An ecological study of the plant communities of Marakele National Park

Please read the abstract in the section 06back of this documentDissertation (MSc)--University of Pretoria, 2009.Centre for Wildlife Managementunrestricte

Effect of scale of operation on heap leaching performance

The extent to which differences in bulk density and in irrigation geometry contribute towards the differences observed in leaching performance between laboratory-scale columns versus commercial-scale heaps was investigated. Furthermore, the contributions of segregation and stratification, which are absent from columns but unavoidable in heaps, were also investigated. Four case studies provided data whereby the column and heap leaching of the respective sample materials could be directly compared. The first involved gold-bearing ore, the second gold-bearing sand, a third was conducted on oxide-copper ore and the fourth case study was performed on sulphidic copper ore. The first case study was published by others, while the other three were conducted by the author himself. Furthermore, custom-designed boxes were constructed whereby the segregation and stratification of ore could be simulated. Tests were performed to observe the leaching performance of segregated and stratified ore samples, compared to unsegregated and unstratified ore samples. The leaching characteristics of each case was quantified in terms of the parameters of a mathematical model, based on dual-porosity hydrology and diffusion with chemical reaction, which provided optimised fits to the experimental data. Furthermore, fundamental relations were derived for the impact that changes in bulk density and changes in drip-irrigation spacing are theoretically expected to have on the same model parameters. These relations were tested against the actual trends observed in the model parameters that best fitted the data of the four case studies and of the segregation/stratification experiments. It was found that the diffusional distance, which places a mass-transfer limitation on the over-all rate of leaching, can be governed by either the ore bulk density, or by the irrigation dripper spacing. The relations derived under this study can be used to estimate the maximum dripper spacing that can be permitted to prevent dripper spacing from becoming the rate-limiting parameter. Estimates of the impact of dripper spacing on the ultimate extent of extraction are also provided. However, neither segregation nor stratification exhibited significant or reproducible effects on leaching kinetics. These findings can place the drafting of heap leaching design parameters on a more fundamental footing

A reclassification and description of the Waterberg mountain vegetation of the Marakele National Park, Limpopo province, South Africa

The description and classification of vegetation are important for conservation and resource management. The aim of this study was to identify, reclassify and describe the plant communities present in the Waterberg Mountain vegetation of the Marakele National Park in the Limpopo province, South Africa. A phytosociological classification, mapping and description of sections of the Waterberg Mountain vegetation in the park were done in 1995. Since 1995, various farms adjacent to the park have been bought and incorporated into it. Little is known about the vegetation and habitat status of these newly acquired areas, which led to this study. The floristic data were analysed according to the Braun-Blanquet procedure using the Braun Blanquet Personal Computer (BBPC) suite as well as the JUICE software package, whilst the diversity of the plant communities was determined using the Shannon–Wiener and Gini–Simpson indices. A total of 12 plant communities were identified and are described according to their diagnostic, constant and dominant plant species as determined from the synoptic table analysis as well as their characteristic species as derived from the phytosociological table. Based on the topography and plant species composition, the vegetation can be grouped into five major groups, namely the: (1) lower midslope and plateau shrub- and woodlands, (2) high altitude midslope woodland, (3) high-lying plateau and midslope grass-, shrub- and woodlands, (4) ravine, footslope and drainage line forests and woodland, and (5) higher-lying plateau wetlands and forblands. The high altitude midslope grassland and shrubland and the lower midslope and plateau areas have the highest diversity. The high-lying vegetation has affinity with Bankenveld and Drakensberg vegetation, whilst the relatively low-lying plateaus and midslope vegetation are typical of the bushveld areas. CONSERVATION IMPLICATIONS : This reclassification, mapping and description of the Waterberg Mountain vegetation have been incorporated into the Management Plan for the park. It will enable managers to make scientifically based decisions on the management of the different ecosystems to ensure biodiversity conservation. This vegetation study also provides baseline information that allows for vegetation assessments to determine veld condition, carrying capacity and stocking density for the park.The University of South Africa (UNISA) and SANParks.http://www.koedoe.co.zaam2022Plant Production and Soil Scienc