Masters Degrees (Conservation Ecology and Entomology)

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Acoustic monitoring and response of katydids (Orthoptera: Tettigoniidae) to the landscape mosaic in a Biosphere Reserve
(Stellenbosch : Stellenbosch University, 2017-03) Thompson, Aileen Celeste; Samways, Michael J.; Bazelet, Corinna S.; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH SUMMARY: A charismatic group within the Orthoptera, katydids can be found in a variety of habitat types world-wide due to their excellent bark and leaf mimicry skills. Most male katydids produce species-specific calls to attract female mates. If katydids, like their close relatives the grasshoppers, can function as effective biological indicators, then acoustic monitoring of katydid songs may result in a novel and non-invasive method to rapidly assess local biodiversity. Furthermore, information regarding threat statuses, distributions and life history traits can be inferred for all South African katydid species, leading to the development of a Katydid Biotic Index (KBI) based on the highly effective Dragonfly Biotic Index. If proven effective, the KBI would allow for biodiversity assessments to account for detailed aspects of katydid species composition in addition to the diversity measures normally utilized for biodiversity assessment (e.g. species richness and abundance). In this thesis, I provide the first steps towards determining whether the KBI could be an effective assessment technique. First I assess the utility of the KBI at a coarse-scale by determining its ability to identify regions of high conservation priority. Secondly, I conduct a fine scale study to determine the response of the katydid assemblage to habitat quality. And lastly, the first two aims are combined to determine whether the KBI is an appropriate method to assess habitat quality at a fine-scale. In Chapter 2, by using a subset of museum records, I investigate the distribution of the katydids within the Cape Floristic Region (CFR), a global biodiversity hotspot. The katydids found within the CFR follow the same trends with regards to threat status, endemism and life history traits to the overall South African katydid assemblage. The KBI assessment method was able to select, at this coarse-scale, the ecosystems of conservation priority. For Chapters 3 and 4, the Kogelberg Biosphere Reserve (KBR) was selected as a study area as it allowed for the acoustic monitoring and direct comparison of katydid assemblages and responses across the core, buffer and transition zones through the use of passive recordings. In Chapter 3 I found that the katydids of the KBR are not complementary across the zones. However, they respond positively in terms of abundance to measured habitat quality when the entire assemblage is considered. In Chapter 4 I found that katydids responded towards coarse-scale habitat quality and they were not as sensitive towards habitat change as was expected. By including abundances of the katydid species in to the KBI calculations, the sensitivity of the KBI as an assessment method was improved. For this reason, katydids in the fynbos biome are likely to not be effective indicators of habitat change on a small scale, likely due to the surprisingly low diversity of katydid species in the KBR. However, if the KBI were to be tested out in forest patches or areas with higher diversity, the KBI may prove more promising. For these reasons, a rapid assessment technique based on the KBI is likely to be more appropriate for some habitat types over others.
Alien grass invasion of Renosterveld : influence of soil variable gradients
(Stellenbosch : Stellenbosch University, 2008-12) Muhl, Sara Ann; Esler, Karen J.; Milton, S. J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
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.
Approaches towards a critical evaluation and update of the red list of South African Butterflies
(Stellenbosch : Stellenbosch University, 2006-03) Ball, Johathan Bradford; Geertsema, H.; Samways, Michael J.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
Using the World Conservation Union’s (formerly the International Union for the Conservation of Nature) IUCN 2001 categories and criteria, the conservation status of the South African butterfly fauna has been reassessed. This study includes an assessment of the 62 globally threatened South African taxa and 1 that has a marginal distribution in this region.
Arthropods associated with commercial Proteaceae in the Western Cape Province, South Africa
(Stellenbosch : University of Stellenbosch, 2011-03) Sasa, Archbold; Samways, Michael J.; University of Stellenbosch. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: The commercial cultivation of Proteaceae is an important industry in the Western Cape, however, farmers are challenged with arthropod infestation which compels them to solely rely on chemical pesticides. Past studies in South Africa have shown that Proteaceae comprise a rich and diverse arthropod fauna. However, as most of these studies were conducted on wild Proteaceae, they may not be representative of cultivated proteas. Moreover, most of these species remained unidentified due to lack of identification expertise. These past studies, however, form a useful baseline for arthropod studies in proteas, e.g. the feeding guilds found in proteas. The aim of this research was to conduct an intensive and extensive survey of the arthropod-fauna associated with commercially-cultivated proteas across an entire year. Specifically, this survey was designed to document the composition of the arthropod fauna (creating a comprehensive reference collection for pest management purposes) and to assess whether the arthropod fauna differed between seasons and pesticide treatments. Infructescences, inflorescences and foliage of mainly commercial Proteaceae were sampled for arthropods seasonally for a period of twelve months by collection of plant material and direct searching. Seven commercial protea blocks, and a wild protea block (remnant patch of fynbos vegetation), were used as the sampling sites, and two sprayed blocks were used for assessing pesticide efficacy. Individual arthropods were identified as far as possible, with 37% identified to species level. A species accumulation curve showed that rare (minor) arthropod species made up of 70% of arthropods occurring in cultivated proteas. More than 8 700 individuals from more than 140 species and about 80 families were collected and identified, revealing that cultivated proteas have a rich and diverse insect fauna. These arthropods represent the full range of plant-feeding guilds: leaf miners, leaf chewers, flower bud borers, sap suckers and seed feeders. Flower visitors/free living guild was the most abundant (72%) and speciose (25%). In addition to phytophages, there was a large suite of insect predators and parasitoids. A large number of the arthropods were endemic to the Cape Floristic Region (CFR) and some (7.86%) have a pest status, in that they cause significant damage to the protea plants (for example, 60% of Safari sunset cultivar (Leucadendron salignum x L. laureolum) new flush stems and leaves were affected by Epichoristodes acerbella (Tortricidae). Capys alphaeus (Lycaenidae) and Phyllocnistis sp. (Phyllocnistidae) appear to be specialist pests, as they attack mainly Protea cynaroides and Susara cultivar (Protea magnifica x P. susannae) respectively. Arthropod abundance did not differ significantly between seasons, although significant seasonal effects were observed in species richness when the protea cultivars were examined separately. Pesticide application did not affect arthropod abundance, but did decrease species richness in sprayed blocks. Pesticides appeared to negatively affect minor (rare) species disproportionately, probably due to their lack of prior exposure to pesticides and hence sensitivity. Due to this inefficacy of pesticides in cultivated proteas, an increasing emphasis on the importance of non-chemical control measures, and our improved knowledge of the predatory and parasitic species in this system, integrated pest management strategies deserve greater research attention. Monitoring and use of threshold values for arthropod pests were suggested here, as well as the use of biological, cultural, physical and chemical (optimal use) control. For instance, in cultural control, polycropping and intercropping in proteas to increase plant diversity in the monocultures to promote a higher density of predators and parasitoids can be used. Certain flowering plants are known to provide greater temporal and spatial distribution of nectar and pollen sources, which can increase parasitoid reproductive potential and abundance of alternative hosts/prey when the pest species are scarce or at an inappropriate stage.
