Faculty of Health, Applied Sciences and Natural Resources

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The effect of a prescribed burn, followed up with browsing pressure, on rangeland condition in the mountain savanna and karstveld of Namibia.
(DINTERIA, 2002) Zimmermann, Ibo; Mwazi, Fidelis N.
Measurements were taken before and after the application of a prescribed burn, aimed at controlling bush thickening, on a commercial farm in the Mountain savanna and Karstveld of Namibia. The high fuel load, due to high rainfall during the previous season, resulted in an intense fire that caused considerable top kill of bushes. However, the bushes, dominated by Dichrostachys cinerea, resprouted at varying time intervals after the fire, mostly from the ground level. The occasional goat browsing pressure that was subsequently applied was insufficient to keep the majority of bushes under control. Hence browsing pressure would need to be applied more frequently and over a longer time period after a fire, in order to keep more of the bush regrowth under control. The goats also grazed significantly on the regrowth from perennial grasses. Therefore the browsing pressure should not be excessive, as the goats also threaten the perennial grasses.
The distribution and invasive potential of fountain grass pennisetum setaceum in Namibia.
(Dinteria, 2002) Joubert, David F.; Cunningham, Peter L.
Pennisetum sataceum is an exotic alien grass species from North Africa which invasive potential in Namibia. The distribution and invasive potential of this species was investigated. The current distribution of this species was compared with the reported distribution in the mid 1980s. It has increased its range in Namibia dramatically since then and is now found in a number of locations throughout Namibia, albeit mostly on road verges and other distributed areas predominantly in the Highland Savanna and Mountain Savanna biomes. It's popularity as an ornamental grass, particularly amongst farmers, is responsible for it's introduction and spread. Observations on a dense stand of P. setaceum west of Windhoek indicate this species preference for road verges and schist cuttings in association with relatively mesophytic grasses such as heteropogon contortus, Cenchrus ciliaris and panicum maximum. Its ability to form a major component of the vegetation of each of these habitats suggests that it has a broader tolerance range than the associate indigenous grasses. A range of control measures is suggested to prevent the species spreading further whilst it is still feasible.
The potential impacts of wood harvesting of bush thickening species on biodiversity and ecological processes.
(Namibia, Ministry of Environment and Tourism, 2002) Joubert, David F.; Zimmermann, Ibo
Studies of the effects of bush clearing have mostly focussed on economic issues such as production. In this paper, biodiversity and ecological effects of bush clearing were investigated, largely through a literature survey. Vertebrate and plant taxa were focussed upon. Two future scenarios were discussed. The first scenario was that future wood harvesting would follow Forestry Stewardship Council Principles and Forestry Guidelines. The second scenario was that demand exceeded supply and that sound sustainable principles would be abandoned in certain areas, in order to chase demand. In the first scenario, biodiversity would be improved, as would ecological processes. In the second scenario, arboreal species, including cavity users, and species requiring microhabitats and shelter would be badly affected, with local extinctions of these species likely. Management recommendations are provided. Biodiversity research should be viewed as a priority, in order to better understand the effects of different wood harvesting management strategies.
A crude quantification of wood that is and can be harvested from bush thickening species in Namibia.
(Namibia, Ministry of Environment and Tourism, 2002) Zimmermann, Ibo; Joubert, David F.
The increasing rate at which thickening bushes are being harvested in Namibia requires better information on the availability and sustainability of the resource, in order to improve management. Two sources of data from the literature were combined to give a rough approximation of the standing biomass of wood of appropriate size for charcoal production, in each of nine bush-thickened zones. The overall estimate came to roughly 135 million tons of dry wood in about 260 000 square kilometres of Namibia, or an average of just over 5 t/ha. The legal commercial harvest for the 1999/2000 financial year came to the equivalent of just under 0.2 million tons of dry wood. Interviews with ten charcoal producers, and field data gathered at one site, suggest that harvesting could take place at intervals of roughly 20 years, provided that harvesting is selective and leaves sufficient bushes of different size classes for regeneration. However, it is likely that subsequent harvests would be lower and more difficult to obtain. Previously chopped bushes could then only be re-harvested on every third or fourth cycle, preferably after being pruned to maintain a more appropriate growth form, which is easier to harvest and more conducive to grass growth.
