Southern Central Africa Research Articles

Labial-velar stops in Sakata (Bantu C34)

Labial-velar stops in Sakata (Bantu C34)

The analysis of the fault system in the passive rift basin—an example from the Muglad Basin, central Africa

Introduction: The Muglad basin, located on the southern Central Africa Shear Zone, is an intracontinental passive rift basin. The Fula sag, situated in northeastern of the basin, is a hydrocarbon-rich depression. As exploration advanced, the Fula sag has entered the stage of fine exploration for complex fault blocks. Therefore, studying the characteristics and evolution of faults can aid in deepening the understanding of hydrocarbon accumulation rules in the area, and guide the next steps of oil and gas exploration. Previous studies have primarily focused on the division of fault level and their role in hydrocarbon accumulation, but have not delved into the geometric features and evolution of the fault system across the entire Fula sag.Methods: In this paper, we systematically studied the fault system and its hydrocarbon control within the sag using petroleum seismic reflection profiles, as well as logging data.Results and Discussion: And the conclusions are as followed: 1) tectonic features in diverse areas of the Fula sag vary significantly from a shovel-like half-graben to the asymmetric graben, and faults in the study area can be classified into five combination features. 2) Three complete rift-sag cycles have developed since the early Cretaceous, with continuously active faults controlling the formation of “inherited” sag. 3) The strong activity of faults in the first and second riftting period led to the development of mainly AG-Formation source rocks and middle reservoir-forming assemblages in the Fula sag. Additionally, the formation and distribution of oil and gas reservoirs in the sag were controlled by the faults in the central fault zone and the western steep slope zone. Furthermore, hydrocarbons migrated and formed reservoirs through the main faults in the central fault zone and the western main fault. Our research will provide a valuable insight for understanding the petroleum geological characteristics of basins with a similar genesis mechanism.

Potential to Setting Up of Maritime Clusters in Angola

This paper seeks to address the relationship between the concentration of economic activities associated with the sea and Angola’s economic development. The investigation on Maritime Clusters arises from the fact that Angola has maritime infrastructures and a strong maritime activity being the sea hinterland of landlocked countries in Southern and Southern Central Africa. It is also experiencing socio-economic and demographic changes generated by economic activities with a relevant impact on the business environment, bringing about opportunities for the establishment of industrial clusters in particular maritime clusters. Thus, this paper aims to understand that the setting up of clusters might reduce regional asymmetries and poverty in the country, showing the importance of maritime clusters for economic development and job creation by enhancing the growth of solid micro, small and medium-sized enterprise (MSME). It also enables to understand that maritime clusters are relevant not only to the diversification of country’s economy that is still largely dependent from the oil industry but also to the integration of the Angolan economy in the Southern African Development Countries (SADC). Regarding the existing gap in knowledge about the issue, this research work represents an analytical contribute for further research initiatives, particularly quantitative nature.

Macrotermes natalensis termite colonies in seasonally flooded savannas

In seasonally inundated landscapes of southern central Africa very large termite mounds of Macrotermes natalensis offer a refuge for flood-intolerant trees during the flood season. In the matrix landscape surrounding these islands the seasonally waterlogged and then anaerobic soil conditions and the browsing by megaherbivores during the dry season allow for grass and herbaceous vegetation only. During the rainy season each termitarium forms an isolated island which due to its relative dryness allows survival of the trees and the associated fauna. During the dry season the termites try to establish new colonies with new mounds. However, the successful formation of new termitaria islands seems to be a rare event. In this case study from Dundumwezi in the Kafue National Park, Zambia, we provide a description of the termitaria islands and their vegetation. Furthermore, we analyse spatial patterns of termite mound islands in the surroundings of Kafue National Park und Bangweulu Plains / Kasanka National Park based on remote sensing imagery. Our results confirm that competition among colonies of large termitaria in homogeneous habitats causes very regular spatial patterns.

How do coupled models represent the African Easterly Jets and their associated dynamics over Central Africa during the September–November rainy season?

Climate models are vital to the assessment of the impacts of climate change in the Central African regions. Establishing how well models reproduce key processes is important to the confidence we attach to these tools. This study examines model representation of the September to November characteristics, such as location and intensity, of the African Easterly Jet (AEJ) north and south in a sample of 16 commonly evaluated CMIP5 and CMIP6 models and in two reanalyses (ERA5 and MERRA2). The analysis evolves to assess key drivers of the AEJ from energetic interactions, the characteristics of mid-level highs and thermal lows and the nature of surface thermal heating. Over West Africa, several models miss the southeast-northwest orientation of the AEJ-N core, leading to a gap of around 60 in the location of the jet while most CMIP5 models also fail to locate AEJ-S over southern Central Africa. In general, the spread of simulated AEJ locations around reanalyses is larger for the CMIP5 sample compared to CMIP6 equivalent models, indicating improvement from CMIP5 to CMIP6 in this 16 model subset. However, this improvement in some CMIP6 models (e.g. GISS-E2-1-G and MIROC6) is not related to a maximum surface meridional gradient in temperature. Most CMIP5 and CMIP6 models underestimate the surface temperature gradient over AEJ-N region. As a first order diagnostic of the jet's acceleration, most coupled models better simulate the atmospheric energetic interactions over AEJ-N region that leads to its strong contribution to AEJ-N maintenance compared to AEJ-S. This study strengthens our understanding of the mid-level circulation over Central Africa by detecting gaps in the mechanisms maintaining the AEJ in coupled models and highlights processes that should be improved in future ensembles.

Observations of supermicron-sized aerosols originating from biomass burning in southern Central Africa

During the 3 years of the ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) campaign, the NASA Orion P-3 was equipped with a 2D stereo (2D-S) probe that imaged particles with maximum dimension (D) ranging from 10 < D < 1280 μm. The 2D-S recorded supermicron-sized aerosol particles (SAPs) outside of clouds within biomass burning plumes during flights over the southeastern Atlantic off Africa’s coast. Numerous SAPs with 10 < D < 1520 μm were observed in 2017 and 2018 at altitudes between 1230 and 4000 m, 1000 km from the coastline, mostly between 7–11° S. No SAPs were observed in 2016 as flights were conducted further south and further from the coastline. Number concentrations of refractory black carbon (rBC) measured by a single particle soot photometer ranged from 200 to 1200 cm−3 when SAPs were observed. Transmission electron microscopy images of submicron particulates, collected on Holey carbon grid filters, revealed particles with potassium salts, black carbon (BC), and organics. Energy-dispersive X-ray spectroscopy spectra also detected potassium, a tracer for biomass burning. These measurements provided evidence that the submicron particles originated from biomass burning. NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) 3 d back trajectories show a source in northern Angola for times when large SAPs were observed. Fire Information for Resource Management System (FIRMS) Moderate Resolution Imaging Spectroradiometer (MODIS) 6 active fire maps showed extensive biomass burning at these locations. Given the back trajectories, the high number concentrations of rBC, and the presence of elemental tracers indicative of biomass burning, it is hypothesized that the SAPs imaged by the 2D-S are examples of BC aerosol, ash, or unburned plant material.

Projected future daily characteristics of African precipitation based on global (CMIP5, CMIP6) and regional (CORDEX, CORDEX-CORE) climate models

We provide an assessment of future daily characteristics of African precipitation by explicitly comparing the results of large ensembles of global (CMIP5, CMIP6) and regional (CORDEX, CORE) climate models, specifically highlighting the similarities and inconsistencies between them. Results for seasonal mean precipitation are not always consistent amongst ensembles: in particular, global models tend to project a wetter future compared to regional models, especially over the Eastern Sahel, Central and East Africa. However, results for other precipitation characteristics are more consistent. In general, all ensembles project an increase in maximum precipitation intensity during the wet season over all regions and emission scenarios (except the West Sahel for CORE) and a decrease in precipitation frequency (under the Representative Concentration Pathways RCP8.5) especially over the West Sahel, the Atlas region, southern central Africa, East Africa and southern Africa. Depending on the season, the length of dry spells is projected to increase consistently by all ensembles and for most (if not all) models over southern Africa, the Ethiopian highlands and the Atlas region. Discrepancies exist between global and regional models on the projected change in precipitation characteristics over specific regions and seasons. For instance, over the Eastern Sahel in July–August most global models show an increase in precipitation frequency but regional models project a robust decrease. Global and regional models also project an opposite sign in the change of the length of dry spells. CORE results show a marked drying over the regions affected by the West Africa monsoon throughout the year, accompanied by a decrease in mean precipitation intensity between May and July that is not present in the other ensembles. This enhanced drying may be related to specific physical mechanisms that are better resolved by the higher resolution models and highlights the importance of a process-based evaluation of the mechanisms controlling precipitation over the region.

Human impact on landscapes in early Africa

Archaeology Although fire has been used by many cultures to improve the availability of subsistence resources, the antiquity of this practice is poorly understood. Thompson et al. investigated the northern basin of Lake Malawi in southern-central Africa using archaeological, geomorphological, and palaeoecological data and reconstructed the environmental context of the Middle Stone Age hunters and gatherers who lived in this region around 92,000 years ago. These peoples used fire to clear forests and thin understory growth. The signature of these fires differs from those created by natural phenomena and signals an abrupt transformation of regional ecology when compared with earlier periods. This record of anthropogenic burning is much earlier than similar practices in prehistory. Sci. Adv. 10.1126/sciadv.abf9776 (2021).

Early human impacts and ecosystem reorganization in southern-central Africa.

Modern Homo sapiens engage in substantial ecosystem modification, but it is difficult to detect the origins or early consequences of these behaviors. Archaeological, geochronological, geomorphological, and paleoenvironmental data from northern Malawi document a changing relationship between forager presence, ecosystem organization, and alluvial fan formation in the Late Pleistocene. Dense concentrations of Middle Stone Age artifacts and alluvial fan systems formed after ca. 92 thousand years ago, within a paleoecological context with no analog in the preceding half-million-year record. Archaeological data and principal coordinates analysis indicate that early anthropogenic fire relaxed seasonal constraints on ignitions, influencing vegetation composition and erosion. This operated in tandem with climate-driven changes in precipitation to culminate in an ecological transition to an early, pre-agricultural anthropogenic landscape.

Kobus vardonii(Artiodactyla: Bovidae)

AbstractKobus vardonii (Livingstone, 1857) is a bovid commonly known as the puku. It is a medium-sized antelope with a golden-yellow coat and white underparts, sexually dimorphic as only males carry lyre-shaped horns, and according to current taxonomy it is one of 12 extant species in the genus Kobus. Adult males defend territories, whereas females and young move around in unstable groups. Feeding on a great variety of grasses, K. vardonii occurs in grasslands along rivers and lakes in southern central Africa with Zambia being the center of its distribution and Tanzania holding the largest population. It is classified as “Near Threatened” on the IUCN Red List of Threatened Species.

Increase in Antiretroviral Therapy Enrollment Among Persons with HIV Infection During the Lusaka HIV Treatment Surge - Lusaka Province, Zambia, January 2018-June 2019.

Within Zambia, a landlocked country in southern-central Africa, the highest prevalence of human immunodeficiency virus (HIV) infection is in Lusaka Province (population 3.2 million), where approximately 340,000 persons are estimated to be infected (1). The 2016 Zambia Population-based HIV Impact Assessment (ZAMPHIA) estimated the adult HIV prevalence in Lusaka Province to be 15.7%, with a 62.7% viral load suppression rate (HIV-1 RNA <1,000 copies/mL) (2). ZAMPHIA results highlighted remaining treatment gaps in Zambia overall and by subpopulation. In January 2018, Zambia launched the Lusaka Province HIV Treatment Surge (Surge project) to increase enrollment of persons with HIV infection onto antiretroviral therapy (ART). The Zambia Ministry of Health (MoH), CDC, and partners analyzed the U.S. President's Emergency Plan for AIDS Relief (PEPFAR) Monitoring and Evaluation Reporting data set to assess the effectiveness of the first 18 months of the Surge project (January 2018-June 2019). During this period, approximately 100,000 persons with positive test results for HIV began ART. These new ART clients were more likely to be persons aged 15-24 years. In addition, the number of persons with documented viral load suppression doubled from 66,109 to 134,046. Lessons learned from the Surge project, including collaborative leadership, efforts to improve facility-level performance, and innovative strategies to disseminate successful practices, could increase HIV treatment rates in other high-prevalence settings.

Recurrent Collection of Drosophila melanogaster from Wild African Environments and Genomic Insights into Species History.

A long-standing enigma concerns the geographic and ecological origins of the intensively studied vinegar fly, Drosophila melanogaster. This globally distributed human commensal is thought to originate from sub-Saharan Africa, yet until recently, it had never been reported from undisturbed wilderness environments that could reflect its precommensal niche. Here, we document the collection of 288 D. melanogaster individuals from multiple African wilderness areas in Zambia, Zimbabwe, and Namibia. The presence of D. melanogaster in these remote woodland environments is consistent with an ancestral range in southern-central Africa, as opposed to equatorial regions. After sequencing the genomes of 17 wilderness-collected flies collected from Kafue National Park in Zambia, we found reduced genetic diversity relative to town populations, elevated chromosomal inversion frequencies, and strong differences at specific genes including known insecticide targets. Combining these genomes with existing data, we probed the history of this species’ geographic expansion. Demographic estimates indicated that expansion from southern-central Africa began ∼13,000 years ago, with a Saharan crossing soon after, but expansion from the Middle East into Europe did not begin until roughly 1,800 years ago. This improved model of demographic history will provide an important resource for future evolutionary and genomic studies of this key model organism. Our findings add context to the history of D. melanogaster, while opening the door for future studies on the biological basis of adaptation to human environments.

