Drought In Africa Research Articles

Vulnerability and the Impact of Climate Change in South Africa's Limpopo River Basin

With likely long-term changes in rainfall patterns and shifting temperature zones, climate change is expected to increase the frequency of climate-related shocks, such as floods and droughts in Sub-Saharan Africa. For farm households, an increase in the frequency of climate-related income shocks could lead not only to lower expected income, but also to higher income variance, which in turn can cause them to pursue costly risk-coping strategies and to fall below poverty trap thresholds. For this reason, it is important to understand how a changing distribution of risk will lead to increased vulnerability, not just decreased expected income. This brief is based on a paper that uses farm households' responses to climate-related shocks in South Africa's Limpopo River Basin to gauge how farmers are likely to respond to future climate change shocks. The increased frequency and severity of droughts associated with global warming may induce farmers to change their behavior to reduce their risk of negative impacts from future climaterelated shocks. While it is difficult to predict farmers' behavior and how it will affect welfare, coping strategies used in response to shocks today can be used to predict whether and how rural South Africans will cope in the future. The study examines household responses to droughts in 2005 and household vulnerability to future climate change by assessing their probability of falling below an income threshold as a result of future climate-related shocks. Assessing household vulnerability is important because efficient social policy needs to go beyond poverty alleviation in the present to prevent poverty in the future. A poverty reduction strategy that does not distinguish between transient and structural poverty leads to inefficient use of resources, in that it focuses on those who are temporarily poor but may be able to escape poverty on their own, at the expense of those who have a high probability of becoming chronically poor. from text

Modifying land management in order to improve efficiency of rainwater use in the African highlands

Water scarcity and drought in Africa are often in the news. The widespread tendency to relate farmers’ notion of drought to changes in the occurrence of dry spells is misguided: several recent studies have yielded little evidence of an increase in the length and/or frequency of such spells. The farmers’ concept of drought is contextual and an indirect result of land degradation. Plant production suffers because water is not available due to deteriorated physical properties of soil. Farmers’ perception of drought refers to the Green Water Use Efficiency (GWUE), i.e. the fraction of rain that is used for plant transpiration. GWUE in Africa is remarkably low: in sub-Saharan Africa, only 15% of the terrestrial rainwater is used by plants for the production of food, fodder and fibre. Although a millet crop grown under traditional circumstances uses only 50 mm in transpiration, the crop frequently suffers from agricultural drought due to excessive losses of rainwater. A range of land management practices is available to help improve GWUE. They can be classified according to their function. Hedgerow barriers and terraces can mitigate runoff; infiltration rates below hedgerows in Kenya were found to be three to eight times higher than where the crop was grown. Mulch that triggers soil fauna can improve water availability; mulching with straw from a local perennial grass in Burkina Faso doubled the water use efficiency from 1 kg mm −1 without fauna to 2 kg mm −1 with fauna. Water harvesting and water–nutrient synergy can improve water use; in case permeable barriers combined with the use of compost Sorghum yield in Burkina Faso was 2.3 times higher than in the control plots and the plots with the barriers only. Green water deserves more attention from policy makers, planners, land users, water engineers and managers.

The 1877–1878 El Niño episode: associated impacts in South America

At times when attention on climate issues is strongly focused on the assessment of potential impacts of future climate change due to the intensification of the planetary greenhouse effect, it is perhaps pertinent to look back and explore the consequences of past climate variability. In this article we examine a large disruption in global climate that occurred during 1877–1878, when human influence was negligible. The mechanisms explaining this global disturbance are not well established, but there is considerable evidence that the major El Nino episode that started by the end of 1876 and peaked during the 1877–1878 boreal winter contributed significantly to it. The associated regional climate anomalies were extremely destructive, particularly in the Northern Hemisphere, where starvation due to intense droughts in Asia, South-East Asia and Africa took the lives of more than 20 million people. In South America regional precipitation anomalies were typical of El Nino events, with rainfall deficit and droughts in the northern portion of the continent as well as in northeast Brazil and the highlands of the central Andes (Altiplano). In contrast, anomalously intense rainfall and flooding episodes were reported for the coastal areas of southern Ecuador and Northern Peru, as well as along the extratropical West coast of the continent (central Chile, 30° S–40° S), and in the Parana basin in the southeast region. By far the most devastating impacts in terms of suffering and loss of life occurred in the semiarid region of northeast Brazil where several hundreds of thousands of people died from starvation and diseases during the drought that started in 1877.

