Browsing Okavango Research Institute (ORI) by Title
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Phorano, O.M.; Nthomang, K.; Ngwenya, B.N. (Botswana Society, NaN, 2005)[more][less]
Abstract: Batswana have been hard-hit by the HIV/AIDS pandemic. The Botswana government has initiated the Community Home-Based Care programme to provide material support for HIV/AIDS patients cared for at home by family members and relatives. This paper identifies and explores emerging home care issues and pays specific attention to potential risks related to poorly managed clinical human and solid waste disposal generated through home-based care of HIV/AIDS patients in Ngamiland and Kweneng Districts in Botswana. Data were collected through focus group discussion with care-givers, discursive interviews with professional service providers, and participant observation. The results of the study indicate that the majority of care givers received material benefits provided through the CHBC programme. However, it was clear that CHBC did not have the capacity to address other critical needs for the proper care of patients in the home. Most households studied are very poor and lack basic facilities such as toilets, basic waste receptacles and regular collection of solid waste. Access to these facilities is important for disposing of both clinical and ordinary human and solid waste from HBC patients. Poor sanitation facilities - especially the improper handling of soiled laundry and inadequate ventilation - increase risks of infection. The study recommends the formation of care-giver support groups to reduce risks associated with poorly managed clinical solid waste disposal generated from home care-giving of HIV/AIDS patients. URI: http://hdl.handle.net/10311/952 Files in this item: 1
Phorano 2005 HIV.pdf (2.631Mb) -
Ngwenya, B.N.; Butale, B.M. (Botswana Society, NaN, 2005)[more][less]
Abstract: Home care involves the transfer of a patient’s medical supervision from a formal institution to a family setting in the context of a community. The aim of this paper is to assess the resource capacity of families to provide immediate home care to HIV/AIDS related chronically or terminally ill member/s in Maun in Ngamiland District. Data for the study was obtained through cross-sectional interviews with 61 care-givers. Ethnographic methods were also used: these included informal interviews with key informants, unobtrusive participant observation, and narratives of individual and family life experiences. Data collection focused on assessing family resource capacity to access three forms of capital, namely social, productive and produced. Issue focus analysis on qualitative data, and descriptive frequencies and cross-tabulations on quantitative data were carried out. Generally, care-givers reported receiving non-material support from multiple sources. These included moral support from close family members, especially their own children, siblings, parents and spouses, and less from parents’ in-law and their extended family. The threshold of care-giving resource demands could either fragment the family unit, on precipitate ‘enclave-like’ or ‘disengaged’ co-existence or passive aggression. On the other hand, caregiving resource demands may enhance mutual obligation and shared responsibility among family members. A high level of tolerability tends to reduce vulnerability and facilitate pooling limited resources in ways that enhance family capacity. Conversely, adversarial intra-family relations compromise the ability of a family to mobilize its resources. About 70% of care-givers were dependent on non-farming activities as their source of livelihood. Care-giving depletes family resources, including the abandonment of income generating activities. About 81% of care-givers said that they could not do anything to recover or reverse the loss. Access to produced capital such as telecommunication infrastructure is important in terms of the dissemination of public education information aimed at helping reduce risks and the prevention of infection. A significant proportion of care-givers had access to a radio (60%) and cell-phone (48%). The paper ends with some policy recommendations. URI: http://hdl.handle.net/10311/953 Files in this item: 1
Ngwenya 2005 AIDS.pdf (3.334Mb) -
Mmopelwa, G.; Kgathi, D.L.; Masamba, W.R.L.; Thukuza, A. (Botswana Society, NaN, 2005)[more][less]