Degradation gradient as a basis for monitoring the ephemeral Omatako floodplains of central Namibia.
(Global Wetlands, 2003) Zimmermann, Ibo
A group of Herero cattle farmers initiated a community grazing trial within a floodplain of the ephemeral Omatako River in central Namibia. A degradation model was constructed from measurements of various characteristics, for determining changes in wetland condition. Species data for Canonical Correspondence Analysis (CANOCO) came from the nearest perennial grass, if present within 5m of the sample point, otherwise from the nearest annual grass. The first ordination axis indicates a degradation gradient, with perennial grass species towards one extreme and annual grasses towards the other. The second axis appears to reflect a moisture gradient, although it was not measured.
Joint action research at Queen Sofia Resettlement Project between community members and students of the Agriculture Diploma Program.
(NUST, School of Natural Resources and Tourism., 2003) Zimmermann, Ibo; Mbai, Salomo; Kafidi, Lucia; Meroro, Alex
Joint action research at Kwandu Conservancy between community members and students of the Agriculture Diploma program.
(NUST, School of Natural Resources and Tourism., 2006) Zimmermann, Ibo
Overview of a variety of trials on agricultural applications of effective microorganisms (EM).
(2008) Zimmermann, Ibo; Kamukuenjandje, Richard
Effective Microorganisms (EM) is a commercially available liquid containing a variety of lactic acid bacteria, yeasts and phototrophic bacteria. These organisms create conditions which favour mutual support and enable them to outcompete harmful pathogens, while producing useful substances such as vitamins, enzymes, hormones, amino acids and anti-oxidants that create a reducing environment. Various EM agricultural application trials were run, mostly in partnership with farmers. The diverse applications included the following: improving soil conditions for better plant growth, treating waste water, controlling pests and diseases, improving animal growth, enhancing compost production and extending the shelf life of harvested crops. Generally EM appears to give the best results in situations where the natural balance of microorganisms has been severely disrupted or where agricultural inputs are in short supply. In situations where natural microorganism populations are reasonably intact, or where a balanced supply of inputs is available, the addition of EM does not seem to make a significant difference.
The fish industry in Eritrea: From comparative to competitive advantage.
(2008) Teweldemedhin, Mogos Y.
The paper examines the main constrains in stimulating extent of production driven supply chains, that could able to transform into market driven supply chain management.; Questionnaires, were developed and administered to marketing agents using purposive sampling, with the application of Porter’s diamond of national competitive advantage. Red sea being underexploited resource; and it is unique opportunity for the development of the country (MOF, 1997). However, this comparative advantage has never been converted to competitive advantage. Comparing to the percentage of fish population with in 100km from the coastal, Eritrea has the larger fish resource concentration in the region (73%). However, the sector has never made significant contribution to the country food security. The study confirms that all the role payers in the fish market chain and policy makers need to take a strategic approach, in identifying target markets, and ways to build strong and sustainable production. Moreover, all stack holder in the sector needs to formulate how to move up to: the value chain; niche marketing opportunity; converting comparative into competitive advantage; specifically focus on the services revolution; and overcoming technical and structural barriers.
Case study of adaptive rangeland management by an innovative Kalahari farmer.
(2008) Zimmermann, Ibo; Joubert, David F.; Smit, G.N.
Scientists can learn a great deal from innovative farmers who apply adaptive management principles based on experience gained over decades. This paper records 31 observations that a farmer, Jan Labuschagne, made on his farm to the south of Gobabis. The observations relate to aspects such as animal behaviour and performance, animal trampling, and applications of grazing and fire. They are tabulated together with their possible explanations and their management applications. The conceptual model the farmer has built to aid his understanding and decision making is also shown as a diagram and explained. Of critical importance is the strategic timing of management interventions on different parts of the farm in relation to rainfall events, texture and organic content of the soil and maturity of the vegetation. Data are presented to support some of the observations
A problem tree to diagnose problem bush.
