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Atlas of Namibia: A Portrait of the Land and its People

Authors:
  • RAISON, Windhoek, Namibia
  • JARO Consultancy: http://www.jaroconsultancy.com
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... The regional mean annual air temperature is 22.6 • C (range 1.8-43.9 • C), while the mean annual precipitation sum is 527 mm (range 348-816 mm), markedly summer rainfall [28,29]. Soils are generally classified as Arenosols, primarily dominated by a deep soil layer with rapid permeability, low water-holding capacity, and low nutrient content [29][30][31]. ...
... • C), while the mean annual precipitation sum is 527 mm (range 348-816 mm), markedly summer rainfall [28,29]. Soils are generally classified as Arenosols, primarily dominated by a deep soil layer with rapid permeability, low water-holding capacity, and low nutrient content [29][30][31]. ...
... The regional mean annual air temperature is 22.6 °C (range 1.8-43.9 °C), while the mean annual precipitation sum is 527 mm (range 348-816 mm), markedly summer rainfall [28,29]. Soils are generally classified as Arenosols, primarily dominated by a deep soil layer with rapid permeability, low waterholding capacity, and low nutrient content [29][30][31]. ...
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Agroforestry systems hold potential for wood and tree biomass production without the need of felling trees. Branch wood harvesting provides access to considerable amounts of lignocellulosic biomass while leaving the tree standing. Aiming at alternatives for wood provision, we assessed the actual woody structure of a silvopastoral system in the African Savannah ecoregion, utilising terrestrial LiDAR technology and quantitative structure models to simulate branch removals and estimate harvesting yields. In addition, the stand structure and harvested wood were examined for the provision of four types of assortments meeting local needs, and operational metrics for each treatment were derived. The stand had large variability in woody structures. Branch harvesting interventions removed up to 18.2% of total stand volume, yielded 5.9 m3 ha−1 of branch wood, and delivered 2.54 m3 ha−1 of pole wood quality, retaining on average more than 75% of the original tree structures. Among the most intense simulations, a mean of 54.7 litres (L) of branch wood was provided per tree, or approximately 34.2 kg of fresh biomass. The choice of an ideal harvesting treatment is subject to practitioners’ interests, while the discussion on aspects of the operation, and stand and tree conditions after treatment, together with outputs, assist decision making. The partitioning of tree structures and branch removal simulations are tools to support the design of tending operations aiming for wood and tree biomass harvesting in agroforestry systems while retaining different functional roles of trees in situ.
... The mean temperatures for summer are from 10˚C to 38˚C and in winter from 1˚C to 24˚C (Initial Environmental Review Report, 1997). According to Mendelsohn et al. (2009) frost is rare in the area. ...
... Karibib falls within a semi desert and savannah ecotone with the main vegetation dominated by Acacia shrubs and trees, also called thorn bush savannah (Initial Environmental Review Report, 1997). The vegetation structure is classified as sparse shrubland dominated by grasslands and scattered trees with an average plant production and high variation in green vegetation biomass (Mendelsohn et al., 2009). ...
... It predominantly occupies a higher elevational range (about 1000-2100 m) than other clade members, but with two records from the Swakopmund area nearer to sea level (Dinter 19, Z; Craven 2495, WIND; see Appendix S1). In addition, populations occur in the most mesic areas of any clade member (average annual rainfall range about 100-900 mm; Mendelsohn et al. 2002;Schulze 2008). The ameliorating effect of elevation on temperature (especially in summer) or natural stratification of seeds in winter may be important determinants of its distribution. ...
... The altitudinal range is about 550-1500 m. Arctotis namibiensis occupies the most arid portion of the range of the Arctotis Annual Clade and receives an average annual rainfall of about 50-150 mm (Mendelsohn et al. 2002). It is particularly common in ecotones where there is some transitional summer rain and especially where fog also is an important contributor to the moisture regime. ...