Abstract: Water supply in Maun is unreliable and unpredictable, and most households experience water shortage all year round. Coping strategies for households include water storage in tanks. Water quality is also poor due to its salty taste, presence of sediments and colour. The majority of households have henceforth embarked on coping strategies such as buying bottled water. On average, households spend about P71 per month as avoidance cost. A contingent valuation method assessment was carried out and it was found that the mean maximum household’s willingness to pay for a water quality improvement fund was P55 per month. Chemical analysis carried out on water samples from the study area confirm that the water has high electrical conductivity, sediments, colour, and iron and manganese levels. URI: http://hdl.handle.net/10311/938 Files in this item: 1
Mmopelwa 2005 House.pdf (1.540Mb) -
Kurugundla, C.N.; Bonyongo, M.C.; Serumola, O. (Taylor & Francis, December 22, 2010)[more][less]
Abstract: The risk and effect of the insecticide deltamethrin, applied aerially in Botswana to control and eradicate tsetse fly, was studied on the non-target weevil Cyrtobagous salviniae, a biocontrol agent of the aquatic weed Salvinia molesta. Environmentally-simulated short-term toxicity bioassay used open iron cages and closed plastic basins containing weevils and salvinia placed in riverine water bodies, where they were exposed to the aerial applications of deltamethrin over the Kwando–Linyanti system in 2006. Control samples were placed 40 km outside the sprayed area. Weevil mortality, determined at 12, 36 and 60 hours after the aerial application, reached a maximum of 27%. No significant difference in mortalities was observed between the closed basins and the open cages. The amount of deltamethrin deposited at ground level was between 1.2 and 6.4 μg m–2 and the insecticide toxicity was related to the weevil mortality. Simultaneous field monitoring through five spray applications showed that weevil abundance declined in late winter. Deltamethrin had a negligible impact on the weevil’s ability to control salvinia under field conditions, probably due to the weevils’ protective mechanism and because vegetation could act as a barrier, preventing the insecticide from reaching the weevils. Minimum impacts of deltamethrin on the weevils in the present study and their recovery in the field are consistent with those of earlier spray applications in the Okavango Delta, Botswana. URI: http://hdl.handle.net/10311/808 Files in this item: 1
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Magole, L.; Thapelo, K. (Botswana Society, NaN, 2005)[more][less]
Abstract: This paper presents the results of a study carried out on the impact of the recent (2004) severe flooding of the Okavango River on the livelihood of the molapo (flood recession) farming community of Tubu village in Ngamiland sub-district. Government and NGO disaster relief organisations responded to the floods in panic and desperation while affected communities appeared calm and laid-back. To the extent that they (communities) refused to evacuate flood plains and island settlements to make way for the considerably high and potentially dangerous flood of 2004; the communities' reaction was surprising as the floods were so severe upstream, that they caused damage to property, threatened lives and reduced yields significantly. However, studying the farming community of Tubu revealed that community members have other considerations which make them perceive the inherent risk differently from outsiders. Communities view flooding (whether severe or normal) more as part of the biodiversity production system and a source of livelihood than a destructive force. It was found regarding molapo farming that, first, even under hazardous flooding conditions crop yields are still better compared to those under alternative dryland farming. Secondly, destructive floods occur at 10- to 20-year intervals, making the gamble worthwhile because over time the flood-related benefits outweigh the risks. Thirdly, because the molapo farming communities are poor, other sources of livelihood are not adequately developed to take over from molapo farming. Fourth, the system has evolved into an old tradition which the farmers are not willing to part with. Hence the farmers are adamant that abandoning the production system is not, as yet, an option for them. URI: http://hdl.handle.net/10311/949 Files in this item: 1
Magole 2005 Impact of.pdf (1.900Mb) -
Impact on water quality of land uses along Thamalakane-Boteti River: an outlet of the Okavango DeltaMasamba, W.R.L.; Mazvimavi, D. (Elsevier, July 8, 2008)[more][less]
