Browsing Okavango Research Institute (ORI) by Title
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Masamba, W.R.L.; Muzila, A. (Botswana Society, NaN, 2005)[more][less]
Abstract: The concentration of the metal ions Na, K, Ca, Mg, Zn, Cu, Mn, Co, Fe, Cr, Ni, and Pb were determined in water samples of the Okavango Delta’s panhandle - Maunachira-Khwai water system during periods of high (June 2004) and low (November 2004) water flow. The concentrations of Na (1.67 to 12.77 mg/L), K (1.37 to 5.80 mg/L), Ca (2.46 to 6.98 mg/L) and Mg (0.69 to 2.83 mg/L) increased with distance from Mohembo indicating concentration of these metal ions by evaporation. Cu (up to 0.028 mg/l), Co (up to 0.053 mg /L), Fe (0.010 to 0.60 mg/L), Ni (up to 0.052mg/L), Mn (up to 0.044 mg/L) and Pb (0.017 to 0.28 mg/L) generally decreased in concentration with increase in distance from Mohembo, indicating that the Delta acts as a filter for these ions. Zn (0.049 to 0.101 mg/L) had lower concentrations at Mohembo than the other sampling sites, indicating solubilisation of previously deposited metals ions, or presence of Zn within the Delta. Chromium was not detected except at Seronga (0.026 mg/L) during periods of high water flow. URI: http://hdl.handle.net/10311/951 Files in this item: 1
Masamba 2005 Spatial.pdf (2.281Mb) -
Wondie, M.; Schneider, W.; Melesse, A.; Teketay, D. (MDPI Publishing; www.mdpi.com, January 5, 2011)[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/10311/1001 Files in this item: 1
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Swatuk, L.A. (Elsvier, www.elsevier.com, NaN, 2003)[more][less]
Abstract: This paper explores possibilities for achieving 'wise use’, defined as the sustainable utilization of resources of the Okavango Delta system, within the framework of the Ramsar Convention on Wetlands of International Importance. The paper argues that while the Ramsar Convention’s wise use strategic plan forms an important basis for collective action toward sustainably managing the Okavango River Basin as a whole, there are numerous barriers to success, the most important of which is the abiding behaviour of the region’s state-makers in defense of sovereignty and pursuit of narrow national interest. In spite of this formidable barrier to success, the paper highlights a number of on-going multilateral activities that may serve to further the aims of wise use of the Okavango River Basin system. It also provides a number of practical suggestions for furthering progressive frameworks of action. The paper is based on a close reading of published and unpublished written materials and the findings of a number of open-ended interviews conducted with stakeholders active in the Okavango River Basin. URI: http://hdl.handle.net/10311/988 Files in this item: 1
Swatuk_state Interests_2003.pdf (2.238Mb) -
Abiyu, A.; Lemenih, M.; Gratzer, G.; Aerts, R.; Teketay, D.; Glatzel, G. (BioOne, www.bioone.org, May NaN, 2011)[more][less]
Abstract: Exclusion of grazing animals and tree plantations are 2 methods that have been used for restoration of degraded lands in tropical semiarid areas. These 2 options can foster secondary forest succession by improving soil conditions, attracting seed-dispersal agents, and modifying microclimate for understory growth. We compared native woody plant diversity and soil chemical and physical attributes under exclosure and on Eucalyptus globulus (EGP) and Cupressus lusitanica (CLP) plantations. Vegetation data were collected by an inventory of stands with circular plots of 5.64 m radius, and soil samples were collected from the 4 corners and center of 20 × 20 m plots. As a result, 15 native woody plant species belonging to 13 families were recorded. Importance value index (IVI), Shannon-Wiener, Simpson's diversity, and species richness were higher in the exclosure, followed by EGP and CLP. Contents of soil organic carbon and total nitrogen showed significance difference and were highest in the exclosure, followed by CLP, EGP, and grazing land. Although the difference was not significant, an increasing trend was observed for cation exchange capacity and K+. Bulk density was highest on the grazing land, followed by EGP, CLP, and exclosure. Our results suggest that degraded land reclamation can be achieved with plantation of rapidly growing tree species as well as exclosure. However, native woody species diversity and improved soil attributes are better achieved with exclosure. Exclosures can be established interspersed strategically with single- or mixed-species plantations to facilitate restoration of native vegetation. However, it is important to conduct further research on the comparative advantage of enrichment planting of exclosures with preferred tree species or exclosures interspersed within blocks of plantation. URI: http://hdl.handle.net/10311/989 Files in this item: 1
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Mbaiwa, J.E. (Society of South African Geographers; http://www.journals.co.za/ej/ejour_sageo.html, NaN, 2004)[more][less]
