Browsing by Title
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Moleele, N.M.; Reed, M.S.; Motoma, L.; Seabe, O. (John Wiley and Sons, http://www.wiley.com, NaN, 2005)[more][less]
Abstract: Laboratory-based seed storage systems have been developed as an alternative to in situ conservation for indigenous woody plant species. However, interactions between seed quality and environmental variables must be known for each species prior to seed collection, storage and sowing to ensure effective conservation. This study investigated Acacia tortilis seed weight/quality patterns across seven Botswana seed provenances in relation to: soil nutrient status, altitude; latitude; slope angle; % grass cover; height and density of other woody plants nearby. The higher rainfall and relatively eutrophic seed provenances of northwestern Botswana (Chobe, Okavango and Makgadikgadi) were associated with large A. tortilis species and seeds, as well as higher densities of woody plants. Spatial variation in seed weights of A. tortilis was principally a function of rainfall and soil organic carbon. Although more work is required to establish the relationship between seed weight and germination rates for A. tortilis, this research suggests that seed collection should focus on sites with high levels of rainfall and soil organic carbon. URI: http://hdl.handle.net/10311/947 Files in this item: 1
Moleele African Jour Eco.pdf (705.1Kb) -
Nsinamwa, M.; Sebego, R.J. (Botswana College of Agriculture, http://www.bca.bw/Research/bojaasBca/InstructionToAuthors.htm, NaN, 2007)[more][less]
Abstract: Grasses and forbs in Southern Africa have been understudied in terms of species richness and factor that affect diversity patterns. To gain a better understanding of factors affecting patterns of herbaceous plant species seedbank around water points, six boreholes ( three in each land zone) were randomly selected for sampling. Top soil layers of 20cm depth were sampled from six boreholes at distances of 50, 100, 200, 400, 800, 1500, and 3000m ( the Piosphere approach) in fenced and unfenced plots to determine the density and composition of the seedbank. The samples were allowed to germinate in the growth tray (10 x 15 x 8cm³) under controlled conditions (temperature, moisture) in a green house followed by daily counting of seedlings. Herbaceous plant species diversity was analyzed by using Simpson's diversity index. Analysis of varience on herbaceous species diversity was determined using the SAS software. Herbaceous plant community clustering was determined by using TWINSPAN, a FORTRAN programme. Significant (p=0.0001) germination variants were observed along the distance from livestock watering points. Most grass seedlings recorded germinated from soil samples obtained from from fenced plots, while less than 40% of the forb seedlings were. Most of the forbs species were recorded within 400m from the water points and that soils closer to water points also contained grass seeds despite the level of degradation and /or trampling. URI: http://hdl.handle.net/10311/313 Files in this item: 1
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Aghdasi, F.; Bhasin, A. (University of Botswana, NaN, 2004)[more][less]
Abstract: Asynchronous sequential circuits offer improved speed of operation when compared to their synchronous counterparts. However, the standard methods of asynchronous design require careful examination of the flow table for possible critical races and hazards. This complicates the design procedure and often leads to extra states and additional hardware. A number of new design methodologies which involve locally generating a clock and using it to self synchronize the machine have been proposed. Such clock signals are generated wherever an input changes, or by controlled excitation whenever a change of inputs necessitates a change of state. All such designs, where the circuit is timed by locally generated clocks, are called Self-Clocked Sequential Circuits. This paper uses a design methodology for the State variable toggling through data driven clocks to implement a Direct Memory Access Controller (DMAC) as a design example. The design is simulated on software and also implemented using discrete hardware components. The methodology can be extended to parallel controllers for neutral networks and automated using state assignment techniques already for synchronous parallel controllers. URI: http://hdl.handle.net/10311/648 Files in this item: 1
Aghdasi_BJT_2004.pdf (1.145Mb) -
Lumande, E.; Ojedokun, A.A.; Lebotse, E.K.; Mbangiwa, A.M. (Emerald/www.emeraldinsight.com, NaN, 2000)[more][less]