Abstract: Botswana is a semiarid country and yet has one of the world’s famous wetlands: the Okavango Delta. The Thamalakane- Boteti River is one of the Delta’s outlets. The water quality of the Thamalakane-Boteti River was determined and related to its utilisation. The major land uses along the Thamalakane River within Maun are residential areas, lodges, hotels, and grazing by cattle and donkeys. The water is used as a source of water for livestock, wildlife in a game park, horticulture and domestic applications including drinking. The river is also used for fishing. To check whether these activities negatively impact on the water quality, pH, electrical conductivity, dissolved oxygen, temperature, total dissolved nitrogen and phosphorus, Faecal coliforms and Faecal streptococci and selected metals were determined from July 2005 to January 2006. The pH was near neutral except for the southern most sampling sites where values of up to 10.3 were determined. Dissolved oxygen varied from 2 mg/l to 8 mg/l. Sodium (range 0.6–3.2 mg/l), K (0.3–3.6 mg/l), Fe (1.6–6.9 mg/l) conductivity (56–430 lS/cm) and Mg (0.2–6.7 mg/l) increased with increased distance from the Delta, whereas lead showed a slight decline. Total dissolved phosphorus was low (up to 0.02 mg/l) whereas total dissolved nitrogen was in the range 0.08–1.5 mg/l. Faecal coliform (range 0–48 CFU/100 ml) and Faecal streptococci (40–260 CFU/100 ml) were low for open waters with multiple uses. The results indicate that there is possibility of pollution with organic matter and nitrogen. It is recommended that more monitoring of water quality needs to be done and the sources of pollution identified. URI: http://hdl.handle.net/10311/740 Files in this item: 1
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Aranibar, J.N.; Anderson, I.C.; Ringrose, S.; Macko, S.A. (Elsvier, www.elsevier.com, NaN, 2003)[more][less]
Abstract: Cyanobacterial soil crusts may be important in arid and semi-arid ecosystems because of their ability to fix atmospheric nitrogen (N2). These crusts are very sensitive to trampling by animals, and their destruction can decrease ecosystem N inputs, affecting the productivity of the region. The objective of this study was to quantify the nitrogen-fixing activity in soil crusts during the wet season in southern African ecosystems using in situ acetylene reduction assays. The average acetylene reduction rates for each site ranged from 88 to 535 nmol m-2 h-1, were highly variable, and were lower than previously reported for other arid areas. All soil samples showed acetylene reduction activity; however, soils with crusts supported higher rates than did "non-crusty" soils under litter, moss, or sand. High values of 15N natural abundance (delta15N) indicated that processes other than N fixation were more important in the crusts than N fixation. For example, coupled and ammonia volatilization or atmospheric deposition of 15N-enriched nitrate or ammonium may have caused shifts in delta15N within the soil crusts. The estimated annual N fixation rates ranged from 8 to 44 g N ha-1 year-1, orders of magnitude lower than values estimated in other studies. The anomalous wet conditions experienced during the year of the study may have increased the temporal availability of soil mineral N and decreased N fixation rates. However, the presence of N fixation activity in all crusts analysed and their ability to survive at high temperature and after long dry periods may provide ecosystem resilience, facilitating ecosystem recovery after severe droughts. URI: http://hdl.handle.net/10311/983 Files in this item: 1
Ringrose_Importance_of_Nitrogen_2003.pdf (2.069Mb) -
Kiker, G.; Munoz-Carpena, R.; Wolski, P.; Cathey, A.; Gaughan, A.; Kim, J. (Inderscience, http://www.inderscience.com, NaN, 2008)[more][less]
Abstract: In this paper, we present a review and conceptual design to integrate hydrological/ecological models, global uncertainty and sensitivity analysis, integrative modelling and decision analysis for complex and adaptive transboundary challenges. The research uses the transboundary issues within the Okavango River basin, a shared water resource among the nations of Angola, Namibia and Botswana, as an example for constructing these integrated tools. The objective of this paper is to present a design that integrates a set of tools that builds systematically on past basin modelling research to incorporate the inherent uncertainty within the system and its application for answering practical management questions. URI: http://hdl.handle.net/10311/864 Files in this item: 1
