This study investigated the effects of the Triffid weed Chromolaena odorata on small and large mammals in Hluhluwe-iMfolozi Park. C. odorata is a widespread invasive alien plant that poses threat to the highly maintained natural vegetation in HiP and most other protected areas in KwaZulu-Natal. Following the opinion that the effects of invasive alien plants on all levels of biodiversity need to be recognised for their effective control, we compared small and large mammal species richness and diversity between areas with differing C. odorata invasion durations, areas with differing clearing times and an area with no history of invasion as a control area. Small mammal trapping was done using Sherman live traps and mark-recapture techniques. Track counts were used to estimate large mammal species abundance, richness and diversity. The control area had higher small mammal species richness and diversity than the invaded areas, which suggests that invaded areas were not suitable habitats for small mammals. It was also found that small and large mammal species richness and diversity decreased with the increase in invasion duration, which shows that the more time C. odorata is left to establish the more disturbance it causes to the habitat. We found the uninvaded treatment to have the highest diversity of large mammal species than all the invaded treatments, which suggests that large mammalian species show some degree of avoidance to the invaded areas. We also found that there were significant differences between the treatments with regard to large mammal species diversity indices. Some of the large mammalian species appeared to neither avoid nor prefer invaded areas. It is hypothesized that they use invaded areas to hide away from predators as most of them fall prey to many carnivores. Also, C. odorata invaded areas could provide suitable shelter from climatic extremes. The treatments cleared of C. odorata showed an increase in both small and large mammalian species richness and diversity, suggesting that clearing of this plant helps in rehabilitation of the ecosystem. However, large mammal species composition in the cleared treatments remained different to preinvasion state, which suggests that the habitat may remain changed for a long time after clearing. Managers of conservation areas should therefore prioritise alien plant removal in order to maintain healthy ecosystems. / Dissertation (MSc (Wildlife Management))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

Butia odorata (Barb. Rodr.) Noblick, é nativa da região Sul do Brasil e Sudeste do Uruguai. As áreas de butiazais do Rio Grande do Sul, formadas por B. odorata, vêm sofrendo redução devido à expansão agrícola e urbana. Além disso, a espécie apresenta dificuldades para germinar causando entraves na produção de mudas e assim a produção se torna extrativista, o que reduz a renovação dos butiazais. A embriogênese somática (ES) é uma alternativa para multiplicação in vitro de B. odorata. Análises anatômicas e o uso de marcadores moleculares podem contribuir para a determinação do processo da ES. O presente trabalho teve por objetivo principal propor uma metodologia para obtenção de embriões somáticos in vitro da espécie a partir de diferentes explantes. Para isso foram avaliados os efeitos das auxinas 2,4-D e picloram e a influência dos meios de cultura MS e Y3 sobre embriões zigóticos maduros. A técnica Thin Cell Layer (TCL) foi testada como fonte alternativa de explante para indução da ES em B. odorata. Para uma melhor compreensão das mudanças morfológicas e celulares foi realizado um estudo histo-anatômico mais detalhado das fases durante a ES. Para verificar a expressão do gene SERK foi isolado, clonado e sequenciado um gene candidato a partir de calos embriogênicos de B. odorata. 9Continua) Os resultados apresentaram uma resposta heterogênea produzindo calos embriogênicos e embriões somáticos em ambos os meios combinados com diferentes concentrações das auxinas. Dentre os resultados obtidos para TCL destacam-se o meio de cultura Y3 com a auxina picloram, nas concentrações de 452,49; 542,99 e 633,48 μM/L, induzindo a formação de calos embriogênicos e embriões somáticos. A análise histo-anatômica permitiu verificar os principais eventos celulares ocorridos durante a ES, como a presença de centros meristemáticos, proembriões, embriões globulares e grãos de amido como fonte de reserva em embriões somáticos. A obtenção de uma sequência parcial do gene SERK em butiá, além de confirmar a indução da ES, pode ser usada, juntamente com as análises anatômicas, como marcador molecular específico para ES. A metodologia proposta apresenta resultados promissores até a fase de diferenciação dos embriões somáticos globulares e alguns mais desenvolvidos, contudo a conversão desses em plântulas não foi completa. / Butia odorata (Barb. Rodr.) Noblick, is native to Southern Brazil and Southeastern Uruguay. Butiazais areas of Rio Grande do Sul, formed by B. odorata, have been reduced due to the agricultural and urban expansion. In addition, the species presents difficulties to germinate