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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

The role of fire in bush encroachment in Ithala Game Reserve.

Gordijn, Paul Jan. 27 May 2014 (has links)
The increase of woody vegetation (also known as bush or shrub encroachment) in savannas has become of global concern to conservationists and rangeland managers alike. Bush encroachment has been associated with a decrease in rageland palatability. In addition, the increase in woody biomass has consequences for climate change, carbon sequestration, rangeland hydrology and nutrient cycling. As a result of these large changes in ecosystem functioning with bush encroachment, biodiversity may be threatened. Fire is considered to be one of the most important management tools used to control woody biomass in savannas. However, despite the use of fire in Ithala Game Reserve, areas have become encroached. This thesis assesses the role of fire in bush encroachment in Ithala Game Reserve. I start this thesis with a discussion of the bottom-up (water, nutrients, and light) and topdown (fire and herbivory) ecosystem components in the literature review. This sets the foundation for an understanding of the factors that affect savanna tree:grass ratios for the rest of this thesis. In addition the review discusses the potential effects of climate change on savanna tree:grass ratios. Recently, it has been proposed that increasing atmospheric carbon dioxide concentrations result in an increased competitive ability for C3 woody plants against C4 grasses. Many models have been produced to explain savanna dynamics. By assessing the role of fire in Ithala Game Reserve, its functioning is assessed in light of the current issues of bush encroachment. Textural analysis is a remote sensing technique that has been used to detect changes in woody vegetation using aerial photographs. Textural analysis was used to assess changes in woody vegetation cover and density from 1943 (earliest period for which aerial photographs were available for the study area) to 1969, 1990 and 2007 in Ithala Game Reserve (IGR). Field surveys were performed to assess the effects of the fire regime in IGR on woody vegetation structure and composition. Transects were performed in areas with different fire frequencies. The effects of fire frequency were compared between similar vegetation communities. Textural analysis showed that woody vegetation cover (+32.5%) and density (657.9 indiv. ha-1) increased from 1943 to 2007. Importantly, in some areas of IGR, the suppression of fire led to the rapid invasion of woody plants from 1990 to 2007. Field studies demonstrated the importance of fire in controlling woody vegetation in IGR. The densities of the encroachers, Dichrostachys cinerea and Acacia karroo were resistant to annual burns. However, the height of these deciduous microphyllous woody encroachers was reduced by more frequent fires. Following the suppression of fire, these trees grew taller and their negative impact on the herbaceous layer increased. Consequently, fuel loads (grassy biomass) declined and prevented the use of frequent and intense fires by management. The reduction in fire frequency allowed the invasion of woody evergreen macrophyllous species. Continued development of fire-resistant patches of evergreen macrophyllous vegetation will further reduce the effectiveness of fire in controlling bush encroachment. To control bush encroachment in IGR and the consequential loss of biodiversity, an intermediate fire frequency (one burn every 2 to 4 years) is required. Burns also need to be hot enough to increase the current rate of topkill. Management should act to optimize the accumulation of grassy biomass to fuel fires. / Thesis (M.Sc.)-Unversity of KwaZulu-Natal, Pietermaritzburg, 2010.
242

Resource utilisation of the Chacma baboon in different vegetation types in North-Eastern Mountain Sour Veld, Blyde Canyon Nature Reserve

