Southeastern Africa Research Articles

Temperature change in subtropical southeastern Africa during the past 790,000 yr

Abstract Across the glacial-interglacial cycles of the late Pleistocene (∼700 k.y.), temperature variability at low latitudes is often considered to have been negligible compared to changes in precipitation. However, a paucity of quantified temperature records makes this difficult to reliably assess. In this study, we used the Bayesian method CREST (Climate REconstruction SofTware) to produce a 790,000 yr quantified temperature reconstruction from a marine pollen record from southeast Africa. The results reveal a strong similarity between temperature variability in subtropical Africa and global ice volume and CO2 concentrations, indicating that temperature in the region was not controlled by local insolation, but followed global trends at these time scales, with an amplitude of ∼4 °C between glacial minima and interglacial maxima. The data also enabled us to make an assessment of the impact of temperature change on pollen diversity, with results showing there is no link between glacial-age temperatures/CO2 and a loss of diversity in this record.

Multivariate framework for the assessment of key forcing to Lake Malawi level variations in non-stationary frequency analysis

Lake Malawi in south eastern Africa is a very important freshwater system for the socio-economic development of the riparian countries and communities. The lake has however experienced considerable recession in the levels in recent years. Consequently, frequency analyses of the lake levels premised on time-invariance (or stationarity) in the parameters of the underlying probability distribution functions (pdfs) can no longer be assumed. In this study, the role of hydroclimate forcing factors (rainfall, lake evaporation, and inflowing discharge) and low frequency climate variability indicators (e.g., El Nino Southern Oscillation-ENSO and the Indian Ocean Dipole Mode-IODM) on lake level variations is investigated using a monthly mean lake level dataset from 1899 to 2017. Non-stationarity in the lake levels was tested and confirmed using the Mann-Kendall trend test (α = 0.05 level) for the first moment and the F test for the second moment (α = 0.05 level). Change points in the series were identified using the Mann-Whitney-Pettit test. The study also compared stationary and non-stationary lake level frequency during 1961 to 2004, the common period where data were available for all the forcing factors considered. Annual maximum series (AMS) and peak over threshold (POT) analysis were conducted by fitting various candidate extreme value distributions (EVD) and parameter fitting methods. The Akaike information criteria (AIC), Bayesian information criteria (BIC), deviance information criteria (DIC), and likelihood ratios (RL) served as model evaluation criteria. Under stationary conditions, the AMS when fitted to the generalized extreme value (GEV) distribution with maximum likelihood estimation (MLE) was found to be superior to POT analysis. For the non-stationary models, open water evaporation as a covariate of the lake levels with the GEV and MLE was found to have the most influence on the lake level variations as compared with rainfall, discharge, and the low frequency climatic forcing. The results are very critical in flood zoning especially with various planned infrastructural developments around the lakeshore.

Endemic and Emerging Arboviruses of Mosquitoes in Ecuador

Arboviruses are arthropod-borne viruses that include many viruses of public health concern found in Ecuador. Dengue virus, yellow fever virus and Zika virus are in the Flaviridae family (1), while chikungunya virus and Mayaro virus are in the Togaviridae family (1). Yellow fever has circulated throughout the tropics since at least the17th century, with the first recorded outbreak in Latin America in 1647 (2), with the virus being identified in 1927 (3). Dengue virus is also a long-time source of global outbreaks and was identified in 1943 (4). Dengue has four virus serotypes (DENV 1-4), allowing for repeated infection of individuals. Chikungunya, Zika and Mayaro were identified as causes of febrile disease more recently: the Zika virus was isolated from a monkey in 1947 in Uganda (5), chikungunya virus during an outbreak in south-eastern Africa in 1952 (1), and Mayaro virus from a patient in Trinidad in 1954 (6). Chikungunya has four genotypes: East/Central/South African, Western African, Indian Ocean and Asian (1), while Zika has two genetics lineages: Asian and African (7). Ecuador is susceptible to introductions of arboviruses transmitted by several mosquito vectors that are either well established or recently introduced and has thus experienced multiple and repeated introductions of these diseases. Of these, at present, only yellow fever has a widely available and licensed vaccine.

