Masters Degrees (Geography and Environmental Studies)
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Browsing Masters Degrees (Geography and Environmental Studies) by browse.metadata.advisor "De Klerk, Helen Margaret"
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- ItemDrivers of wildfire behaviour, severity and magnitude in the Limietberg conservation area : understanding the complexity of wildfire risk(Stellenbosch : Stellenbosch University, 2014-12) Moir, Shaun Alexander; De Klerk, Helen Margaret; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies.ENGLISH ABSTRACT: The Western Cape Province in South Africa is home to one of the most diverse plant communities in the world, and has one of the highest concentrations of plants species in any temperate ecosystem in the world. The dominant vegetation is both fire-prone and fire-dependant (Van Wilgen & Scott 2001, Forsyth et al. 2010). The Western Cape in particular is emerging as a province that is increasingly prone to disaster events, particularly the threat of veld fires. The consequences of large wildfire disaster events are often devastating and far reaching (Van Wilgen & Scott 2001, Forsyth et al. 2010). This study was conducted in an attempt to investigate the drivers of wildfire behaviour, severity and magnitude in the Limietberg Conservation Area in order to gain a greater insight and understanding of the complexity of wildfire risk. Recognising the disaster prone character of the Western Cape and the increasing probabilities of future wildfire events in the province, this study aimed to strengthen the understanding of the drivers of wildland fire behaviour (i.e. wildland fire risk) in the Limietberg Conservation Area by analysing a number of fires to identify a range of drivers and patterns; examining the factors driving both fire danger and fire behaviour, including climate, topography, slope and fuel; examining the factors driving fire frequency and regime; and finally, determining possible ecological damage caused by the last 10 – 20 years of wildfire events in the Limietberg Conservation Area as measured by post-fire seedling ratios. This was achieved through the use of statistical techniques including multiple regression (McDonald 2009), ordination in the form of principal component analysis and non-metric multi-dimensional scaling (Clarke & Warwick 1994), and fieldwork in the form of post-fire regeneration (Proteaceae parent:seedling ratio) monitoring techniques (Bond et al. 1984; Vlok & Yeaton 2000; De Klerk et al. 2007). The results indicated that the interactions between factors driving fire danger and fire behaviour were indeed complex, being influenced mainly by meteorological variables (temperature, relative humidity, wind speed) but also quite strongly influenced by physical environmental factors (slope, topography). The use of ordination techniques in this sort of complex analysis was seen as extremely effective and its use in further fire research was strongly recommended.
- ItemFactors affecting lion (Panthera Leo) spatial occurrence in the Zambezi region, Namibia(Stellenbosch : Stellenbosch University, 2014-12) Moeller, Michelle-Louise; De Klerk, Helen Margaret; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies.; Kastern, Micehelle-LouiseENGLISH ABSTRACT: Lion populations globally are on the decrease and their habitats are fragmenting. Despite their importance in the Zambezi Region in Namibia, very little research has yet been undertaken to understand their occurrence in this area. One of the primary motivations behind this study was the Kavango Zambezi Trans Frontier Conservation Area’s (KAZA TFCA) need to identify trans-boundary movement of carnivores. The collaborative approach with the Ministry of Environment and Tourism in Namibia facilitated the collaring of lions in three National Parks. A number of species were collared and this study focuses on the occurrence of lions in the Zambezi Region. From the lion home range analysis we could see that the home-range sizes of the collared lions varied greatly across the study area. The difference in home range size is largely due to human pressure surrounding the protected areas. Geographically weighted regression assisted in understanding which were the main drivers of lion occurrence, but further investigation was needed using the Maximum Entropy (MaxEnt) model for presence-only data. The factors that were investigated as possibly affecting the occurrence of lions included the following: rivers, land cover, land use, elevation and human activity. After pursuing various research models and manipulating data among all these factors, no single factor or combination of factors was found to be reliable predictors on lion occurrence in the study area. As is discussed in recommendations for further research in Chapter 6, it became clear that quantitative data cannot be used in isolation to predict where lions may occur.