Assessing the chemical ecology and shelter-seaking behaviour of the grainchinch bug, Macchiademus diplopterus (hemiptera: lygaeidae) for optimisation of trapping during aestivation
(Stellenbosch : Stellenbosch University, 2016-12) Ngadze, Masimbaashe; Johnson, Shelley; Addison, Pia; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: The grain chinch bug (GCB), Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae) is a key quarantine pest of South African export fruit and is endemic to the Western Cape Province. The pest is troublesome in the drier wheat growing areas where it disperses from wheat in summer to find sheltered sites in which to aestivate. Aestivating adults can end up contaminating export fruit. The aim of the study was to gather more knowledge on the chemical ecology and shelter-seeking behaviour of the GCB. The involvement of pheromones in the aggregation behaviour of GCBs is yet to be fully elucidated. Further investigating the chemical ecology of the GCB in order to optimize its pheromone trapping was the primary focus of the first research chapter in this study. Headspace volatile compounds were identified from active bugs through gas chromatography-mass spectrometry (GC-MS) analysis. A total of 14 volatile compounds were identified from males and females in varying concentrations. For both sexes pooled, tridecane, (E)-2-hexanal and (E)-2-octenal were the three main components; (E)-2-hexenol, (E)-2-octenol, decanal and pentadecane were in medium amounts, while decanoic acid, dodecane, hexadecanal, hexanal, icosane, nonanal and tetradecanoic acid were minor components. The efficacy of synthetic lures using previously identified aggregation pheromone components, and sex pheromone volatile components (identified in present study) was studied in combination with modified traps using rubber septa dispensers in a field trial. There was no significant difference (P > 0.05) between insects caught in the sex pheromone baited traps and the aggregation pheromone baited traps. Traps caught low numbers of GCBs compared to the level of orchard infestation indicated by the amount of bugs that were found sheltering in corrugated cardboard bands tied around tree trunks. The corrugated cardboard bands showed a significant difference in the number of bugs sheltering between bands placed at bottom and top positions (0.5m and 1.5m above ground respectively) on the trees, at site 1 (P = 0.0058), site 2 (P < 0.0169) and site 4 (P < 0.0496) with the exception of site 3 (P > 0.4115). Cardboard band position influenced catches, as more bugs were found in bottom bands. This can be used advantageously in optimising innovative trap placements in the future in order to improve catches. In the second research chapter investigations into the behavioural responses of GCBs to visual objects were conducted. This was done to increase knowledge on how this behaviour can lead to the development of control measures such as the use of coloured traps of different shapes. Behavioural responses of GCBs to different shapes presented in their visual space indicated that there was a significant difference (P = 0.0001) in the choice of shape. Vertical/upright rectangular shapes had the highest number of GCB visits. GCBs responded to upright rectangles of different colours.Black and red rectangles were not significantly different (P > 0.05) from each other but were both significantly different (P = 0.0001) from green and yellow rectangles, off-target and sedentary insects. Vertical rectangles of two different colour patterns (black & white) and (red & white) did not show any significant difference (P > 0.153) in the number of GCB visits. Both black & white and red & white vertical stripes were significantly different (P = 0.0001) from off-target and sedentary insects. This indicates that GCBs were equally responsive to both colour patterns. These results indicate that GCBs exhibit a positive scototactic reaction towards dark upright surfaces. Information generated from this study will facilitate the development of pre-harvest monitoring and management measures against GCBs, using pheromone traps and physical barriers that prevent GCBs from dispersing into fruit orchards at the wheat to fruit orchard interface. This can help to reduce fruit contaminations, ultimately lowering the rejection risk of export fruit from South Africa.
Assessing the values and impacts of invasive alien plants on the livelihoods of rural land-users on the Agulhas Plain, South Africa
(Stellenbosch : Stellenbosch University, 2013-12) De la Fontaine, Samantha; Esler, Karen J.; Malgas, Rhoda R.; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: Invasive alien plants (IAPs) are known for their detrimental impacts on biodiversity and ecosystem goods and services. A substantial body of research has contributed to our understanding of their impacts on ecology. In comparison the socio-economic aspects of IAPs, are not well understood. Additionally, valuation practises have usually excluded the positive and the non-monetary impacts (benefits and uses) that IAPs hold for local livelihoods. Holistic valuation has been regarded as imperative for decision-making and managerial frameworks. A study was conducted in Elim on the southern Cape coast of the Agulhas Plain, South Africa, which aimed to explore the various impacts of IAPs on the livelihoods of rural land-users. Individual qualitative interviews were conducted face to face with landholders (referred to as farmers) (N = 12) and individuals from the economically marginalized community (referred to as marginalized community) (N = 12). The grounded theory approach to data analysis was used and results of the coding method used were displayed by means of superscripts. Results indicate that farmers were aware of broader uses of IAPs although they themselves did not utilise them as extensively as members of the marginalized communities. Invasive alien and problem plants that held value for both land-users were not perceived as being „invasive‟. Invasive alien plants were believed to have detrimental impacts on biodiversity and ecosystems goods and services which support people‟s livelihoods. Alien clearing programmes such as Working for Water (WfW) and LandCare have done much to alleviate the socio-economic burden of unemployment in this marginalized community. Aside from the social development aims set out by WfW (i.e. employment of low-income communities, poverty alleviation and skills training), knock-on social development benefits (e.g. feelings of pride, responsibility and awareness as well as conflict management skills) were also realised by individuals from the marginalized community that were previously employed by the programme. Farmers regarded alien clearing and management as a process that demands excessive time, energy and financial resources. On single occasions it was found that farmers employed methods other than the conventional clearing and management strategies (e.g. livestock that feed on IAPs and giving refuse IAP biomass from clearing and felling to neighbouring poor communities). No clear consensus was reached about regarding alien clearing and management but more support is desired from government. Working for Water relies on private landholders for alien clearing as it is required by law. This study emphasizes that stronger relationships between government and private landholders as well as more substantial incentives to clear IAPs on private land are prerequisites if required outcomes are to be achieved. Educating society at large about the detrimental impacts of IAPs is fundamental. Additionally, informing landholders on effective alien clearing methods and policies and legislation pertaining to it are key activities for the South African government. Finally, clearing and management programmes need to consider the benefits that local land-users obtain from IAPs when prioritising areas for the management of alien vegetation.