causing obstacles in seedlings production and thus the production becomes extractive, what reduces the renewal of butiazais. Somatic embryogenesis (ES) is an alternative to in vitro multiplication of B. odorata. Anatomical analysis and the use of molecular markers may contribute to the determination of the ES process. The present work had as main objective to propose a methodology for obtaining of somatic embryos in vitro of the different explants from species. The effects of 2,4-D auxins and picloram and the influence of MS and Y3 culture media on mature zygotic embryos were evaluated. The Thin Cell Layer (TCL) technique was tested as an alternative explant source for ES induction in B. odorata. For a better understanding of the morphological and cellular changes, a more detailed histo-anatomical study of the phases during ES was performed. To verify the expression of the SERK gene, a candidate gene was isolated, cloned and sequenced from B. odorata embryogenic calli. The results showed a heterogeneous response producing embryogenic calli and somatic embryos in both media combined with different concentrations of auxin. Among the results obtained for TCL include Y3 culture medium with auxin picloram, in concentrations of 452,49; 542,99 and 633,48 μM/L, inducing the formation of embryogenic calli and somatic embryos. Histo-anatomical analysis has shown the main cellular events that occurred during ES, as the presence of meristematic centers, proembryos, globular embryos and starch grains as a reserve source in somatic embryos. Obtaining a partial sequence of the SERK gene in pindo palm, in addition to confirm ES induction, it can be used, along with the anatomical analysis, such as molecular marker specific for ES. The proposed methodology presents promising results until the differentiation phase of the globular somatic embryos and some more developed, however the conversion of these in seedlings was not complete.

Rising atmospheric CO2 (Ca) concentrations have generated concern among scientists, mainly because of CO2’s role as a greenhouse gas and its influence on plant growth and development. Previous research has suggested that future CO2 enriched atmospheres may enhance the success of invasive aliens. Chromolaena odorata is an example of an invasive alien proving to be a serious threat to indigenous vegetation in South Africa, and effective control measures are desperately needed to curb infestations in the future. The current study aimed at assessing the response of C. odorata to elevated Ca and interactive factors, and was divided into two trials. During PART A, C. odorata was grown in competition with 2 grass species: Eragrostis curvula and Themeda triandra (selected for their differential preferences to nutrient availability). All three species were potted in a greenhouse at the University of KwaZulu-Natal (Howard College). There were 16 pots in total, and each pot contained four C. odorata plants, four T. triandra seedlings, and four E. curvula seedlings. Eight pots were exposed to elevated Ca (~700ppm), and eight pots were exposed to ambient Ca (~370ppm). The pots at each Ca treatment were further divided: four received high nutrient treatments (3L per addition), while the other four received low nutrient treatments (300 ml per addition). Studies on growth (e.g. plant height, dry weight, etc.), as well as physiology (e.g. Jmax), were undertaken. Results showed that generally, plants responded positively to high nutrient treatments. In contrast, elevated Ca did not affect growth or any of photosynthetic parameters of C. odorata significantly, but did reduce stomatal limitations. During PART B, C. odorata plants were grown monospecifically to assess whether there was a “chamber effect” associated with planting density. Pots at both Ca treatments contained either four C. odorata or two C. odorata seedlings. Growth and physiology were assessed. The fact that elevated Ca did not affect any of the photosynthetic parameters studied, suggests that photosynthetic down-regulation did not occur. This, together with the fact that no increase in stomatal limitations were observed in elevated Ca, implies that enhancement of photosynthetic assimilation could have occurred in C. odorata plants exposed to CO2 enrichment. Results from this study (PART A and PART B), when compared to previous research on this species, suggests that CO2 enrichment may enhance the success of monoculture populations of C. odorata. However, other species may gain competitive advantages over C. odorata occurring in mixed communites, under CO2 enriched environments. In addition, results of this study support the prediction that increasing Ca will reduce the importance of carbon as an external limiting resource, and that the extent of a plant’s response to Ca enrichment will depend on resources other than CO2. If increases in temperature caused by elevated Ca increases nutrient availability in the soil, then Ca could indirectly enhance the success of C. odorata occurring in mixed communities. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2008.

