Sahelian West Africa Research Articles

Food security and climate shocks in Senegal: Who and where are the most vulnerable households?

In the Sahel of West Africa, food security is a top development priority. Climate shocks threaten communities that rely on a single rainy season to grow crops and raise livestock. We exploit repeat surveys collected by the World Food Programme to quantitatively assess the year-to-year dynamics of household food security. Our methodology singles out the impact of climate shock on food access. We combine three variables, namely the Food Consumption Score, the Food Expenditure Share and the Reduced Coping Strategies Index to explore the access dimension of food security. Cluster analysis on the three variables leads us to 1) classify into categories, and spatially locate less and more food secure households; and 2) discuss the response of each category of household to seasonality and variability in climate. First, we find that in a drought year, some rural households – with average food security status – that normally do not use coping strategies actually have to use them. Second, we notice that food expenditure share increases in all categories of households, except one. Based on the different ways in which categories of households respond to (climatic) shock we recommend the design of targeted and more efficient interventions. We focus on Senegal because of the unprecedented opportunity to access repeat surveys, including an unusual one, taken during a crisis year. However, our methodology and recommendations can inform interventions in other Sahelian countries.

Participatory Mapping with High-resolution Satellite Imagery: A Mixed method Assessment of Land Degradation and Rehabilitation in Northern Burkina Faso.

Sahelian West Africa is a region that suffers from high population densities, frequent severe droughts, and enormous pressure on natural resources. Because of these challenges, it is the place where the term "desertification" was originally coined. Recently, however, experts have identified large zones of "greening" where the amount of vegetation exceeds what one would expect based on rainfall alone. This pattern is well documented, but its mechanisms remain poorly understood. This research employs participatory mapping linked with high-resolution satellite imagery to better understand the human role behind regional vegetation trends. Through a case study of three communities in northern Burkina Faso, this paper presents a pilot methodology for explicitly mapping perceived areas of both land degradation and rehabilitation. Combining participatory mapping exercises with standard image classification techniques allows areas of land degradation and rehabilitation to be precisely located and their extents measured for individual communities and their surrounding terroirs. Results of the spatial analysis show that the relative proportion of greening and browning varies among communities. In the case of Sakou, nearly 60 percent of its terroir is degraded. While in another, Kouka, this is 48 percent. This method also elicits perspectives of Burkinabè agro-pastoralists on the local land-use practices driving these twin environmental processes. Altogether, this case study demonstrates the analytical power of integrating ethnography and high-resolution satellite imagery to provide a bottom-up perspective on social-ecological dynamics.

Pastoral Resource Conflict in the Context of Sudano–Sahelian Security Crises: A Critical Review of Research

ABSTRACT This article reviews recent research on pastoral resource conflict in the context of security crises across Sudano–Sahelian West and Central Africa. The goal is to improve understanding of the linkages between resource–related grievances, conflict escalation, and regional outbreaks of violence. The review focuses on factors perceived to play a role in violent conflicts across the region, including climate change, resource scarcity, and the political forces that mediate their relationships with violent conflict. Future research must draw from a wider body of literature to understand the relationship between resource access and drivers of conflict such as exclusion and perceptions of justice.

Improving agricultural productivity using agroforestry systems: Performance of millet, cowpea, and ziziphus-based cropping systems in West Africa Sahel