Abstract: This paper assesses the success and sustainability of Community-Based Natural Resource Management (CBNRM) in the Okavango Delta. It does so by asking the following questions: a) to what extent has CBNRM contributed to sustainable natural resource use, rural economic development, enhanced rural livelihoods and benefit sharing? b) To what extent has power been devolved to the rural communities especially in relation to resource ownership and management? c) What are the existing and potential challenges facing the successful implementation of CBNRM in the Okavango Delta? With illustrations from the three CBNRM projects of Okavango Community Trust, Okavango Kopano Mokoro Community Trust and the Khwai Development Trust, this paper notes that local communities have successfully established community trusts as institutions to provide leadership in their participation in tourism and natural resource management. They also derive socio-economic benefits from CBNRM such as the participation in decision-making, employment and income generation. However, the lack of entrepreneurships and managerial skills, understanding of the concept of CBNRM, poor benefit sharing on CBNRM participants, and enclave tourism are some of the challenges that face CBNRM in the Okavango Delta. In the event that empowerment issues especially training and capacity building are successfully addressed, CBNRM in the Okavango Delta has the potential to be a successful model of community-based tourism. URI: http://hdl.handle.net/10311/157 Files in this item: 2
license.txt (1.998Kb)mbaiwa_sagj_2004_msm.pdf (111.4Kb) -
Gieske, A.S.; Wubett, M.T.; Timmermans, W.J.; Parodi, G.N.; Wolski, P.; Arneth, A. (SPIE, http://link.aip.org, NaN, 2004)[more][less]
Abstract: Land surface temperatures are important in global change studies, in estimating radiation budget, heat balance studies and as control for climate models. Several algorithms for estimating land surface temperature and emissivity spectra for multispectral thermal infrared images were developed recently for use with data from the Advanced Spacebome Thermal Emission and Reflection Radiometer (ASTER) on the TERRA platform. Similar methods are also used with the MODIS instrument. In this study, surface temperature and broadband emissivities were determined from the five TIR channels of ASTER instrument in an area on the southern fringe of the Okavango Delta (Botswana). MODTRAN 4 was used to determine the necessary atmospheric corrections while software was developed to facilitate MODTRAN post-processing. The results were compared with micrometeorological observations from a flux tower, with a LANDSAT 7 image of the same day, and finally also with reported ASTER surface temperature and emissivities for the same image (high level ASTER product). Results indicate that the surface temperature depends rather sensitively on atmospheric transmissivity and relatively large temperature differences are found between results from imagery analysis and flux tower. No relation was found between broad-band emissivity and NDVI, contrary to earlier findings in Botswana. URI: http://hdl.handle.net/10311/1015 Files in this item: 1
gieske_procSPIE_2003_pw.pdf (317.2Kb) -
Fynn, R.; Morris, G.; Ward, D.; Kirkman, K. (Wiley Online Library, March 4, 2011)[more][less]
Abstract: Question: Following the framework of Suding et al.(2003), we examined whether morphological traits (organismal response), tolerance and competitive effect (specific process response) were associated with grass dominance (abundance response) on burning, mowing, fertilization and soil depth gradients in KwaZulu-Natal (KZN), South Africa. Location: University of KwaZulu-Natal, Pietermaritzburg, South Africa. Methods: Using several pot experiments involving 29 grass species in total, we determined the vegetative traits, competitive effect and response, and tolerance to shading for grasses common in closed, tufted mesic grassland in KZN. Results: The primary axis of grass–trait variation was most strongly related to a negative correlation (trade-off) between growth rate and specific leaf area (SLA), with broad-leaved, rapidly-growing grasses (high SLA) occupying one extreme and narrow-leaved, slow-growing grasses (low SLA) the other extreme of the first principal component. The low SLA, slow-growth strategy was found to be a relatively general strategy among grasses dominant in undisturbed, high litter grassland, as well as those adapted to moisture-stressed habitats. In contrast, grasses dominant in highly productive habitats with some form of disturbance, e.g. mowing, had a broad-leaved, rapid-growth strategy. Intermediate combinations of the SLA–growth rate trade-off were common among grasses dominant under other combinations of disturbance and soil resource availability. Conclusions: Distinct patterns of organismal (SLA, growth rate) and specific process (competitive effect and response, as well as tolerance of shading) responses appeared to be associated with grasses dominant on gradients of burning, mowing, fertilization and soil depth. These organismal and specific process responses were similar to those for North American and European grasses dominant under the same environmental influences, suggesting that some general trait–environment patterns exist at an inter-continental scale. This general trait–environment relationship appears to be driven by functional adaptive selection along the SLA–environment continuum and its unavoidable trade-off with growth rate. URI: http://hdl.handle.net/10311/810 Files in this item: 1