- ItemIdentifying african wild dog (Lycaon pictus) corridors outside Gonarezhou National Park and Save Valley Conservancy using maxent species distribution modeling(Stellenbosch : Stellenbosch University, 2015-04) Marembo, Kudzanai Rosebud; De Klerk, Helen Margaret; Groom, R. J.; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies.ENGLISH ABSTRACT:The African wild dog (Lycaon pictus) is one of the most endangered large carnivores. Gonarezhou National Park (GNP) and Savè Valley Conservancy (SVC) that hold part of the few remaining viable populations report that wild dog populations continue to decline due to high rates of habitat loss and fragmentation. This leads to low pup survival rates due to predators and reduced formation of new packs as the wild dogs have become reluctant to leave the safety of their original packs in pursuit of mating partners in fragmented habitats where higher risks of danger exist. Consequently, this reduces population growth for Lycaon pictus. Therefore, the study sought to identify additional suitable habitat for wild dog outside GNP and SVC and a corridor connecting the two areas using the ecological niche theory. Wild dog satellite collar data from the African Wildlife Conservation Fund (AWCF) was used with spatial and climate data for GNP and SVC from PeaceParks and WorldClim. This data was used to firstly, identify dens using ArcGIS 10.1. Secondly, map geographic and temporal distributions using Time Local Convex Hull (T-LoCoH). Thirdly, to assess biotic and abiotic drivers of different packs and sexes movement and distribution patterns using ARCGIS 10.1 and lastly, map probability distributions (corridor and re-location sites) using Maximum Entropy (MaxEnt). Den locations are in areas away from predators and human settlements. Wild dog geographic distributions are smaller in the cold and dry seasons and differ according to sex whilst temporal distributions depend on their use of resources. The most influential biotic and abiotic variables within reserves were distance to human settlements and elevation whilst the least influential were roads and temperature. However, outside the reserves, the most influential variable was distance from reserve. Malilangwe is a potential corridor between GNP and SVC, whilst Masvingo, Beitbridge, and Mwenezi districts have suitable habitat for re-location sites.
- ItemMapping spatial requirements of ecological processes to aid in the implementation of corridors(Stellenbosch : Stellenbosch University, 2015-04) Mugwena, Thendo; De Klerk, Helen Margaret; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies.ENGLISH ABSTRACT: The ultimate goal of conservation planning is to ensure persistence of biodiversity. Biodiversity patterns and ecological processes are important aspects in conserving biodiversity. Although most researchers in conservation planning have focused on targeting biodiversity patterns, ecological and evolutionary processes can ensure persistence of biodiversity if incorporated into conservation planning. Ecological processes are the main drivers or sustainers of biodiversity. The aim of this research was to identify and map the spatial components of ecological processes in a portion of the Kavango Zambezi Transfrontier Conservation Area to aid in the implementation of biota movement corridors. Different methods have been used to identify suitable corridors but not much has been done on defining and mapping ecological processes that will ensure that the corridors maintain and generate biodiversity. A thorough literature survey was done to make a list of ecological processes that are important in maintaining the biodiversity in the area. Spatial components of ecological processes were mapped as surface elements aligned along linear environmental interfaces or gradients. The last part of the research was to suggest suitable movement corridors based on ecological processes. The results include five spatial components: riverine corridors, areas of high carbon sequestration, edaphic interfaces, upland-lowland interfaces and ecotones. Riverine corridors were mapped using a 1000 m buffer on either side of low lying rivers and 500 m buffer around rivers in the uplands. A map showing the carbon sequestration potential of vegetation in the study area was made using Moderate-Resolution Image Spectroradiometer (MODIS) derived NDVI data and the National Level Carbon Stock dataset done by the Woods Hole Research Center (WHRC) Pantropical. Edaphic interfaces were idenfied using by a 250 m buffer around contrasting soil types. Upland-lowland interfaces identified by a 250 m buffer along upland and lowland habitats. Classification of Landsat 8 was used to identify ecotones in the study area. The results of the spatial components were then compared with the habitat transformation map which shows populated areas.
- ItemProsopis invasion in the Northern Cape: remote sensing analysis of management action effectiveness(Stellenbosch : Stellenbosch University, 2021-12) Barnard, Johannes Jacobus; De Klerk, Helen Margaret; Van Wilgen, Brian W.; Eckert, Sandra; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies.ENGLISH ABSTRACT: Large-scale land acquisitions (LSLAs) for agricultural sector have grown significantly in the past decade, and are mostly prevalent in developing countries. Because LSLAs are not without negative effects on the environment and local communities, and because information about them is scarce and difficult to obtain, systems allowing LSLAs detection, characterization and monitoring in space and time are needed. With the increasing availability of global satellite data products, technological development in cloud computing, image and data mining analysis, remote sensing has evolved to an interesting tool for the detection and characterization of changes in land use systems. This study presents a novel approach to generically detect and characterize LSLAs at regional spatial extents. In order to capture and analyse the full range of land use spectral and spatial signatures related to agricultural LSLAs, this study is based on a 2-level data driven approach (Self-Organizing Maps followed by a clustering algorithm), consisting of two phases: 1) land use/land cover change detection at regional scale within dense temporal stacks of vegetation indices (MODIS-NDVI, 250m) and 2), discrimination of different land use/land cover classes using a set of spectral vegetation indices, textural features and shape metrics computed from landscape-extracted objects (Landsat-8, 30m). Evaluation of the methodology is performed against a ground truth database on LSLAs in Senegal. Results obtained during this exploratory research, are promising and provide some insights in agricultural LSLAs in the northern half of Senegal. With a very limited number of discriminative features (consisting of two Vegetation Indices and two textural features), detection of agricultural LSLAs is possible. Recommendations are given for enhancement of the generalization performance of the unsupervised classifier.