Across the drylands of sub-Saharan Africa, resource-poor farmers typically apply little or no organic or inorganic fertilizers; they remove or graze crop residues, leaving the soils nutrient-depleted and vulnerable to degradation. High temperatures, soil erosion, and declining soil fertility call for farming systems that protect fragile soils as well as improve nutrient availability and water use efficiency (WUE) and soil fertility. In the present study, the agronomic performance of an agroforestry system with millet (Pennisetum glaucum), cowpea (Vigna unguiculata), and Ziziphus (Ziziphus mauritiana) was compared to that of a cropping system without Ziziphus at ICRISAT research station, Sadoré, Niger, for four years. The experiment was a factorial 3 × 4 design with three cropping systems: mono-cropping of millet (MM), mono-cropping of cowpea (CC), and millet/cowpea intercropping (M/C), and with four fertilizer treatments (FT) in a split-split arrangement. The same experimental design was installed on 2 blocks: with Ziziphus trees (ZT) at 80 plants ha−1 and without Ziziphus (WZ).After the four years of cropping, ZT and WZ decreased SOC by 15 and 21 % and K by 105 and 110 %, respectively, compared with the original soil. Soil N was decreased only in the system WZ. Millet grain yields varied from 0.10 to 1.14 t/ha and the highest yields were obtained with NPK fertilizer alone or associated with farmyard manure (FYM) while the lowest yields were obtained with the control without fertilizer and FYM. The ZT system increased millet yields and its WUE with FYM and the control without fertilizer. However, millet yields decreased in ZT system with NPK fertilizer alone or associated with FYM. The ZT system increased the global annual incomes from 2–3 times compared with the system WZ. We concluded that including Ziziphus trees at the density of 80 plants ha−1 to the low input cropping systems of smallholder farmers improve agricultural productivity and farmers’ incomes. The proposed agroforestry system is affordable and compatible with the low input farming systems, and it ensures sustainable management of soils, land resources, and ecosystem services. But future research could contribute by identifying the optimal combinations of the density of Ziziphus trees, cropping systems and the doses of fertilizer on crops to optimize the productivity of the propose agroforestry system.

Disentangling the security traffic jam in the Sahel: constitutive effects of contemporary interventionism

Abstract Despite years of ongoing interventions by multiple external and regional actors, the security situation in west Africa's Sahel region is dramatically deteriorating. In this introduction to the special section of the July 2020 issue of International Affairs, we zoom in on four major external international intervention actors (France, the United States, the European Union and the United Nations) in the Sahel region's escalating ‘security traffic jam’. We argue that the diversity of intervention actors makes the Sahel a paradigmatic case for exploring a set of often-overlooked constitutive intervention effects. By adding new temporal, relational and spatial dimensions to the notion of ‘constitutive effects’ as introduced by post-structuralists in the 1990s, we (re)launch constitutive effects as a conceptual framework for approaching the study of ongoing intervention engagements. From this perspective, and as further illustrated in this special section, intervention continuity and escalation cannot be explained simply with reference to frameworks of ‘success’ or ‘failure’, but require a broader conceptualization of effects, including how specific threat perceptions, rationales and problematizations get constituted and consolidated through and during ongoing intervention practice. Contributions to this special section each unpack a diverse set of constitutive effects including the contested performance of security actorness, the (un)making of security alliances and partnerships, logics of choices produced by ongoing intervention practices, as well as the constitution of conditions for continual international involvement.

Assessing the Skill and Reliability of Seasonal Climate Forecasts in Sahelian West Africa

Abstract Seasonal climate forecasts have the potential to support planning decisions and provide advanced warning to government, industry, and communities to help reduce the impacts of adverse climatic conditions. Assessing the reliability of seasonal forecasts, generated using different models and methods, is essential to ensure their appropriate interpretation and use. Here we assess the reliability of forecasts for seasonal total precipitation in Sahelian West Africa, a region of high year-to-year climate variability. Through digitizing forecasts issued from the regional climate outlook forum in West Africa known as Prévisions Climatiques Saisonnières en Afrique Soudano-Sahélienne (PRESASS), we assess their reliability by comparing them to the Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) project observational data over the past 20 years. The PRESASS forecasts show positive skill and reliability, but a bias toward lower forecast probabilities in the below-normal precipitation category. In addition, we assess the reliability of seasonal precipitation forecasts for the same region using available global dynamical forecast models. We find all models have positive skill and reliability, but this varies geographically. On average, NCEP’s CFS and ECMWF’s SEAS5 systems show greater skill and reliability than the Met Office’s GloSea5, and in turn than Météo-France’s Sys5, but one key caveat is that model performance might depend on the meteorological situation. We discuss the potential for improving use of dynamical model forecasts in the regional climate outlook forums, to improve the reliability of seasonal forecasts in the region and the objectivity of the seasonal forecasting process used in the PRESASS regional climate outlook forum.