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Black, F.J.; Bokhutlo, T.; Somoxa, A.; Maethamako, M.; Modisaemang, O.; Kemosedile, T.; Cobb-Adams, C.; Mosepele, K. (Elsevier, February 20, 2011)[more][less]
Abstract: Mercury is a neurotoxin and global pollutant, and wetlands and newly flooded areas are known to be sites of enhanced production of monomethylmercury, the form of mercury that is readily biomagnified in aquatic food chains to potentially toxic levels. The Okavango Delta in Botswana, Southern Africa, is the largest inland delta in the world and a wetland ecosystem that experiences dramatic annual flooding of large tracts of seasonal floodplains. The Delta was, therefore, expected to be home to high mercury levels in fish and to be an area where local subsistence fishing communities would be at substantial risk of mercury toxicity from fish consumption. Total mercury concentrations measured in 27 species of fish from the Okavango Delta averaged (mean±s.d., wet weight) 19±19 ng g−1 in non-piscivorous fish, and 59±53 ng g−1 in piscivorous fish. These mercury concentrations are similar to those reported for fish from lakes in other areas of tropical Africa, demonstrating that not all wetlands are sites of elevated mercury concentrations in biota. Even more intriguing is that concentrations of mercury in fish from across tropical Africa are systematically and substantially lower than those typically reported for fish from freshwater ecosystems elsewhere globally. The reasons for this apparent “African mercury anomaly” are unclear, but this finding poses a unique opportunity to improve our understanding of mercury's biogeochemical cycling in the environment. Mercury concentrations measured in human hair collected in subsistence fishing communities in the Okavango Delta were similarly low (0.21±0.22 μg g−1 dry weight) despite high levels of fish consumption, and reflect the low mercury concentrations in the fish here. URI: http://hdl.handle.net/10311/806 Files in this item: 1
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Black, F.J.; Bokhutlo, T.; Somoxa, A.; Maethamako, M.; Modisaemang, O.; Kemosedile, T.; Cobb-Adams, C.; Mosepele, K.; Chimbari, M. (Elsevier, NaN, 2011)[more][less]
Abstract: Mercury is a neurotoxin and global pollutant, and wetlands and newly flooded areas are known to be sites of enhanced production of monomethylmercury, the form of mercury that is readily biomagnified in aquatic food chains to potentially toxic levels. The Okavango Delta in Botswana, Southern Africa, is the largest inland delta in the world and a wetland ecosystem that experiences dramatic annual flooding of large tracts of seasonal floodplains. The Delta was, therefore, expected to be home to high mercury levels in fish and to be an area where local subsistence fishing communities would be at substantial risk of mercury toxicity from fish consumption. Total mercury concentrations measured in 27 species of fish from the Okavango Delta averaged (mean ± s.d., wet weight) 19 ± 19 ng g−1 in non-piscivorous fish, and 59 ± 53 ng g−1 in piscivorous fish. These mercury concentrations are similar to those reported for fish from lakes in other areas of tropical Africa, demonstrating that not all wetlands are sites of elevated mercury concentrations in biota. Even more intriguing is that concentrations of mercury in fish from across tropical Africa are systematically and substantially lower than those typically reported for fish from freshwater ecosystems elsewhere globally. The reasons for this apparent “African mercury anomaly” are unclear, but this finding poses a unique opportunity to improve our understanding of mercury's biogeochemical cycling in the environment.Mercury concentrations measured in human hair collected in subsistence fishing communities in the Okavango Delta were similarly low (0.21 ± 0.22 μg g−1 dry weight) despite high levels of fish consumption, and reflect the low mercury concentrations in the fish here. URI: http://hdl.handle.net/10311/782 Files in this item: 1
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Mitsch, W.J.; Nahlik, A.; Wolski, P.; Bernal, B.; Zhang, L.; Ramberg, L. (Springer, http://www.springer.com, NaN, 2010)[more][less]
Abstract: This paper summarizes the importance of climate on tropical wetlands. Regional hydrology and carbon dynamics in many of these wetlands could shift with dramatic changes in these major carbon storages if the inter-tropical convergence zone (ITCZ) were to change in its annual patterns. The importance of seasonal pulsing hydrology on many tropical wetlands, which can be caused by watershed activities, orographic features, or monsoonal pulses from the ITCZ, is illustrated by both annual and 30-year patterns of hydrology in the Okavango Delta in southern Africa. Current studies on carbon biogeochemistry in Central America are attempting to determine the rates of carbon sequestration in tropical wetlands compared to temperate wetlands and the effects of hydrologic conditions on methane generation in these wetlands. Using the same field and lab techniques, we estimated that a humid tropical wetland in Costa Rica accumulated 255 g C m−2 year−1 in the past 42 years, 80% more than a similar temperate wetland in Ohio that accumulated 142 g C m−2 year−1 over the same period. Methane emissions averaged 1,080 mg-C m−2 day−1 in a seasonally pulsed wetland in western Costa Rica, a rate higher than methane emission rates measured over the same period from humid tropic wetlands in eastern Costa Rica (120–278 mg-C m−2 day−1). Tropical wetlands are often tuned to seasonal pulses of water caused by the seasonal movement of the ITCZ and are the most likely to be have higher fire frequency and changed methane emissions and carbon oxidation if the ITCZ were to change even slightly. Description: Some symbols may not come as they are in the abstract. URI: http://hdl.handle.net/10311/832 Files in this item: 1
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Ringrose, S.; Vanderpost, C.; Matheson, W. (Taylor & Francis; http://www.tandf.co.uk/journals/titles/01431161.asp, NaN, 1997)[more][less]
Abstract: Attention worldwide has been focused on the need to assess the appropriateness of land management strategies especially where these occur near sensitive areas of wildlife habitat. This work considers the use of mainly Thematic Mapper data in providing an assessment of the relative impact of different land management strategies on the natural vegetation cover in part of the sensitive Okavango area in Botswana. Supervised classification (maximum likelihood) techniques when used on six-band TM imagery showed that differential degradation was prevalent in land management areas, especially where these are separated by fencelines with an overall accuracy 72 per cent. Marginally more degradation is evident in a controlled hunting area adjacent to the Game Reserve, relative to a communal grazing area. Band transform analyses indicate that distinctive changes in cover type and density frequently take place over boundaries or fencelines separating land management areas. Some degradation in the controlled hunting area appears related to the influence of faultlines on the distribution of soil, hence plant community types. In other cases the pattern of degradation is distributed randomly between the Game Reserve and the cordon fence. Reasons for this unusual distribution pattern may lie in the restriction of movement of migratory wildlife species southwards by the cordon fence separating communal grazing from hunting land uses. A more appropriate management strategy may lie in the prediction of wildlife movements, prior to the erection of cordon fences URI: http://hdl.handle.net/10311/173 Files in this item: 1
ringrose_int_j_remote_sensing_1997.pdf (4.553Mb) -
Ringrose, S.; Jellema, A.; Huntsman-Mapila, P.; Baker, L.; Brubaker, K. (Taylor & Francis; http://www.tandf.co.uk/journals/titles/01431161.asp, October 10, 2005)[more][less]
Abstract: This work determines the value of remotely sensed imagery in developing drying impacts which occur as a result of internal and/or external factors in the Okavango catchment. Three sites provide a preview of the consequences of Delta margin drying as depicted over historical, intermediate and geological timescales. Initially, supervised classification resulted in the identification of sequences of islands and flood plains and their associated vegetation cover on ETM+ imagery, with a classification accuracy of 74- 77%. Comparative results, augmented by patch analysis, suggest that through time, island woody vegetation cover has invaded the flood plains and locally developed protected ecotonal areas (extensions) which are densely treed, relative to adjacent, non-protected flood plains. Over longer time periods, protected areas between extensions became infilled with woody vegetation leading to, in effect, island enlargement or agglomeration. Disadvantages of long-term Delta drying in terms of natural resource management include a reduced availability of wetland-based construction and agricultural resources. If natural regeneration (island agglomeration) is allowed to take place, these resources may ultimately be replaced by dryland timber and potential cropland. URI: http://hdl.handle.net/10311/174 Files in this item: 2