Marais, A. J. (Albertus Johannes) 31 May 2005 (has links)
The Blyde Canyon Nature reserve displays its natural beauty for most National and International visitors all over the World. The region is renowned for its high rainfall and misty weather, which enhances the natural beauty of the area. Because of the mist belt effect, the area is one of the largest commercial forestry areas in South Africa. Baboons also seek after the topography and vegetation type (Northeastern mountain sourveld) that is typical of this area and numerous baboon troops occur in this region. This combination is often the cause of conflict between baboons and humans. The need arise for these baboons to be studied and managed as a component of this very important ecosystem. The main aims of the study were firstly to identify a natural ranging baboon troop, to habituate them and gather data regarding home range sizes, troop sizes, densities and seasonal food selection and secondly to give a detailed habitat description and vegetation map of the troop's home range. The baboon activity data was collected in 15-minute intervals over a one year period on a troop at Bourke's Luck. This included all activities such as walking, social, foraging, and resting. The food parts selected as well as the species foraged on was identified. Numerous statistical methods were used on the baboon data such as; the Shapiro Wilk test, Spearman rank-order correlation, ANOVA, and the Kolmogarov-Smirnov two sample test. There was a positive correlation between home range areas and troop sizes and the baboons preferred certain habitats above others during different seasons. To give a detailed habitat description of the troop's home range, 50 sample plots was stratified-randomly distributed in order to include all the different stratification units. a TWINSPAN classification, refined by Braun-Blanquet procedures was carried out on the Bourke's Luck section that included the baboons home range. 13 Plant communities, which can be grouped into 7 major community types were identified. This study resulted in the ecological interpretation of baboon activities related to the ecological interpretation of the vegetation in the baboon troop's home range. / Agriculture, Animal Health and Human Ecology / M.Tech. (Nature Conservation)
243

Behavioral-ecology of the white rhinoceros (Ceratotherium simum) in the Willem Pretorius Game Reserve

Jordaan, Hermanus Lukas 06 1900 (has links)
The main aim of this study was to classify and describe the plant communities in the home range of white rhinoceros in order to understand the animal seasonal foraging ecology. To provide a detailed habitat description, forty sample plots were stratified randomly. A TWINSPAN classification, refined by Braun-Blanquet procedures, was carried out on the Viewpoint section of the reserve. Ten plant communities, grouped into five major community types, were identified. The veld condition and ecological carrying capacity in these communities were measured, stating an abundance of food on long grass while the short grass equal the number of short grass feeders. A number of behavioural aspects such as activity data, home range utilization and dietary usage were examined. Statistical methods such as the Spearman rank-order correlation, Wilcoxon sign test and Student T-test were used on rhino data. The difference in usage of the home range during wet and dry seasons was insignificant. / Environmental Sciences / M.Sc. (Environmental Management)
244

Remote sensing for assessing wetland-groundwater interaction in the Kogelberg Biosphere Reserve