Assessing translocation effects on an African elephant (Loxodonta africana) source population: demographics, landscape use and response to drones in Majete Wildlife Reserve, Malawi.
(2020-03) Hartmann, Wesley Laurence; Leslie, Alison J.; Fishlock, Vicki; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: Translocations are increasingly common as a wildlife management strategy to reintroduce species that have undergone a local extirpation or to reinforce populations that have become isolated. Translocation effects have been well documented on the moved animals, however, much less is known about the effects these large-scale anthropogenic events have on source populations. The African elephant (Loxodonta africana) is a keystone species which plays a pivotal role in the ecosystems it inhabits. With their wide-ranging impacts, understanding how elephants utilize the space available to them, or how anthropogenic events such as translocations, could influence these patterns, is vital for the effective management of elephant populations. An additional human-associated disturbance on wildlife populations, although on a much smaller scale, is the use of technology for observational purposes. Generally, these technologies have enabled an unobtrusive means by which to detect and observe wildlife (i.e. remote-sensing camera traps), but increasingly the wildlife sciences are using unmanned aerial vehicles, more commonly known as drones, which are not unobtrusive. A great number of review papers have summarized and emphasized the drone’s capabilities in the wildlife sciences, but few have investigated the effect drones have on animals themselves. This study reviews all published translocation events that occurred on the African continent between the years 2000 and 2019 in an attempt to determine the factors that influence the success of translocations in an African context, and investigates how a source elephant population responded demographically and spatially to a large translocation event in Majete Wildlife Reserve where (n=154) 42% of elephants were removed and 70% of adult females. The study also investigated how this population responded behaviourally, post translocation, to the approach and presence of a drone. The demographic status of the Majete elephants was assessed via a combination of aerial survey data and individual identification techniques. Since the translocation, the population has increased from an estimated 200 individuals to 232 over a two-year period. A sex ratio of 5:2 male to female was found for adult elephants (older than 10 years) and a population growth rate of 7% per annum was estimated. The current growth rate is likely due to conception prior to the translocation event and is expected to decrease due to the extreme adult male bias in the current population. The removal of herds, primarily from one region within the reserve, significantly influenced the diversity of use of artificial water points by elephant herds. Herds historically only found in peripheral regions of the reserve were sighted more frequently in the areas other elephant herds had been removed from. While the population tolerated drone use reasonably well, increasing approach speeds and an approach angle of 90° (as opposed to 45°), were found to have significant negative effects on the likelihood of a successful drone approach towards elephants, regardless of sex and herd/group size. No flight or environmental variables were found to significantly influence the success of a sustained drone flight, however the outcome of the preceding approach was found to significantly influence success (GLZ, Estimate = 2.39497, p < 0.0001) i.e. a successful approach was more likely to result in a successful presence flight.
An assessment of alternative postharvest technologies for the disinfestation of fresh Cape Flora cut flowers for export from South Africa
(Stellenbosch : Stellenbosch University, 2018-12) Huysamer, Anton Jean; Johnson, Shelley; Hoffman, Lynne; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: A successful industry has developed around the export of fresh Proteaceae cut flowers from South Africa. Phytosanitary insects are a barrier to export, as South African Proteaceae associates with a considerable entomofauna. The development of alternative postharvest disinfestation technologies could reduce these interceptions and promote market access. Surveys on export material were conducted to determine which pests are most problematic when exporting Proteaceae. A total of 82 interceptions were made, comprising of eight insect orders and 26 insect families. Although many interceptions were as a result of solitary individuals, multiple interceptions consisted of many individuals of western flower thrips (Frankliniella occidentalis) and protea itch mite (Procotolaelaps vandenbergii). These pests were selected as the key pests on which to focus for disinfestation using alternative postharvest technologies not yet utilised for Proteaceae. Controlled Atmosphere and Temperature Treatment Systems (CATTS) technology was assessed as a potential disinfestation tool for fresh Proteaceae cut flowers. The tested commodities were Leucospermum ‗Veldfire‘, Protea magnifica ‗Barbi‘, Leucadendron ‗Safari sunset‘ and ‗Jade pearl‘, and Geraldton wax ‗Ofir‘ (Myrtaceae). CATTS treatments consisted of temperature ramps of 35°C/hour and 30°C/hour from 23°C to 40°C, with a 15 min soak at 40°C, and 35°C/hour and 30°C/hour from 23°C to 50°C, with a 15 min soak at 50°C, under modified atmospheres of 1% O2, 15% CO2 in N2. Treated stems were subjected to vase life studies after treatment, or following air- and sea-freight storage simulations at 2°C for 3 or 21 days respectively. Leucospermum ‗Veldfire‘ did not withstand treatments, as style wilting reduced overall quality. Protea magnifica ‗Barbi‘ withstood some treatments, maintaining comparable quality to control stems in the vase immediately after treatment. Both Leucadendron commodities withstood treatments well, and maintained marketable quality following treatment, air- and sea-freight simulations. Geraldton wax ‗Ofir‘ maintained quality in vase immediately after and following air-freight simulations. CATTS treatments of 35°C/hour and 30°C/hour to 40°C in 1% O2, 15% CO2 in N2 resulted in 100% mortality in western flower thrips and protea itch mites within 24 hours of treatment. Postharvest fumigation treatment with ethyl formate (EF) was also assessed as a potential disinfestation technology. Concentrations ranged from 18.53g/m3 to 151.47g/m3 EF, and durations ranging from 30 mins to 3 hours for the same cut flower commodities listed above for CATTS treatments. Further trials on Geraldton wax ‗Ofir‘ consisted of 10g/m3 and 20g/m3 for 1 and 2 hours. All treatments resulted in reduction in overall quality of treated fresh goods. EF fumigations of 18.53g/m3 for 1 and 2 hours achieved 100% mortality within 24 hours of treatment in western flower thrips and protea itch mites, but excessive post fumigation damage renders EF unsuitable. The information generated from this study has highlighted the most problematic phytosanitary pests in export consignments of fresh Proteaceae from South Africa. It has also highlighted a potential postharvest technology for integration into current disinfestation strategies, and refuted another. This information can assist in the development of postharvest disinfestation strategies, ultimately reducing the phytosanitary pressures and promoting the export of fresh Proteaceae cut flowers from South Africa.
