Kalahari Research Articles

Endemism in Namibia: patterns, processes and predictions

Sandwiched between the Namib and Kalahari Deserts of southwestern Africa are the karooid and escarpment biotopes of Namibia which are rich in endemics of many taxa. Most plant, invertebrate, amphibian, reptile, mammal and bird species endemic to Namibia are found in a zone running through, and to the west of, Namibia's escarpment region. There is also an important region of endemism for succulent plants, reptiles and invertebrates in the Succulent Karoo biome. Congruence between endemism hotspots, particularly on rocky substrates, is remarkably high for most taxa, implying broadly similar speciation processes. Possible speciation mechanisms in different parts of the country include the spatial isolation of rupicolous taxa such as insects and reptiles by the formation of large coastal dune fields; the expansion and contraction of wooded savannas during pluvial and interpluvial periods; and global temperature shifts which created highland refugia for frost-susceptible plants and poikilotherms. Areas of endemism and species richness overlap poorly for Namibia's mainly arid-dwelling endemic vertebrates, as richness is highest in the mesic wetlands and woodlands of northeast Namibia. The overlap for succulent plants, insects and arachnids, however, is relatively high. Centres of endemism for plants and vertebrates fall mainly outside protected areas, as few parks were established with biodiversity indices in mind. Our analysis of endemism congruence provides a strong platform for the promulgation of new protected areas to safeguard Namibia's unique biota. Furthermore, analysis of speciation patterns and processes is a useful predictive tool for the identification of other biotically important sites.

Healing Makes Our Hearts Happy: Spirituality and Transformation among the Kalahari Ju/'hoansi

One of the world's oldest continuing societies, the Ju/'hoansi, or Bushmen of the Kalahari Desert offer profound insights into what is fundamental to human existence. In the face of outside pressures that threaten the complete disruption of their communal way of life, the Ju/'hoansi find deep spiritual resources in their traditional healing dance. Their indigenous method of healing individuals is also a powerful affirmation of the community, and has recently become a means of settling land and property disputes, problems that never existed in the old days. The healing dance promises to be the crucial factor that allows the Ju/'hoansi to preserve their culture into the 21st century. These inspiring people set an example for us to look beyond the false promises of modern technology in search of the spiritual healing that is so desperately needed in our own culture and within ourselves.

New Records of Pteridophytes for Botswana

In a survey of the pteridophytes of Botswana, the family Isoetaceae was encountered and is a new record for Botswana. The family is represented by a single species, Isoetes schwein- furthii. Also recorded for first time in Botswana were three other species: Ophioglossum lancifol- ium, Actinopteris dimorpha, and Marsilea minuta. Although the pteridophytes of southern Africa have been thoroughly and very capably surveyed (Schelpe, 1970; Jacobsen, 1983; Schelpe and Anthony 1986; Burrows, 1990), new explorations are adding to knowledge regarding their specific ranges. Botswana is a semi-arid country situated in the south- central part of the African continent and has three major ecological regions (Parson, 1993). In the northern region there are the Okavango Delta and the ancient lake beds of the Makgadikgali Pans. The southern area comprises the Kalahari Desert, characterized by fossil sand dunes and scrub and bush savan- na. Between the Okavango-Makgadikgali and the Kalahari Desert, is an inter- mediate ecological zone known as the Hardveld region, dominated by sandy soils.

New chronological evidence for the nature and timing of linear dune development in the southwest Kalahari Desert

The age of the linear dunes in the southwest Kalahari Desert has not previously been directly established. By applying the optical dating method to samples from the dunefield a number of questions relating to the timing and nature of linear dune development are addressed. The last major period of simple linear dune development occurred 17,000–10,000 years ago, probably from the reworking of earlier aeolian sediments. Dune emplacement occurred under more arid, probably windier, conditions than those prevailing today, which are only responsible for episodic surficial dune sand movement. As well as simple linear dunes, the dunefield also contains more complex linear dune patterns. Samples from one area in the eastern dunefield demonstrate that multi-phase development is more probable for complex dune patterns as opposed to single-phase evolution under a complex wind regime.