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Ringrose, S.; Vanderpost, C.; Matheson, W.; Wolski, P.; Huntsman-Mapila, P.; Murray-Hudson, M.; Jellema, A. (Elsevier Ltd; www.elsevier.com/locate/jaridenv, January NaN, 2007)[more][less]
Abstract: This work seeks to determine whether riparian woody plant variables respond to drying and salinity regimes in the semi-arid distal Okavango Delta, northern Botswana. Structural and compositional variables were obtained from 47 field sites. Mapping using satellite imagery illustrated differences in the character of riparian zones in terms of species composition and provided data on flood frequency. Salinity data plots show increases downstream. Results imply that woody plant variables respond to desiccation-driven change due to water-table lowering (reduced recharge) and increased salinization through distinct changes in tree and shrub height, plant density and species richness. In the wetter, intermediate distributaries, key biotic indicators of ecosystem change comprise structural variables such as decreases in canopy cover per cent and tree height and increases of shrub height, which are indicative of mainly ground-water declines. Biotic indicators in the less frequently flooded receiver channels comprise plant density and species richness increases involving mainly brackish ground-water-tolerant and dryland species which are indicative of both ground-water declines and/or salinization. These indicators could provide useful parameters for use in long- and short-term monitoring aimed at assessing desiccation-driven change in different parts of the Okavango Delta and possibly other semi-arid wetlands. The indicators are important as a less-expensive alternative to drilling as a means of verifying ground-water declines and/or salinization. URI: http://hdl.handle.net/10311/161 Files in this item: 2
license.txt (1.998Kb)Ringrose_et_al_JAE_07.pdf (1.322Mb) -
Mubyana, T.; Krah, M.; Totolo, O.; Bonyongo, M. (Journal of Arid Environments. http://www.elsevier.com/wps/find/journaldescription.cws_home/622855/description#description, NaN, 2003)[more][less]
Abstract: The effect of flooding on soil total nitrogen, phosphorus and microbial population in different vegetation zones (floodplain, island and woodland) and profile depth (0?1, 0?5, 2?0, 3?0, 4?0 and 5?0m) of the Okavango Delta was studied from February to July 1999. Total nitrogen significantly differed with soil profile depth, moisture regime and months. In the woodlands, insignificant total nitrogen was detected at all depths except at 0?1m, where 0?03% and 1?17% were detected in February and March, respectively. In the island samples, only 0?05% was detected at 4m in February. Nitrogen in the floodplain samples was concentrated in the A1 horizon where 0?12%, 0?61% and 0?03% were detected in February, March, and May, respectively. Organic phosphorus significantly differed with vegetation zone but not with months and depth. Although organic phosphorus was low (0?02–0?52%) at all sites, it was liberally distributed throughout the profiles. On the island, actinomycetes were only detected up to 2m in February and up to 3m in July. Fungi concentrated in the top 0?5m (103–105). In both the floodplain and island samples, bacteria concentrated in the upper 3m. However, after May, populations decreased significantly. In the floodplain, significant actinomycetes populations were only detected in the upper 0?5m. Generally, organic phosphorus showed positive correlations with fungal populations. This study indicates that these soils are low in total nitrogen and phosphorus. URI: http://hdl.handle.net/10311/293 Files in this item: 1
Influence of seasonal flooding.pdf (3.953Mb) -
Heinl, M.; Neuenschwander, A.; Sliva, J.; Vanderpost, C. (Springer: http://www.springerlink.com, NaN, 2006)[more][less]
Abstract: A series of 98 satellite images was analysed to reconstruct the fire and flood history of a floodplain system in southern Africa(Okavango Delta, Botswana). The data was used to investigate interactions between fire and flooding, and to determine the relevance of rainfall and flood-events for fire occurrences on floodplains and on drylands. The aims of the study are (1) to analyse and compare the fire frequency on floodplains and on adjacent drylands, (2) to investigate the influence of rainfall and flooding on the fire occurrence and (3) to determine correlations between fire frequency and flood frequency. The analyses show higher fire frequencies on floodplains than on drylands because of higher biomass production and fuel loads. The fire occurrence on drylands shows a correlation with annual rainfall events, while the fire frequency on floodplains is in principle determined by the flood frequency. Between floodplain types, clear differences in the susceptibility to fire where shown by analysing flood frequency vs. fire frequency. Here, the highest potential to burn was found for floodplains that get flooded about every second year. By calculating mean fire return intervals, the potential to burn could be specified for the different floodplain types. URI: http://hdl.handle.net/10311/792 Files in this item: 1