Assessment of fish as bio-indicators of river health in rivers of the southwestern Cape
(Stellenbosch : Stellenbosch University, 2002-03) Hayes, Johan Barnard; Van Wyk, J. H.; Boucher, C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: In this study, the Fish Assemblage Integrity Index (FAll) was applied on three rivers within the southwestern Cape. This index uses fish as indicators of biological aquatic integrity and is based on indigenous species expected to be present in biological fish habitats. Fish integrity classes were calculated for each of the sites in the three rivers studied. Sites 2 and 4 within the Lourens River were rated as Class C, whereas sites 1 and 3 were rated as Class F and Class D respectively. Sites 1, 2 and 4 within the Palmiet River were rated Class F, whereas sites 3 and 5 were rated as Class E and Class D respectively. Site 1 within the Hout Bay River was rated as a Class F site, in addition to sites 2 and 3 been rated as Class A. It is however, suggested that the FAll needs to be adjusted to accommodate the general low species richness experienced in the southwestern Cape. In addition to the FAll been applied, the effects of long-term exposure to subtle water quality changes associated with human activities, specifically potential estrogenic compounds in fish from the Lourens River were also investigated. The production of the yolk precursor lipoprotein complex, vitellogenin (Vtg) produced in the liver under estrogen control was employed as biomarker for environmental estrogen exposure. Male fish from the Lourens River were studied using SDS-PAGE gel electrophoresis. Results indicated that 60% of male fish showed the presence of Vtg in their plasma. Abnormal gonad morphology in male and female fish were also assessed using standard histological procedures. Results from this study indicated no observed abnormalities in either male or female gonads. The immediate presence of endocrine disrupters with estrogen activity was investigated by screening water samples from the Lourens, Palmiet and Hout Bay Rivers for estrogen activity. Results indicated that none of the samples appeared to be cytotoxic. In addition, estrogen activity of water samples was also investigated by in vitro culturing of water samples with frog, Xenopus laevis, liver slices. Results indicated that none of the water samples from the three rivers studied indicated estrogenic activity. Although cytotoxicity and estrogen activity results were negative, the production of Vtg in male fish suggests further research regarding the presence of estrogenic substances in these rivers.
Assessment of quantitative and genetic molecular variation of Acacia karroo in two extreme populations
(Stellenbosch : University of Stellenbosch, 2006-03) Bayonne Mboumba, Georges; Ward, David; University of Stellenbosch. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
Acacia karroo is widespread in southern Africa and displays remarkable phenotypic plasticity over its geographical range. However, it is currently unknown whether this phenomenon is merely phenotypic variation due to environmental variance or whether such plasticity represents adaptation to different habitats (known as adaptive phenotypic plasticity). Adaptive phenotypic plasticity implies that genotypes differ and that there is local adaptation to the local environment. To shed light on this phenomenon, we used a common-garden experiment to investigate among-population variation in plastic responses to simulated rainfall and browsing in two populations originating from contrasting environments, namely arid Karoo (Leeu Gamka) and subtropical coastal forest (Richards Bay). We also studied genetic variation among populations by means of allozyme markers. The results suggest that the populations investigated are both genetically distinct and phenotypically plastic. In addition, there were high levels of polymorphism within populations and great differences in their range of plastic responses to treatments. Of the two populations investigated, the slow-growing one (Leeu Gamka) was phenotypically more plastic with regard to defence-related traits (longer spines, more tannin) while the fast-growing one (Richards Bay) was phenotypically more plastic regarding growth-related traits (taller, with longer leaves). Patterns of performance revealed that the populations have pure strategies of either growth (forest) or defence (arid). The interactions between populations and environments in some traits indicated genetic differentiation in plastic responses between populations and, consequently, that phenotypic plasticity is locally adaptive and not merely due to environmental differences. The two populations appear to have pure strategies; when environmental conditions were improved by addition of water, the forest population increased investment in growth but not defence, while the arid populations increased defence production but not growth.
Assessment of the alien marine intertidal invertebrates in the Kogelberg Biosphere Reserve, South Africa
(Stellenbosch : Stellenbosch University, 2011-12) Malherbe, Hanlie; Samways, Michael J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: The privilege of utilising resources from the globe's marine ecosystems is threatened. Adequate regional and global conservation efforts are vital. Understanding species' distributions and the environmental variables influencing community structures are important for instigating optimum conservation plans. A major threat facing marine ecosystems is the introduction and proliferation of alien invasive species. The distribution and geographical expansion of marine alien invasive species, along with environmental variables driving their increase is also critical for drawing up conservation plans. In response to this point, this study addresses gaps in our knowledge regarding intertidal marine invertebrate species distributions particularly that of marine alien species in the Kogelberg Biosphere Reserve (KBR) and adjacent Betty's Bay Marine Protected Area (MPA) in the Western Cape of South Africa, a prime area for south-coast marine conservation. Species identifications were done in September 2010. Two marine alien invertebrate species were identified along the coastline. These were the invasive mytilid Mediterranean mussel Mytilus galloprovincialis and the bryozoan Watersipora subtorquata. A quantitative systematic survey of the intertidal region, consisting of seven rocky shore sites was then undertaken from October 2010 to December 2010. The abundance of all focal marine invertebrate species, within six selected habitat types was assessed. Environmental variables were also recorded. Statistical tests were done to investigate for significant interaction in mean abundance and mean species richness among intertidal zones and protection status (MPA and non-MPA), and among intertidal sampling units (SU‟s) and protection status. There was also investigated for significant difference in mean abundance and mean species richness across intertidal zones and habitat types where protection status was not taken into account, and to test for significant differences in mean abundance and mean species richness between the intertidal zones and habitat types. Correspondence analyses were used to illustrate relationships between species composition and the defined environmental variables. Tests were done to investigate for significant differences in mean abundance of the identified marine alien species between the MPA and non-MPA, study sites, SU's, and wave exposures. These results indicated that vertical and horizontal stress gradients along the shore mainly influence abundance and species richness. The significantly higher abundance of M. galloprovincialis outside the MPA is due to its preference for wave-exposed areas. The reason for the difference in the total abundance of W. subtorquata in the different habitats is not clear, although it appears that the higher abundance of this species in the MPA is because the sheltered nature of the MPA. M. galloprovincilais displaces indigenous species. W. subtorquata does not cause any significant harm along the coast of South Africa. This study indicates that the abundance of M. galloprovincialis and W. subtorquata in the MPA is relatively low. The MPA is therefore in good condition with regards to intertidal alien species. It is important that the MPA and adjacent KBR's coastline maintain its current pristine status.