Long term context for recent drought in northwestern Africa

Anthropogenic climate change is projected to exacerbate midlatitude aridity. Here, we analyze newly developed multi‐century tree‐ring records for a long‐term perspective on drought in Tunisia and Algeria. We use a new set of 13 Cedrus atlantica and Pinus halepensis chronologies with a strong signal for warm‐season drought (May–August) to generate a robust, well‐validated reconstruction of the Palmer Drought Severity Index (PDSI) for the period AD 1456–2002. Key features of the reconstruction reveal the magnitude of pre‐instrumental droughts from the historic record. Remarkably, the most recent drought (1999–2002) appears to be the worst since at least the middle of the 15th century. This drought is consistent with the early signature of a transition to more arid midlatitude conditions, as projected by general circulation models.

DROUGHT AND HUNGER IN AFRICA: DENYING FAMINE A FUTURE. Edited by M. H. Glantz

New Zealand Journal of GeographyVolume 88, Issue 1 p. 22-22 DROUGHT AND HUNGER IN AFRICA: DENYING FAMINE A FUTURE. Edited by M. H. Glantz TIM BRANGWIN, TIM BRANGWINSearch for more papers by this author TIM BRANGWIN, TIM BRANGWINSearch for more papers by this author First published: October 1989 https://doi.org/10.1111/j.0028-8292.1989.tb00816.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume88, Issue1October 1989Pages 22-22 RelatedInformation

ROOT STUDIES ON CACTUS PEARS OPUNTIA FICUS-INDICA AND O. ROBUSTA ALONG A SOIL–WATER GRADIENT

Due to the regular occurrence of drought in southern Africa, there is need for more research on drought tolerant fodder plants such as Opuntia species. The influence of different water applications was evaluated in terms of root and cladode mass, root length, and water-use efficiency for one-year-old cactus pear plants of the species Opuntia ficus-indica (L.) Miller (Morado cultivar) and O. robusta Wendl. (Monterey cultivar). One-year-old cladodes were planted in pots (210 mm diameter × 550 mm deep soil) and grown in the greenhouse at day/night temperatures of 25–30/15–18°C. The water treatments applied were 0–25%, 25–50%, 50–75% and 75–100% depletion of total plant available water. Water-use efficiency (WUE) was defined as the cladode or root dry-mass production per unit of water used. Root mass decreased and root length increased significantly (p < 0.01) for both species with water stress. Due to the finer root system of O. robusta, the root mass was smaller than that of O. ficus-indica. In contrast, the root length/root mass ratio was higher for O. robusta than for O. ficus-indica. The influence of water stress on root die-back was clearly observed in O. ficus-indica but was less noticeable in O. robusta. The lateral roots per taproot increased significantly (p < 0.01) with water stress, with as many as 35 and 70 side roots per taproot for O. ficus-indica and O. robusta, respectively. On average, for all water treatments, the roots of O. ficus-indica and O. robusta composed only 12% and 10%, respectively, of the total plant biomass. In terms of root production, both species used water less efficiently with water stress, but if expressed in terms of cladode production, the WUE decreased for O. ficus-indica and increased for O. robusta with water stress. A water application of only 11 mm was enough to completely hydrate the cladodes of both species at the lowest water treatment. It is clear that O. ficus-indica is more sensitive to water stress than O. robusta. The unique root systems of these species make them adaptable under especially dry conditions.