Engelbrecht, Jeanine 12 1900 (has links)
Thesis (MA)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: The Table Mountain Group (TMG) Aquifer System is a regional fractured aquifer system with a large potential as a source of future water supplies in the Western and Eastern Cape. This system is currently under consideration for large-scale water abstraction. Many terrestrial ecosystems, however, are dependent on these groundwater resources for survival. Exploitation of ground water resources at a rate exceeding the rate of natural recharge would result in a lowering of the water table and the drying up of seeps. The main objective of this study was to determine if satellite remote sensing data can be used for the detection of groundwater-dependent wetlands, and secondly, to use multi-temporal imagery for estimating seasonal changes experienced in wetland communities in relation to surrounding vegetation. The Kogelberg Biosphere Reserve, situated approximately 30km to the east of Cape Point in the Western Cape, South Africa, was selected for investigation. To accomplish the objectives, three Landsat 7 ETM+ images (path/row: 175/84) captured on 22 September 2001, 18 May 2002 and 23 September 2002 were acquired. Image fusion of the multispectral bands (30m resolution) with the panchromatic band (15m resolution) provided 15m multispectral images for analysis purposes. Geometric correction, radiometric normalisation and atmospheric corrections was performed in order to ensure pixel-level comparability between images. Once comparability between images was guaranteed, vegetation indices and tasselled cap components were derived to provide threshold values of moisture stress indicators and productivity estimations of wetland communities in relation to surrounding non-wetland communities. Additionally, change vector analysis on these transformations provided the ability to detect and assess the seasonal changes experienced by these communities during an annual cycle. The results of these transformations were combined in a rule-based image classifier in order to assist in estimating the seasonal dependency of observed wetland communities. The ability to use Landsat 7 images and the abovementioned image processing procedures to identify wetland communities with a high probability of groundwater interaction was demonstrated with a high degree of accuracy (78%). It is recommended that future studies concentrate on increasing classification accuracies, while focusing on incorporating these techniques into a remote monitoring system for assessing the impacts of groundwater extraction on the groundwater-dependent wetland communities. / AFRIKAANSE OPSOMMING: Die Tafelberg Groep (TBG) Akwifer is 'n regionale verskuiwingsakwifer sisteem met groot potensiaal as toekomstige waterbron vir die Wes- en Oos-Kaap. Grootskaalse grondwateronttrekking uit hierdie sisteem word tans ondersoek. Baie terrestriële ekosisteme is egter vir oorlewing van grondwaterbronne afhanklik. Grondwaterontginning teen 'n tempo hoër as die natuurlike aanvultempo sal die watertafel laat daal en syfersones laat opdroog. Die hoofdoel van die studie was om te bepaal of satellietbeelde gebruik kan word om grondwater-afhanklike vleilande waar te neem, en om 'n tydsreeks van beelde te gebruik om die seisoenale verandering in vleilandgemeenskappe relatief tot omliggende plantegroei te raam. Die Kogelberg Biosfeer Reservaat, ongeveer 30km oos van Kaappunt, is as studiegebied geïdentifiseer. Drie Landsat 7 beelde (baan/ry: 175/84) van 22 September 2001, 18 Mei 2002 en 23 September 2002 is ontleed. Die Landsat 7 multispektrale bande (30m resolusie) is met behulp van beeld-fusietegnieke met die panchromatiese band (15m resolusie) gekombineer om multispektrale beelde te lewer met 15m grondresolusie. Geometriese korreksie, radiometriese normalisering en atmosferiese korreksie is op elk van die beelde toegepas om beeld-selvlak vergelykings tussen beelde 'n moontlikheid te maak. Met beeldvergelykbaarheid verseker, is plantegroei-indekse en 'tassled cap' transformasies gebruik om afsnywaardes vir vleiland-identifikasie te bereken. Verder is veranderingsvektoranalises op die transformasies bereken om die seisoenale veranderinge oor die jaarsiklus in vleilande te bepaal. Die resultate hiervan is vervat in 'n reël-gebaseerde beeldklassifiseerder waarmee vleilande se seisoenale grondwater afhanklikheid geraam is. Die vermoë om vleilande met 'n hol! waarskynlikheid van grondwater interaksie uit Landsat 7 beelde te identifiseer is met 'n hol! vlak van totale akkuraatheid (78%) gedemonstreer. Die aanbeveling is dat toekomstige studies moet fokus op die verhoging van hierdie klassifikasie akkuraathede. Die tegnieke moet toegespits word op die ontwikkeling van 'n afstandswaarnemingstelsel om die
245

Resource utilisation of the Chacma baboon in different vegetation types in North-Eastern Mountain Sour Veld, Blyde Canyon Nature Reserve

Marais, A. J. (Albertus Johannes) 31 May 2005 (has links)
The Blyde Canyon Nature reserve displays its natural beauty for most National and International visitors all over the World. The region is renowned for its high rainfall and misty weather, which enhances the natural beauty of the area. Because of the mist belt effect, the area is one of the largest commercial forestry areas in South Africa. Baboons also seek after the topography and vegetation type (Northeastern mountain sourveld) that is typical of this area and numerous baboon troops occur in this region. This combination is often the cause of conflict between baboons and humans. The need arise for these baboons to be studied and managed as a component of this very important ecosystem. The main aims of the study were firstly to identify a natural ranging baboon troop, to habituate them and gather data regarding home range sizes, troop sizes, densities and seasonal food selection and secondly to give a detailed habitat description and vegetation map of the troop's home range. The baboon activity data was collected in 15-minute intervals over a one year period on a troop at Bourke's Luck. This included all activities such as walking, social, foraging, and resting. The food parts selected as well as the species foraged on was identified. Numerous statistical methods were used on the baboon data such as; the Shapiro Wilk test, Spearman rank-order correlation, ANOVA, and the Kolmogarov-Smirnov two sample test. There was a positive correlation between home range areas and troop sizes and the baboons preferred certain habitats above others during different seasons. To give a detailed habitat description of the troop's home range, 50 sample plots was stratified-randomly distributed in order to include all the different stratification units. a TWINSPAN classification, refined by Braun-Blanquet procedures was carried out on the Bourke's Luck section that included the baboons home range. 13 Plant communities, which can be grouped into 7 major community types were identified. This study resulted in the ecological interpretation of baboon activities related to the ecological interpretation of the vegetation in the baboon troop's home range. / Agriculture, Animal Health and Human Ecology / M.Tech. (Nature Conservation)
246

Population size, demography and spatial ecology of cheetahs in the Timbavati Private Nature Reserve, South Africa

Dyer, Siobhan Margaret January 2013 (has links)
The cheetah (Acinonyx jubatus) has experienced a drastic decline in numbers over the last 20 years globally and is currently listed as vulnerable by the International Union for the Conservation of Nature (IUCN). In South Africa, there are only an estimated 763 free-ranging cheetahs and conflict with humans is arguably the most significant reason for this low number. The aim of my study was to determine the population size and demographic characteristics of the cheetah population within the Timbavati Private Nature Reserve (TPNR), South Africa, and to contribute to a better understanding of cheetah space use and habitat selection. The research was conducted on TPNR between November 2009 and June 2011 and I used a photographic survey to assess cheetah population size and demographic characteristics. Location data was obtained by collaring two adult male cheetahs with GPS/GSM collars and ad hoc sightings data from across the reserve for an adult female with cubs and three adolescent females. A relatively high minimum population density of 4.46 cheetahs/100km² was estimated, signifying a relatively healthy cheetah population. The sex ratio data indicated a higher male to female ratio and an average litter size of three cubs. The relatively high cub survival rate and density is promising in terms of the status of species within the area, as the data denote the success and potential persistence of the species. Cheetah home ranges varied between 20.97km² for the female with cubs and 659.65km² for the younger collared male. Season did not appear to be a determining factor in terms of home range sizes for the three social groups within the TPNR. However, the males did show a slight increase in their home range sizes during the dry season when resources where presumably more widespread. My results indicate that the cheetah is an adaptable species, flexible in behaviour and able to tolerate a variety of habitat types. Such knowledge is fundamental for planning and implementing the effective management and conservation of cheetahs in South Africa.
247

Behavioural-ecology of the white rhinoceros (Ceratotherium simum) in the Willem Pretorius Game Reserve

Jordaan, Hermanus Lukas 06 1900 (has links)
The main aim of this study was to classify and describe the plant communities in the home range of white rhinoceros in order to understand the animal seasonal foraging ecology. To provide a detailed habitat description, forty sample plots were stratified randomly. A TWINSPAN classification, refined by Braun-Blanquet procedures, was carried out on the Viewpoint section of the reserve. Ten plant communities, grouped into five major community types, were identified. The veld condition and ecological carrying capacity in these communities were measured, stating an abundance of food on long grass while the short grass equal the number of short grass feeders. A number of behavioural aspects such as activity data, home range utilization and dietary usage were examined. Statistical methods such as the Spearman rank-order correlation, Wilcoxon sign test and Student T-test were used on rhino data. The difference in usage of the home range during wet and dry seasons was insignificant. / Environmental Sciences / M.Sc. (Environmental Management)
248

Niche Expansion of an Invasive Predator (Neovison vison), Prey Response, and Facilitative Interactions with Other Invasive Mammals at the Southern End of the Americas: Conservation Challenges and Potential Solutions

Crego, Ramiro Daniel 12 1900 (has links)
The Cape Horn Biosphere Reserve is located at the southern tip of South America. This large archipelago is considered one of the last pristine areas left on the world. Despite it being an unpopulated area with most of the native forest cover intact, it has not been exempt from biological invasions, one of the major drivers of biodiversity loss. Three species that naturally interact in their native range in North America – American beavers (Castor canadensis), muskrats (Ondatra zibethicus), and American mink (Neovison vison) – were independently introduced in this remote region. In my dissertation, I investigated (i) the hypothesis of niche expansion in the invasive mink population on Navarino Island towards terrestrial habitats; (ii) potential mink impact on breeding success of forest-bird populations; (iii) habitat selection of small-rodent species and their perception on the mink's novel predation risk; and (iv) the dynamics of multiple-species invasions under the hypothesis of an invasional meltdown. Additionally, I worked within the framework of environmental philosophy. I provide an example of combining ecological and cultural dimensions within the International Long-Term Ecological Research network to disentangle the ethical dilemmas that surround the management of invasive species. I finally proposed a management plan based on the idea of multiple invasive species management, discussing potential solutions to overcome the challenges that the control of invasive species represent and to more effectively protect the biological integrity of the native ecosystems.
249

Wildlife-human conflict in Kenya : integrating wildlife conservation with human needs in the Masai Mara Region

Omondi, Paul January 1994 (has links)
Masai Mara, a large nature reserve in south-western Kenya, was created in the midst of semi-arid agropastoralist rangelands to protect wildlife. Wildlife and indigenous people co-existed for many years, usually with limited conflict; but in recent years, the conflict has intensified, mainly due to increasing human population, changing land use patterns, and altered perceptions of wildlife. This study examines the causes and nature of wildlife-human conflict in the Masai rangelands of Kenya, and considers how wildlife conservation and human development needs can best be integrated. / Findings indicate that common conflicts are livestock depredation and crop damage, human deaths or injuries, transmission of diseases, and competition for resources. Land surrounding the reserve can be divided into two distinct topographic and agroclimatic regions. The degree of conflict is spatially varied within the region. Upland ranches have high land use potential, high human and livestock population densities, and more development of agriculture. They experience limited conflict with wildlife. Lowland ranches are more arid, have lower human population density and little agriculture, but have high wildlife and livestock population densities and experience a high degree of conflict. These conflicts vary seasonally, and with distance from the protected area. / Perceptions of wildlife and attitudes towards conservation are related to past experience with wildlife. The degree of loss, effectiveness of damage control, fairness of government compensation, and involvement in wildlife tourism affect the degree of tolerance for wildlife conflict. Various socio-economic factors including level of education, knowledge of conservation priorities, and system of land ownership are related to attitudes towards wildlife. As human activity increases in the region, wildlife is more likely to be displaced. Because most animals are migratory, conflict in the land surrounding the reserve puts the viability of animal population in the protected area in question. / A two-phase program for integrating wildlife conservation with human needs is proposed. The first phase involves designation of the region into four zones: Zone A--the protected area, Zone B--the peripheral area, Zone C--multiple use, and Zone D--agriculture. The second phase of the program is the integration of the wildlife conservation with human interests through: community wildlife-damage-control, compensation for loss, sharing of tourism benefits with local people, conservation education, and local participation in wildlife conservation policy. The program provides a framework within which operational decisions can be made, and serves broader natural resource management and community development objectives in the rangelands.
250

Die ekologie van die swartwitpens in die Sandveld Natuurreservaat, Vrystaat Provinsie (Afrikaans)

Jooste, Madaleinn Heleen 03 April 2006 (has links)
Please read the abstract in the section 00front of this document / Dissertation (MSc Wildlife Management)--University of Pretoria, 2006. / Animal and Wildlife Sciences / unrestricted

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