An assessment of the impacts of invasive Australian wattle species on grazing provision and livestock production in South Africa
(Stellenbosch : Stellenbosch University, 2013-12) Yapi, Thozamile Steve; O'Farrell, Patrick; Esler, Karen J.; Dziba, Luthando; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: I investigated the impacts of the invasive wattle species (Acacia mearnsii, A. dealbata, A. decurrens), on the ecological function and productivity of rangelands in South Africa and their ability to sustain livestock production. More specifically, this study set out to: (1) assess grazing areas at a national scale; (2) identify evidence of progressive impacts of these species on livestock production across a selection of magisterial districts; (3) determine the effects of A. mearnsii density on growth form dominance of indigenous plant species, and highlight how this translates into impacts in forage quality and quantity; (4) determine the effects of A. mearnsii invasion on soil resources and conditions (key determinates of ecological function) required to support grazing production; and finally (5) determine to effects that clearing operations have had on the provision of grazing resources. My results indicate that the level of overlap between wattle invasion and areas with a high grazing potential, at the national scale, is relatively low (2.9%). However, at a magisterial district scale, areas with a high grazing potential have a moderate (approximately 35.1% high grazing potential area under wattle invasion for highest invaded district) level of invasion. Scattered and moderate levels of invasion currently dominate or characterise these species invasion patterns. Both light and dense A. mearnsii invasions reduce grazing capacity. Dense invasion had the most severe effect reducing grazing capacity from 2 ha, required to support one large stock unit, to 8 ha. The clearing of this species was found to improve grazing capacity within 5 years. The reduction in grazing capacity following invasion was largely due to reduced basal cover and herbaceous biomass. The clearing of invaded sites was found to increase both basal cover and herbaceous biomass to pre-invasion levels. Acacia mearnsii invasion was found to affect certain soil properties. Under an A. mearnsii canopy, plant litter, carbon content of the soil and nitrogen concentrations were all found to be elevated. Overall, this study demonstrates that Acacia invasions have a significant effect on grazing resources at a local or site scale, and that for the eastern region of South Africa, these effects are ultimately scaled up to a district level. This is likely to have important financial and human well-being repercussions. However clearing and restoration programs are clearly able to reverse or mitigate these effects. This study therefore lends support to or complements other ecosystem service provision arguments for clearing alien invasive species.
Assessment of the invasive German wasp, Vespula germanica, in South Africa
(Stellenbosch : Stellenbosch University, 2015-04) Haupt, Karla; Veldtman, Ruan; Addison, Pia; Prozesky, Heidi; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: The invasive social wasp, Vespula germanica (Fabricius, 1793) (Hymenoptera: Vespidae), stands out as a remarkably successful insect invader worldwide. It flourishes in newly invaded ecosystems, where it has become a major problem in urban settings due to its close association with humans. The wasp is characterised by its devastating economic, social and environmental impact. Since its initial discovery in 1974 in Cape Town, all aspects of the wasp’s invasion throughout South Africa have been poorly documented. The wasp’s occurrence in the Cape Floristic Region (CFR) in the Western Cape Province (WCP), an area highly valued for its unique biodiversity, is of great concern due to the possible detrimental environmental effect of the wasp on this vulnerable biome. In this study, the present distribution of V. germanica was determined. Results indicate V. germanica’s distributional range is presently restricted within a small region of the WCP and it is thought that the Cape Fold Mountain range has acted as a natural barrier limiting the range expansion of the wasp. Field trials were conducted to determine V. germanica’s bait preference (protein versus carbohydrate) under local conditions and identify the best method in trapping the wasp. Fresh meats (lean smoked ham and minced beef) were overall the most preferred bait in both 2013 and 2014. Future studies should consider investigating the use of volatile meat extracts instead of fresh meat baits, as it could be as attractive but more practical for use in the field. Heptyl butyrate showed the most promising result of the artificial lures and warrants further investigation. Other lures (heptyl butyrate + acetic acid, isobutanol, isobutanol + acetic acid) were highly unattractive and possible reasons explaining this phenomenon, are discussed. A questionnaire survey was used during face-to-face interviews to explore the perspectives of forty farmers with regard to V. germanica occurring on their property. The current impact of the wasp in the agricultural context in the WCP was also determined. The majority of the respondents presented a negative view of the wasp and eradication seems to be a high priority for them. V. germanica is presently more of a social than an economic pest. Although indications are that with an increase in its density and distributional range, agro-economic problems and an increasing negative impact on local biodiversity can be expected. Management efforts should focus on its peripheral distribution, in order to curb further natural spread. The wasp’s distribution should also continue to be monitored, to enable early detection and rapid response, in the event that it succeeds in establishing itself in a new location. Further investigations into the suitability of a monitoring tool, including bait preferences, as well as continuing studies on the wasp’s overall impact, are recommended.
Assessment of the pathogenicity of fusarium euwallaceae to grapevine and deciduous fruit trees in South Africa and its rapid detection in woody tissues
(Stellenbosch : Stellenbosch University, 2022-04) De Jager, Muriel Mignon; Roets, Francois; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: A myriad of different tree species in South Africa are under threat from the invasive woodboring beetle, Euwallacea fornicatus (Coleoptera: Curculionidae: Scolytinae), the polyphagous shot hole borer, PSHB. While constructing galleries in the wood of hosts these beetles release spores of a mutualistic fungus, Fusarium euwallaceae (Hypocreales; Nectriaceae).The fungus colonises the xylem tissues and acts as the primary food source for the beetle, but colonisation can lead to Fusarium dieback disease in susceptible hosts. Many economically important fruit tree species have been identified as possible hosts; however, no assessments have specifically tested the pathogenicity of F. euwallaceae towards these. The work presented in this thesis set out to evaluate the susceptibility of different deciduous fruit trees (plum, nectarine and apple) and grapevine to F. euwallaceae. The effect of branch diameter and increased inoculum load on the rate of lesion development was also assessed. Fusarium euwallaceae was pathogenic to all fruit tree species and cultivars tested but no evidence of disease development was recorded in grapevine. There were no significant differences in virulence between the different isolates. There was also no evidence that differences in branch diameter or differences in the number of inoculation points on a branch can affect the growth rate of F. euwallaceae. For monitoring, the presence of PSHB is often determined by positive identification of F. euwallaceae without collection of the beetle, particularly when beetles are not able to establish viable colonies. Standard approaches to identify F. euwallaceae are costly and labour- and time intensive as the fungus needs to be isolated and cultivated from freshly collected material, the DNA needs to be extracted and purified, and the DNA needs to be sequenced for a marker that can be used to identify it. In this thesis a faster, more accessible, and cheaper tool for the identification of F. euwallaceae in both fresh and dried wood samples which increases monitoring capacity when resources are limited is presented. A species-specific marker was identified from literature and an optimized PCR protocol for the identification of F. euwallaceae was developed that removes requirements to rear the fungus, purify its DNA and to sequence a DNA marker. This protocol was tested on eleven different hosts, all but one of which that produced positive results in at least one of the replicates. Amplification was not possible in one of the hosts likely due to the high concentration of PCR inhibitory compounds. In cases like this, a secondary measure based on the protocol developed here can be used where fungal isolates are first obtained from diseased woody tissues and these subjected to the rapid detection protocol. Amplification of F. euwallaceae DNA using this approach had a 100% reproducibility rate.