Observed changes in dry-season water availability attributed to human-induced climate change

Human-induced climate change impacts the hydrological cycle and thus the availability of water resources. However, previous assessments of observed warming-induced changes in dryness have not excluded natural climate variability and show conflicting results due to uncertainties in our understanding of the response of evapotranspiration. Here we employ data-driven and land-surface models to produce observation-based global reconstructions of water availability from 1902 to 2014, a period during which our planet experienced a global warming of approximately 1 °C. Our analysis reveals a spatial pattern of changes in average water availability during the driest month of the year over the past three decades compared with the first half of the twentieth century, with some regions experiencing increased and some decreased water availability. The global pattern is consistent with climate model estimates that account for anthropogenic effects, and it is not expected from natural climate variability, supporting human-induced climate change as the cause. There is regional evidence of drier dry seasons predominantly in extratropical latitudes and including Europe, western North America, northern Asia, southern South America, Australia and eastern Africa. We also find that the intensification of the dry season is generally a consequence of increasing evapotranspiration rather than decreasing precipitation. Regional changes in dry-season water availability over recent decades can be attributed to human-induced climate change, according to analyses of global reconstructions.

Demographic responses of forest-utilizing bats to past climate change in South Africa

AbstractHistorical forest contractions may have restricted the distributions of forest-utilizing fauna while providing opportunities for range expansions for open-habitat species. We aimed to test if habitat associations have played an important role in determining population genetic structure and demographic responses of six bats to oscillations in forest extent since the Last Glacial Maximum (LGM). We hypothesized that forest-associated species would display high levels of population structure and past population contractions as their distribution is dependent on fragmented forests. By contrast, habitat generalists would demonstrate low geographical structuring and historical population stability as suitable habitats are widely available. We used mitochondrial DNA to generate genetic diversity and population structure metrics of three forest-associated species and three habitat generalists in South Africa. Neutrality tests and Bayesian skyline plots were used to investigate demographic histories. A forest habitat association did not inform the population genetics of the study species. Rather, species-specific traits of roosting requirements, philopatry to the natal range and dispersal ability informed the observed structure. All species demonstrated population expansions during the Pleistocene, with no apparent decline during the LGM. It appears that the lower climate change footprint and refuge-status of eastern South Africa prevented population declines of insectivorous bats during the LGM.

Using Photo Voltage Solar and Light Emitting Diodes to Reduce Energy Consumption: Case Study in Port Sudan City

Port Sudan city is a capital of the Red Sea State in the republic of Sudan in south-eastern Africa. The city has high consumption of power for street lighting. The lighting is needed for 12 h/day. This consumes about 11.5 Mw day. The aim of this paper is study the proposed system to reduce the streetlight power consumption use in Port Sudan City and to explore the renewable energy to work alternative energy sources. The present paper studies the proposed system called (all-in-one) street lighting system consisting of PV panel, lithium ion battery and light sensor with LED lamp, all connected and constructed in single unit. The proposed system is to be used in Port Sudan city to decrease the electricity consumption, especially in summer. The problem has been treated theoretically. The proposed system has been compared with two types of plant the first plant used 250W lamp Ac and the second plant used 100W LED lamp. The results show that the proposed system has low cost, about 80 USD and much better economically. The proposed system can solve the power loss in Port Sudan city, saving 11.5 Mw day for this city and more than 428,000 SUP/day. The results show that the proposed system could be utilized to reduce lighting consumption, save energy and developments on environment. We therefore recommended to uses the proposed system in many countries not only in Port Sudan City.

Irrigators’ willingness to pay for the adoption of soil moisture monitoring tools in South-Eastern Africa

ABSTRACT Contingent valuation is used to elicit irrigators’ willingness to pay for soil moisture tools in irrigation schemes in Africa, with various econometric methods employed to mitigate potential bias. Key results include that there is a neighbourhood effect influencing adoption, and that being located downstream and spending more on irrigation water positively and statistically significantly influenced willingness to pay for tools. The result suggests that although focusing on economic incentives and promoting farmer learning by those using the tools may promote greater adoption, there is likely to still be a need for co-investment by other bodies.

Chemical evidence of dairying by hunter-gatherers in highland Lesotho in the late first millennium AD.

The recovery of Early Iron Age artefacts and domestic animal remains from hunter-gatherer contexts at Likoaeng, Lesotho, has been argued to indicate contact between highland hunter-gatherers and Early Iron Age agropastoralist communities settled in lowland areas of southeastern Africa during the second half of the first millennium AD. However, disagreement between archaeozoological studies and ancient DNA means that the possibility that those hunter-gatherers kept livestock themselves remains controversial. Here we report analyses of pottery-absorbed organic residues from two hunter-gatherer sites and one agriculturalist site in highland Lesotho to reconstruct prehistoric subsistence practices. Our results demonstrate the exploitation of secondary products from domestic livestock by hunter-gatherers in Lesotho, directly dated to the seventh century AD at Likoaeng and the tenth century AD at the nearby site of Sehonghong. The data provide compelling evidence for the keeping of livestock by hunter-gatherer groups and their probable incorporation as ancillary resources into their subsistence strategies.

Assessing spatiotemporal settlement patterns in Eastern Free State, South Africa, pre and post transition from apartheid to majority rule

Spatial patterns of human settlements, their changes and their geographical implications are important for understanding the drivers of land use and land cover change. This paper examines the spatiotemporal pattern of settlement development in three different settlements of Thabo Mofutsanyane municipal district namely Harrismith, Vrede and Ladybrand using GIS, remote sensing and spatial metrics techniques. The study is based on 30 years of time-series data compiled from satellite images with emphasis on pre and post 1994’s (the year of change in government from apartheid to majority rule) spatial change in settlement development. Landsat 4–5 imageries for 1989, 1999, 2009 and Landsat 8 OLI for 2018 were downloaded and classified for land use/land cover change (LULCC). Also, landscape and class metrics were computed using Fragstats QGIS 2.18.9 to generate spatial analysis. A dynamic spatial pattern is observed in the settlements under study. Urban built-up areas had a rapid trend of growth in Harrismith from 1989 (5 years before transition from apartheid to majority rule) to 1999 (5 years after transition from apartheid to majority rule) but later slowed down in the subsequent years under study while Ladybrand and Vrede had moderate growth trend in the subsequent years under study. The settlement development process has developed fragmented and heterogeneous land use combinations in the years after 1994. At landscape level, land fragmentation occurred due to land use changes and significant urban expansion; Ladybrand experienced more physical connectedness than Harrismith and Vrede. While at class level, Harrismith and Vrede are more aggregated or physically connected than Ladybrand; this means Ladybrand was relatively more fragmented than the other two settlements. The study results show that a LULCC and landscape metrics integrated approach is effective to analyse and describe the spatial patterns of urban landscapes.

Topographic, Hydraulic, and Vegetative Controls on Bar and Island Development in Mixed Bedrock‐Alluvial, Multichanneled, Dryland Rivers

AbstractWe investigate processes of bedrock‐core bar and island development in a bedrock‐influenced anastomosed reach of the Sabie River, Kruger National Park, eastern South Africa. For sites subject to alluvial stripping during an extreme flood event (~4,470–5,630 m3 s−1) in 2012, preflood and postflood aerial photographs and LiDAR data, 2‐D morphodynamic simulations, and field observations reveal that the thickest surviving alluvial deposits tend to be located over bedrock topographic lows. At a simulated peak discharge (~4,500 m3 s−1), most sediment (sand, fine gravel) is mobile but localized deposition on bedrock topographic highs is possible. At lower simulated discharges (<1,000 m3 s−1), topographic highs are not submerged, and deposition occurs in lower elevation areas, particularly in areas disconnected from the main channels during falling stage. Field observations suggest that in addition to discharge, rainwash between floods may redistribute sediments from bedrock topographic highs to lower elevation areas, and also highlight the critical role of vegetation colonization in bar stability, and in trapping of additional sediment and organics. These findings challenge the assumptions of preferential deposition on topographic highs that underpin previous analyses of Kruger National Park river dynamics, and are synthesized in a new conceptual model that demonstrates how initial bedrock topographic lows become topographic highs (bedrock‐core bars and islands) in the latter stages of sediment accumulation. The model provides particular insight into the development of mixed bedrock‐alluvial anastomosing along the Kruger National Park rivers, but similar processes of bar/island development likely occur along numerous other bedrock‐influenced rivers across dryland southern Africa and farther afield.

High-resolution geochemical records of extreme drought in southeastern Africa during the past 7000 years

The magnitude and frequency of extreme events is projected to increase under future climate change and understanding the major drivers of global climate variability is dependent on the development of detailed records from critical regions. Subtropical Africa is known to have undergone phases of significant change resulting from variations in broad-scale atmospheric and oceanic circulation patterns, but the nature and cause for these variations remain intensely debated. Here we present a highly resolved sedimentary record from the eastern margin of South Africa to reconstruct hydroclimate in southeast Africa over the past 7000 years. Stratigraphic and inorganic proxies preserve a highly sensitive record that document dramatic shifts in moisture balance, with phases of severe drought recorded at 4700–4200 and 3700–2600 cal yr BP. We suggest that pronounced hydroclimate variability observed in the Mkhuze record was likely triggered by changes in the activity of El Niño-Southern Oscillation (ENSO), which acted to control the transport of moisture from the Indian Ocean across southeast Africa. We show that rapid shifts in moisture availability were a characteristic feature of mid-late Holocene climate across the summer rainfall region of southern Africa, with these events broadly anti-phased with hydroclimatic shifts in East Africa and northwest Madagascar. These findings suggest that evaluating drought frequency, ecological risk and food security within the region is likely to be closely tied to ENSO and its response to future global warming.

Recent diversification of Chrysoritis butterflies in the South African Cape (Lepidoptera: Lycaenidae)

Although best known for its extraordinary radiations of endemic plant species, the South African fynbos is home to a great diversity of phytophagous insects, including butterflies in the genus Chrysoritis (Lepidoptera: Lycaenidae). These butterflies are remarkably uniform morphologically; nevertheless, they comprise 43 currently accepted species and 68 currently valid taxonomic names. While many species have highly restricted, dot-like distributions, others are widespread. Here, we investigate the phylogenetic and biogeographic history underlying their diversification by analyzing molecular markers from 406 representatives of all described species throughout their respective ranges. We recover monophyletic clades for both C. chrysaor and C. thysbe species-groups, and identify a set of lineages that fall between them. The estimated age of divergence for the genus is 32 Mya, and we document significantly rapid diversification of the thysbe species-group in the Pleistocene (~2 Mya). Using ancestral geographic range reconstruction, we show that West Fynbos is the most likely region of origin for the radiation of the thysbe species-group. The colonization of this region occurred 9 Mya and appears to have been followed by a long period of relative stasis before a recent increase in diversification. Thus, the thysbe radiation does not appear to have resulted from the colonization of new biogeographic areas. Rather, the impact of species interactions (with ants and plants), the appearance of key innovations, and/or the opening of new ecological niche space in the region might explain the sudden burst of speciation that occurred in this group 2 Mya. The biogeographic model suggests two different diversification processes with few historical cross-colonisations, one in eastern South Africa for the C. chrysaor group and the other in western South Africa for the remaining taxa. Distributional range assessments and ecological niche models for each species show important niche overlap, and in a few cases, complete overlap. However, these shared traits are not explained by phylogenetic history. Chrysoritis taxa frequently fly in sympatry and gene tree reticulation appears to be widespread at the species level, suggesting that several episodes of range shifts might have led to secondary sympatries, allowing limited gene flow that challenges species delimitation efforts. In addition, the unusually high diversification rate for the thysbe clade of 1.35 [0.91–1.81] lineages per million years also suggests the possibility of taxonomic oversplitting. The phylogeny presented here provides a framework for a taxonomic revision of the genus. We highlight cases of potential synonymy both in allopatry and sympatry, and stress the importance of dedicated studies to assess potential pre- and post-zygotic barriers giving rise to species delimitations of the thysbe group.