Interannual Variability of Rainfall over the West Africa Sahel

Interannual variability of the precipitation over West Africa Sahel is analyzed based on 32 years (1979-2010) from monthly and daily database of the Global Precipitation Climatology Project (GPCP). In this region, we found that there is a link between the West Africa Monsoon (WAM) and the daily means of the precipitation in the summer, unseasonal rains can occur in the transition seasons and even in the heart of the dry season. Rainfall is the most important element for agro-pastoral activities in this region. The 850-hPa wind and wind divergence structure show a maximum convection over Mountain region (Fouta-Djalon and Mont-Cameroon) which corresponds to the high precipitation and OLR observed in these regions. The trend and empirical orthogonal function (EOF) of the precipitation are presented, including the mid-July variability of the precipitation. The dominant EOF of GPCP precipitation accounts for around 25.3% of the variance with slightly large amplitude in the north while relatively small in the equatorial band respectively. The second and third EOF which accounts for 20.5% and 14%, describes a longitudinal contrast with a zonal gradient.

A unified strategy for West African pearl millet hybrid and heterotic group development

AbstractSmallholder farmers in Sahelian West Africa (WA) grow pearl millet [Pennisetum glaucum (L.) R. Br.] as a staple cereal in harsh and highly variable environments, predominantly relying on landraces or open‐pollinated varieties (OPVs) with an average grain yield of 648 kg ha−1 (2017). Encouraging initial results with experimental pearl millet population or topcross hybrids and the available diversity in its WA center of origin offer a great opportunity for a regionally coordinated hybrid breeding approach. This review is therefore meant to summarize information on pearl millet hybrid breeding with emphasis on WA and to suggest a unified strategy as a way forward. Observed average better‐parent heterosis ranged from 4–18% and 0–88% in population and topcross hybrids, respectively, across several studies, and the yield stability was comparable with or better than the parental OPVs. Diversity and combining ability studies pointed at eastern and western WA as promising starting points for systematic development of heterotic groups. Building on respective groups, reciprocal recurrent selection in combination with integration of further adapted genetic resources is recommended to systematically diversify and build up the heterotic parental pools, increase combining ability to the opposite group, and create a continuous output of OPV and hybrid varieties. Molecular markers supporting cytoplasmic male sterility (CMS) introgression are available, and genomic tools can improve hybrid prediction. Regarding the unpredictability and intensity of biotic and abiotic stresses, heterogeneous population and topcross hybrids appear most suitable to sustainably increase pearl millet yields and give maximal benefits to WA farmers.

Mapping the potential use of endectocide-treated cattle to reduce malaria transmission

Treating cattle with endectocide is a longstanding veterinary practice to reduce the load of endo and ectoparasites, but has the potential to be added to the malaria control and elimination toolbox, as it also kills malaria mosquitoes feeding on the animals. Here we used openly available data to map the areas of the African continent where high malaria prevalence in 2–10 year old children coincides with a high density of cattle and high density of the partly zoophilic malaria vector Anopheles arabiensis. That is, mapping the areas where treating cattle with endectocide would potentially have the greatest impact on reducing malaria transmission. In regions of Africa that are not dominated by rainforest nor desert, the map shows a scatter of areas in several countries where this intervention shows potential, including central and eastern sub-Saharan Africa. The savanna region underneath the Sahel in West Africa appears as the climatic block that would benefit to the largest extent from this intervention, encompassing several countries. West Africa currently presents the highest under-10 malaria prevalence and elimination within the next twenty years cannot be contemplated there with currently available interventions alone, making the use of endectocide treated cattle as a complementary intervention highly appealing.

Flight activity in pallid swiftsApus pallidusduring the non‐breeding period

Flight activity recorders have recently confirmed that alpine and common swifts spend the majority of their non‐breeding period on the wing, which may last 6–10 months. Here we test the hypothesis that the closely related pallid swift, a species with a breeding distribution around the Mediterranean, lead a similar aerial life‐style during its migration and wintering periods. The pallid swift usually lays two clutches in one season and therefore spends more time in the breeding area than the common swift. We successfully tracked four pallid swifts with data loggers that record light for geolocation and acceleration every 5 min to monitor flight activity. The birds wintered south of the Sahel in west Africa from the Ivory Coast to Cameroon. The pallid swifts spent the majority of their non‐breeding time in flight, especially the first two months after leaving the breeding area in autumn, while a few landing events occurred during the winter. The total time grounded was < 1%, similar to that of the common and alpine swifts. The mass specific flight metabolic rate of swifts is similar to the average non‐breeding metabolic rate of a long distance terrestrial migrant, suggesting swifts are not more likely to procure oxidative damage as a consequence of continuous flight than other migrants. The open airspace used by swifts may provide a relatively safe habitat that explain the high survival rate found in swifts.