Alien plant invasions and human-induced land transformations are the two most important factors contributing to loss of biodiversity, and Chromolaena odorata (C. odorata) is one of the world’s worst invader plants. It impacts negatively on biodiversity conservation, forestry and agriculture due to its rapid rate of spread, fast growth and hence an ability to transform habitats. It was introduced into KwaZulu-Natal, South Africa in the mid-1940s, and has spread north and southwards along the coastline and adjacent interior. In 1961 it was observed in Hluhluwe Game Reserve, and has invaded and transformed large parts. In this thesis I use C. odorata distribution maps from 1978 to 2001 to investigate invasion pathways, and whether these are related to species or habitat characteristics. Invasion in the twelve vegetation types identified in the Reserve showed two patterns. In some vegetation types invasion expanded linearly, while in others there were three phases of invasion, driven by interactions between habitat suitability, habitat fragmentation and propagule pressure. Expansion of existing invasions (phalanx or wave invasion) through short distance seed dispersal was the primary mode of spread, rather than the formation of new infestations (guerrilla or diffuse invasion). Known distribution of dense stands was used to develop a spectral signature and run a supervised classification of satellite images. I utilized the dense stands and other GIS data sets of climate, altitude, solar radiation, distance from roads, distance from rivers and normalized differential vegetation index from 1973 and 2001 to determine a probability model, and assess the impact of the invasion on biodiversity conservation. The supervised classification underestimated the extent of the invasion, as C. odorata is a cryptic understory species in some habitats. Supplementation by using multiple regression to develop a probability model, and combining these into one map provided a realistic result. I used this map and GIS data sets of vegetation types and protected areas to assess the impact of the invasion on biodiversity conservation. This showed that C. odorata was preferentially impacting sensitive areas, and the conservation of threatened vegetation types is not guaranteed by including them in protected areas. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2009.

Despite increased interest in the control and spread of the alien weed, Chromolaena odorata, little is known of its photosynthetic characteristics under field conditions. The aim of the study was to obtain a better understanding of the ecophysiological attributes of C. odorata that contribute to its invasive success. Photosynthetic performance of C. odorata was evaluated by monitoring diurnal changes in gas exchange, chlorophyll a fluorescence and plant water relations. Gas exchange characteristics of plants growing in exposed and shaded environments, as well as seasonal patterns, were evaluated. The response of C. odorata to water stress was also determined. Chromolaena odorata exhibited high CO2 uptake rates with no light saturation. Shade plants had significantly larger leaf surface areas and greater concentrations of total chlorophyll, total carotenoids and chlorophylls a and b than sun plants. Relatively high photosynthetic uptake rates in C. odorata may allow for greater carbon gain in high light environments thus contributing to increased growth and spread of the species. Chromolaena odorata can successfully acclimatise to low photosynthetic photon flux density (PPFD), thus, outcompeting less tolerant species under low light conditions. Leaf conductance, CO2 uptake, transpiration and chlorophyll fluorescence parameters in winter were tightly coupled to summer. Plants had higher water use efficiency (WUE) in summer compared to winter, probably to maximise CO2 uptake and minimise water loss. There was a progressive decrease in leaf water potential with increase in water stress in water stressed (WS) plants. The leaves of WS plants showed signs of severe wilting 10 days after the onset of stress compared to well watered (WW) plants. Increased proline concentration and leaf wilting probably increase (WUE) and may be an adaptive strategy to protect against dehydration injury.The effects of the herbicide, glyphosate, on gas exchange and translocation were studied. Glyphosate treatment decreased leaf conductance leading to a reduction in CO2 uptake and transpiration. Glyphosate is a mobile herbicide that is transported from leaves to roots and caused death of plants within a week of treatment. The potential antimicrobial properties of the weed were evaluated using selected bacteria and fungi. Crude leaf extracts exhibited some antibacterial and antifungal activity. Extracts from the weed are unlikely to be useful antimicrobial sources due to low concentrations of active compounds. A co-ordinated strategy, taking into account the high plasticity of the weed, is needed to curtail the spread of C. odorata. The ecophysiological responses to environmental conditions should be considered when planning management and control strategies for C. odorata. / Ph.D. University of KwaZulu-Natal, Durban 2013.