(2008) Zimmermann, Ibo; Joubert, David F.; Smit, G.N.
The term “problem tree” refers to a conceptual model used as a diagnostic tool to analyse a sequence of events that leads to a problem (such as bush encroachment in rangelands). A problem tree is useful because the consequences of different interventions can be visualised and understood more easily in diagrammatic form, thereby guiding management decisions regarding the problem. A problem tree was constructed to show multiple causes of bush encroachment. It was generalised by considering many possible causes, and not only those applying to particular areas of encroachment or specific species of bush. If the problem tree is to be useful in decision-making, one needs to determine which of the multiple pathways are of greater significance in any particular situation. Management decisions are bound to be more effective in the long run if they address causes higher up in the tree and closer to the root causes, than the proximate causes or symptoms at the bottom of the tree.
Mysterious circles in the Namib Desert.
(Elsevier, 2008) Jankowitz, W. J.; Van Rooyen, M. W.; Shaw, D.; Kaumba, J. S.; Van Rooyen, N.
There is currently still no scientifically sound explanation as to the origin of the so-called ''fairy circles'' in the Namib. An in situ experiment was conducted in the NamibRand nature Reserve to test hypothesis that the circles are the result of a semi-volatile gas that inhibits plant growth. Stipagrostis ciliata grass plants were planted in containers filled with soil from the circle or from outside the circle. Some containers were sealed at the bottom, to prevent any gases from entering from below, while others were left open. Containers were placed both inside the circle as well as outside the circle. The origin of the siol, i.e. whether it came from inside or outside the circle, did not affect the performance of the plants when they were growing in the same position and container type. All plants growing outside the circle, irrespective of the origin of the soil or the container type, performed better than those growing inside the circle. It is concluded that there is a factor inhibiting plant growth in the circle and that this factor could possibly be a semi-volatile gas, because growth was more negativelly affected in the open containers than in the sealed containers.
The use, challenges and economic importance of draught oxen on small farms in Namibia`s eastern Caprivi region.
(NUST, School of Natural Resources and Tourism., 2009) Teweldemedhin, Mogos Y.; Conroy, Andrew
Bush encroachment in the Auas-Oanob Conservancy, Namibia.
(2009) Zimmermann, Ibo
Risk management strategies of cattle farmers in Namibia - Case study from Omaheke and Otjozondjupa region.
(2009) Teweldemedhin, Mogos Y.; Kafidi, Lucia
A sample survey of 269 questionnaires was administered to commercial and communal cattle farmers in the two regions of Namibia, (Omaheke and Otjozondjupa) to identify factors which affect the adoption of livestock insurance. About 205 questionnaires were collected and the 64 questionnaires were regarded as irregular responses or not returned. A computer software programme was used to generate a logit model. This model was used to test the alternative risk management strategies used by farmers in the two regions. In addition, this research took into account the off-farm investment and farm enterprise diversification. The logit model produced results that are statistically significant and negative estimated coefficient of the household characteristics. This implies that the Namibian livestock industry growth can be achieved with improved education, experience and support from other income as way of diversifying risk strategy. However, the positive relationship of variables FTHEFT and PROD implies the sector is suffering from continuous risk of theft and requires quality production to get market access. This necessitates the need for policy makers and insurers to design programme to educate farmers so that they can adopt proper risk management tools and thereby increase their participation in insurance. The low level of education of many farmers in the study area may have negatively influenced the decision to purchase livestock insurance in addition to other factors.
AIDS-related knowledge and sexual behaviour among married and previously married persons in rural Mozambique.