Article
Previous phylogenetic analysis of ITS nrDNA sequence data for Arctotidinae species resolved a strongly supported clade containing all but one of the showy annual Arctotis species (informally designated the Arctotis Annual Clade). In the present study, phylogenetic relationships in the Arctotis Annual Clade were investigated by Bayesian inference and maximum parsimony analyses of cpDNA (trnT-trnLtrnF and trnH-psbA) and nrDNA (ITS) sequence data. The cpDNA and nrDNA phylogenies were notably incongruent. Arctotis venusta and a putative unnamed species (A. ‘sp. B’) were strongly supported as monophyletic by both data sets. The monophyly of A. leiocarpa was strongly supported by the ITS data set, whereas the remaining accessions formed a poorly resolved complex (the ‘A. fastuosa complex’). Within the A. fastuosa complex, A. hirsuta was monophyletic with strong support in the ITS phylogeny. A statistical parsimony-derived cpDNA haplotype network resolved five broad groups of haplotypes and showed no consistent geographical structure, but species-specific haplotype lineages for A. venusta and A. sp. B were resolved. Arctotis fastuosa accessions were distributed among four haplotype groups. Incongruence between the data sets and poor resolution within the A. fastuosa complex may reflect reticulate evolution, ancestral polymorphism, and incomplete lineage sorting, in tandem with the low information content of the data sets. The greatest phenotypic diversification in the clade is in cypsela morphology. Comparison of cypsela morphology with the phylogenies suggests a general trend for reduction in the sizes of the cypsela, abaxial wings, pappus scales, and loss of pubescence during diversification. A revised taxonomy, integrating currently available evidence, accompanied by full descriptive accounts and a key to the taxa are presented. Eight species are recognized, including the nomenclatural novelties Arctotis chrysantha (sp. nov.) and Arctotis namibiensis (sp. nov.). The names Arctotis karasmontana, Venidium fugax, and Venidium macrocephalum are lectotypified.
... The resulting precipitation in the southwestern Kalahari follows a strong NE-SW gradient of >600 mm/a in the northeast (Caprivi/Kavango region) and <50 mm/a along the Namibian coastline. The highest rates of evaporation occur in the southeast of Namibia (>3800 mm/a) whereas lowest values are observed in the northeast (Caprivi/Kavango region) as well as along the coastline (~2400 mm/a; Mendelsohn et al. 2002). ...
Chapter
Pans, playas and similar morphological structures occur across all continents. They are small, closed sedimentSediment sinks that are characteristic of arid and semi-arid regions with low relief. In the Kalahari BasinKalahari Basin, small pans are widespread and they function as ephemeral lakesLake and sedimentary sinks. They are characterised by their flat, salty to clayey surface and slightly elevated surroundings. Some principle sedimentary processes are distinctive for pans. Showers during the short rainy season deliver siliciclastic material by runoffRunoff from the local catchment. During the dry season, evaporites precipitate by evaporation of the surface water and supersaturated pore water and groundwaterGroundwater. Additionally, fine-grained sedimentsSediment are transported on the dry pan surface by strong windWind regimes (long-term) or by vortices/eddies from thermal upliftsUplift (short-term). The marginal lunetteLunettedunesDune, a characteristic feature of many small Kalahari pans, resulted from temporary phases of significant aeolian sediment transport. However, there is no hint of longer sedimentation gaps or significant periods of erosionErosion. The prevailing depositional processes contradict the former assumption that deflationDeflation is the most prominent process in salt pan formationFormation. The pans contain sediment sequences that are several decimetres to metres in thickness, which reach back until the Late PleistocenePleistocene. They contain different kinds of proxy information that can be used for environmental reconstruction and climate modelling throughout the pans’ history.
... The Namib Desert Due to the fundamental nature of the research questions, a site with a flat, horizontally homogeneous surface cover and negligible latent heat transfer was needed to fulfill standard theoretical assumptions and avoid complications. The central Namib, on the southwestern coast of the African continent and reaching approximately 200 km inland, is one of the driest places on Earth (Mendelsohn et al. 2002) and fulfills these criteria. The NamTEX field site (23.516°S, ...