The provisioning of nineteenth century Zulu capitals, South Africa: Insights from strontium isotope analysis of cattle remains

This study examines animal provisioning at royal capitals in the Zulu Kingdom, the most powerful polity in south-eastern Africa during the nineteenth century (c. 1816–1879). Historical records indicate the royal family and its retainers at the king’s residence (royal amakhanda) were supported by the collection of surpluses from rural chiefdoms and special herds and crops worked by the army, while regiments were largely sustained by the homesteads from which they originated. It is implied that cattle were acquired through a combination of local production, tribute from allied chiefdoms, and plunder from raiding. In this paper, we present the first archaeological evidence for cattle mobility through Sr ratios (87Sr/86Sr) for 46 cattle teeth and one sheep/goat tooth from King Dingane’s capital at uMgungundlovu in the emaKhosini basin (1828–1839). Relative to a local biologically available strontium isotope framework we establish for the basin, the results show that over half the cattle were raised within the basin. Regional isotopic data indicate cattle were transferred from herd land to the west of the capital, by tribute or expropriation in the south of the kingdom, and raiding is suggested by cattle from areas controlled by the Swazi Kingdom to the north.

A synoptic review of the aloes (Asphodelaceae, Alooideae) of KwaZulu-Natal, an ecologically diverse province in eastern South Africa.

The KwaZulu-Natal province of South Africa has a varied topography, geology and climate and presents diverse habitats that support a rich and diverse flora. Aloes are well represented in KwaZulu-Natal, with four genera [Aloe L., Aloiampelos Klopper & Gideon F.Sm., Aloidendron (A.Berger) Klopper & Gideon F.Sm. and Aristaloe Boatwr. & J.C.Manning] and 49 taxa occurring in the province. Fourteen of these are endemic and eleven near-endemic to the province. A floristic treatment of the aloes of KwaZulu-Natal is presented in the form of a synoptic review. Included are an identification key to the aloes that occur naturally in the province, species-level distribution maps and accompanying images, so providing for the first time, an atlas of aloe occurrence in this part of the subcontinent.

Moral Majority redivivus

John de Gruchy’s 1995 work Christianity and Democracy: Theology for a Just World Order was published at a heady time, not only in society but in the ecumenical churches, who were prominent as “midwives of democracy.” While the changes in Eastern Europe and South Africa were in the foreground, the book also covered emerging movements for democracy in sub-Saharan Africa outside South Africa. Sadly, De Gruchy’s optimism was not borne out in the decades that followed. Partly, this was due to internal problems within the movements themselves; partly, it was a transformation in the identity of Christianity away from the role of an enabling midwife to that theocratic master. A new kind of Christian politics asserted itself, modelled on and enabled by conservative Christianity in the United States. Moreover, it asserted itself in rivalry to a new “other”: fundamentalist Islam, which succeeded communism as America’s global enemy. This article traces the emergence of this new assertive religious politics, criticizing both its theologically problematic “Christian nationalism” and its lack of concern for sustaining the human rights gains of the early 1990s.

Phylogenetic biogeography of Hamamelidaceae s. l. based on molecular data

«Вестник Санкт-Петербургского университета. Науки о Земле» — научно-теоретический рецензируемый журнал, обобщающий результаты исследований в области геологии, гидрогеологии и геохимии, петрологии и экологии, ландшафтного планирования и геоморфологии, экономической и социальной географии.

A new species of Onitis Fabricius, 1798 from south-eastern Africa (Coleoptera, Scarabaeidae, Scarabaeinae, Onitini).

Onitis albertcollartisp. nov. is described and illustrated. The new species is closely related to and occurs sympatrically with O. lycophron Klug, 1855.