Economics of Increasing Sorghum Productivity in Sub-Saharan Africa: The Mali Case.

Sorghum retains a crucial role in Sub-Saharan Africa for food and in the future feed. Unfortunately, the movement of sorghum technology onto farmers' fields in Sub-Saharan Africa has been slow in spite of substantial research since the great African drought of 1968-1973. What is necessary to get African sorghum yields and profitability up?After reviewing the situation of sorghum in the world, the USA, and Sub-Saharan Africa from 2007 to 2017 the results and the lessons of a twelve-year program in the Sahel of West Africa to introduce new sorghum technology and marketing strategies are the focus of the rest of the paper. In Mali, the program identified new technologies that were extended into a large number of farmers' associations. The Mali program then collaborated with two other agencies to scale up this pilot program. The pilot project demonstrated that yields with moderate fertilization, new varieties, and improved agronomic practices could be increased 50 to 100% and prices increased 30 to 50%. The 2012 military coup and then invasion of Al Queda from the north shut down both the pilot and the scaling up activities as the US government banned collaboration with Malian government agencies after the coup. The pilots were continued in Niger and Burkina Faso through 2014 and then with a Gates Foundation grant from 2014 to 2016. The pilot program in Mali responded to two of the three Second Generation problems identified. But more significantly the pilot project identified the lack of funds for responding to Second Generation problems as a major constraint for implementing a technology-marketing program in a low-income country.

Trends in flood events and their relationship to extreme rainfall in an urban area of Sahelian West Africa: The case study of Ouagadougou, Burkina Faso

Urban areas in Sahelian West Africa are highly vulnerable to extreme hydro‐meteorological events. In recent years, Burkina Faso has experienced several natural disasters with floods being the most frequent. This study investigates flood trends in Ouagadougou and their relationship to extreme rainfall events. Fourteen rainfall indices were analysed to characterise the frequency and intensity of extreme rainfall. A frequency analysis of annual maximum daily rainfall series was performed using three statistical distributions. The results showed that few of the rainfall indices have significant trends at 5% level over the period 1961–2015. The generalised extreme value distribution satisfactorily fit the time‐series of annual maximum daily rainfall. An analysis of media flood reports revealed that Burkina Faso experienced approximately three flood events per year throughout the period 1986–2016. In the 2000s, the number of flood events increased to five per year. Most flood events are caused by rainfall events with return periods of less than or equal to 5 years. The results indicated that the significant increase in flood risk in Ouagadougou is not only related to heavy rainfall but also due to human and environmental factors.

Assessing Cropland Area in West Africa for Agricultural Yield Analysis

Accurate estimates of cultivated area and crop yield are critical to our understanding of agricultural production and food security, particularly for semi-arid regions like the Sahel of West Africa, where crop production is mainly rain-fed and food security is closely correlated with the inter-annual variations in rainfall. Several global and regional land cover products, based on satellite remotely-sensed data, provide estimates of the agricultural land use intensity, but the initial comparisons indicate considerable differences among them, relating to differences in the satellite data quality, classification approaches, and spatial and temporal resolutions. Here, we quantify the accuracy of available cropland products across Sahelian West Africa using an independent, high-resolution, visually interpreted sample dataset that classifies all points across West Africa using a 2-km sample grid (~500,000 points for the study area). We estimate the “quantity” and “allocation” disagreements for the cropland class of eight land cover products in five Western Sahel countries (Burkina Faso, Mali, Mauritania, Niger, and Senegal). The results confirm that coarse spatial resolution (300 m, 500 m, and 1000 m) land cover products have higher disagreements in mapping the fragmented agricultural landscape of the Western Sahel. Earlier products (e.g., GLC2000) are less accurate than recent products (e.g., ESA CCI 2013, MODIS 2013 and GlobCover 2009). We also show that two of the finer spatial resolution maps (GFSAD30, and GlobeLand30) using advanced classification approaches (random forest, decision trees, and pixel-object combined) are currently the best available products for cropland identification. However, none of the eight land cover databases examined is consistent in reaching the targeted 75% accuracy threshold in the five Sahelian countries. The majority of currently available land cover products overestimate cultivated areas by an average of 170% relative to the cropland area in the reference data.