Butia odorata é uma palmeira nativa do Sul da América do Sul. É um importante recurso genético regional, principalmente devido à adaptação edafoclimática e potencial para exploração hortícola. A propagação comercial é dificultada pela falta de informações fitotécnicas sobre sementes e formação de mudas. Este trabalho teve por objetivo conhecer aspectos relacionados à germinação e conservação de sementes, desenvolvimento de plântulas, indução à embriogênese somática in vitro e adubação e desenvolvimento de mudas em casa de vegetação. Diásporos de populações naturais do Rio Grande do Sul foram analisados e tiveram a viabilidade das sementes analisada in vitro. A superação da dormência das sementes foi testada através da escarificação mecânica. Com as plântulas obtidas foram testados o enraizamento in vitro e o desenvolvimento de mudas em casa de vegetação. Também foi conduzido um estudo com indução à embriogênese somática a partir de embriões zigóticos e explantes oriundos de inflorescência imatura. Diásporos de B. odorata apresentaram teor de água com variação significativa entre matrizes e entre condições visuais de maturação. A massa de 1000 diásporos também foi bastante variável, sendo encontrados, em média, 1890 g, com teor de umidade próxima a 11%. Tão logo estabelecidos in vitro, mais de 83% dos embriões germinaram. Sementes de B. odorata armazenadas sob baixa umidade do ar e temperatura moderada mantiveram viabilidade elevada por, pelo menos, três anos. A abertura da cavidade embrionária das sementes permitiu a superação da dormência, tanto em semeadura in vitro como in vivo. As plântulas apresentaram enraizamento in vitro satisfatório em meio de cultivo com ácido naftalenoacético combinado a concentrações de sacarose entre 3 e 4,5%. Embriões zigóticos formaram calos em meio de cultivo com concentrações elevadas de ácido 2,4-diclorofenoxiacético. Mudas desenvolvidas em recipientes com substrato orgânico até a fase juvenil não apresentaram exigência elevada em adubação e pH. Na fase juvenil o desenvolvimento foi prejudicado quando a condutividade elétrica do substrato superou 5 mS.cm-1. Mudas conduzidas em casa de vegetação emitiram as primeiras folhas pinadas em torno de quinze meses após a germinação. / Butia odorata is a palm tree native from southern South America. It is an important regional genetic resource, mainly due to it climate and soil adaptation and its potential for horticultural exploitation. The commercial propagation requires information about seed technology and seedling production. This work was conducted in order to get information concerning aspects related to conservation and germination of seeds, seedling growth, induction of in vitro somatic embryogenesis, plant nutrition and seedling growth in greenhouse. Diaspores from natural populations of Rio Grande do Sul State were analyzed and the viability of the seeds was tested in vitro. The overcoming seed dormancy was tested by means of mechanical scarification of isolated seeds. Seedlings obtained from these previous tests were submitted to assays for in vitro rooting and plant development in greenhouse. Subsequently a study was conducted related to the induction of somatic embryogenesis from zygotic embryos and immature inflorescence tissues. Diaspores of B. odorata presented water content with significant variation among donor plants and among visual maturation stages. The mass of 1000 seeds have were been quite variable, being found an average of 1890 g, for a moisture content near 11%. Immediately to the in vitro establishment, more than 83% embryos germinated. Seeds of B. odorata stored under low humidity and moderate temperature maintained high viability for at least three years. The opening of the cavity of the embryonic seeds allowed to break dormancy in both in vitro and in vivo samples. Seedlings presented satisfactory in vitro rooting in culture medium with naphthaleneacetic acid combined with sucrose concentrations from 3 to 4.5%. Zygotic embryos formed callus in culture medium containing 2,4-diclorophenoxiacetic acid. Developed seedlings in containers with organic substrate up to the juvenile stage do not have high demand in fertilizer and pH conditions. Development was hampered in juvenile plants when the electrical conductivity of the substrate exceeded 5 mS.cm-1. Seedlings conducted in greenhouse formed the first pinnate leaves approximately fifteen months after germination.