Heinl_Michael_LE_2006.pdf (1.827Mb) -
Wolski, P.; Murry-Hudson, M.; Fernkvist, P.; Liden, A.; Huntsman-Mapila, P.; Ramberg, L. (Botswana Society, NaN, 2005)[more][less]
Abstract: Groundwater under islands in the Okavango Delta is a known sink of inorganic dissolved minerals, preventing salinisation of this virtually enclosed evaporation-dominated hydrological system. The Okavango Delta is an oligotrophic, yet very productive system, and it is important to understand sources, pathways and recycling of nutrients in order to fully comprehend its ecology. In order to investigate the role of islands as nutrient sinks, concentrations of nitrogen and phosphorus, as well as major inorganic ions were measured in island and floodplain groundwater. The electrical conductivity was found to be up to 50 times higher in the island centre groundwater than in the surrounding floodplain groundwater. The amount of total phosphorus was found to be up to 400 times higher and total nitrogen up to five times higher in the interior of the island than in the surrounding floodplain. These show that major nutrients are, like other inorganic ions, accumulated under islands. Importantly, the ratio of nitrogen to phosphorus was 5:1 in floodplain water and water in island fringe soils, but 1:4 in island centres. his indicates an intensive removal of nitrogen along the floodplain-island groundwater flow path by the floodplain fringe and riparian biota, resulting in a relative enrichment in P. URI: http://hdl.handle.net/10311/950 Files in this item: 1
Wolski 2005 Islands.pdf (1.469Mb) -
Chimbari, M.J.; Shiff, C.J. (Taylor & Francis, May 5, 2008)[more][less]
Abstract: Preliminary laboratory studies were conducted to determine the molluscicidal potency of Jatropha curcas, the physic nut. Biomphalaria glabrata and Bulinus globosus snails were exposed to varying concentrations of aqueous extracts of crushed J. curcas seeds from unripe, ripe and overripe fruits collected from two geographically different sites, (Bindura and Kariba, Zimbabwe). Snail mortalities were compared between different developmental stages of J. curcas and between seed collection areas, and LC50 and LC90 values for the different extracts tested were computed. Biomphalaria glabrata was most susceptible to unripe fruit seed extract (with LC50 values of 282 and 389 mg l-1 being recorded for Kariba-origin and Bindura-origin plants, respectively) and least susceptible to ripe fruit seed extracts (with LC50 values of 605 and 708 mg l-1 being recorded for Kariba-origin and Bindura-origin plants, respectively). Bulinus globosus was most susceptible to overripe fruit seed extract (Kariba-origin plants: LC50, 389 mg l-1) and least susceptible to unripe fruit seed extract (Kariba-origin plants: LC50, 687 mg l-1). The area from which fruits were collected did not influence the potency of J. curcas. The potency of J. curcas depends on both the developmental stage of the fruit and the species of the target snail. In view of its many other uses, besides as a molluscicide, we recommend further studies on J. curcas. URI: http://hdl.handle.net/10311/809 Files in this item: 1
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Lezine, A-M.; von Grafenstein, U.; Andersen, N.; Belmecheri, S.; Bordon, A.; Caron, B.; Cazet, J.-P.; Erlenkeuser, H.; Fouache, E.; Grenier, C.; Huntsman-Mapila, P.; Hureau-Mazaudier, D.; Manelli, D.; Mazaud, A.; Robert, C.; Sulpizio, R.; Tiercelin, J.-J.; Zanchetta, G.; Zeqollari, Z. (Elsevier, January 11, 2010)[more][less]