Mid- and low latitude effects on eastern South African rainfall over the Holocene

Climate variability and its forcings in eastern South Africa during the late Quaternary remain poorly understood with data suggesting temporal variability and spatial heterogeneity. To constrain the variability and the drivers of past climate, we explore vegetation (C3/C4) and hydrological change using stable carbon and hydrogen isotopes of plant-waxes and X-ray fluorescence (XRF) analysis in marine core GeoB20610-2 offshore the Limpopo River. We find evidence for two climatic phases: an initial arid phase (c. 7–3 cal kyr BP), followed by a wetter phase (c. 3–0 cal kyr BP). To put our findings into a regional context, we investigate a latitudinal transect of sites along eastern South Africa and divide the region into three distinct hydro-climatic zones, with significantly different climate drivers. During the last c. 3 cal. ka BP, wet climatic conditions dominated the northern summer rainfall zone (SRZ) and the southern South African zone (SSAZ), whereas arid conditions prevailed in the central and eastern SRZ. In the northern SRZ the climate was driven by local insolation, where heightened insolation resulted in more precipitation. The aridity during the last c. 3 cal. ka BP in the central and eastern SRZ and the increased humidity in the SSAZ are attributed to an equatorward displacement of the southern hemisphere westerlies, the South African high-pressure cell and the South Indian Ocean Convergence Zone (SIOCZ). For the Holocene we find little evidence for an Indian Ocean SST control on climate. The results for the Limpopo River catchment region highlight the spatial heterogeneity of Holocene climate conditions in eastern South Africa and indicate significant latitudinal differences in climate drivers.

The role of drought in agrarian crisis and social change: the famine of the 1890s in south-eastern Africa

During the second half of the 1890s, south-eastern Africa was hit by a drought-driven ecological crisis. Using records previously unexploited for climate and climate impact research, and which cover the area from modern-day Zimbabwe and Botswana to eastern South Africa, this study explores the complexity of this crisis through an analysis of the spatial extent, duration and severity of the regional drought and its associated socio-economic and environmental repercussions. This interdisciplinary study stands at the nexus of environmental, economic and social history. The records used include (a) British administrative sources, (b) reports and letters by members of various Protestant missionary societies from diverse environments across the study area, together with (c) local newspapers. Analysis of these materials reveals that generally the period was marked by a sequence of considerably delayed rainy seasons, which in turn negatively impacted upon the rain-fed agriculture. Below-average levels of summer rainfall also adversely affected the development of young crops. The drought was more severe and continuous in the interior of the region than towards the Indian Ocean coast. The prolonged dry conditions were accompanied by, and likely exacerbated, locust outbreaks and the spread of cattle plague (Rinderpest). We demonstrate in this paper that drought, as the original driver of the crisis, triggered a cascade of responses from harvest failure to famine and ultimately led to profound socio-economic change.

Population genetic structure of the thick-tailed bushbaby (Otolemur crassicaudatus) from the Soutpansberg Mountain range, Northern South Africa, based on four mitochondrial DNA regions

Greater bushbabies, strepsirrhine primates, that are distributed across central, eastern and southern Africa, with northern and eastern South Africa representing the species’ most southerly distribution. Greater bushbabies are habitat specialists whose naturally fragmented habitats are getting even more fragmented due to anthropogenic activities. Currently, there is no population genetic data or study published on the species. The aim of our study was to investigate the genetic variation in a thick-tailed bushbaby, Otolemur crassicaudatus, population in the Soutpansberg mountain range, Limpopo Province, South Africa. Four mitochondrial regions, ranging from highly conserved to highly variable, were sequenced from 47 individuals. The sequences were aligned and genetic diversity, structure, as well as demographic analyses were performed. Low genetic diversity (π = 0.0007–0.0038 in coding regions and π = 0.0127 in non-coding region; Hd = 0.166–0.569 in coding regions and Hd = 0.584 in non-coding region) and sub-structuring (H = 2–3 in coding regions and H = 4 in non-coding region) was observed with two divergent haplogroups (haplotype pairwise distance = 3–5 in coding region and 6–10 in non-coding region) being identified. This suggests the population may have experienced fixation of mitochondrial haplotypes due to limited female immigration, which is consistent with philopatric species, that alternative haplotypes are not native to this population, and that there may be male mobility from adjacent populations. This study provides the first detailed insights into the mitochondrial genetic diversity of a continental African strepsirrhine primate and demonstrates the utility of mitochondrial DNA in intraspecific genetic population analyses of these primates.