Butia odorata é uma palmeira nativa do Sul da América do Sul. É um importante recurso genético regional, principalmente devido à adaptação edafoclimática e potencial para exploração hortícola. A propagação comercial é dificultada pela falta de informações fitotécnicas sobre sementes e formação de mudas. Este trabalho teve por objetivo conhecer aspectos relacionados à germinação e conservação de sementes, desenvolvimento de plântulas, indução à embriogênese somática in vitro e adubação e desenvolvimento de mudas em casa de vegetação. Diásporos de populações naturais do Rio Grande do Sul foram analisados e tiveram a viabilidade das sementes analisada in vitro. A superação da dormência das sementes foi testada através da escarificação mecânica. Com as plântulas obtidas foram testados o enraizamento in vitro e o desenvolvimento de mudas em casa de vegetação. Também foi conduzido um estudo com indução à embriogênese somática a partir de embriões zigóticos e explantes oriundos de inflorescência imatura. Diásporos de B. odorata apresentaram teor de água com variação significativa entre matrizes e entre condições visuais de maturação. A massa de 1000 diásporos também foi bastante variável, sendo encontrados, em média, 1890 g, com teor de umidade próxima a 11%. Tão logo estabelecidos in vitro, mais de 83% dos embriões germinaram. Sementes de B. odorata armazenadas sob baixa umidade do ar e temperatura moderada mantiveram viabilidade elevada por, pelo menos, três anos. A abertura da cavidade embrionária das sementes permitiu a superação da dormência, tanto em semeadura in vitro como in vivo. As plântulas apresentaram enraizamento in vitro satisfatório em meio de cultivo com ácido naftalenoacético combinado a concentrações de sacarose entre 3 e 4,5%. Embriões zigóticos formaram calos em meio de cultivo com concentrações elevadas de ácido 2,4-diclorofenoxiacético. Mudas desenvolvidas em recipientes com substrato orgânico até a fase juvenil não apresentaram exigência elevada em adubação e pH. Na fase juvenil o desenvolvimento foi prejudicado quando a condutividade elétrica do substrato superou 5 mS.cm-1. Mudas conduzidas em casa de vegetação emitiram as primeiras folhas pinadas em torno de quinze meses após a germinação. / Butia odorata is a palm tree native from southern South America. It is an important regional genetic resource, mainly due to it climate and soil adaptation and its potential for horticultural exploitation. The commercial propagation requires information about seed technology and seedling production. This work was conducted in order to get information concerning aspects related to conservation and germination of seeds, seedling growth, induction of in vitro somatic embryogenesis, plant nutrition and seedling growth in greenhouse. Diaspores from natural populations of Rio Grande do Sul State were analyzed and the viability of the seeds was tested in vitro. The overcoming seed dormancy was tested by means of mechanical scarification of isolated seeds. Seedlings obtained from these previous tests were submitted to assays for in vitro rooting and plant development in greenhouse. Subsequently a study was conducted related to the induction of somatic embryogenesis from zygotic embryos and immature inflorescence tissues. Diaspores of B. odorata presented water content with significant variation among donor plants and among visual maturation stages. The mass of 1000 seeds have were been quite variable, being found an average of 1890 g, for a moisture content near 11%. Immediately to the in vitro establishment, more than 83% embryos germinated. Seeds of B. odorata stored under low humidity and moderate temperature maintained high viability for at least three years. The opening of the cavity of the embryonic seeds allowed to break dormancy in both in vitro and in vivo samples. Seedlings presented satisfactory in vitro rooting in culture medium with naphthaleneacetic acid combined with sucrose concentrations from 3 to 4.5%. Zygotic embryos formed callus in culture medium containing 2,4-diclorophenoxiacetic acid. Developed seedlings in containers with organic substrate up to the juvenile stage do not have high demand in fertilizer and pH conditions. Development was hampered in juvenile plants when the electrical conductivity of the substrate exceeded 5 mS.cm-1. Seedlings conducted in greenhouse formed the first pinnate leaves approximately fifteen months after germination.