Nutrient release dynamics from decomposing organic materials and their mulching-effect on pearl millet yields in a low-input Sahelian cropping system

Organic material inputs for increased crop yields are insufficient in the Sahelian West Africa. There is a need for diversifying organic amendment sources for improved nutrient supply in low-input cropping system. The 2-year study aimed to (1) explore the rates of mass losses and nutrient release dynamics from Acacia tumida prunings (AT) and millet straw (MS) under field conditions, (2) assess termite’s contribution to the decomposition of AT and MS, and (3) ascertain the mulching-effect of these organic materials on pearl millet yields. The study was conducted in Niger using field experiment and litterbag methodology and the data modelled using single exponential decay equations. Under field conditions, mulching with AT and MS increased millet grain yield by 35 and 33%, respectively compared to control. The harvest index (HI) in 2014 increased by 21% compared to that obtained in 2013 with the highest HI being recorded for the AT mulched treatment. The results from litterbag experiment indicated a greater dry mass losses from MS decomposition in 2013 whereas relatively higher mass losses were recorded from AT decomposition in 2014. The differences in mass losses among the organic materials could be related to the interaction of soil moisture dynamics and termites’ population which are positively correlated with mass losses. The contribution of termites to the decomposition was estimated to be 36% for MS and 8% for AT. In 2013, at 126 days after litterbags placement, the amounts of N, P, and K released from MS were 16, 1, and 25 kg ha−1 of initial nutrient applied, respectively compared with the 22, 1, and 23 kg ha−1 recorded from AT treatment. During the same period in 2014, the total amounts of N, P and K released from MS were 15, 0.6, and 29 kg ha−1, respectively compared to the 32 kg ha−1 of N, 1 kg ha−1 of P, and 29 kg ha−1 of K released from the AT treatment. The intrinsic organic material quality could explain markedly the variation in nutrient released among the organic material. These results indicate that Acacia tumida prunings have a potential to provide nutrient through mineralization for enhanced crop yield in the Sahel.

Evaluation of direct and indirect effects of seasonal malaria chemoprevention in Mali

Randomized controlled trials have established that seasonal malaria chemoprevention (SMC) in children is a promising strategy to reduce malaria transmission in Sahelian West Africa. This strategy was recently introduced in a dozen countries, and about 12 million children received SMC in 2016. However, evidence on SMC effectiveness under routine programme conditions is sparse. We aim to measure the effects of the nationwide SMC programme in Mali on the prevalence of malaria and anemia in children 6–59 months. We used data from the 2015 nationally representative malaria indicator survey. A post-test only with non-randomized control group study was designed. We fitted a generalized structural equation model that controlled for potential bias on observed and non-observed variables (endogenous treatment effect model). Having received SMC reduced by 44% (95% CI [0.39–0.49]) the risk of having a positive rapid diagnostic test for malaria. In addition, the programme indirectly reduced by 18% the risk of moderate-to-severe anemia (95% CI [0.15–0.21]). SMC in Mali has substantial protective effects under routine nationwide programme conditions. Endogenous treatment effects analyses can contribute to rigorously measuring the effectiveness of health programmes and to bridging a widening gap in evaluation methods to measure progress towards achieving malaria elimination.

Social institutions mediating seed access in West African seed systems

Contemporary approaches to market-oriented agricultural development focus on increasing production and economic efficiency to improve livelihoods and well-being. For seed system development, this has meant a focus on seed value chains predicated on standardized economic transactions and improved variety seeds. Building formal seed systems requires establishing and strengthening social institutions that reflect the market-oriented values of efficiency and standardization, institutions that often do not currently exist in many local and informal seed systems. This paper describes and analyzes efforts to develop formal seed systems in Sahelian West Africa over the past 10 years, and identifies the impacts for farmers of the social institutions that constitute formal seed systems. Using qualitative and spatial data and analysis, the paper characterizes farmers’ and communities’ experiences with seed access through the newly established formal seed system. The results demonstrate that the social and spatial extents of the formal and informal seed systems are extended and integrated through social institutions that reflect values inherent in both systems. The impacts of current market-oriented agricultural development projects are, therefore, more than in the past, in part because the social institutions associated with them are less singular in their vision for productive and economic efficiency.