license.txt (1.998Kb)ringrose_int_j_remote_sensing_2005.pdf (3.625Mb) -
Huntsman-Mapila, P.; Ringrose, S.; Downey, W.S.; Modisi, M.; Coetzee, S.H.; Tiercelin, J-J.; Kampunzu, A.B.; Vanderpost, C. (Elsevier; http://www.elsevier.com/wps/find/journaldescription.cws_home/865/description#description, February 7, 2007)[more][less]
Abstract: [Please note chemical formulae do not display correctly in this abstract]. Sediment samples from a continuous 4.6m profile in the dry bed of Lake Ngami in NW Botswana were analysed for geochemistry and dated using both 14C and TL methods. Certain units in the profile were found to be diatom rich and these, with the geochemical results, were used as indicators of high and low lake levels within the basin. The Lake Ngami sediments contain a high proportion of SiO2 (51-92.5 wt%, avg. 72.4 wt%) and variable levels of Al2O3 (2.04-17.2 wt%, avg. 8.88 wt%). Based on elevated Al2O3 and organic matter (LOIorgc) results, lacustrine conditions occurred at ca. 42 ka until 40 ka and diatom results suggest that relatively deep but brackish conditions prevailed. At 40 ka, the lacustrine sedimentary record was terminated abruptly, possibly by tectonic activity. At ca. 19 ka, shallow, aerobic, turbulent conditions were prevalent, but lake levels were at this time increasing to deeper water conditions up until ca. 17 ka. This period coincides with the Late Glacial Maximum, a period of increased aridity in the central southern Africa region. Generally, increasing Sr/Ca ratios and decreasing LOIorgc and Al2O3, from ca. 16 to 5 ka, suggest decreasing inflow into the basin and declining lake levels. Based on the enrichment of LREE results, slightly alkaline conditions prevailed at ca. 12 ka. Diatom results also support shallow alkaline conditions around this time. These lake conditions were maintained primarily by local rainfall input as the region experienced a warmer, wetter phase between 16 and 11 ka. Lake levels rose rapidly by 4 ka, probably in response to enhanced rainfall in the Angolan catchment. These results indicate that lake levels in the Lake Ngami basin are responding to rainfall changes in the Angolan catchment area and local rainfall. The results confirm that the present-day anti-phase rainfall relationship between southern Africa and regions of equatorial Africa was extant during the late Quaternary over the Angolan highlands and NW Botswana. URI: http://hdl.handle.net/10311/152 Files in this item: 2
huntsman_mapila_quatint.pdf (5.573Mb)license.txt (1.998Kb) -
Mosepele, K.; Onalethata, B.; Mosepele, B.; Thethela, B. (Botswana Society, NaN, 2005)[more][less]
Abstract: Populations of three cichlid species from the upper and lower Okavango Delta were compared in terms of biological population parameters, in order to investigate whether the fish species of the Delta consist of one continuous, or two or more separate, stocks. Data were collected from the lower Delta and upper Delta using experimental fishing nets to ensure that representative samples were obtained. While no statistical tests for significance were conducted, the results show that the same species between the upper and lower Delta have different biological parameters. Therefore, it is concluded that these observed differences suggest that, for the three investigated species, there are at least two different populations in the Okavango Delta. URI: http://hdl.handle.net/10311/941 Files in this item: 1
Mosepele 2005 Using popul.pdf (1.635Mb) -
Ringrose, S.; Matheson, W.; Wolski, P.; Huntsman-Mapila, P. (Elsevier; www.elsevier.com/locate/jaridenv, NaN, 2003)[more][less]
Abstract: Vegetative response aspects of climate change studies include the determination of vegetation cover changes across climatic gradients. Vegetation characteristics and soil moisture measurements were obtained from four locations with decreasing rainfall along the Botswana Kalahari transect. These are referred to as Pandamatenga, (698mmyear_1), Maun (460 mmyear_1), Okwa (407 mmyear_1) and Tshane (365 mmyear_1). Trends in major vegetative cover and soil components included species types and richness assessments which reflected certain changes southward but also showed interesting degrees of variability. This occurred despite the apparent homogeneity of the Kalahari sands and predominantly semi-arid savanna shrubâ woodland vegetation cover. Despite linear decreases, both in rainfall and soil moisture content, results indicated high soil moisture variability at the Okwa location which relates to unique climatic and geological factors. Also many species are unique to specific locations for instance Pandametanga is characterized by Zambesian species while the Maun location is characterized by Colophosphermum mopane. This changes southwards as Acacias become more dominant and significantly co-occur with Grewia flava. While the average total numbers of plants decreased, total numbers