Abstract: Multi-proxy analyses on core JO2004-1 recovered from Lake Ohrid (40°55.000 N, 20°40.297E, 705 m a.s.l.) provide the first environmental and climate reconstruction in a mountainous area in Southern Europe over the last 140,000 years. The response of both lacustrine and terrestrial environments to climate change has been amplified by the peculiar geomorphological and hydrological setting, with a steep altitudinal gradient in the catchment and a karstic system feeding the lake. The karstic system was active during interglacials, leading to high carbonate production in the lake, and blocked during glacials as a result of extremely cold climate conditions with permafrost in the mountains. At the Riss–Eemian transition (Termination 2) the increase in lacustrine productivity predated forest expansion by about 10,000 years. In contrast, the Late Glacial–Holocene transition (Termination 1) was characterized by the dramatic impact of the Younger Dryas, which initially prevented interglacial carbonate production and delayed its maximum until the mid- Holocene. In contrast, forest expansion was progressive, starting as early as ca. 38,000 ago. The proximity of high mountains and the probable moderating lake effect on local climate conditions promoted forest expansion, and contributed to make the surroundings of Lake Ohrid favourable to forest refugia during the last glacial, usually steppic, period. Our study of sedimentology, mineralogy, geochemistry, magnetics, palynology and isotopes illustrates the non-linear response of terrestrial and lacustrine ecosystems to similar climate events, and demonstrates the potential of Lake Ohrid as an excellent paleoclimatic archive during the Quaternary. URI: http://hdl.handle.net/10311/607 Files in this item: 1
LakeOhrid.pdf (1.662Mb) -
Darkoh, M.; Mbaiwa, J. (Blackwell, http://www.wiley-blackwell.com, NaN, 2009)[more][less]
Abstract: This study assesses land-use conflicts in the Okavango wetland ecosystem. A survey of the livelihood activities of a sample of four villages has been carried out and a stakeholder approach used to identify and analyse the key actors involved in resource competition and conflicts in the area. Traditional and emerging stakeholders were identified and found to be in conflict not only with each other but within themselves. Institutional policies on land use in the area are not properly harmonized, and there has been a top-down approach to development planning and implementation of development programmes. As a result, land-use conflicts have escalated in the area. The Okavango Delta Management Plan adopted in 2007 should integrate and harmonize all the land-use policies, and land management in the area. URI: http://hdl.handle.net/10311/828 Files in this item: 1
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Darkoh, M.B.K.; Mbaiwa, J.E. (Wiley, NaN, 2009)[more][less]
Abstract: This study assesses land-use conflicts in the Okavango wetland ecosystem. A survey of the livelihood activities of a sample of four villages has been carried out and a stakeholder approach used to identify and analyse the key actors involved in resource competition and conflicts in the area. Traditional and emerging stakeholders were identified and found to be in conflict not only with each other but within themselves. Institutional policies on land use in the area are not properly harmonized, and there has been a top-down approach to development planning and implementation of development programmes. As a result, land-use conflicts have escalated in the area. The Okavango Delta Management Plan adopted in 2007 should integrate and harmonize all the land-use policies, and land management in the area. URI: http://hdl.handle.net/10311/730 Files in this item: 1
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Bond, J.M.; Veenedaal, E.M.; Hornby, D.D.; Gray, A.J. (Kluwer Academic Publishers, http://www.springerlink.com, November 28, 2002)[more][less]
Abstract: One of the major problems in determining the origin of invasive species is that often their arrival is unnoticed. Only when population levels increase is their presence noticed but by this time determining the point of arrival is confounded by the extensive spread of the species. Here we use molecular markers (ISSRs) to determine the origin of an invasive weed in the Kalahari region, a species for which several origins could be possible. We show that molecular markers can be useful tools in determining the origin of invasive species. URI: http://hdl.handle.net/10311/1025 Files in this item: 1
Bond_2002.pdf (2.049Mb) -
Meck, M.; Atlhopheng, J.; Masamba, W.; Ringrose, S.; Diskin, S. (Bentham Open, NaN, 2010)[more][less]