Butia odorata é uma palmeira nativa do Sul da América do Sul. É um importante recurso genético regional, principalmente devido à adaptação edafoclimática e potencial para exploração hortícola. A propagação comercial é dificultada pela falta de informações fitotécnicas sobre sementes e formação de mudas. Este trabalho teve por objetivo conhecer aspectos relacionados à germinação e conservação de sementes, desenvolvimento de plântulas, indução à embriogênese somática in vitro e adubação e desenvolvimento de mudas em casa de vegetação. Diásporos de populações naturais do Rio Grande do Sul foram analisados e tiveram a viabilidade das sementes analisada in vitro. A superação da dormência das sementes foi testada através da escarificação mecânica. Com as plântulas obtidas foram testados o enraizamento in vitro e o desenvolvimento de mudas em casa de vegetação. Também foi conduzido um estudo com indução à embriogênese somática a partir de embriões zigóticos e explantes oriundos de inflorescência imatura. Diásporos de B. odorata apresentaram teor de água com variação significativa entre matrizes e entre condições visuais de maturação. A massa de 1000 diásporos também foi bastante variável, sendo encontrados, em média, 1890 g, com teor de umidade próxima a 11%. Tão logo estabelecidos in vitro, mais de 83% dos embriões germinaram. Sementes de B. odorata armazenadas sob baixa umidade do ar e temperatura moderada mantiveram viabilidade elevada por, pelo menos, três anos. A abertura da cavidade embrionária das sementes permitiu a superação da dormência, tanto em semeadura in vitro como in vivo. As plântulas apresentaram enraizamento in vitro satisfatório em meio de cultivo com ácido naftalenoacético combinado a concentrações de sacarose entre 3 e 4,5%. Embriões zigóticos formaram calos em meio de cultivo com concentrações elevadas de ácido 2,4-diclorofenoxiacético. Mudas desenvolvidas em recipientes com substrato orgânico até a fase juvenil não apresentaram exigência elevada em adubação e pH. Na fase juvenil o desenvolvimento foi prejudicado quando a condutividade elétrica do substrato superou 5 mS.cm-1. Mudas conduzidas em casa de vegetação emitiram as primeiras folhas pinadas em torno de quinze meses após a germinação. / Butia odorata is a palm tree native from southern South America. It is an important regional genetic resource, mainly due to it climate and soil adaptation and its potential for horticultural exploitation. The commercial propagation requires information about seed technology and seedling production. This work was conducted in order to get information concerning aspects related to conservation and germination of seeds, seedling growth, induction of in vitro somatic embryogenesis, plant nutrition and seedling growth in greenhouse. Diaspores from natural populations of Rio Grande do Sul State were analyzed and the viability of the seeds was tested in vitro. The overcoming seed dormancy was tested by means of mechanical scarification of isolated seeds. Seedlings obtained from these previous tests were submitted to assays for in vitro rooting and plant development in greenhouse. Subsequently a study was conducted related to the induction of somatic embryogenesis from zygotic embryos and immature inflorescence tissues. Diaspores of B. odorata presented water content with significant variation among donor plants and among visual maturation stages. The mass of 1000 seeds have were been quite variable, being found an average of 1890 g, for a moisture content near 11%. Immediately to the in vitro establishment, more than 83% embryos germinated. Seeds of B. odorata stored under low humidity and moderate temperature maintained high viability for at least three years. The opening of the cavity of the embryonic seeds allowed to break dormancy in both in vitro and in vivo samples. Seedlings presented satisfactory in vitro rooting in culture medium with naphthaleneacetic acid combined with sucrose concentrations from 3 to 4.5%. Zygotic embryos formed callus in culture medium containing 2,4-diclorophenoxiacetic acid. Developed seedlings in containers with organic substrate up to the juvenile stage do not have high demand in fertilizer and pH conditions. Development was hampered in juvenile plants when the electrical conductivity of the substrate exceeded 5 mS.cm-1. Seedlings conducted in greenhouse formed the first pinnate leaves approximately fifteen months after germination.