of different species varied little from the wetter to the drier end of the moisture gradient. The association between rainfall and woody cover is negative implying that canopy cover extents (in terms of vegetation density) increase along the gradient due to increases in bush encroachment in drier areas. Therefore, while representing a continuum in terms of species numbers, in other respects (e.g. species types and ground cover components) vegetation zones in the Kalahari may be regarded as discontinuous units. Differences between mapped vegetation zones may be accounted for in terms of relatively unique ecosystem factors which function partly in response to geological conditions and partly in response to local (as opposed to regional) climatic factors. This appears to have led to ecosystem adaptive measures (in terms of species responses) rarely mirrored elsewhere along the gradient. Hence adaptability in terms of species migrations in response to relatively rapid climate changes may not readily take place over the Kalahari in Botswana. URI: http://hdl.handle.net/10311/175 Files in this item: 2
license.txt (1.998Kb)ringrose_jae_2003.pdf (3.823Mb) -
Andersson, L.; Gumbricht, T.; Hughes, D.; Kniveton, D.; Ringrose, S.; Savenije, H.; Todd, M.; Wilk, J.; Wolski, P. (Elsvier, www.elsevier.com, September 8, 2003)[more][less]
Abstract: As part of the EU-funded project ‘Water and Ecosystem Resources in Regional Development––Balancing Societal Needs and Wants and Natural Resources Systems Sustainability in International River Basin Systems’ (WERRD) (www.okavangochallenge.com), work is carried out aiming to improve and develop scientific methods that will facilitate the understanding of fluctuations of hydrological and ecosystem variables and likely human-induced trends concerning key characteristics of the Okavango River Basin in Southern Africa. URI: http://hdl.handle.net/10311/980 Files in this item: 1
Andersson_PhysChemEarth_2003_Pw.pdf (1.840Mb) -
Bartlam-Brooks, H.; Bonyongo, M.; Harris, S. (Fauna & Flora International, April 7, 2010)[more][less]
Abstract: Terrestrial wildlife migrations, once common, are now rare because of ecosystem fragmentation and uncontrolled hunting. Botswana historically contained migratory populations of many species but habitat fragmentation, especially by fences, has decreased the number and size of many of these populations. During a study investigating herbivore movement patterns in north-west Botswana we recorded a long-distance zebra Equus burchelli antiquorum migration between the Okavango Delta and Makgadikgadi grasslands, a round-trip distance of 588 km; 55% of 11 animals collared in the south-eastern peripheral delta made this journey. This was unexpected as, between 1968 and 2004, the migration could not have followed its present course because of the bisection of the route by a veterinary cordon fence. As little evidence exists to suggest that large-scale movements by medium-sized herbivores can be restored, it is of significant interest that this migration was established to the present highly directed route within 4 years of the fence being removed. The success of wildlife corridors, currently being advocated as the best way to re-establish ecosystem connectivity, relies on animals utilizing novel areas by moving between the connected areas. Our findings suggest that medium-sized herbivores may be able to re-establish migrations relatively quickly once physical barriers have been removed and that the success of future system linkages could be increased by utilizing past migratory routes. URI: http://hdl.handle.net/10311/804 Files in this item: 1
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Sekhwela, M.B.M. (Elsevier Science Ltd, http://www.elsevier.com/locate/cag, July 22, 2002)[more][less]
Abstract: This paper investigated changes in economically important woody vegetation resources around seven settlements located along an aridity gradient in the Kalahari. Available data at different rainfall levels were analysed for different vegetation aspects. Total woody plant density and number of species at each site increased with increasing rainfall level, while individual species density differed at each site irrespective of rainfall, due to other factors, for example, land use as indicated by high stump densities around old and high population settlements. Drought resulted in high mortality of certain species, increasing availability of fuelwood resource in the form of dead wood. However, prolonged drought from climatic changes could result in browse shortage, a vital resource in the Kalahari. There was generally low wood resource availability throughout the studied gradient, without any distinct relation to rainfall, reflecting the influence of other factors such as soils, land use and natural variability. URI: http://hdl.handle.net/10311/1024 Files in this item: 1
Sekhwela M.B.M_2002.pdf (552.9Kb)
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