Historical Trajectory in Vegetation Cover in Northeastern Namibia Based on AVHRR Satellite Imagery (1982–2015)

The negative impact of the reduction of vegetation cover is already being felt in the Zambezi Region in northeastern Namibia. The region has been undergoing various land cover changes in the past decades. To understand the historical trend of vegetation cover (increase or decrease), we analyzed 8-km resolution Global Inventory Monitoring and Modeling Studies (GIMMS) from the Advanced Very High Resolution Radiometer (AVHRR) and 0.25° × 0.25° (resampled to 8 km) resolution Global Precipitation Climatology Center (GPCC). We used the Time Series Segmented Residual Trends (TSS-RESTREND) method. We found that the general trajectory of vegetation cover was negative. Pixel-wise analysis and visual interpretation of historical images both revealed clear signs of vegetation cover change. We observed a single breakpoint in the vegetation trajectory which correlated to the 1991–1992 drought in southern Central Africa. Potential drivers of land cover change are the (il)legal expansion of subsistence farming, population growth, and wood extraction. These findings will serve as a reference for decision makers and policymakers. To better understand the human-induced land cover change at the micro scale and sub-regional level, we recommend using higher resolution remote sensing datasets and historical documents to assess the effect of demographic change, disease, civil unrest, and war.

Redescription of Ceriagrion mourae with notes on its position in the genus Ceriagrion (Odonata: Coenagrionidae)

The poorly known Ceriagrion mourae is redescribed based on the first material from Zambia and compared with the similar C. banditum, C. junceum and C. suave. Molecular data place C. mourae as a sister taxon to the clade (C. bakeri (C. banditum, C. junceum)). Genetic distances between the above-mentioned species are similar at c.7–9% (K2P). Analysis of all published Ceriagrion COI sequences revealed a barcoding gap (c.2–6.5%) in the pairwise distance distribution and grouped African sequences according to the known species, except C. suave and C. glabrum. C. mourae was only found at a pool on a temporary stream, which differed from others in the study area by its combination of vegetation and shading. The Zambian locality and two earlier known sites in Mozambique and Tanzania are scattered across the plains and low hills of eastern and southern central Africa.

Copper, Trade and Polities: Exchange Networks in Southern Central Africa in the 2nd Millennium CE

A rare, scattered resource in Central Africa, copper was produced in the Copperbelt since the 4th–7th centuries CE and traded over large distances from the 9th to the 19th centuries. It was exchanged mainly in the form of cross-shaped ingots, also called croisettes, varying in form and size over time and space. In this article, we explore and compare the spatial distribution of these ingots over time. This approach offers an opportunity to study pre-colonial trade. Indeed, during the 2nd millennium CE, the use of the same type of ingots is attested in distant regions, from the Great Zimbabwe area to the Upemba depression (north Katanga, Democratic Republic of Congo [DRC]). Over the centuries, changes in geographic distribution patterns and styles indicate shifts in contacts and the appearance of new boundaries. These variations reflect changes in the regional distribution networks and suggest areas of exclusive political influence. Historical information available for the 19th century shows that it is possible to link the diffusion of copper with political entities, a hypothesis supported by evidence related to other kinds of production, such as ceramics and salt. For remote periods, confrontation of the croisettes’ distribution with other aspects of material culture suggests that such links between socio-political spaces and copper distribution may also have occurred in the distant past.

Y-chromosomal evidence of a pastoralist migration through Tanzania to southern Africa

Although geneticists have extensively debated the mode by which agriculture diffused from the Near East to Europe, they have not directly examined similar agropastoral diffusions in Africa. It is unclear, for example, whether early instances of sheep, cows, pottery, and other traits of the pastoralist package were transmitted to southern Africa by demic or cultural diffusion. Here, we report a newly discovered Y-chromosome-specific polymorphism that defines haplogroup E3b1f-M293. This polymorphism reveals the monophyletic relationship of the majority of haplotypes of a previously paraphyletic clade, E3b1-M35*, that is widespread in Africa and southern Europe. To elucidate the history of the E3b1f haplogroup, we analyzed this haplogroup in 13 populations from southern and eastern Africa. The geographic distribution of the E3b1f haplogroup, in association with the microsatellite diversity estimates for populations, is consistent with an expansion through Tanzania to southern-central Africa. The data suggest this dispersal was independent of the migration of Bantu-speaking peoples along a similar route. Instead, the phylogeography and microsatellite diversity of the E3b1f lineage correlate with the arrival of the pastoralist economy in southern Africa. Our Y-chromosomal evidence supports a demic diffusion model of pastoralism from eastern to southern Africa approximately 2,000 years ago.