Gene action controlling grain yield and secondary traits in southern African maize hybrids under drought and non-drought environments

Breeding maize hybrids for drought tolerance would significantly reduce yield loss due to drought in southern Africa. Mode of gene action controlling yield and secondary traits was investigated by mating 27 inbred lines, in sets according to a North Carolina design II scheme. The resultant 72 experimental and eight commercial hybrids were evaluated in 8 × 10 α-lattice design with two replications, in four drought and two non-drought environments. Under drought conditions, only general combining ability (GCA) variance was significant for yield, indicating predominance of additive effects. In non-drought environments, both GCA and specific combining ability variances were significant for yield, indicating importance of additive and non-additive effects, respectively. Contributions of male (GCAm) and female GCA (GCAf) effects to hybrids varied depending on the trait and conditions. Superior GCAf to GCAm effects for yield under drought conditions, and for ASI, prolificacy and ear aspect under both drought and non-drought conditions, suggested that maternal effects might have modified these traits. Larger GCAm than GCAf for ASI and silking dates under normal conditions indicated that paternal genotypes played a greater role in determining these traits. Similar GCAm and GCAf for yield under normal conditions, silking and anthesis dates under drought indicated that both parents made similar contribution to hybrids. Possibly, complications due to modification of traits by cytoplasmic effects and cross-over G × E for yield might partly explain why only a few drought tolerant hybrids have been developed. Practical implications of these findings in breeding drought tolerance in maize are discussed.

Viewpoint: Climate change and planning: responding to the challenge

Climate is the typical behaviour of the atmosphere. It is usually described in terms of mean (or average) conditions and variations about these conditions, including extreme events and the frequency of their occurrence (Wuebbles and Edmonds, 1991). Climate change, then, is change in the average behaviour of the atmosphere as well as change in the patterns of variation around this behaviour. Climate scientists are as much, if not more, concerned about changes in variability as they are about changes in average conditions; changes in variability may entail fundamental changes in our knowledge base. Climate change is real, has been going on since the earth was formed, and is anticipated to continue for the foreseeable future. Since the industrial revolution, however, much of the change in climate has been discernibly induced by human activity and, in particular, activity producing emissions of so-called 'greenhouse gases' (GHGs) carbon monoxide, methane, nitrous oxide and fluorinated gases. It is anticipated that anthropogenic climate change will have consequences for human health, ecosystems, economic activity, and social wellbeing that are on the whole more negative than positive.1 The human beings who appear to be most vulnerable to climate change are low-income and minority populations living in societies with developed economies, especially in coastal areas, and populations in countries with developing economies in equatorial latitudes. It may be too late to avert such near-term effects of climate change as unusual fluctuations in temperature, the increased incidence of extreme weather events, persisting droughts in Australia, sub-Saharan Africa and other areas, flooding in coastal areas, and melting of glaciers and sea level rise, which may cover low-lying land masses such as islands in the South Pacific. But scientists (and environmental economists) generally agree that it is not too late to ward off possibly irreversible changes in climate and quality of life for future generations through efforts to mitigate emissions and adapt to the effects of climate change (Stern et al., 2006). Contributors to the Stern Review believe that mitigation of and adaptation to climate change can be brought about through a combination of command-and-control and market-inducement policies. They also estimate that the cost of effective mitigation and adaptation

Little Ice Age drought in equatorial Africa: Intertropical Convergence Zone migrations and El Niño–Southern Oscillation variability

High-resolution analyses of the Mg concentration in authigenic calcite in five cores from Lake Edward provide a water balance history of central equatorial Africa spanning the past 1400 yr. A high ratio of Mg to Ca (%Mg) indicates strong droughts in central Africa during the Little Ice Age (A.D. 1400–1750), in contrast to records from Lake Naivasha, Kenya, which suggest a wet Little Ice Age. This spatial pattern in Africa likely arose due to coupled changes in the high latitudes, the position of the Intertropical Convergence Zone, and the El Nino–Southern Oscillation (ENSO) system. Our results further suggest that the patterns and variability of twentieth-century rainfall in central Africa have been unusually conducive to human welfare in the context of the past 1400 yr.