Abstract: This study set out to establish the major minerals at Dorowa and determine which of those are likely to host metals that may leach into surface and groundwater. This study comes after a preliminary assessment of the water quality in the Save River downstream of the Dorowa phosphate mine in Zimbabwe showed an increase in conductivity, iron content, manganese content, nitrates and hardness when compared to those taken before the mining area. X-Ray Diffractometry (XRD) was used to establish the major minerals at Dorowa whilst Inductively Coupled Plasma Mass Spectrometry (ICP- MS) was used to establish the chemistry of the rocks. The results from this study show that the major minerals in the rocks around Dorowa are feldspars, pyroxenes, apatite, magnetite and calcite. The metals hosted by the rocks include Ag, As, Be, Cd, Co, Cu, Pb, Hg, Ni, Sb, Se and Zn. The study concludes that the minerals likely to host metals are calcite and apatite. Metal hosting is higher in apatite minerals than in calcite. Metal hosting by the other minerals observed in the study area is low. URI: http://hdl.handle.net/10311/932 Files in this item: 1
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Moleele, N.M.; Ringrose, S.; Matheson, W.; Vanderpost, C. (ScienceDirect, www.sciencedirect.com, NaN, 2002)[more][less]
Abstract: the cattle-dominated grazing areas of Botswana. Bush encroachment species – for instance Acacia tortilis, A. erubescens, A. mellifera, Dichrostachys cinerea, Grewia flava, and Terminalia sericea –are increasing in cover and density around foci points (e.g. water points and kraals) at the expense of the grass cover. A number of factors have the effect of encouraging the germination and survival of bush encroachment species. The practice of cattle husbandry and continual shifting of foci points within grazing areas have resulted in the spread of the distribution of bush encroachment species across the country. This is evidenced by the potential extent of 37 000 km2 (6 4% of Botswana) of darkened and near infrared (NIR) reflective bush encroached areas in 1994. This paper suggests that specific management strategies should be adopted to help overcome the bush encroachment problem, which is causing a significant reduction in the extent of Botswana’s high quality rangeland. These strategies may vary from the enforced reduction of grazing intensity in areas identified as being heavily bush encroached to the selective management of opportunistic (communal) grazing in better quality predominantly grassland areas. Further work is however required to update this analysis and especially to consider trends since 1994–1995. While some work on the extent of woody cover and the further causes of bush encroachment is being undertaken under the SAFARI2000 project, more research is needed in specific areas to pinpoint causes and responses to the bush encroachment problem. URI: http://hdl.handle.net/10311/985 Files in this item: 1
Moleele_ et al_More_Woody_2002.pdf (3.119Mb) -
O'Halloran, L.; Shugart, H.; Wang, L.; Caylor, K.; Ringrose, S.; Kgope, B. (Elsevier, February 19, 2010)[more][less]
Abstract: The Kalahari Transect (KT) is an International Geosphere–Biosphere Programme mega-transect designed to examine hydrological and ecological patterns and processes throughout the savannas of southern Africa. The KT traverses a precipitation gradient ranging from w920 mm rain/year in the north to w260 mm rain/year in the south. Previous research shows a positive correlation between canopy cover and precipitation suggesting a water limitation on productivity. However, there has been minimal research on other possible sources of limitations, such as soil Nitrogen (N) and/or Phosphorus (P). We used a factorial in-situ experimental design to test for increased aboveground grass production (measured as peak season standing stock) under elevated soil P and Pþ N levels. Four sites along the KT precipitation gradient were used in this study: Mongu (Zambia), Pandamatenga (Botswana), Ghanzi (Botswana) and Tshane (Botswana). Soils at each site were amended with N and P fertilizers during the dry season. We extracted soil samples during the following growing season to analyze for plant available soil P. Vegetation samples were harvested from which we measured foliar P and aboveground grass biomass production. We saw differences in foliar P at the treatment and site level but not for the interaction between treatment and site. There were individual effects from site on biomass but not for any interactions with nutrient treatments. Despite higher levels of foliar P, we did not detect an increase in aboveground biomass. This may be explained by luxury uptake or allocation to below ground resources. URI: http://hdl.handle.net/10311/797 Files in this item: 1