(2009) Noden, Bruce H.; Gomes, Aurelio; Ferreira, Aldina
HIV prevalence in central Mozambique is the highest in the country with high urban rates impacting on the rural areas. To identify potential factors influencing the spread of HIV in three sparsely populated districts in southern Sofala province, 847 married and previously married persons were surveyed for their knowledge, practices and beliefs regarding HIV/AIDS and STIs. 21.9% and 6.5% of males and females, respectively, were engaged in casual sexual partnerships in the past year. Being male, married, educated, and having genital discharge and ulcers in the last year were significantly associated with risky sexual activity. Risky behaviour was significantly associated with being Catholic or Protestant when compared with those from Zionist churches. Knowledge of ABC prevention strategies and condom usage was significantly associated with being male, married, having an STI in the past year, and being educated, particularly at the secondary level (Grade 8+). Attitudes and behaviour were influenced by cultural and religious involvement, as well as sex and marital status. It is imperative that prevention strategies take into account the cultural, economic and religious conditions present in rural African settings to create HIV prevention programmes that are culturally relevant and acceptable to the participants.
A collocation multistep methods for integrating ordinary differential equations on manifolds.
(Academic Journals, 2009) Fatokun, J. O; Ajibola, I. K. O.
This paper concerns a family of generalized collocation multistep methods that evolves the numerical solution of ordinary differential equations on configuration spaces formulated as homogeneous manifolds. Collocating the general linear method at x x for k s n k = = 0,1,... + , we obtain the discrete scheme which can be adapted to homogeneous spaces. Varying the values of k in the collocation process, the standard Munthe-Kass (k = 1) and the linear multistep methods (k = s) are recovered. Any classical multistep methods may be employed as an invariant method and the order of the invariant method is as high as in the classical setting. In this paper an implicit algorithm was formulated and two approaches presented for its implementation.
The effects of 'pebble mulch' on acacia mellifera seedling responses to rain.
(Namibian Scientific Society., 2009) Joubert, David F.
"Pebble mulch" (a layer of quartz and schist pebbles that often forms an almost 100% cover on the slopes of the Highland Savannah in Namibia) influences the dynamics of this vegetation type. A controlled experiment to determine the effects of "pebble mulch" on seed germination and early seedling establishment of Acacia mellifera (ubsp. detinens) was conducted. A. mellifera forms dense thickets in the area. Seeds were germinated under four treatments: A: planted below soil (2 seed widths depth) without pebble cover; B: planted below soil (2 seed widths depth) with pebble cover; C: plated on top of soil underneath a 100% pebble cover; and D: planted on top of a 100% pebble cover. Emergence/germination in all cases was high (overall 82% s.d. 17.5%). Soil moisture was significantly higher in all "pebble mulch" treatments (B, C and D). Although initial establishment was poor in Treatment D (33%), survival thereafter of seedlings whose radicals reached the soil was very high (97%). Seedling survival and vigour were significantly higher in all "pebble-mulch" treatments. The implications of these results for bush encroachment on Highland Savannah rangelands are discussed.
Joint action research at Vasdraai Farm between resettled farmers and students of the Agriculture program.
(Department of Agriculture; NUST, 2010) Zimmermann, Ibo; Shiimi, Theofilus; Zaire, Helga; Kafidi, Lucia; Mbai, Salomo
The international trade prospective of agriculture sector in Southern African.
(Academic Journals, 2010) Teweldemedhin, Mogos Y.; Van Schalkwyk, H. D.
The objective of this paper is to analyse the international trade performance of the South African agricultural industry in aggregate and by product group categories. A useful tool in this regard is the Gini and intra-industrial trade coefficient (IIT), which is used to examine the international trade balance of South Africa. Moreover, Ordinary Least Squares (OLS) is also used to identify factors that may be necessary to achieve high IIT. The IIT coefficient, after 1994, achieved more than 85 percent, which is a record level even for industrialised countries. This high IIT performance reveals trade liberalisation between the Southern Africa Customs Union (SACU) and the European Union (EU), opening South Africa’s market to the world. It also reveals that South Africa is able to increase its specialisation and flexibility to gain market access, and has shown a greater ability to compete in a changing trade environment. The results of the econometric analysis of IIT determinants give a greater magnitude to the coefficients export to Gross Domestic Product (GDP) and export -to -import ratios. These results imply that if South Africa’s industries take measures to increase trade liberalisation, diversity, and the level of industrial specialisation, the IIT level would be higher, and significant economic gain might be achieved by minimising costs.

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