- ItemReconstruction of a fire regime using MODIS burned area data : Charara Safari Area, Zimbabwe(Stellenbosch : Stellenbosch University, 2013-03) Magadzire, Nyasha; De Klerk, Helen Margaret; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies.ENGLISH ABSTRACT: Current efforts to address Zimbabwe‘s decade long veld fire crisis has partly been hindered by a lack of financial resources and fire data. This study illustrates the potential of using the MODIS burned area product as an alternative cost- and time-effective method for reconstructing historical fire records in Zimbabwe. Two MODIS burned area products were evaluated, namely the MCD45A1 and WAMIS (Meraka Institute‘s MODIS burned area product). Both products yielded similar levels of accuracy despite the difference in algorithms. However, it is assumed that at certain thresholds, either in tree cover or fire intensity, WAMIS ceases to map fires as accurately as the MCD45A1. Ten years of fire data for Charara Safari Area (CSA) was extracted from the MCD45A1, and used as a basis to establish six parameters: fire incidence, extent, seasonality, fire size, frequency and fire return interval (FRI). It was observed that approximately 50% of CSA burned annually, with an average of 132 fires occurring every year. Although there was no overall increase or decrease in the extent of area burned over the 10 year study period, an increasing trend in fire incidence was noted. Through an assessment of effective fire size, it was established that more fires in CSA were gradually becoming smaller in size, while the extent of area burned remained fairly constant. Hence, the increase in fire incidences and lack of a corresponding increase in area burned. This study was also used to identify areas in the fire regime that may be a potential ecological risk to the miombo woodland in CSA. Three points of concern were revealed: firstly, a high prevalence of late season fires was observed in the northern bounds of CSA. Secondly, 64.2% of the total area burned in CSA burned between 6 and 10 times over the 10 year period, and lastly, 85% of the total area burned over the period 2001 and 2010 had a FRI of less than 2 years. The combination of late season fires, high fire frequency and short FRI in CSA is indicative of possible alterations in the state of the miombo woodlands, which may have negative socio-economic implications on CSA and its surrounding communities. This study has demonstrated that the MCD45A1 is a useful source of much needed fire information for Zimbabwe. Therefore, the possibility of integrating methods employed in this study into the current collection of fire data should be given due consideration.
- ItemUsing remote sensing indices to evaluate habitat intactness in the Bushbuckridge area : a key to effective planning(Stellenbosch : Stellenbosch University, 2015-04) Motswaledi, Mokhine; De Klerk, Helen Margaret; Luck-Vogel, M.; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies.ENGLISH ABSTRACT: Anthropological influences are threatening the state of many savanna ecosystems in most rural landscapes around the world. Effective monitoring and management of these landscapes requires up to date maps and data on the state of the environment. Degradation data over a range of scales is often not readily available due to a lack of financial resources, time and technical capabilities. The aim of this research was to use a medium resolution multispectral SPOT 5 image from 2010 and Landsat 8 images from 2014 to map habitat intactness in the Bushbuckridge and Kruger National Park (KNP) region. The images were pre-processed and segmented into meaningful image objects using an object based image analysis (OBIA) approach. Five image derivatives namely: brightness, compactness, NIR standard deviation, area and the normalised difference vegetation index (NDVI) were evaluated for their capability to model habitat intactness. A habitat intactness index was generated by combining the five derivatives and rescaling them to a data range of 0 to 10, with 0 representing completely transformed areas, 10 being undisturbed natural vegetation. Field data were collected in October 2014 using a field assessment form consisting of 10 questions related to ecosystem state, in order to facilitate comparisons with the remote sensing habitat intactness index. Both satellite data sets yielded low overall accuracies below 30%. The results were improved by applying a correction factor to the reference data. The results significantly improved with SPOT 5 producing the highest overall accuracy of 62.6%. The Landsat 8 image for May 2014 achieved an improved accuracy of 60.2%. The SPOT 5 results showed to be a better predictor of habitat intactness as it assigned natural vegetation with better accuracy, while Landsat 8 correctly assigned mostly degraded areas. These findings suggest that the method was not easily transferable between the different satellite sensors in this savanna landscape, with a high occurrence of forest plantations and rural settlements too. These areas caused high omission errors in the reference data, resulting in the moderate overall accuracies obtained. It is recommended that these sites be clipped out of the analysis in order to obtain acceptable accuracies for non-transformed areas. The study nevertheless demonstrated that the habitat intactness index maps derived can be a useful data source for mapping general patterns of degradation especially on a regional scale. Therefore, the methods tested in this study can be integrated in habitat mapping projects for effective conservation planning.