Academic literature on the topic 'Grasses – Kwazulu Natal – Hluhluwe Game Reserve'

SUMMARYThe polymerase chain reaction was used to detect trypanosomes in samples collected from cattle, wild animals and tsetse flies in KwaZulu-Natal Province, South Africa. A total of 673 samples from cattle and 266 from tsetse flies in the study area located near the Hluhluwe-Umfolozi Game Reserve were analysed. Both Trypanosoma congolense and T. vivax were found as single or mixed infections in cattle and tsetse flies. Moreover, the T. congolense in the infections were found to comprise 2 genotypic groups: the Savannah-type and the Kilifi-type, which were present either as single or mixed infections in cattle and in tsetse flies.

Across the globe, crop-raiding has been known to have a significant impact on subsistence farmers livelihoods in developing countries. However, the relationship between crop-raiding and food security of small-scale farmers is not well-studied. We investigated the effects of crop-raiding on homestead food security of a subsistence farming community on the edge of the Hluhluwe Game Reserve in northern KwaZulu-Natal Province, South Africa. We analyzed the relative calories lost to important food security crops (maize, common bean, spinach, and beetroot) damage by crop raiders. In addition, we conducted questionnaire surveys of resident farmers and conservationists of the Hluhluwe Game Reserve to explain the effect of crop-raiding on food security. We firstly assessed how crop loss influenced relative calorie loss as an indicator of food security by comparing relative calorie loss with two predictors of food security: homestead size and contribution of crops to the farmers' food basket. Larger homesteads were more prone to food insecurity as compared to smaller households as they experienced higher calorie loss, especially in terms of maize (Zea mays), the most important food security crop in South Africa. This was because maize contributed the highest (91–100%) to the homestead food basket of these farmers. Secondly, we assessed farmers and conservationists' perceptions and opinions on crop-raiding issues. Farmers reported maize as the crop most damaged by crop-raiding animals. Conservationists reported crop-raiding with other major problems in and around the Reserve; this showed that conservationists acknowledge the issue of crop-raiding as a problem for subsistence farming communities abutting protected areas. Both farmers and conservationists reported insects as the most damaging crop raider. Our study suggests that larger homesteads, particularly where maize contributes substantially to homestead food baskets, are more prone to food insecurity in the rural subsistence farming community that we studied. In concordance with many studies, insects were reported as the culprits by both farmers and conservationists. Small, ubiquitous animals, such as insects are reported to cause much crop damage where they occur. The findings of our study suggest that the food security of the studied farmers is threatened by crop-raiding.

