het die Kontrole behandeling (onbewerk) die grootste aantal groot (14-17 mm deursnit) en medium bolle gehad. Samevattend het T. sinuata die potensiaal om gebruik te word in die rehabilitasie van ou lande in kombinasie met die tilting bewerkings-metode. Aandag moet geskenk word aan die effek van 0. pes-caprae, veral op heuwetjies waar hierdie spesies 'n totale dominansie in die rehabilitasie eksperiment getoon het.

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.