The woodland vegetation of the Katavi-Rukwa ecosystem in western Tanzania

We describe tree diversity, forest community composition and vegetation structure in dry forest miombo woodland in the Katavi-Rukwa ecosystem of western Tanzania. Tree diversity was high (45 families, 117 genera, 229 species) and concentrated in the Fabaceae (30 genera, 73 species). A strong majority (75%) of 19,481 sampled trees were aggregated in just 12 genera spread among 11 families, with individuals in the genera Grewia (17.42%), Markhamia (13.20%) and Combretum (13.13%) dominating abundance. Assessing dominance in terms of a combined importance value (IV300, summed relative abundance, basal area and frequency), showed Terminalia sericea, Combretum adenogonium, and C. colinum as the dominant tree species. Thus, woodlands in this region are atypical of the miombo biome in which it is embedded with only six of fifty 0.1 ha quantitative plots dominated by species in one of the classic miombo genera ( Brachystegia, Julbernardia, or Isoberlinia). Ordination of data from these 50 plots revealed a diffuse structure of communities. Moreover, trees were found to be spatially clumped within, as well as among, plots. By documenting how the Katavi-Rukwa ecosystem is comprised of a patchwork of locally dominant common trees intermixed with a diverse assemblage of less common species, which have few specific associations with particular dominants, our study begins to fill an important gap in understanding composition and structure of dry forests that still occupy so much of southern-central Africa.

Three major tree nut oils of southern central Africa: Their uses and future as commercial base oils

Summary There is a pressing need for sustainability of the ecology and environment of Africa. Deforestation is taking place at an alarming rate, and this situation will continue to escalate unless local communities can be given a sufficiently attractive and viable reason to look after their forests and animals. The development of international markets for the tree seed oils is a major step towards solving this growing dilemma. In Zambia the development of sustainable harvest systems and market outlets for the highly valued indigenous tree seed oils, along with the establishment of sustainable wild harvest for ‘non-timber forest products’ to accredited international certification criteria has enable sustainable livelihoods for large numbers of disadvantaged rural communities from indigenous plant products at the same time as helping to maintain the natural environment.

Seed dispersal of Acacia erioloba by African bush elephants in Hwange National Park, Zimbabwe

Approximately two‐thirds (64%) of all dry season samples of elephant dung analysed during a 3‐year study in the Main Camp subregion of Hwange National Park, Zimbabwe, contained seed and/or pod materials from Acacia erioloba. Most seeds were recovered intact and actively germinating seeds were not uncommon. Very little pod mass relative to seed mass was recovered in most instances, with pod fragments recorded from only 56% of all exhaustively sampled elephant dung piles containing A. erioloba fruit materials. Nonetheless, large pod fragments and even entire intact pods were recovered occasionally from elephant dung. Seeds and pods of A. erioloba may comprise 12% or more of total wet‐weight dung mass; individual dung piles were found which contained &gt; 5000 A. erioloba seeds. Birds and smaller mammals search out and consume A. erioloba seeds present within elephant dung piles. The findings of this study indicate that potential digestibility of A. erioloba seeds for bush elephants (Loxodonta africana africana) may be much higher than expected from previous studies. In controlled feeding trials with captive bush elephants (age 11–15 years old) maintained on predominantly free‐range dry season diets, the estimated efficiency of digestion for A. erioloba seeds consumed in pods was 81% to 96%, with a gut‐transit time of between 24.5 and 36.0 h. On the basis of throughput times determined in experimental feeding trials, potential elephant‐dispersal distances of 20–50 km are predicted for A. erioloba in the Kalahari Sands landscapes of southern central Africa.

The status of elephant on the Zambian bank of the Middle Zambezi Valley

The elephant population in the middle Zambezi has been one of the most heavily affected by hunting in southern Central Africa. Since the 15th Century when the Portuguese invaded the area, elephants have never recovered from legal and illegal hunting. In 1991 a survey covering 1,270 sq kms revealed a total of 359, almost half of the number which existed in 1970. Results revealed a high illegal off take and inadequate policy by wildlife authorities in the area.