In South Africa, trypanosomosis also known as Nagana, transmitted by Glossina brevipalpis and G. austeni, is the major cause of anaemia and chronic debilitating condition in cattle. There is a wealth of entomological information on the ecology of the two tsetse species generated following the devastating outbreak in cattle due to Nagana in 1990. However, it is unfortunate that these entomological data has not been supported by parallel studies on the epidemiology of the disease. Therefore, the present study presents the first intensive epidemiological investigations since 1990 to address the problem of animal trypanosomosis in South Africa. The relationship between trypanosomes herd average prevalence (HAP), herd average anaemia (HAA) and herd average packed cell volume (HA-PVC) were investigated in cattle in three communal diptanks located by the Hluhluwe-uMfolozi Game Reserve by regular monthly sampling for 15 months. The tsetse challenge with G. brevipalpis in two of the diptanks, Mvutshini and Ekuphindisweni, was high but low in the third (Ocilwane). In addition, G. brevipaplis and G. austeni coexist in Mvutshini diptank. This high and low tsetse challenge presented different disease scenarios. Cattle at Mvutshini and Ekuphindisweni diptanks had the highest HAP of 12.3% and 8.9%, respectively, which is significantly different (p = 0.001) from the HAP obtained from cattle at Ocilane (2.9%). Both cattle herds at Mvutshini and Ekuphindisweni diptanks also had the highest HAA, 27.7 and 33.4%, respectively, while cattle at Ocilwane had the lowest, 11.1% (statistically different; p = 0.001). Conversely, cattle at Ocilwane diptank had the highest HA-PCV, ranging between 29-32% while cattle at Mvutshini and Ekuphindisweni diptanks had the lowest HA-PCV (24-29%). The interaction between HAP and HAA is significant (p = 0.021). The overall effect of HAP on the animal health condition is clearly demonstrated when comparing the anaemia in trypanosomes infected and uninfected cattle at the 3 diptanks. Fifty percent, 63% and 100% of trypanosomes infected cattle were anaemic at Mvutshini, Ekuphindisweni and Ocilwane diptanks, respectively. In comparison, the prevalence of anaemia in uninfected cattle in the 3 diptanks was 20, 30 and 10% at Mvutshini, Ekuphindisweni and Ocilwane diptanks, respectively. By combining the data from the 3 diptanks (1,800 observations), the overall HAA in infected and uninfected cattle was 62 and 20%, respectively The results of trypanosomes seasonal surveys conducted at 7 communal diptanks in tsetse infested areas, showed that all cattle at the diptanks were infected with trypanosomes with mean HAP and HAA of 10.3 and 35.3%, respectively. The highest HAP (range 15-31%, n=4) was recorded in Ngwenyambili diptank. This high infection in the cattle herds produced high values of HAA (50%; range 40-60). The infection rate with trypanosomes in G. brevipalpis caught from the field showed immature infections in the midgut of 3.5% (16/458) while only one fly was found with mature infection in the proboscis (1/458, 0.22%). Very few G. austeni were collected (total of 9) during the same period and dissected. The infection rate with trypanosomes immature and mature infections was found to be very high; 5/9 (55.5%). Blood samples were collected from a total of 132 buffaloes randomly immobilized for tuberculosis testing by the Hluhluwe-uMfolozi Game Reserve Authority. Two buffaloes were found to have T. congolense infection by the buffy coat technique. The presence of trypanosomes infected buffaloes in this study confirms the occurrence of sylvatic cycle at the tsetse/livestock/Hluhluwe-uMfolozi Game Reserve, thus, presenting a high risk of serious disease to cattle. The objective of the study on the strategic treatment of trypanosomosis conducted on one farm in endemic area was to treat adult cows and calves at an arbitrary HAP threshold before the disease produces any clinical symptoms or production losses. The strategic use of ethidium bromide and novidium chloride produced attractive results whereby cattle were protected for an extended period of 3 to 6 months with no development of anaemia during this period. Therefore, two to four treatments per year may be sufficient to keep cattle productivity on the farm under the tsetse challenge Copyright
Dissertation (MSc)--University of Pretoria, 2012.
Veterinary Tropical Diseases
unrestricted

Diatoms are microscopic algae found in almost all aquatic environments. They are habitat specific and have silica frustules which preserve well in sediments. They have been used extensively to provide a multitude of palaeoecological data relating to pH, nutrient loads and water levels. Here, the diatoms in a lake sediment core from Hluhluwe-Imfolozi, South Africa, are analysed to show fluctuations in littoral to benthic taxa, and brackish to freshwater taxa as indicators of lake level changes over time. Changes in lake level act as a proxy for warm/dry or cold/wet periods over time. During the last 240 years lake levels have remained consistently low but nevertheless indicate four alternating periods of cold/wet and warm/dry climate. From c. A.D. 1770 (the last few decades of the Little Ice Age) to the c. A.D. 1840 the climate was cool and wet, but nonetheless gradually warmed up and became drier. From c. A.D. 1840 through to c. A.D. 1920 a there was a gradual increase in temperature and corresponding decrease in rainfall. Then, from c. A.D. 1920 till c. A.D. 1980 there was another colder, wetter period. Finally, very recently, from around c. A.D. 1980 till the present day, Hluhluwe-Imfolozi has experienced warmer, drier conditions once. Pollution-tolerant diatoms increase during the last 100 years and indicate eutrophication of the lake, a consequence of anthropogenic activity in the region. The diatom sequence from Phindiswene provides a high resolution climatic proxy for the critical period covering the latter stages of the Little Ice Age (LIA), post LIA warming, and recent increasing anthropogenic impacts.