Climate and Society

Climate, in particular rainfall, is one of the main determinants of ecological productivity, which in turn is the basis of agricultural economies. However, the distribution of rain varies enormously, not only in space, but also in time. For example, in the Sahara huge lakes have come and gone as global climate changed in the last 10,000 years (Gasse, 2000), southern Africa has experienced extended periods of both warm wet and cold dry weather over the last 1000 years (Holmgren et al., 2003) and eastern Africa has suffered severe droughts within the last few hundred years (Gillson, 2006). This variation would be expected to have a major influence on human societies (Weiss & Bradley, 2001). Indeed, drying of the Sahara from about 5300 years ago can be related to development of pharaonic civilisation on the Nile and spread of pastoralism (Kuper & Krpelin, 2006). In southern Africa, sudden collapse of the city of Mapungubwe in 1290 AD and subsequent rise of Great Zimbabwe can be linked to first drought and then wetter conditions (Holmgren & Oberg, 2006). Whilst, in eastern Africa the disastrous Emutai period for the Maasai from 1883 to 1902, when cattle disease, small pox and famine devastated the population, was associated with drought (Gillson, 2006). However, we still have much to learn about African climate fluctuations and their socio-economic effects. Firstly, just when we thought we could relate climate change in Africa to fluctuations in sea surface temperatures in the Pacific Ocean, the so-called El Nino Southern Oscillation (Cane, Eshel & Buckland, 1994), a remarkable discovery has revealed a previously unknown climate driver, the Indian Ocean Dipole (Marchant et al., in press) which helps to explain observed divergence between ENSO activity and east African climate (Latif et al., 1999). Secondly, the relationship between society and climate is complex and unpredictable. For example the Mahlatule droughts in southern Africa in the early 19 century coincided with war, famine and dislocation amongst the Nguni peoples (p. 257 Newitt, 1995). This political instability was probably due not only to drought, but also increasing population and reliance on water-demanding maize (Holmgren & Oberg, 2006). The contrasting simultaneous rise of the Zulu Kingdom has been associated with changing environmental conditions leading to reorganisation and consolidation of control (Guy, 1980). Even more complicated, and in keeping with the principle of unintended consequences, drought-induced northward migration of the Nguni at this time into the Southern Highlands of Tanzania led to military development of the Hehe people as they coped with the incoming warlike Nguni (p. 56 Iliffe, 1979). This meant that when German colonisers arrived in Iringa at the end of the 19 century they encountered an efficient Hehe fighting force, which inflicted a famous defeat at Lugalo (p. 109 Iliffe, 1979) and which was subsequently avenged by strict German military rule. The upshot of this was massive socio-economic disruption resulting in vast tracts of unpopulated forested land which were later gazetted as forest reserves in the 1950s and as the Udzungwa National Park in 1992 (Lovett, 2003). Another interesting Tanzanian tale of the interplay between climate and politics is the strange case of the Ground Nut Scheme in the 1940s. The then British administered Tanganyika government implemented a massive public-works scheme devoted to cultivating ground nuts in a huge area of arid bush at Kongwa. The scheme was forced to end because of a drought in 1949, but not before £35,870,000 had been spent, equivalent to the total expenditure of the Tanganyika Government in the four years between 1946 and 1950 (p. 441, Iliffe, 1979). Speaking later, the Governor at the time, Sir Edward Twining, put a positive spin on the debacle: ‘‘Among the assets that the Ground Nut Scheme has left us was a great deal of knowledge of how to farm in dry areas and research work which has been of considerable value.’’ (p. 18, Twining, 1959) Correspondence: Jon C. Lovett, Centre for Ecology, Law and Policy, Environment Department, University of York, York, YO10 5DD England. E-mail: JL15@york.ac.uk

FDA’s regulation of genetically engineered foods: Scientific, legal and political dimensions

The controversy over genetically engineered (GE) food during the southern Africa drought in 2002/03 raised questions concerning the safety of GE foods and the basis for the safety assurances issued by national and international agencies. In the case of foods grown in the US, these assurances must be interpreted in relation to the Food and Drug Administration’s (FDA) 1992 policy, which remains in effect today. This paper provides a detailed examination of the roles of scientific, legal and political considerations in the development of that policy. This paper reveals that the FDA responded to political pressure for a permissive regulatory approach by exploiting gaps in scientific knowledge, creatively interpreting existing food law and limiting public involvement in the policy’s development. Common statements by the government and other proponents concerning sound science, rigorous testing, no evidence of harm and “as safe as conventional foods” are found to be misleading unless the scientific, legal and political basis for the US policy is taken into account. While this paper finds that the evidence for the safety of GE foods has been exaggerated by government agencies and other parties, nothing in this paper suggests that GE foods currently on the market are harmful to human health. To the contrary, the situation is one of great uncertainty. Repeated recommendations that this issue be the topic of a major public research effort have yet to be acted upon.

Micronutrient Fortification: WFP Experiences and Ways Forward

Micronutrient deficiencies represent a largely invisible, but often devastating, form of malnutrition that is particularly prevalent among WFP's beneficiary populations already lacking sufficient food. Known effects of micronutrient deficiencies include impaired physical and mental growth among children, iron-deficiency anemia, maternal mortality, low adult labor productivity and blindness. WFP makes important, often pioneering contributions to overcoming such deficiencies through: Careful attention to micronutrients in needs assessment and ration planning, Delivering fortified foods, particularly to nutritionally-vulnerable groups, on an increasingly large scale, Promotion and use of locally-produced and fortified commodities in more than a dozen low income, food deficit countries, Advocacy for fortification at national and international policy levels. Important activities in local processing and fortification have recently taken place in countries like Zambia, Angola, Bangladesh, India, Nepal, and in the context of the regional southern Africa drought emergency. Each case demonstrates that where micronutrient deficiencies are an operational concern local fortification is possible, albeit challenging. Several ongoing assessments of the impact of such initiatives suggest important nutritional benefits. That said, challenges remain in terms of technical and managerial capacity constraints, the need for systematic compliance with procurement specifications and quality control, clearer policies on micronutrient content labeling, and the need for cash resources to support many aspects associated with local processing and fortification activities.

Breeding for Africa's new smallholder maize paradigm

This paper describes the evolution of a newly emerging smallholder maize paradigm in southern Africa beginning in 1996. This new paradigm involves the breeding, extension, and adoption of a new generation of open-pollinated ‘flinty’ maize varieties that specifically address the needs of southern African smallholder farmers for seed varieties that can be replanted (recycled) and that resist drought and low fertility problems increasingly common in southern Africa. The described mechanism is the extension and breeding work of the Southern Africa Drought and Low Fertility programme (SADLF) of the Centro Internationale por la Mejoridad de Maize y Trigo (CIMMYT). This paper explains the devolution of southern African maize production in the past two decades from centralized large-scale producers to smallholder farms, signalling a shift in research and plant breeding needs. The research/extension approach described here had profound consequences beyond the technical benefits of screening maize varieties for tolerance to stress; it empowered small-scale farmers to become informed consumers of agricultural technology. The transformation of the smallholder from a passive consumer to one actively seeking the best opportunity and seed to produce food, create economic opportunities and address local social conditions is an important development in the history and sustainability of maize production in southern Africa, and one consistent with modern African history of economic liberalization in the global food economy.