Chromolaena odorata (L.) King and Robinson is an alien invasive weed to most of the Old World tropical regions of the earth, including South Africa where it is morphologically distinct from most other C. odorata plants examined from both its native and invasive range. It is thought that these morphological differences are related to difficulties encountered in successful establishment of biological control agents on the South African population of C. odorata. It has been postulated that the source population of the South African population will harbour potential biocontrol agents that will be suited to successful establishment on the South African plants. Several morphological, cytological and isozyme studies have been attempted to identify the source population of the South African population, but these have failed to identify the origin of the South African population. In this dissertation two PCR-based methods were attempted, in an investigation into whether the morphological differences and difficulties in establishment of biocontrol agents have a genetic basis. The two techniques attempted were: Inter Simple Sequence Repeat (ISSR) amplification, and DNA sequencing. Results could not be obtained using the ISSR method, and the reason for this was not discovered despite extensive trials. The internal transcribed spacer region and the external transcribed spacer region sequences were obtained from five samples, and compared. It was found that the ETS region gave more phylogenetic signal at the intraspecific level than the ITS region. However, due to difficulties in amplification of the external transcribed spacer region, work here focussed on obtaining Internal Transcribed Spacer sequences for 61 samples. Each of the samples sequenced had a unique ITS sequence, displaying a high level of intraspecific genetic diversity. The degree of this diversity is discussed with reference to the possible influences of polyploidy and concerted evolution on genetic structure. The ITS data indicated that some of the physical traits used to define ‘morphotypes’ of C. odorata were not correlated to genotype. From discussion and comparison of morphological character distributions and the ITS-based phylogeography it is suggested that the geographical origin of the South African population is Greater Antilelan, rather than from the continents of North and South America, which is where the Australasian, West African and Mauritian infestations are suggested to have originated.

Biological indicators measure components of the biota and are used to give general information about complex ecosystems in which they occur, playing key roles in conservation planning and management. This study illustrates the impact of habitat change by factors that are extrinsic to the habitats in question and the importance of spider responses in aiding management decisions. The spider responses illustrated existence of environmental change and represent responses of other biota. The conclusions drawn from this study have important management implications for protected areas with grazing herbivores and occurrence of alien invasive plants. Grazed sites showed the highest abundance, diversity and species richness, while ungrazed had the lowest. The implications from this study are that no grazing has negative implications on lower trophic levels, whereas grazing seems to result in favourable conditions for optimal abundance, diversity and species richness. The higher abundance, diversity and species richness associated with grazed sites could result from increased ground cover, greater variation in habitat structure, increased plant diversity and enhanced soil/plant nutrient concentrations. But, ungrazed sites in turn become more monotonous and provide less habitat diversity. However, the characteristic species for each grazing intensity level demonstrates the difficulty in making generalizations for management even for closely related species. The results further opposed the assumption that grazing lawns are a result of overgrazing and thus highly undesirable. This grassland type in comparison to tall bunch grassland displayed the highest spider diversity and species richness. This evidence further supports the conclusion that grazing lawns are steady state communities of their own and not a sub-set of any other grassland type. Therefore, veld management decisions that eradicate grazing lawns are negative for the park as the fauna and flora associated with this grassland type will be lost, leading to cascading effects. Additionally, this study illustrated that habitat modification by invasion of invasive alien plant species has detrimental consequences for the endemic fauna. C. odorata invasion results in a monotonous habitat structure. Consequently, structural heterogeneity is a primary determinant for spider diversity as opposed to abundance of prey, because plant height and architecture drive spider colonization. Therefore, removal of alien invasive weeds results in returning a system to close approximation of its condition prior to disturbance with both structure and function recreated. Assemblage patterns can be selected as endpoints to measure the ecological rehabilitation; thus, the non-significant differences in assemblage patterns of the control versus cleared sites imply that the system is rehabilitating with clearing without further management intervention. This study adds to the limited information on the implications of grazing intensities, grassland types, short and long-term invasion and clearing of an alien invasive plant on spider communities. Copyright / Dissertation (MSc)--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted