Thesis (M.A.)--University of Wyoming, 2007. / Title from PDF title page (viewed on Dec. 1, 2008). An interdisciplinary thesis in Sociology and Environment & Natural Resources. Includes bibliographical references (p. 81-86).

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The 28-month study assessed the impacts of five syntopic medium-sized mammalian browsers and one fire event in a woodland savanna in the Matobo Hills, Zimbabwe. Aspects of herbivory, mechanical pressures, seed dispersal and nutrient cycling were investigated for three species of small antelope (common duiker [Sylvicapra grimmia]1, klipspringer [Oreotragus oreotragus] and steenbok [Raphicerus campestris]) and two medium-sized species (bushbuck [Tragelaphus scriptus] and greater kudu [T. strepsiceros]). Focusing on Burkea africana2 woodland, in a system that does not include elephant (Loxodonta africana), effects of browsing antelope on woody and herbaceous vegetation development were investigated using exclusion plots. Browsers regulated woody plant cover (measured as basal stem area), with smaller antelope having a greater impact than larger species. This was linked to feeding height, feeding selectivity and mechanical pressures (e.g. twig breakage and trampling). Fire caused an initial reduction in above-ground standing biomass, but in the presence of fauna, pre-fire equilibria were attained within 15 months. In antelope exclosures, herbaceous biomass increased and woody biomass decreased following fire. Responses by woody vegetation to browsing varied among species, with highly palatable species typically exhibiting compensatory regrowth. Woody species richness and abundance (especially of palatable species) increased in the absence of browsers, but species richness of the herbaceous layer was promoted by moderate disturbance (trampling or fire). Faecal deposition behaviour, primarily the use of latrines by small antelope, resulted in localised soil enrichment within defended territories. Decomposition rates (and therefore return of nutrients to the soil) varied among species and seasons, due to defecation site selection, accessibility to decomposers and desiccation rates of faecal pellets. Controlled seed germination experiments indicated that ingestion by small antelope enhances germination rates of large, hard-seeded fruits such as Sclerocarya birrea. However, germination of savanna seeds may require multiple cues. This study demonstrated the critical roles of small antelope in ecosystem functioning, and highlights the importance of the less visible impacts of frequently overlooked smaller mammalian herbivores. Perturbations to the faunal community, especially small antelope, are predicted to have substantial impacts on woody plant cover.

Please read the abstract (Uittreksel) in the section, 00front of this document. See also 10summary / Dissertation (MSc (Zoology))--University of Pretoria, 2007. / Zoology and Entomology / MSc / unrestricted

The study involved the predator-prey interaction of three species namely the predator (Cheetah Acinonyx jubatus), the super-predator (Lion Panthera leo), and their common prey (Impala Aepyceros melampus). The study area is the Kruger National Park. The predator being an endangered species, faces a survival problem. It is frequently killed by the super-predator to reduce competition for prey. The super-predator also scares away the predator o_ its kills. The prey forms the main diet of the predator. The plight of the predator motivated the author to formulate disease and reaction-diffusion models for the species interactions. The purpose of the models were to predict and explain the effect of large competition from the super-predator on the predator population. Important parameters related to additional predator mortality due to presence of super-predator, the disease incidence rate and induced death rate formed the focal points of the analysis. The dynamics of a predator-prey model with disease in super-predator were investigated. The super-predator species is infected with bovine Tuberculosis. In the study, the disease is considered as biological control to allow the predator population to regain from low numbers. The results highlight that in the absence of additional mortality on the predator by the super-predator, the predator population survives extinction. Furthermore, at current levels of disease incidence, the super-predator population is wiped out by the disease. However, the super-predator population survives extinction if the disease incidence rate is low. Persistence of all populations is possible in the case of low disease incidence rate and no additional mortality imparted on the predator. Furthermore, a two-species subsystem, prey and predator, is considered as a special case to determine the effect of super-predator removal from the system, on the survival of the predator. This is treated as a contrasting case from the smaller parks. The results show that the predator population thrives well in the total absence of its main competitor, with its population rising to at least twice the initial value. A reaction-diffusion three-species predator-prey model was formulated and analysed. Stability of the temporal and the spatio-temporal systems, existence and non-existence of stationary steady state solutions were studied. Conditions for the emergence of stationary patterns were deduced. The results show that by choosing the diffusion coeffcient d2 > _D 2 suffciently large, a non-constant positive solution is generated, that is, stationary patterns emerge, depicting dispersal of species. Predators were observed to occupy habitats surrounding prey. However, super-predators were observed to alternate their habitats, from staying away from prey to invading prey habitat. In the investigation, strategies to determine ways in which the predator species could be saved from extinction and its population improved were devised, and these included isolation of the predator from the super-predator.

D.Phil. (Nematology) / This was the first study on aquatic nematodes from the Kruger National Park. Samples were taken more or less randomly over a period of two years from the four main rivers in the park, viz. the Crocodile, Sabie, Olifants and Luvuvhu rivers. A total of 33 species representative of 24 genera were found. Dorylaimida seemed to be dominant in most of the sampling sites in the Sabie, Olifants and Luvuvhu Rivers, but there was no dominant group in the Crocodile River. Five new Dorylaimida species are described: Dorylaimus deaconi spec. nov., Laimydorus olifanti spec. nov., Laimydorus africanus spec. nov.; proleptonchus krugeri spec. nov. and Aporcelaimellus glandus spec. nov. Previously known dorylaim species which were redescribed in detail are Mesodorylaimus sp.cf paralitoralis Basson & Heyns, 1974; M. potus Heyns, 1963, M. aegypticus (Andrassy, 1958), Aquatides thornei (Schneider, 1937), Afractinolaimus zairensis (Baqri, Coomans & Van der Heiden, 1975) and Oxydirus gangeticus Siddiqi, 1966. Further dorylaim species recorded are Aporcelaimellus micropunctatus Botha & Heyns, 1990, Discolaimus monoplanus Heyns, 1963, D. major Thorne, 1939, Xiphinema italiae Meyl, 1953, Thornenema baldum (Thorne, 1939), Tyleptus striatus Heyns, 1963 and Dorylaimellus (Axodorylaimellus) caffrae (Kruger, 1965) . The following Tylenchida species were found: Hemicycliophora labiata Colbran, 1969, Helicotylenchus africanus (Micoletzky, 1916) and Scutellonema brachyurum (Steiner, 1939). Three Araeolaimida species were recorded, viz. Chronogaster africana Heyns & Coomans, 1980, Plectus cirratus Bastian, 1865 and Rhabdolaimus terrestris de Man, 1880. The latter species is redescribed in full collected and (de Man, 1979). Only one species of the Cromadorida viz. Achromadora ruricola 1880), Enoplida viz. Eutobrilus annetteae (Joubert & Heyns, Monhysterida viz. Monhystera somereni Allgen, 1952, were Detailed descriptions are given to incorporate additional morphological information obtained. Brief descriptions and new distribution records are also given for Mononchus truncatus Bastian, 1865, M. aquaticus Coetzee, 1968 and Mylonchulus minor (Cobb, 1893) of the Mononchida and Ironus longicaudatus de Man, 1884 and I. ignavus Bastian, 1865 of the Iro~idae.A diagnostic compendium for the Mesodorylaimus species of South Africa and a checklist of the free-living and plant parasitic nematode species from both terrestrial and aquatic habitats in the park are also included. Most of this work has already been published or submitted for publication in scientific journals and is presented in this thesis in the same format as required by the editors of the journals concerned.