Food security implications of staple food substitution in Sahelian West Africa

Low-income households in Sahelian West Africa face multiple shocks that risk compressing their already-low food consumption levels. This paper develops a multi-market simulation model to evaluate the impact of common production and world-price shocks on food consumption of vulnerable groups in Sahelian West Africa. Empirical analysis confirms that poor households bear the brunt of ensuing consumption risks, particularly in closed markets, where trade barriers restrict imports, and the poor find themselves in a bidding war with richer consumers for limited food supplies. In the absence of trade, a drought that reduces domestic rainfed cereal production by 20% would compress already low calorie consumption of the rural poor by as much as 15%, four times as much as other household groups. Conversely, a 50% spike in world rice prices hits the urban poor hardest, compressing calorie consumption by up to 8%.Policy responses need to focus on two basic mechanisms that can help to moderate this pressure – consumer substitution among staple foods and trade. Immediately south of the Sahel, coastal West African countries enjoy higher rainfall, dual rainy seasons, more stable staple food production based on root crops (cassava and yams) as well as frequent double cropping of maize.Our simulation results suggest that regional trade in maize, yams and cassava-based prepared foods like gari and attieké could fill over one-third of the consumption shortfall resulting from a major drought in the Sahel. Increasing substitutability across starchy staples, for example through expansion of maize, cassava and sorghum-based convenience foods, would further moderate consumption pressure by expanding the array of food alternatives and hence supply responses available during periods of stress.

SEASONAL MALARIA CHEMOPREVENTION WITH SULPHADOXINE-PYRIMETHAMINE AND AMODIAQUINE SELECTS DHFR-DHPS QUINTUPLE MUTANT GENOTYPE IN MALI

BackgroundSeasonal malaria chemoprevention (SMC) with sulfadoxine-pyrimethamine (SP)+amodiaquine (AQ) is being scaled up in countries of the Sahel in West Africa. However, the potential development of Plasmodium falciparum resistance to the...

Ground-truthing Sahelian Greening: Ethnographic and Spatial Evidence from Burkina Faso.

Historically, the Sahel of West Africa has been considered synonymous with desertification. In recent decades, however, satellite images reveal patterns of enhanced vegetation termed the "greening of the Sahel." This greening is well-documented but its mechanisms remain poorly understood. The Sahel is also a region emerging from a thirty-year period of reduced rainfall in which several severe droughts occurred. As a response to droughts and land degradation, farmers have rehabilitated thousands of hectares of degraded soils by constructing low barriers of rock through widespread soil and water conservation (SWC) development projects. Remote sensing analyses suggest that these extensive soil conservation projects may explain greening in northern Burkina Faso. This study combines ethnographic fieldwork with the analysis of Geographic Information System (GIS) and remote sensing (RS) data to test whether SWC investments contribute to greening. Ethnographic data reveals a tension between the perceptions of rural producers who feel that their SWC efforts contribute to greening and those of state officials who contend that SWC has only local impacts and that the regional landscape continues to degrade. Our analysis of GIS and RS data suggest that both perspectives are valid but contingent on particular spatial and temporal scale used for analysis.

Rethinking Land Endowment and Inequality in Rural Africa: The Importance of Soil Fertility

Summary Access to land has been a major emphasis of previous work on socioeconomic differentiation within rural African communities. Land endowment has generally been measured in terms of area without much consideration to variation in the qualities of land at the level of village territories. Building from work on the variation of soil fertility, this paper considers the potential relationship between soil fertility variation and wealth inequality within rural communities in Sahelian West Africa. The management history, yields, and characteristics (livestock and land wealth, labor, tenure security, cropped area) of the households managing and owning 181 sampled fields within two village territories in southwestern Niger are analyzed to evaluate the relative importance of land area and soil fertility in affecting the ability of households to produce food and the factors that affect household investments into soil fertility. Soil fertility variation is found to play a major role in the crop production achieved in the study area. This variation results in part from contemporary and historic investments by farmers largely through manure application. Manuring rates are found not to be affected by the extent of land owned or managed nor by the security of land tenure. Instead, these investments are determined by livestock wealth, the major store of wealth in rural parts of the Sahel. These findings point to a major mechanism for increased inequality in areas where subsistence cropping prevails—a mechanism that is mediated through soil fertility variation.