Holocene aeolian activity in the southwestern Kalahari Desert, southern Africa: significance and relationships to late-Pleistocene dune-building events

Little is known about the timing of dune-building episodes in the southwestern Kalahari Desert. Previously, arid phases when dune activity occurred have been inferred from gaps in chronologies derived from information that attests to former humid periods. To redress this, optically stimulated luminescence (OSL) dating was applied to sediment samples taken from a range of aeolian landforms in the SW Kalahari. Four periods of dune building are identified in the late Pleistocene and Holocene. Holocene aeolian activity at 6 ka and 1-2 ka led to the construction of localised dune forms, in contrast to late Pleistocene times when the extensive field of linear dunes that dominates the region was emplaced. Late-Holocene aridity was however sufficient to allow rapid emplacement of the lunette dune at Witpan. The record of aeolian activity is evaluated in the context of humid chronologies and an ocean-atmosphere model of Holocene climate change, with good agreement obtained. It is concluded that the application of optical dating to a range of aeolian landforms has the potential to establish the style as well as timing of dune-building. It is also demonstrated that the climate during dune-building periods must have differed significantly from the prevailing semi-arid climate with drought periods of today, which may have been the predominant climate regime through much of the Holocene.

Breeding status and ecology of the Martial Eagle in the Kalahari Gemsbok National Park, South Africa

Herholdt, J.J. & Kemp, A.C. 1997. Breeding status and ecology of the Martial Eagle in the Kalahari Gemsbok National Park. Ostrich 68 (24): 80–85. The success of 16 nesting areas (territories) of Martial Eagles was monitored for seven successive years (1988–1994) in a protected area in the Kalahari desert of South Africa. Martial Eagles mostly laid in consecutive years (38 out of 53 attempts) and fledged, on average, 0.43 young/pair/year (38/88). Most Martial Eagles laid eggs in May and June (72.2%; n = 13 attempts). Almost all located Martial Eagle nests were in the Acacia erioloba savanna in the dry Auob and Nossob riverbeds. Martial Eagle nesting areas were spaced at intervals of 24.1 km (1144.6 km; n = 6) along the Nossob River, 15.1 km (8–34 km; n = 7) in the Auob River and 31.3 km (25–43 km, n = 4) in the interior dune area. A total of between 20 and 30 Martial Eagle pairs (20 known active nesting areas) occurred in the Kalahari Gemsbok National Park during the study period. There was no evidence of a decline in active nesting areas of Martial Eagles during the seven year study. There was no safe buffer zone around the Kalahari Gemsbok National Park and Martial Eagles were at times persecuted when foraging in the adjacent farmlands.

Dunefield Activity and Interactions with Climatic Variability in the Southwest Kalahari Desert

An analysis is undertaken of the temporal variability of climatic parameters that influence dunefield aeolian activity. Data from seven meteorological stations in the southwestern Kalahari Desert are used, spanning the period 1960–1992. Erosivity is considered through analysis of wind data, and erodibility through analysis of precipitation and potential evapotranspiration, which together influence dune surface plant growth. The data are integrated using Lancaster's ‘mobility’ index which provides a measure of potential dune surface sand transport. This is renamed ‘potential dune surface activity index’, to reflect the actual characteristic that is measured. The subsequent analysis indicates that dunefield activity is episodic and temporally variable, that both erosivity and erodibility vary through time, and that present levels of activity cannot be characterized by a single simple state. © 1997 by John Wiley & Sons, Ltd.

Dunefield Activity and Interactions with Climatic Variability in the Southwest Kalahari Desert

An analysis is undertaken of the temporal variability of climatic parameters that influence dunefield aeolian activity. Data from seven meteorological stations in the southwestern Kalahari Desert are used, spanning the period 1960–1992. Erosivity is considered through analysis of wind data, and erodibility through analysis of precipitation and potential evapotranspiration, which together influence dune surface plant growth. The data are integrated using Lancaster's ‘mobility’ index which provides a measure of potential dune surface sand transport. This is renamed ‘potential dune surface activity index’, to reflect the actual characteristic that is measured. The subsequent analysis indicates that dunefield activity is episodic and temporally variable, that both erosivity and erodibility vary through time, and that present levels of activity cannot be characterized by a single simple state. © 1997 by John Wiley & Sons, Ltd.

On the use of NDVI for estimating rainfall fields in the Kalahari of Botswana

This article presents the results of an experiment to estimate rainfall from the normalized difference vegetation index (NDVI). The study was carried out in the semi-arid region of south and southern Botswana, principally the Kalahari desert, where few rainfall-reporting stations exist. A statistical regression between NDVI and rainfall is developed for four areas with diverse soil conditions. These are used to estimate rainfall at an independent station or group of stations. The estimates reliably capture both the seasonal cycle and inter-annual variability. These regressions are used to produce a map of mean annual rainfall for the period 1982 to 1993, based on NDVI data, for the region 22 to 27°S and 20 to 26°E. The estimates are verified using all data available in the Meteorological Services' archive for these years.