An assessment of the potential of irradiation as a postharvest control treatment against the banded fruit weevil, Phlyctinus callosus (Coleoptera: Curculionidae): effects on adult weevils and host fruit (‘Flavor Fall’ pluots)
(Stellenbosch : Stellenbosch University, 2013-12) Duvenhage, Andries J.; Johnson, Shelley; Jooste, Mariana; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: The export of South African fruit to some of its biggest international markets may be rejected if the phytosanitary pest, Phlyctinus callosus (Coleoptera: Curculionidae) is found in fruit consignments. An alternative to methyl bromide fumigation is needed and one of the most promising of the alternative treatments is phytosanitary irradiation as it is environmentally friendly, does not leave residues on food or in the environment and it is effective against a wide variety of insects. Field-collected weevils were treated with five doses of gamma irradiation (5, 10, 20, 40 and 80 Gy) and the fecundity and fertility of mating crosses of treated males and females with treated and untreated individuals of the opposite sex, were determined to evaluate the effect on P. callosus reproductive ability post-treatment. Results indicated that irradiation treatment did not affect fecundity, but fertility was significantly affected, decreasing as the irradiation dose increased. Females were more susceptible to the irradiation treatment than males, and after treatment with 80 Gy, eggs laid by females and mated with either treated or untreated males, did not hatch. A generic dose of 400 Gy for all insect pests except tephritid fruit flies and pupae and adult Lepidoptera is currently approved by USDA-APHIS (United States Department of Agriculture – Animal and Plant Health Inspection Services) for use on certain commodities. Results from the present study support the development of a species-specific dose for P. callosus, as well as the development of a group generic dose for the Curculionidae that is lower than 400 Gy. Effective phytosanitary irradiation treatments are only feasible if the treatment does not adversely affect fruit quality and the marketability of export fruit. Therefore, an investigation of the effects of irradiation disinfestations treatments on the quality of the new pluot cultivar, ‘Flavor Fall’ was made. Packed cartons were treated with three doses of gamma irradiation: 400 Gy, 900 Gy and 1400 Gy. After treatment fruit underwent a PD 7 dual temperature cold storage regime for 42 days and a shelf-life simulation for 7 days. The impact of insect-proof bags, sometimes required by importing countries to keep insects off packaged fruit, was also investigated. Respiration rate of the fruit was measured throughout and fruit quality evaluations were done after cold storage and after shelf-life. The results indicated that quality parameters measured at the end of cold storage, which would be after the fruit arrives at the export markets, were above the minimum standards for overseas markets. Gel breakdown was unacceptably high after the higher temperature exposure of shelf-life for fruit treated with the 900 and 1400 Gy doses. The insect-proof bags reduced shrivel, but resulted in higher incidence of gel breakdown. The use of irradiation, together with the use of the insect-proof bag, has potential as an alternative postharvest mitigation treatment for plums. Lastly, an investigation into potential rearing methods for P. callosus, including recommendation for the future, was made as the availability of a sustainable rearing method that ensures a consistent supply of high quality P. callosus adults would enable continuous research with greater numbers of this pest. The information generated in this study provides a greater understanding of the radiation biology of, not only this curculionid species, but the Curculionidae as a group, and is valuable in advancing the development of alternative postharvest control measures against this phytosanitary pest.
Assessment of toxic baits for the control of ants (Hymenoptera : Formicidae) in South African vineyards
(Stellenbosch : Stellenbosch University, 2008-12) Nyamukondiwa, Casper; Addison, Pia; Addison, M. F.; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: Ant infestations comprising the Argentine ant Linepithema humile (Mayr), common pugnacious ant Anoplolepis custodiens (F. Smith) and cocktail ant Crematogaster peringueyi Emery are a widespread pest problem in South African vineyards. Integrated Pest Management (IPM) programmes aimed at suppressing the problematic honeydew excreting vine mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) on grapes must include ant control to optimize the effectiveness and efficacy of mealybug natural enemies. If ants are eliminated, natural enemies are able to contain mealybugs below the Economic Threshold Level (ETL). Current strategies for ant control are limited and generally include the application of long term residual insecticides that are detrimental to the environment, labour intensive to apply and can disrupt natural biological control if applied incorrectly. A more practical method of ant control using low toxicity baits was therefore investigated. Field bait preference and bait acceptance assessments aimed at determining bait repellency and palatability, respectively, were carried out during spring, summer and autumn in three vineyards of the Cape winelands region during 2007/08. Five toxicants comprising gourmet ant bait (0.5%), boric acid (0.5%), fipronil (0.0001%), fenoxycarb (0.5%) and spinosad (0.01%) dissolved in 25% sugar solution were tested against a 25% sucrose solution control. Gourmet ant bait was significantly more preferred and accepted by all ant species than the other baits. Laboratory bait efficacy assessments using four insecticides (gourmet, boric acid & spinosad) at concentrations of 0.25; 0.5; 1; 2 and 4 times the field dose and fipronil at 0.015625; 0.03125; 0.0625; 0.125; 0.25 times the field dose were carried out. Results revealed that boric acid (2%), gourmet ant bait (2%) and fipronil (1.0 X 10-5%) exhibited delayed toxicity for L. humile and C. peringueyi while spinosad (0.01%) showed delayed action on L. humile. Field foraging activity and food preference tests were also carried out for the three ant species during 2007/08. Foraging activity trials revealed that vineyard foraging activity of L. humile is higher relative to A. custodiens and C. peringueyi. This means fewer bait stations are required for effective L. humile control making low toxicity baits a more affordable and practical method of controlling L. humile than the other two ant species. Food preference trials showed that L. humile and C. peringueyi have a high preference for sugar while A. custodiens significantly preferred tuna over other baits. However, all ant species had a preference for wet baits (25% sugar water, 25% honey, tuna & agar) as opposed to dry ones (fish meal, sorghum grit, peanut butter & dog food). This research concludes that low toxicity baits show potential in ant pest management and can offer producers with a more practical, economical and environmentally friendly method of ant control which is compatible with vineyard IPM programmes.