The two-faced keeper of gates to heaven

There are several reasons why Janus the ancient roman god sive cancer conferences to ensure that quality reigns over might be adopted as a patron of oncology. Suitably the guardian of the Gate of Heaven, Janus was represented with two faces, one in front and one behind. January is the month dedicated to Janus who presided over the entrance to the New Year, and with his two faces could look back to the past year and forward to the year ahead – we welcome the latter. 2005 was truly an ‘‘annus horribilis’’. Of all professions, oncologists are particularly used to tragedy and the unfairness of life-threatening illnesses at an inappropriate age, but last year the whole world witnessed natural disasters on an unprecedented scale: the Asian Tsunami; appalling drought in Africa and Western Europe; and in the USA, the hurricane Katrina. The now famous conference centre in New Orleans hosted many oncology conferences, for example, the huge 2004 ASCO meeting and it is through such events that many cancer researchers came to know and love the uniqueness of the ‘‘old’’ New Orleans. The future of this city is uncertain – especially as a conference venue upon which so much of the city s economy depended. Our heartfelt sympathy has been extended to all those involved. The world is already short of venues capable of hosting the ever increasingly large conferences for which there seems to be an insatiable appetite. Year on year there are more and more conferences attended by more and more enthusiasts – will it ever cease? I have written in these pages before to express a personal hope that we will move to fewer more comprehen-

Late Holocene climate change in the North Atlantic and equatorial Africa: Millennial‐scale ITCZ migration

Climate proxy data and numerical models suggest that latitudinal displacements of the Intertropical Convergence Zone (ITCZ) occur during millennial‐scale cold events in the North Atlantic region, but the potential effects of these ITCZ movements on the climate of equatorial regions are unclear. Here we present a 5400‐year geochemical record of rainfall and drought from Lake Edward in equatorial Africa. We observe a non‐linear correlation in which drought in equatorial Africa occurs during both cold and warm extremes in the North Atlantic's 1500‐year quasi‐cycle. We propose that this relationship occurs due to northward/southward displacement of the ITCZ from its equatorial mean position during warm/cold events. Our results show that millennial‐scale high‐latitude climate events are linked to changes in equatorial terrestrial climate even during the late Holocene and suggest important constraints on the mechanisms linking tropical and extratropical climate variability.

AIDS, drought, and child malnutrition in southern Africa

To investigate trends in child malnutrition in six countries in southern Africa, in relation to the HIV epidemic and drought in crop years 2001/2 and 2002/3. Epidemiological analysis of sub-national and national surveys with related data. Data from Lesotho, Malawi, Mozambique, Swaziland, Zambia and Zimbabwe, compiled and analysed under UNICEF auspices. Secondary data: children 0-5 years for weight-for-age; HIV prevalence data from various sources especially antenatal clinic surveillance. Child nutritional status as measured by prevalence of underweight deteriorated from 2001 onwards in all countries except Lesotho, with very substantial increases in some provinces/districts (e.g. from 5 to 20% in Maputo (Mozambique, 1997-2002), 17 to 32% in Copperbelt (Zambia, 1999-2001/2) and 11 to 26% in Midlands province (Zimbabwe, 1999-2002)). Greater deterioration in underweight occurred in better-off areas. Areas with higher HIV/AIDS prevalences had (so far) lower malnutrition rates (and infant mortality rates), presumably because more modern areas--with greater reliance on trade and wage employment--have more HIV/AIDS. Areas with higher HIV/AIDS showed more deterioration in child nutrition. A significant area-level interaction was found of HIV/AIDS with the drought period, associated with particularly rapid deterioration in nutritional status. First, the most vulnerable may be households in more modern areas, nearer towns, to whom resources need to be directed. Second, the causes of this vulnerability need to be investigated. Third, HIV/AIDS amplifies the effect of drought on nutrition, so rapid and effective response will be crucial if drought strikes again. Fourth, expanded nutritional surveillance is now needed to monitor and respond to deteriorating trends. Finally, with or without drought, new means are needed of bringing help, comfort and assistance to the child population.