RAPD variation within and between natural populations of morama [Tylosema esculentum (Burchell) Schreiber] in southern Africa

RAPD markers were used to investigate genetic variation in natural populations of morama [ Tylosema esculentum (Burchell) Schreiber]. This species is a wild, perennial, outbreeding legume indigenous to the Kalahari Desert region of southern Africa. Morama seed has a high protein content and has traditionaliy been an important wild source of food for the people of this region. It is considered to have great potential for development as a new crop for the semi-arid tropics. Investigation of genetic diversity is a prerequisite for the genetic improvement of any species and this is the first such investigation in morama. Considerable RAPD variability was detected in each of the three morama populations sampled. Most of this variation (85%) occured within, rather than between, populations in agreement with other studies involving outbreeding perennial species. This suggests that sufficient genetic variation for breeding purposes may be found by sampling 30–40 plants from only one or two populations. There were significant differences in the frequency of RAPD loci between populations but no population-specific RAPD markers were found. Although there was no clear evidence of population differentiation between the morama populations, more intensive sampling may reveal details of within-population genetic structure in these populations. This analysis confirms the usefulness of RAPD markers for investigation of genetic variation in natural populations and the technique is fast and provides numerous polymorphic markers.

Subsistence Hunting And Resource Management Among The Ju/'Hoansi Of Northwestern Botswana

An assessment of subsisten~e hunting and natural resour~e management among Ju/'hoansi Bushmen (San) over a period of 30 years from the 1960s In 1995 was carried out as part of anthropological investigations of remote foraging and food-producing populations in the northwestern Kalahari Desert region of Botswana and Namibia. The Ju/'hoansi pursue a diversified set of resource management and utilization strategies, exploiting over 50 species of mammals, birds, and other fauna using a variety of tools and techniques. Wildlife offtake rates in the 1960s 'ere well below repla~cment rates. Although changes have occurred over time in technology and in the use of dogs, donkeys, and horses in hunting, the numbers of animals taken by subsistence hunters were still below sustainable yields in 1995, and wildlife products continue to play a significant role in the socioeconomic and ideological systems of Ju/'hoansi. These findings underscore the importance of ensuring a continuation of the right to hunt legally and to engage in local community-based natural resource management projects.

On the Dry Valleys of the Kalahari: Documentary Evidence of Environmental Change in Central Southern Africa

Dry 'fossil' valleys (mekgacha) are an important landscape feature in the semi-arid to arid Kalahari Desert of central southern Africa. The majority of valleys do not contain flow, except in their headwater regions, but may contain pools of water on a seasonal basis. As a result, they are frequently mentioned in historical accounts of the region recorded by European travellers, and from these reports it is possible to assemble a picture of hydrological change. This paper describes the evidence for such change, for the period c. 1750 until c. 1910. Discussion mainly concerns the most frequently observed valleys, the Molopo and Kuruman, although Middle Kalahari systems are also considered. The picture which emerges is one of little change in Middle Kalahari systems. A decline in flow in the Kuruman since c. 1750 is tentatively identified, pre-dating the period of permanent human settlement in this region. The river appears to have established its present regime after 1800. A previously unrecognized flood event in the Kuruman in 1820 is also identified. These hydrological changes are placed within the context of historical climate evidence from the southern Cape of South Africa and show close correlation. This suggests that documentary evidence may be used to extend the climate record established for the southern African summer rainfall zone into the Kalahari.

Holocene climatic optimum in Southwest Africa—evidence from the marine clay mineral record

Sediment composition, grain size and clay mineral record of a high-resolution sediment core from the continental slope off Namibia was investigated to gain information on the deposition of terrigenous matter in this part of the Southwest African continental margin during the last 18 k.y. The depositional processes involved are fluvial input by the Kunene River and eolian input from the Namib and Kalahari deserts, each supplying characteristic mineral suites. During low sea level, erosion of the exposed shelf yields additional material. The amount of eolian or fluvial matter depends on the strength of the transport process, which is a function of aridity or humidity of the source area, thus allowing paleoclimatic interpretations. Arid conditions prevailed during a low sea level from 18 to 15 ka and unconsolidated shelf sediment was mobilized and supplied to the slope by short-distance transport by southerly winds. A dramatic increase in the accumulation of terrigenous sediment is recorded from 15 to 10 ka without major changes in sediment composition, which is attributed to increased runoff of the Kunene River and fluvial erosion of shelf sediments. This period coincides with a strengthening of the monsoonal system during a precessional minimum, which is observed in numerous sites in Central Africa and indicates an intensified influence of the monsoon at the Kunene headwaters. A distinct shift in clay mineralogy towards river-derived material marks a second period of increased river runoff—during high sea level—from 9 to 5 ka, indicating maximum humidity in the source area from 6 to 5 ka. This corresponds to the Holocene climatic optimum observed in the arid belts of Northern Africa. The present balance between fluvial and eolian input was reached approximately at 4 ka.

Field metabolism and water flux of Sociable Weavers Philetairus socius in the Kalahari Desert

Sociable Weavers Philetairus socius build large communal nests which they occupy year‐round. White et al. suggested that use of this large nest complex significantly reduced the energy expenditure of Sociable Weavers during winter, thus lowering their resource requirements at that time. In this study we have used the doubly labelled water technique to examine the hypothesis that Sociable Weavers have a reduced field metabolic rate during the winter. Further, we measured their water influx and compared our findings with data from other desert‐adapted birds. The field metabolic rate of Sociable Weavers (mean mass = 25.5 g) in the Kalahari Desert in winter averaged 48.7 ± 10.1 kj per day, a much lower energy expenditure than birds of similar size living in more mesic environments. We suggest that this results from a combination of communal roosting and possibly a reduced basal metabolic rate. The water influx of Sociable Weavers averaged 4.6 ml water per day, one of the lowest values reported for a bird of this size. Our analysis indicates that Sociable Weavers cannot rely on seeds as a food source without another source of water because the seeds do not provide enough water to meet their needs.

Anemia and the transition of nomadic hunter-gatherers to a sedentary life-style: Follow-up study of a Kalahari community

Iron profiles of communities of hunter-gatherers and former hunter-gatherers conducted between 1969 and 1987 at Dobe in the Kalahari Desert of Botswana exhibited pronounced differences during periods of rapid culture change. The loss of good health and particularly the increase in anemia through time was attributed to notable changes in diet, although changes in mobility patterns were considered a secondary cause. In 1988 and 1989, studies were conducted at Kutse, also in the Kalahari Desert of Botswana, to ascertain the frequency of anemia at a recently sedentary community in which residents still relied primarily on wild animals for meat. Although not identical, the hematological presentation in 1989 was similar to that in 1988. The studies together suggest that our findings characterize the pattern of health and disease at Kutse, which is unrelated to any specific year or to diet. Additional measures of disease, specifically ESR (erythrocyte sedimentation rate) and oral temperatures, support an interpretation of anemia of chronic disease as the cause of hypoferremia at Kutse. Morbidity is high, in spite of adequate diets, because the residents are transitional from a nomadic to a sedentary lifestyle and from a relatively dispersed to an aggregated settlement pattern. These changes have introduced new health problems.

Trickster by Trade: Thomas Riccio on Indigenous Theatre. An Interview

The scene is one of great incongruity. A white man, wearing a plastic Roman helmet and sporting huge white foam hands bounds into a group of black children in a squalid township in Natal, South Africa. He is a pied piper, leading them to an open space where a group of Zulu actors begins a performance that both recalls their cultural traditions and confronts their troubled present-day reality. Variations of this scene repeat in Zambia, and with the !Xuu and Khwe Bushmen in the Kalahari Desert.'