Assessment of veld utilisation practices and veld condition in the Little Karoo
(Stellenbosch : University of Stellenbosch, 2005-03) Cupido, Clement F.; Milton, S. J.; Visser, N.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
The veld condition in the Little Karoo is in various states of degradation and grazing by domestic livestock is considered as the major anthropogenic force that changed the landscape. This region with its extremely rich plant species diversity and endemics, has supported small livestock for at least 2 000 years, and since colonization (250 years ago) been intensively used for the production of a variety of livestock. Ostrich production developed as the major source of income for this region. The first part of this study investigates the current veld management practices employed by livestock farmers in the Little Karoo region. Recommended veld management practices considered in this study are grazing rotation, moderate stocking rate control, moderate veld utilisation, separation of ecotopes, veld rehabilitation, controlling declared weeds and alien vegetation and regular assessment of veld condition. One hundred randomly selected farmers were personally interviewed by means of a structured questionnaire. Questions were grouped into the following categories: (a) demography of farmers, (b) ostrich farming, (c) perceptions and knowledge of farmers on farming practices, (d) grazing rotation, (e) stocking rate, (f) veld utilisation and veld assessment, (g) separation of ecotopes, (h) veld rehabilitation, (i) control of alien vegetation and (j) farmers’ knowledge on legislation. This was used to obtain information on the Little Karoo farming community, sizes of farms and camps, types of farming enterprises and on adoption of recommended veld management practices in the region. The main findings from this section are that relatively small farming units with few camps, poor separation of ecotopes and a low estimated grazing capacity, limit extensive livestock farming within the region. Perceptions of farmers on veld condition, grazing rotation, stocking rate, separation of ecotopes are fairly optimistic. As a result grazing capacities are overestimated and overstocking occurs within this region. The current stocking rate in ostrich camps (67.7% overstocked) and mammalian livestock camps (55.1% overstocked) is evidence that farmers overstock to compensate for these limiting factors in order to make a living from the land. The majority of farmers are well aware of the Articles in the Conservation of Agricultural Resources Act of 1983, which are applicable to veld management. Only more that 50% comply with this legislation by rehabilitating veld and 80% of them control invasive alien species on their farm. In the second part, veld assessments were done in randomly selected veld camps, using the multi-criterion, semi-subjective Quick Rangeland Health Assessment (QRHA) Method. Veld condition was significantly poorer closer to water or feeding points due to the piosphere effect caused by livestock. Veld condition in the Little Karoo can be related to altitude, vegetation types and land use. Therefore, the lowlying Little Succulent Karoo vegetation type is in a poorer condition compared to Spekboom Succulent Thicket and South and South-west Coast Renosterveld. Ostrich production on plains in the Little Succulent Karoo vegetation type is the main cause for the degradation of this vegetation type. It would seem as if historically high stocking rates cannot be ignored in explaining the current veld condition. A positive correlation between veld condition and the diversity of plant species (species density) were found, which highlights the importance of good veld management practices in sustainable agriculture. The third part tested whether all indicators in the QRHA method are equally sensitive and whether there is a positive correlation between the QRHA method and the Grazing Index Method. A significant positive linear correlation was found between the two methods. Cover was the least sensitive indicator of rangeland condition, and livestock induced disturbances (which include the indicators grazing intensity, disturbance indicators, soil health and species richness) were the most sensitive for Karoo veld assessment. A major benefit of the QRHA method is heuristic; therefore this method may have value in agricultural extension work.
An assessment of water quality and endocrine disruption activities in the Eerste/Kuils River catchment system, Western Cape, South Africa
(Stellenbosch : Stellenbosch University, 2005-04) Fourie, Shani; Van Wyk, J. H.; Pool, E. J.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: Water quality analysis forms the basis in assessing and monitoring catchments. As urban development continuously increase, pollution sources increase in either point source (wastewater treatment works, industrial effluents) and/or non-point source origin (storm water discharge, domestic pollutants), accumulating pollutants in the environment. It was only recently discovered that certain pollutants have subtle disrupting effects on the endocrine system resulting in health related problems associated with the reproductive system and thyroid system (growth and development) of animals and potentially humans. Natural water resource management proves to include limited biological assays measuring endpoints for cytoxicity, inflammatory activity and endocrine disruption. The broad objective of this study was therefore to include several bioassays, not normally used in municipal (City of Cape Town) monitoring programmes, along with water quality data collected by the City of Cape Town. The Eerste/Kuils River catchment system, Western Cape, under the auspices of the City of Cape Town was chosen, and although this catchment does not contribute to drinking water resources, is subjected to a range of anthropogenic influences (industrial effluents, household wastewater, agricultural runoff). Within the short time-frame available for this study (six months) two months, July (following a dry summer and autumn season) and October (following a wet winter and early spring season) were selected for water quality monitoring. Spatial variation (with relevance to specific point and non-point contamination) among sampling sites were also obtained by choosing several (n=10) along the catchment. Specific aim of the study therefore included: Firstly (Chapter 2), the use of in vitro bioassays, lactate-dehydrolises assay (LDH) for cytotoxic activity, pro-inflammatory hormone Interleukin-6 (IL-6) secretion by human blood cells and a specific Salmonella ELISA for faecal contamination, in conjunction with routine chemical and biological (mostly microbiological) monitoring activities. The study indicated significant variation among sites in all microbiological measures as well in IL-6 secretion and Salmonella presence. Between months, variations were also evident in certain variables. Secondly (Chapter 3), two bioassays using the yolk precursor protein, vitellogenin (Vtg) as endpoint was implemented in a) an in vitro Xenopus laevis liver slice assay (five day exposure) and b) an in vivo Zebrafish (Danio rerio) bioassay (seven day exposure) assessing estrogenic activity in the Eerste/Kuils River catchment. Although estrogen spiked positive control water samples stimulated Vtg production in vitro as well as in vivo, no dramatic estrogenic activity was measured at any of the selected sites. Thirdly (Chapter 4), a bioassay using the thyroid controlled metamorphosis in Xenopus laevis tadpoles to assess effects on the thyroid hormonal system was implemented. Thyroid stimulatory activity, compared with a negative control sample, was measured at two sites along the catchment. Although the practical implementation of the tadpole semi-static exposure protocol (water replacement) proved to be labour intensive, all the added bioassays proved to be valuable tools to add valuable information regarding water quality. It is clear that more research related to anthropogenic influences along the Eerste/Kuils River catchment system are needed, specifically in monitoring monthly variations to better understand annual variation in several of the endpoints studied.