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The Namib Turbulence Experiment (NamTEX) was a multinational micrometeorological campaign conducted in the central Namib Desert to investigate three-dimensional surface layer turbulence and the spatiotemporal patterns of heat transfer between the subsurface, surface, and atmosphere. The Namib provides an ideal location for fundamental research that revisits some key assumptions in micrometeorology that are implicitly included in the parameterizations describing energy exchange in weather forecasting and climate models: homogenous flat surfaces, no vegetation, little moisture, and cloud-free skies create a strong and consistent diurnal forcing, resulting in a wide range of atmospheric stabilities. A novel combination of instruments was used to simultaneously measure variables and processes relevant to heat transfer: a 3-km fiber-optic distributed temperature sensor (DTS) was suspended in a pseudo-three-dimensional array within a 300 m × 300 m domain to provide vertical cross sections of air temperature fluctuations. Aerial and ground-based thermal imagers recorded high-resolution surface temperature fluctuations within the domain and revealed the spatial thermal imprint of atmospheric structures responsible for heat exchange. High-resolution soil temperature and moisture profiles together with heat flux plates provided information on near-surface soil dynamics. Turbulent heat exchange was measured with a vertical array of five eddy-covariance point measurements on a 21-m mast, as well as by collocated small- and large-aperture scintillometers. This contribution first details the scientific goals and experimental setup of the NamTEX campaign. Then, using a typical day, we demonstrate (i) the coupling of surface layer, surface, and soil temperatures using high-frequency temperature measurements, (ii) differences in spatial and temporal standard deviations of the horizontal temperature field using spatially distributed measurements, and (iii) horizontal anisotropy of the turbulent temperature field.
... The occurrence, distribution, and extension of surface runoff are seasonal and depend on precipitation [1,3,21,22]. Namibia has often experienced drought periods, especially over the past few decades [23][24][25], but one of the worst drought episodes in the country occurred in 2019 [26][27][28][29][30]. ...
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The water supply in drylands mainly relies on groundwater, making it a crucial resource. Springs in southern Africa are often underutilized, and are neither protected nor monitored. Thus, the aim of this study was to evaluate their quality in a sample area in northwestern Namibia and to propose solutions for the sustainable use of springs. In total, 35 springs and hot springs were evaluated in the study area located in the drier part of Namibia (Pmean = 150–400 mm/year), an area highly impacted by ongoing climate change with longer and more frequent drought seasons. The springs there are mostly uncaptured and the discharge is in the form of surface runoff, which is mainly lost to the atmosphere by evaporation. Most of the studied springs were perennial, despite a severe drought period. Local communities rely on the springs mainly for livestock and human consumption, as well as for irrigation. However, 71% of the springs do not have any protective measures. The temperature, pH, conductivity and alkalinity were tested in situ. In total, 20 samples were collected and analyzed for major ions (boron, fluoride, silica and strontium) and total dissolved solids (TDS). The physical and inorganic results mostly indicated good and excellent quality water for human consumption, while the hot springs tended to have poor water quality in terms of Namibian standards, indicating that the water was not fit for human consumption.
Chapter
Significance Statement Cities in sub-Saharan countries are simultaneously facing climate change, rapid urbanisation, and social inequalities. Nature-based Solutions harness nature’s benefits to address these environmental, social, and economic challenges. In this study, we investigate how taking into account temporal dynamics and multiple values of nature helps to implement better Nature-based Solutions. Through satellite images and interviews with practitioners and residents, we look at how green spaces and dry riverbeds are distributed, managed, and perceived in the capital city of Namibia, south-western Africa. We find that apartheid spatial segregation legacies persist through the unequal distribution of urban green spaces, and that, although their current management limits their capacity to deliver benefits, riverbeds have the potential to support sustainable development and climate change adaptation.
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In arid and semi-arid ecosystems, rainfall and rainfall temporal distribution shape species communities and multi-trophic interactions. Whereas the relationship between climate change-induced decline of precipitation and plants is well know, there is little knowledge of these relationships with consumers, such as arthropods of different trophic levels. In a 6-year period we studied precipitation effects and microhabitat conditions on multi-trophic interactions of ground-dwelling arthropods in an arid savannah. We analysed the effects of seasonal rainfall, plant cover and soil texture on community composition and activity density of arthropods of different trophic levels and investigated the critical window of vegetation and occurrence arthropods in relation to rainfall. Our result show, that arthropod community composition was determined by seasonal rainfall and plant cover. Soil texture did not explain arthropod response sufficiently. Especially detritivorous arthropods were strongly affected by precipitation and can therefore serve as indicators of droughts. Further, multi-trophic interactions can better be explained by short-term rainfall pulses, rather than by seasonal patterns, with a window of seven days being most suitable to explain the influence of rainfall. Plant cover responded immediately after the rainfall, followed by herbivorous and predatory arthropods, and with a lag of 23 days omnivorous arthropods. This highlights the importance of short-term rain pulses for multi-trophic interactions among arthropods and emphasized the relevance of studying detailed precipitation effects for the arthropod diversity and ecosystem stability in arid ecosystems.
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