Crisis & renewal: meeting the challenge of organizational change

Hurst, D. K. (1995). Crisis & renewal: Meeting the challenge of organizational change. From The Management of Innovation and Change Series, Michael L Tushman and Andrew H. Van de Ven, Series Editors. Boston MA: Harvard Business School Press. By Virgil Smith Biola University This book will prove useful to the practitioner who believes his or her organization is growing stagnant. Hurst uses ideas from Population Ecology Theory and Chaos Theory, augmented by case histories of firms that have faced dramatic change, to explain why organizations cease to innovate, and what the owner/manager can do about it. He begins by using an analogy of an organizational system - the Bushmen culture in the Kalahari Desert. This hunter-gatherer culture, overtime, was transformed into a herder society - the point is that organizations follow the same patterns. Hurst's argument is that many of the features that managers seek in the modern organization were present in hunter bands. Each person within the band was multi-skilled, there was little hierarchy, and there was a high level of open communication, trust, and empowerment. These hunter bands were traditionally self-organizing entities which appeared chaotic from the outside, but made perfect sense to the band itself. More recently the lure of material wealth has caused the Bushmen hunter-gatherer culture to be transformed into a herder culture. With the advent of the possible ownership of material property the hunter bands suddenly needed a hierarchy to resolve disputes over ownership of the property, and the hierarchy diminished the power of the individuals at lower levels of the hierarchy. Also, band members tended to specialize for material productivity, becoming single skilled. Since members were afraid that someone might be trying to get what they had, communication became less open, and trust diminished. Once the transformation had occurred from a hunter way of life to a herder society the Bushmen culture looked very much like a traditional organization. While the hunter culture was self-organizing and looked chaotic, the herder culture was structured from the top down and looked much more orderly. Hurst uses the analogy of the hunters and the herders throughout the book. The hunter culture with its open communication, trust, and empowerment allows for the learning necessary for quick, creative responses and adaptation to opportunities. This, in turn, allows the clan to deal with an environment that is treacherous and constantly changing. Indeed, when the Bushmen were hunters, they were constantly on the move, seeking sustenance where they could get it. On the other hand, the herder culture with its hierarchy and specialization allows the band to be maximally productive in a much more stable herding environment, where they stay in one place and gather possessions. Using the previous analogy, Hurst says that most entrepreneurial firms start out as hunters but, over time and with success, they are transformed into herders. However, they still need the innovative skills of the hunters. He says, [Y]oung businesses begin their lives as informal, learning organizations, but if successful, they become formal, performance organizations. It is thus helpful to think of learning and performing as two ends of a continuum with the young organizations starting off on the left-hand side and moving toward the right as they age (Page 33, italics in original). According to Hurst, the current adoption of organizational methods such as interdisciplinary teams and networks is an attempt on the part of managers to go back to being hunters. Small, new organizations are held together through the self-selection of members into the organization, and an overriding agreement with the organizational mission - everything else is worked out as needed. Strategy in new organizations tends to be emergent, while it is top down in more established companies. …

Paleoenvironment and Archaeology of Drotsky’s Cave: Western Kalahari Desert, Botswana

Test excavations conducted at Drotsky’s Cave have provided important new information on the paleoenvironment and archaeology of the western Kalahari desert during the late and terminal Pleistocene. An occupation layer dated to the terminal Pleistocene was rich in Late Stone Age artefacts, pieces of ostrich egg shell, the remains of carnivorous bullfrogs, springhare, and other fauna. A detailed sediment study, along with the evidence of Angoni vlei rat, climbing mouse, an aquatic Xenopusfrog, and side neck turtle confirms that conditions were for the most part, substantially more moist than at present between approximately 30,000 and 11,000 years ago. Analysis of a diatom assemblage dated to the terminal Pleistocene implies that the currently dry Gcwihaba Valley was most likely flowing for much of the year. Our evidence supports findings made at other localities in the Kalahari documenting the existence of especially moist conditions during the terminal Pleistocene.

Airflow and roughness characteristics over partially vegetated linear dunes in the southwest Kalahari Desert

There is little understanding of the flow-field surrounding semi-vegetated linear dunes, and predictions of dune mobility are hampered by a lack of empirical data concerning windflow. In an attempt to characterize the near-surface airflow upwind of and over partially vegetated linear dunes in the southwest Kalahari Desert, this study presents measurements of vertical and horizontal wind velocity profiles across cross-sectional transects of seven partially vegetated linear dunes. Vegetation surveys combined with velocity measurements from vertical arrays of cup-anemometers, placed up to 2·3 m above the ground surface, were used to gain information concerning the modification of airflow structure caused by the intrusion of the dunes into the atmospheric boundary layer and to predict the variability of aerodynamic roughness (z0) from interdune to crest. The results suggest an acceleration of flow up the windward slopes of the dunes and, as such, the data correspond to classical theory concerning flow over low hills (essentially Jackson and Hunt (1975) principles). Where the theory is incapable of explaining the airflow structure and acceleration characteristics, this is explained, in part, by the presence of a spatially variable vegetation cover over the dunes. The vegetation is important both in terms of the varying aerodynamic roughness (z0) and problems concerning the definition of a zero-plane displacement (d). It is considered that any attempts to characterize surface shear stress over the Kalahari linear dunes, in order to predict sand transport and dune mobility, will be hampered by two problems. These are the progressively non-log-linear nature of the velocity profiles over the dunes caused by flow acceleration, and the production of thin near-surface boundary layers caused by areally variable aerodynamic roughness as a result of the partially vegetated nature of the dunes.

Airflow and roughness characteristics over partially vegetated linear dunes in the southwest Kalahari Desert

Airflow and roughness characteristics over partially vegetated linear dunes in the southwest Kalahari Desert