Intensity and spatial extent of droughts in southern Africa

The standardized precipitation index allows for monitoring the intensity and spatial extent of droughts at different time scales. We used it to do a retrospective analysis of the spatial extent of droughts in Southern Africa (South of 10°S), from 1901 to 1999. Accordingly, the 8 most severe droughts at the 6‐month scale (October–April) for the summer rainfall region of Southern Africa ended in 1916, 1924, 1933, 1949, 1970, 1983, 1992 and 1995. At the 2‐year scale, they ended in 1906, 1933, 1983, 1984, 1992, 1993, 1995 and 1996. Areas affected by those droughts ranged from 3.4 to 2 106 km2. Eight of those 12 years are El Niño years. Preliminary data indicates that 2001/2002, 2002/2003 and 2003/2004 experienced severe droughts at a number of scales. This confirms the increase in the spatial extent of drought in Southern Africa since the 1970's due to stronger ENSO Southern African rainfall relationship

Large temperature variability in the southern African tropics since the Last Glacial Maximum

The role of the tropics in global climate change is actively debated, particularly in regard to the timing and magnitude of thermal and hydrological response. Continuous, high‐resolution temperature records through the Last Glacial Maximum (LGM) from tropical oceans have provided much insight but surface temperature reconstructions do not exist from tropical continental environments. Here we used the TEX86 paleotemperature proxy to reconstruct mean annual lake surface temperatures through the Last Glacial Maximum (LGM) in Lake Malawi, East Africa (9°–14°S). We find a ∼3.5°C overall warming since the LGM, with temperature reversals of ∼2°C during the Younger Dryas (12.5 ka BP) and at 8.2 ka BP. Maximum Holocene temperatures of ∼29°C were found at 5 ka BP, a period preceding severe drought in Africa. These results suggest a substantial thermal response of southeastern tropical Africa to deglaciation and to varying conditions during the Holocene.

A Review of the Factors Affecting the Survival of Donkeys in Semi-arid Regions of Sub-Saharan Africa

The large fluctuations seen in cattle populations during periods of drought in sub-Saharan Africa are not evident in the donkey population. Donkeys appear to have a survival advantage over cattle that is increasingly recognized by smallholder farmers in their selection of working animals. The donkey's survival advantages arise from both socioeconomic and biological factors. Socioeconomic factors include the maintenance of a low sustainable population of donkeys owing to their single-purpose role and their low social status. Also, because donkeys are not usually used as a meat animal and can provide a regular income as a working animal, they are not slaughtered in response to drought, as are cattle. Donkeys have a range of physiological and behavioural adaptations that individually provide small survival advantages over cattle but collectively may make a large difference to whether or not they survive drought. Donkeys have lower maintenance costs as a result of their size and spend less energy while foraging for food; lower energy costs result in a lower dry matter intake (DMI) requirement. In donkeys, low-quality diets are digested almost as efficiently as in ruminants and, because of a highly selective feeding strategy, the quality of diet obtained by donkeys in a given pasture is higher than that obtained by cattle. Lower energy costs of walking, longer foraging times per day and ability to tolerate thirst may allow donkeys to access more remote, under-utilized sources of forage that are inaccessible to cattle on rangeland. As donkeys become a more popular choice of working animal for farmers, specific management practices need to be devised that allow donkeys to fully maximize their natural survival advantages.

Intensity and spatial extension of drought in South Africa at different time scales

The standardised precipitation index (SPI) is an index that allows monitoring the intensity and spatial extension of droughts at different time scales (3, 6, 12 and 24 months). The SPI is linked to the probability occurrence of dry or wet events. The SPI allows monitoring operationally any location with a 30-year time series. It is also used here to do a retrospective analysis of the spatial extension and intensity of droughts in South Africa since 1921. According to this index, the 8 most severe droughts at the 6-month time scale for the summer rainfall region of South Africa happened in 1926, 1933, 1945, 1949, 1952, 1970, 1983 and 1992. There is considerable decadal variability and an 18 to 20 year cycle is only found in the number of dry districts. The total number of wet and dry districts per decade seems to have increased since the 1960s. Drought lasting 3 years is not uncommon for each of the 8 South African rainfall regions defined by the South African Weather Service. Combining the retrospective analysis with real time monitoring could be extremely beneficial in the development of response, mitigation strategies and awareness plans.