Contemporary and historical studies of the flora of the Hluhluwe Game Reserve (HGR), have emphasised the woody component whilst little work has been performed on the herbaceous vegetation. This is particularly true with regard to the responses of grasses to historical fire and bush clearing. This study attempted to elucidate some of these responses. Of all the variables considered in this study, woody cover, altitude, the number of fire events, geological and soil parent material are the most important affecting the abundance of grasses in this reserve. Most of these variables are not independent in their effects on grass abundance, with varying degrees of correlation between each other. Certain species appear to be restricted to particular geological substrates. Along with successional changes in the composition and cover of the woody community, due to seemingly inevitable bush encroachment, there is a parallel change in grassland communities in this reserve. In the absence of clearing, numerous fires, higher altitudes, igneous geology and soils derived from igneous parent material delays this succession, whilst sedimentary geology at lower altitudes and fire frequencies accelerates the trend to high woody cover and associated grass species. The grass communities in HGR were shown to be significantly affected by bush clearing and fire. Specifically the number of clearings and fire events, physical bush clearing during 1957 - 1963 and chemical bush clearing during 1968 - 1978. From the responses of species in relation to the various key environmental variables, viz. geological substrate, woody cover and burning and clearing, a model of species response to these variables was developed. With increased fire and bush clearing frequency, the grass communities shift from closed woodland, shade tolerant species through to more open fire climax grassland. These are also more productive communities producing palatable grasses. Validation of aspects of the model were successful - the model having a relatively high predictive capability. Further testing of the model over different substrates and under different clearing regimes is necessary. With regular fires and re-clearing in some bush cleared areas, the vegetation of this reserve should be able to be maintained as productive and diverse grasslands. In the absence of this management, the grass communities will shift towards species associated with woodlands. Bush clearing activities would appear to be most effective over sites on igneous substrate, at higher altitudes, where successional rates are slowest. This is in comparison to sites at lower altitudes over sedimentary geology.
Thesis (M.Sc.)-University of Natal, Durban, 1992.

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.

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.

The Okavango Delta is an extremely dynamic system with variable vegetation comprised of permanent swamps, seasonal swamps, dry islands, floodplains and dry grassland, savanna and woodland. The system is largely driven by the interaction between fire and the annual flood, which filters down from the Okavango River catchments in Angola. While extensive research has been conducted on the flood-driven vegetation little is known about the dry woodland and savanna regions bordering these flood-driven habitats. A taxonomic classification of woody species composition resulted in eleven vegetation types. These data were then reanalyzed in terms of woody species morphology allowing these eleven vegetation types to be grouped into four functional response groups in order to provide a platform for improving the understanding of how dry woodland and savannas interact with the environment. These four groups were the savanna group mixed thornveld and the three woodland groups; mixed broadleaf woodland, shrub mopane woodland and tall mopane woodland. Burning in mixed thornveld and mixed broadleaf woodland was found to decrease woody species density and grass fuel loads and could be used for grazing management to remove unpalatable growth and improve grass species composition, while burning in shrub mopane woodland and mixed mopane woodland merely decreased the woody understory and is not recommended. Utilization dominated by grazing livestock resulted in overutilization of the grass sward leading to bush encroachment in both mixed thornveld and shrub mopane woodland, while utilization by goats alone resulted in underutilization of the grass sward and a dominance of herbaceous annuals. Livestock utilization had no effect on the occurrence of Pecheul-loeschea leubnitziae, a shrubby pioneer previously thought to be an indicator of overgrazing, however extensive P. leubnitziae cover was associated with a sward dominated by shade-tolerant grasses with low forage quality. Shrub mopane woodland and tall mopane woodland appear to be more stable vegetation states than mixed broadleaf woodland and mixed thornveld being less vulnerable to colonization by pioneer species and alteration as a result of utilization or environmental factors. For this reason management and monitoring of mixed thornveld and mixed broadleaf woodland is essential to prevent vegetation degradation and to ensure optimal forage availability for both livestock and wildlife.
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.