Abstract: Inconsistency and/or a lack of a clear understanding of the criteria for serial selection and evaluation have been observed to characterise the presentation of requests for approval of serials at the University of Botswana Library (UBL). This, on a number of occasions, has made decision taking difficult and sometimes inconclusive. The paper provides a case study of the examination of guidelines in use in other academic libraries. It also describes the process and procedure currently in use at the UBL. The study identified some anomalies and suggests modifications to ensure consistency in the presentation of submissions to guide better decision making by the Serials Selection Committee of the Library. URI: http://hdl.handle.net/10311/873 Files in this item: 1
Lumande_LM_2000.pdf (808.7Kb) -
Laletsang, K.; Modisi, M.P.; Shemang, E.M.; Moffat, L.; Moagi, O.R. (Elsevier www.elsevier.com/locate/jafrearsci, NaN, 2007)[more][less]
Abstract: A seismic refraction analysis was carried out on data acquired on an 8.5 km profile at Lake Ngami, NW Botswana, to determine the structure and stratigraphy underlying the lake. The seismic spread comprised a 48-channel seismograph with a 9.5 m receiver and source spacing. The seismic source comprised 10 hammer blows on an aluminum plate, from which a vertical stack was recorded. The data were processed with WinSismTM version 10 program using the intercept time method. A total field magnetic survey was also carried out along the same line. The seismic refraction profile shows a low velocity layer (400–1600 m/s) extending from the surface at the southern end of the line to a maximum depth of 30 m in the middle of the profile, returning to a depth of 20 m from 4.5 km to the northern end of the line. The low velocity layer consists of the unconsolidated sediments and is underlain by more compact and saturated material with seismic velocities of 1600–3600 m/s. This material is interpreted to comprise semi- to fully consolidated sandstone. The base of these sandstones, however, could only be mapped near the southern end of the line out to 2 km. High seismic velocity rocks (3600–5000 m/s), interpreted to be weathered to fresh basement, were mapped below the sandstones at the southern end of the line. The magnetic profile shows a high at the beginning of the line which progressively declines to a low at 3 km. The field strength increases rapidly over the next 1.5 km to reach a plateau level at 4.5 km. The magnetic high at the beginning of the line corresponds to shallow basement which is mapped in the refraction profile. The magnetic low at 3 km is indicative of a thickened sediment section at this location. The southern end of the line with high seismic velocities comprises basement rocks located in the footwall block of the Kunyere Border Fault of the Okavango Rift. The step-wise downthrown hanging wall block consists of the low to intermediate velocity basin deposits in the northern part of the profile. URI: http://hdl.handle.net/10311/376 Files in this item: 1
Modisi2007ShallowSeismic.pdf (656.3Kb) -
Togarasei, L. (Edinburgh University Press, http://www.euppublishing.com/, NaN, 2009)[more][less]
Abstract: The article discusses the politics of bible translation focusing on the Shona Bible. Specifically it looks at the translation of the word 'banquetings' into 'mabira' in the Union Shona Bible, the first complete translation of the Shona Bible. It also discusses the history of the translation of the Bible from the time the missionaries arrived among the Shona peoples in the 1890s to the time when the first complete Bible was translated into the Shona language in the late 1940s. It discusses the political and cultural factors that influenced the way the Bible was translated. How did missionaries’ understanding of the Shona worldview influence their translation? How did the translators address the dialectical differences in the Shona language considering that it has five dialects? How did Shona cosmology and spirituality influence translation? To answer these and other questions concerning the politics behind biblical translation, specific biblical examples (here the translation of ‘banquetings’ into mabira in 1 Peter 4:3) are analysed. The article also briefly looks at subsequent ‘improvements’ to the Shona Bible to see how translators have responded to cultural and linguistic changes over the years in their use of the bible among the Shona. URI: http://hdl.handle.net/10311/596 Files in this item: 1
Togarasei_SWC_2009.pdf (112.8Kb) -
Maruapula, S.D.; Jackson, J.C.; Holsten, J.; Shaibu, S.; Malete, L.; Wrotniak, B.; Ratcliffe, S.J.; Mokone, G.G.; Stettler, N.; Compher, C. (PHN, http://journals.cambridge.org/action/displayJournal?jid=phn, August NaN, 2011)[more][less]
Abstract: Objective: To describe patterns of food consumption associated with overweight\obesity (OW/OB) and their links to socio-economic status (SES) and urbanization. Design: A nationwide cross-sectional survey. Setting: Secondary schools in cities, towns and villages in Botswana, Africa. Subjects: A total of 746 adolescent schoolchildren. Results: OW/OB is associated with greater SES, city residence and a snack-food diet pattern. Students belonging to higher SES compared with those from a lower SES background reported significantly (P,0?01) more daily servings of snack foods (1?55 v. 0?76) and fewer servings of traditional diet foods (0?99 v. 1?68) and also reported that they ate meals outside the home more often (90% v. 72 %). Students in cities ate significantly (P,0?01) more servings of snacks (1?69 v. 1?05 v. 0?51) and fewer servings of traditional foods (0?67 v. 1?52 v. 1?61) compared with those in urban and rural villages. The odds of OW/OB were increased 1?16-fold with a snack-food diet, a result that was diminished when controlled for SES. Conclusions: These data suggest that nutritional transition occurs at different rates across urbanization and SES levels in Botswana. In cities, increasing the availability of fruit while reducing access to or portion sizes of snack items is important. Emphasis on continued intake of traditional foods may also be helpful as rural areas undergo economic and infrastructural development. URI: http://hdl.handle.net/10311/1137 Files in this item: 1
Maruapula_PHN_2011.pdf (112.3Kb) -
Magole, L. (http://www.routledge.com/, NaN, 2009)[more][less]
Abstract: This paper analyses land management policy using land use mapping, interviews with farmers and other stakeholders, and a review of secondary material. The study was carried out in the Lake Ngami area of Ngamiland District in Botswana. It found that the net effect of policy and development initiatives implemented to curb perceived overstocking, overgrazing, open access tenure and low-output subsistence production was to narrow down the livelihood options for the rural poor and cause further damage to the rangeland. Policy-makers ignored the multi-purpose land use systems and goals of traditional pastoral systems, and emphasised commercialisation of livestock farming and privatisation of communal land. This unfortunately weakened or destroyed the local, traditional land management institutions and set in motion the shrinking of the commons. These policies are a colonial legacy that has survived the transitions from colonial rule to independence. URI: http://hdl.handle.net/10311/807 Files in this item: 1
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Mladenov, N.; McKnight, D.M.; Wolski, P.; Murray-Hudson, M. (Elsevier, www.elsevier.com/locate/ecolmodel, NaN, 2007)[more][less]
Abstract: In order to examine dissolved organic matter (DOM) fluxes in seasonal wetland systems that expand and contract seasonally, a time-variable model of dissolved organic carbon (DOC) was developed for a seasonal floodplain in the Okavango Delta of Botswana. The model simulates DOC concentrations from March 2001 to November 2002, during which time DOC concentrations varied between 8 and 31mgCL−1. The model uses a continuously stirred tank reactor (CSTR) approach to describe the hydrologic and biogeochemical controls on DOC leached from litter within the floodplain and transported into the floodplain from upstream. In 2002, a fire burned the floodplain and less litter was available for leaching than in 2001. The model was driven by observations of discharge, water temperature, upstream DOC concentrations, and DOC leaching rates from leaching experiments. Leaching experiments with sedges and grasses indicated that on average 23mgDOCg−1 were leached during the first day ofwetting and 0.6mgDOCg−1 d−1 were continuously leached afterwards. Leaching experiments also showed a decreased amount of DOC released from burned litter and soils than from unburned litter and soils. A two-pool first-order decaymodel that represents both rapidly (0.14 d−1 (at 22 ◦C)) and slowly (0.045 d−1) decaying pools of DOC provided the best representation of observed patterns in DOC concentration in 2001. The decay rate of the first pool decreased by nearly half in 2002, when an estimated 78% of litter was removed by fire. Upstream DOC transport into the floodplain was the dominant source of DOC (representing approximately 70% and 75% of the DOC input in 2001 and 2002, respectively), followed by DOC leaching from litter and DOC originating from microbial sources. In 2001, decomposition (representing approximately 36% of the DOC loss), outflow to an adjacent floodplain (36%) and infiltration (28%) were the major removal mechanisms for DOM from the study floodplain. The large amount of DOC transported by infiltration implies storage of DOC in the subsurface, whichmay influence subsurface heterotrophic activity. In light of future climate change anticipated for the region, a scenario using a 2 ◦C increase in average water temperature and 10% reduction in upstream DOC mass was performed and resulted in significant (11%) reduction in annual DOC mass within the study floodplain. URI: http://hdl.handle.net/10311/497 Files in this item: 1
Mladenov2007Simulation.pdf (2.048Mb) -
Masale, M. (Elsevier Science Ltd. http://www.elsevier.com/locate/physb, NaN, 2004)[more][less]
Abstract: The energy spectrum of an electron confined near a current-carrying core is obtained as a function of the azimuthal applied magnetic field within the effective-mass approximation. The double degeneracy of the non-zero electron's axial wave number (kz) states is lifted by the current-induced magnetic field while that of the non-zero azimuthal quantum number (m) states is preserved. A further analysis is the evaluations of the oscillator strengths for optical transitions involving the lowest-order pair of the electron's energy subbands within the dipole approximation. The radiation field is taken as that of elliptically polarized light incident along the core axis. In this polarization and within the dipole approximation, the allowed transitions are only those governed by the following specific selection rules. The azimuthal quantum numbers of the initial and final states must differ by unity while the electron's axial wave number is conserved. The azimuthal magnetic field is also found to lift the multiple degeneracies of the kz=0 interaction integrals as well as those of the oscillator strengths for optical transitions. URI: http://hdl.handle.net/10311/244 Files in this item: 2
license.txt (1.998Kb)Masale_PB_2004.pdf (1.197Mb) -
Iwisi, D.S.; Kitindi, E.G.; Basson, N. (Emerald Group Publications, www.emeraldinsight.com, NaN, 2007)[more][less]
Abstract: Auditing lends credibility to financial statements of enterprises. The Southern African Development Community (SADC) has committed itself to the promotion of small businesses in member countries. This implies that auditors will become more involved with small businesses as a result of their expected growth and expansion. However, small businesses are said to have characteristics that cause difficulties to their auditors. This study investigates the characteristics of small businesses in three SADC countries, problems auditors of small businesses in those countries face, frequency of occurrence of those problems, and their impact on auditing. The findings suggest that characteristics of small businesses in the selected SADC countries are similar to those of small businesses in other countries. Many of twenty-three problems suggested to auditors rarely occured, or occurred only occassionally. However, some problems are considered to have an important effect on auditing. URI: http://hdl.handle.net/10311/1060 Files in this item: 1
IWISI_ARA_2002.pdf (1.365Mb) -
Temtime, Z.T.; Pansiri, J. (Asian Network for Scientific Information, www.ansinet.org, NaN, 2004)[more][less]
Abstract: Although the discovery of diamonds has propelled Botswana from one of poorest countries in 1966 to its current economic status as a middle-income country, the country still face the problem of economic diversification, employment creation, income generation and distribution, and poverty alleviation. Governmental and non-governmental organisations have put many efforts on the developments of small and medium enterprises (SMEs)to diversify away the economy from mining, to create jobs, generate income and alleviate poverty. However, the pace of development of SMEs, after 30 years, is slow. The small business failure rate is currently estimated to be over 80 percent. There is a general consensus among policy makers, politicians, and researchers in Botswana that this trend should not be allowed to continue indefinitely. The purpose of this paper is to investigate the perceived critical success/factors (PCSFSs) affecting the development of SMEs by collecting primary data from 203 SMEs in 3 cities in the Republic of Botswana through questionnaire. Both descriptive and inferential statistics were employed to present the empirical data. The findings showed that ten PCSFs (human resource development, organizational development, managerial background, managerial leadership and competitive strategy) affect the performance of SMEs. The PCSFs are strongly related among themselves, indicating the need for a holistic and systematic approach in addressing them. Important relationships were also found between the PCSFs and firm-specific demographic variables such as ownership status, experience and operating period. Recommendations and implications for policy and research are also forwarded. URI: http://hdl.handle.net/10311/849 Files in this item: 1
Temtime_AJAS_2004.pdf (998.3Kb) -
Cassidy, L.; Binford, M.; Southworth, J.; Barnes, G. (Taylor & Francis, October 23, 2009)[more][less]
Abstract: The trend of land cover (LC) and land cover change (LCC), both in time and space, was investigated at the Simen Mountains National Park (SMNP), a World Heritage Site located in northern Ethiopia, between 1984 and 2003 using Geographical Information System (GIS) and remote sensing (RS). The objective of the study was to generate spatially and temporally quantified information on land cover dynamics, providing the basis for policy/decision makers and resource managers to facilitate biodiversity conservation, including wild animals. Two satellite images (Landsat TM of 1984 and Landsat ETM+ of 2003) were acquired and supervised classification was used to categorize LC types. Ground Control Points were obtained in field condition for georeferencing and accuracy assessment. The results showed an increase in the areas of pure forest (Erica species dominated) and shrubland but a decrease in the area of agricultural land over the 20 years. The overall accuracy and the Kappa value of classification results were 88 and 85%, respectively. The spatial setting of the LC classes was heterogeneous and resulted from the biophysical nature of SMNP and anthropogenic activities. Further studies are suggested to evaluate the existing LC and LCC in connection with wildlife habitat, conservation and management of SMNP. URI: http://hdl.handle.net/10311/811 Files in this item: 1
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Fako, T. (Taylor & Francis, NaN, 2006)[more][less]
Abstract: In spite of extensive campaigns to promote voluntary counselling and testing through the radio, television, newspapers and mass rallies, testing for HIV remains a challenge in Botswana. Using a representative sample of 1,294 students from secondary schools and tertiary institutions, the study investigates the effects of socio-demographic background variables, family coherence, interpersonal relations, sexual experience and knowledge about sexual health, on willingness to test for HIV infection. The results show that willingness to test for HIV infection was negatively associated with being sexually active and having a number of partners. Indicators of family, coherence, psychological bonding and personal adjustment such as common residence among parents, emotional support from the family attachment to parents, happiness with life in general and satisfaction with life as a student were associated with willingness to test. The importance of sexual activity, number of partners, happiness with life in general, level of attachment to father and physical fights with other children were identified as the social and psychological predictors of willingness to test for HIV using multiple logistic regression. The study highlights the importance of continued education about voluntary counselling and testing among sexually active young people, especially those from poorer backgrounds in rural areas. URI: http://hdl.handle.net/10311/780 Files in this item: 1
Fako_AC_2006.pdf (600.1Kb) -
Mbaiwa, J.E. (Routledge, http://www.informaworld.com, NaN, 2004)[more][less]
Abstract: The objective of this article is to assess the socio-cultural impacts of tourism development in the Okavango Delta, Botswana. This paper largely relied on the research work and reports by the author in the Okavango Delta from 1998 to 2004. In all instances, both primary and secondary data sources were used. However, much of the paper is based on the results of a survey carried out between April 2001 and July 2002. Findings indicate that tourism development in the Okavango Delta has both positive and negative socio-cultural impacts. Some of the positive socio-cultural impacts include income generation and employment opportunities from both community-based tourism projects and safari companies, infrastructure development such as airport and airstrips, tarred roads, hotels, lodges and camps, the improvement of social services such as banking, health, telecommunications and access to electricity. The negative socio-cultural impacts include enclave tourism, racism, relocation of traditional communities, breaking up of the traditional family structure, increase in crime, prostitution, the adoption of the Western safari style of dressing and a traditionally unacceptable ‘vulgar’ language by young people. This article argues that tourism needs to be sensitive to local cultural norms and beliefs for it to be accepted by local people and promote sustainable development. This is possible if all the stakeholders (government, operators and local people) collaborate in policy formulation, implementation and monitoring. This can minimise the negative cultural impacts and instead promote the positive. URI: http://hdl.handle.net/10311/946 Files in this item: 1
Mbaiwa 2004 Tourism Culture.pdf (4.520Mb) -
Mbaiwa, J.E. (Channel view publications, http://www.multilingual-matters.net/jtc/default.htm, NaN, 2004)[more][less]
Abstract: The objective of this article is to assess the socio-cultural impacts of tourism development in the Okavango Delta, Botswana. This paper largely relied on the research work and reports by the author in the Okavango Delta from 1998 to 2004. In all instances, both primary and secondary data sources were used. However, much of the paper is based on the results of a survey carried out between April 2001 and July 2002. Findings indicate that tourism development in the Okavango Delta has both positive and negative socio-cultural impacts. Some of the positive socio-cultural impacts include income generation and employment opportunities from both community-based tourism projects and safari companies, infrastructure development such as airport and airstrips, tarred roads, hotels, lodges and camps, the improvement of social services such as banking, health, telecommunications and access to electricity. The negative socio-cultural impacts include enclave tourism, racism, relocation of traditional communities, breaking up of the traditional family structure, increase in crime, prostitution, the adoption of the Western safari style of dressing and a traditionally unacceptable ‘vulgar’ language by young people. This article argues that tourism needs to be sensitive to local cultural norms and beliefs for it to be accepted by local people and promote sustainable development. This is possible if all the stakeholders (government, operators and local people) collaborate in policy formulation, implementation and monitoring. This can minimise the negative cultural impacts and instead promote the positive. URI: http://hdl.handle.net/10311/311 Files in this item: 1
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Cheng, C.; Jose, P.E.; Sheldon, K.M.; Singelis, T.M.; Cheung, M.W.L.; Tiliouine, H.; Alao, A.A.; Chio, J.H.M.; Lui, J.Y.M.; Chun, W.Y.; De Zavala, A.G.; Hukuzimana, A.; Hertel, J.; Liu, J.T.; Onyewadume, M.; Sims, C. (JCCP, http://jcc.sagepub.com, July NaN, 2011)[more][less]
Abstract: In this study, the authors tested four cultural models—independence, interdependence, conflict, and integration—that describe the hypothesized relationships between dimensions of self-construal and components of subjective well-being among individualistic and collectivistic countries. Collectivistic countries that have undergone rapid socioeconomic changes (i.e., East Asian countries) and those with limited changes (i.e., African countries) were differentiated. Participants were 791 university students from four Western countries, 749 university students from three East Asian countries, and 443 university students from three African countries. Findings provided some support for the applicability of (a) the independence model to individuals from Western countries and (b) the integration model to individuals from East Asian countries. Mixed results were found among the African countries. The interdependence model is more applicable to African participants from the sub-Saharan region, but the integration model is more applicable to those from the North African region. URI: http://hdl.handle.net/10311/1110 Files in this item: 1
Onyewadume_JCCP_2011.pdf (5.837Mb) -
Kamwendo, G. H. (Southern African Comparative and History of Education Society (SACHES). http://www.journals.co.za/ej/ejour_sare.html, October NaN, 2006)[more][less]
Abstract: During the first 30 years of Malawi’s independence (1964-1994), the country was under President Hastings Kamuzu Banda’s one-party authoritarian rule. In line with Banda’s nation-building ideology, Malawi pursued the policy of one nation, one party (the Malawi Congress Party), one leader (Life President Banda) and one national language (Chichewa). Despite the fact that Malawi is multilingual and multiethnic, the Banda regime created a political atmosphere under which non-Chewa ethnic and/or linguistic identities were suppressed. A political system was established that muzzled academic and other freedoms. Academia, for instance, was deprived of its critical and objective voice. The then only university, the University of Malawi, was carefully monitored to ensure that so-called subversive disciplines or topics were not on offer. Sociolinguistic research was one of the academic disciplines that did not enjoy meaningful academic freedom. The demise of the Banda regime in 1994 and the adoption of a new constitution that embraces various freedoms (including academic freedom) have meant that there are no longer political constraints on academic freedom. However, new forms of constraint on academic freedom have arisen. These are economic constraints, many emanating from the research-funding agencies’ agendas. URI: http://hdl.handle.net/10311/1106 Files in this item: 1
Kamwendo_SAREEP_2006.pdf (99.15Kb) -
Bird, M.I.; Veenendaal, E.M.; Lloyd, J.J. (John Wiley and Sons, www.wiley.com, NaN, 2004)[more][less]
Abstract: We present a study of soil organic carbon (SOC) inventories and δ13C values for 625 soil cores collected from well-drained, coarse-textured soils in eight areas along a 1000 km moisture gradient from Southern Botswana, north into southern Zambia. The spatial distribution of trees and grass in the desert, savannah and woodland ecosystems along the transect control large systematic local variations in both SOC inventories and δ13C values. A stratified sampling approach was used to smooth this variability and obtain robust weighted-mean estimates for both parameters. Weighted SOC inventories in the 0–5 cm interval of the soils range from 7 mg cm−2 in the driest area (mean annual precipitation, MAP=225 mm) to 41±12 mg cm−2 in the wettest area (MAP=910 mm). For the 0–30 cm interval, the inventories are 37.8 mg cm−2 for the driest region and 157±33 mg cm−2 for the wettest region. SOC inventories at intermediate sites increase as MAP increases to approximately 400–500 mm, but remain approximately constant thereafter. This plateau may be the result of feedbacks between MAP, fuel load and fire frequency. Weighted δ13C values decrease linearly in both the 0–5 and 0–30 cm depth intervals as MAP increases. A value of –17.5±1.0‰ characterizes the driest areas, while a value of −25±0.7‰ characterizes the wettest area. The decrease in δ13C value with increasing MAP reflects an increasing dominance of C3 vegetation as MAP increases. SOC in the deeper soil (5–30 cm depth) is, on average, 0.4±0.3‰ enriched in 13C relative to SOC in the 0–5 cm interval. URI: http://hdl.handle.net/10311/942 Files in this item: 1
Bird Veneendaal 2004.pdf (1.620Mb) -
Shaikh, M.; Moleele, N.; Ekosse, G.I.E.; Totolo, O.; Atlhopheng, J. (JASEM http://www.ajol.info/index.php/jasem/article/view/43693/27216, June NaN, 2006)[more][less]
Abstract: Since 1988 Botswana has been experiencing an unprecedented increase in vehicular traffic which is suspected to be having contamination effects on soils along heavily used roads in the country. This study aimed at understanding the contamination trends of heavy metals on soils due to vehicular emissions. The soil physicochemistry (bulk density, particle size distribution, pH, electrical conductivity and cation exchange capacity), mineralogy (using x-ray diffraction techniques) and heavy metals (Cd, Pb, Cu and Zn) concentrations were determined for soil samples obtained along the roadside at 2m, 4m, 6m and 100 m of the Gaborone – Tlokweng Emigration/Immigration Boarder Post Road, which is one of the busiest in the country. Bulk density of soil samples were from 1.19 to 1.4; and sand, loamy sand and sandy loam textural classes constituted the soil samples. The soil pH was from 5.09 to 8.57; the EC ranged from 6.27 μS cm-1to 20.3 27 μS cm-1 and the CEC values were from 10.2 meq100g-1 to 27.2 meq100g-1. Clay minerals were identified in the samples as well as feldspar and quartz. The concentration levels for Pb were from 0 mgkg-1 to 71 mgkg-1; Zn were from 5.23 mgkg-1 to 51.26 mgkg-1 ; Cu were from 0.3 mgkg-1 to 18.1 mgkg-1 and Cd 0 mgkg-1 to 2.4 mgkg-1 . The interplay of soil physico-chemistry and mineralogy on heavy metals concentrations is discussed. Although levels of heavy metals concentrations fell below normal ranges, the values obtained were generally higher than those from some developed and developing countries. URI: http://hdl.handle.net/10311/361 Files in this item: 1
Shaikh_JASEM_2006.pdf (1.018Mb)