Attitudes and behaviour of landholders towards the conservation of Overberg Coastal Renosterveld, a threatened vegetation type in the Cape Floral Kingdom
(Stellenbosch : Stellenbosch University, 2003-12) Winter, Susan Jean; Esler, Karen J.; Prozesky, H.; Stellenbosch University. Faculty of Agrisciences. Department of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: This thesis describes the findings of a survey to investigate the attitudes and behaviour of private landholders towards the conservation of Overberg Coastal Renosterveld, a highly endangered grassy-shrubland of the Cape Floral Region (CFR) lowlands, now 94% transformed. Personal interviews were conducted with 36 farmers in the Overberg region of the Western Cape, by administering a questionnaire. The following aspects were quantitatively described using the Statistical Package for Social Scientists (SPSS): Renosterveld management and utilisation behaviour, perceived value of Overberg Coastal Renosterveld; landholder knowledge of its conservation importance and willingness to conserve it. Attitudes towards incentives for conservation; conservancies; and the provincial conservation authorities were also investigated. Willingness to conserve was explored further using SPSS cross-tabulation analyses. It was found that farmers who were more willing to conserve were younger, did not necessarily have a better education, and owned larger farms (> 500 ha) with a greater amount of remnant renosterveld (> 300 ha) than farmers less willing to conserve. Attitudes towards Overberg Coastal Renosterveld were largely negative, due to certain associated plants and animals which are problems for farmers, and because it is not economically advantageous to retain it. However, provision of incentives (of which assistance with fencing and land management was most attractive) and increased extension support will provide practical positive inducements for conservation. There is also a need for more landholder education regarding the scarcity of coastal renosterveld to prevent transformation of remaining fragments. The second component of the study aimed to construct a user-friendly index to measure the conservation attitudes of landholders towards conserving Overberg Coastal Renosterveld. An interative item analysis was executed on the data, using Spearman Rank Order correlations and Cronbach's Alpha. Results yielded an index with two dimensions and a Cronbach Alpha co-efficient of 0.67. The dimensions or components of conservation attitude towards renosterveld included: (i) a landholders' perception of the perceived benefit of Overberg Coastal Renosterveld; and (ii) their willingness to conserve it. The mean conservation attitude score was 0.6 (± 0.03), indicating that landholder attitudes were generally sympathetic towards renosterveld conservation. This suggests that while many landholders do not place a high value on Overberg Coastal Renosterveld due to its low agricultural value, their willingness to conserve it is in some cases higher than expected, which possibly explains the above-average mean conservation attitude score. An analysis of variance showed that the following variables were significantly, positively correlated with conservation attitude: (i) area of Overberg Coastal Renosterveld; (ii) landholder environmental group membership status; (iii) presence of ecotourism activities on the property; and (iv) how long the property had been in the owner's family. The intended application of the index is that index scores (amenable for use in a Geographical Information System database) can assist conservation practitioners in deciding where resources should be allocated, on the assumption that high-scoring individuals are more likely to want to take part in conservation initiatives.
Avian impact of South Africas first concentrating solar power tower facility in the Northern Cape
(Stellenbosch : Stellenbosch University, 2020-03) Van Heerden, Hendrik Petrus; Esler, Karen J.; Hudson, Adrian; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: Through its commitment to a greener economy that is less dependent on nonrenewable energy resources, South Africa’s Integrated Resource Plan aims to diversify the energy system by including energy resource alternatives such as concentrating solar power (CSP). All CSP facilities harvest solar thermal energy by utilising reflectors that focus energy to a receiver where the energy is concentrated and eventually converted into electricity via a conventional thermoelectric power cycle. Four main types of CSP technologies exist in today’s global market of which central receivers, also known as CSP towers, are one of the dominant types. Recent studies suggest that the potential impacts of utility-scale CSP tower facilities on avian populations may be substantial given that these impacts are driven by factors such as project location, footprint size and technology. It is anticipated that these factors mainly impact avifauna by altering the demography of avian communities and by exposing birds to singeing and collision risk. However, given the novelty of tower CSP and the global shortfall of publicised data on avian impacts, conclusive investigations into the avian impact of these facilities have yet to be established. Further rigorous investigation of these factors is therefore encouraged. This study was the first to investigate the impact of a solar power tower facility in South Africa, seeing that it was conducted on the only operational CSP tower facility in southern Africa. The study aimed to evaluate the impact of the Khi Solar One CSP tower facility on avifauna of the area with special attention to biodiversity dynamics and avian mortalities and injuries. Industry best practice guidelines and peer-reviewed literature were used as the point of departure from which the fieldwork methodology was developed. Data on avian mortality and injury were gathered over four seasons by conducting weekly monitoring and identifying patterns of avian use by means of vantage point surveys and parallel-line transects that were conducted inside and outside the facility footprint. Data collected during the field surveys were analysed to determine a suitable risk analysis model for this kind of development and to determine whether and to what extent the development had caused a change in avian behaviour. The findings demonstrate that concerns about the impacts of CSP towers on bird populations are not completely unsubstantiated, even though some results remain inconclusive. Avian species diversity, abundance and density per unit area were found to be higher in the neighbouring untransformed habitat than within the facility footprint. Data suggest that certain shrubland/woodland species favoured the CSP facility, however, they did not represent an unaffected population by default. In contrast, generalist and open country/grassland species were not adversely affected by impacts caused by the CSP tower facility. The presence of constructed water bodies and structures within the transformed habitat also appeared to have an indirect impact as in this otherwise rural habitat, they lure a diversity of aquatic and other species that favour a more urban habitat. Breeding observations indicated that reproductive activity within the transformed habitat was lower than within the untransformed habitat. A total of 324 avian impact detections were recorded during the monitoring year, involving 34 identified species. Of the total avian impact detections, 61% of injuries/mortalities were found to be caused impact trauma and 14% by singeing related trauma. Most collisions were recorded in the solar field with trending evidence of impact occurring on the lower quarter of the heliostats’ reflective surfaces. Singeing data displayed a significant increase in detections during the summer months and revealed that most recorded detections were of aerial feeding migratory birds. A clear correlation was found between the peak singeing detection months and the positioning of heliostats into the standby position during this period. It was difficult to make a meaningful assessment of the overall avian fatality at CSP tower facilities and to formulate accurate hypotheses regarding the risk of avian mortality among these facilities and other sources of solar electricity generation. Still, data suggested that fatalities per area may be a more suitable metric for estimating cumulative impacts among CSP tower facilities since the efficiency of this technology is continuing to improve and change in design and operation over time. Ultimately, this study offers several findings and recommendations that may contribute to the compilation of a mitigation framework that will ensure that the industry develops in a sustainable manner in South Africa.