Genetic diversity of Sclerocarya birrea subspecies birrea populations in Burkina Faso detected by RAPDs

Sclerocarya birrea, multipurpose plant is characteristic of the Sahel-Sudanian savanna and is widespread in West Africa. Although this species has a high socio-economic importance, its genetic organization was not well characterized in Burkina Faso. In this study, the intra and interpopulation genetic diversity of S. birrea was determined by random amplified polymorphic deoxyribonucleic acid (RAPD) markers. We found a high average of intra population genetic diversity (He = 0.20) among S. birrea populations. The species populations were also characterized by their low genetic differentiation (Gst = 0.24), indicating a significant exchange of genes flow between populations. The whole population was clustered into four groups without reference of site and climatic zone. The Mantel test suggested that genetic distances between populations were not correlated to geographic distances. Our results strongly suggest that the structure and the level of this species’ genetics diversity may be due to its mode of dissemination involving ruminants.Key words: Genetic, variation, Sclerocarya birrea subspecies birrea, populations, RAPDs markers, Burkina Faso

Fertilisation des sols avec la litiere foliaire en zone Subsahelienne du Burkina Faso: Diversite des especes, effets sur les rendements du sorgho

Organic matter sources management for soil fertility improvement has been the subject of many researches. Agroforestry is one of the topics addressed by these researches. In Burkina Faso\u2019s Northern Center, leaf litter of woody species is collected, piled, crumbled before spreading in fields. This practice is not well known in the rest of the country. The present study aims to provide information on the diversity of spontaneous plant species concerned, farmers\u2019 motivations of litter crumbling and to evaluate, empirically the effects of litter spreading on sorghum yields. A participatory study, using qualitative surveys and biometric field measurements, was conducted in five villages in the Northern Center of Burkina Faso. Because of their availability, accessibility, and agronomic performance, plants such as Vitellaria paradoxa , Anogeissus leiocarpa , Combretum micranthum , Lannea microcarpa and Diospyros mespiliformis were the species whose leaf litter was valued most. Measurements achieved in situ indicate that sorghum yields from fields that received Vitellaria leaf litter for the first time were lower than those in the control plots. On the other hand, fields that received this litter for three consecutive years were more productive. A scientific study on leaf litter chemical characteristics and their influence on soil fertility parameters should be considered in order to validate local knowledge and to improve knowledge about these practices.La gestion des sources de mati\ue8res organiques, pour am\ue9liorer la fertilit\ue9 des sols, a fait l\u2019objet de nombreuses recherches. L\u2019agroforesterie est une des th\ue9matiques abord\ue9es par ces recherches. Dans le Centre-Nord du Burkina Faso, la liti\ue8re foliaire des esp\ue8ces ligneuses est ramass\ue9e, mise en tas, \ue9miett\ue9e avant d\u2019\ueatre \ue9pandue dans les champs. Cette pratique est peu connue dans le reste du pays. La pr\ue9sente \ue9tude visait \ue0 fournir des informations sur la diversit\ue9 des esp\ue8ces v\ue9g\ue9tales spontan\ue9es concern\ue9es, les motivations paysannes de l\u2019\ue9miettement de la liti\ue8re et \ue0 \ue9valuer, empiriquement et par des mesures, les effets de l\u2019\ue9pandage de ces liti\ue8res sur les rendements du sorgho. Une \ue9tude participative, \ue0 l\u2019aide d\u2019enqu\ueates qualitatives et des mesures biom\ue9triques dans des champs, a \ue9t\ue9 men\ue9e dans cinq villages du Centre Nord du Burkina Faso. A cause de leur disponibilit\ue9, leur accessibilit\ue9, leur performance agronomique, les plantes telles que Vitellaria paradoxa , Anogeissus leiocarpa , Combretum micranthum , Lannea microcarpa , Diospyros mespiliformis ont \ue9t\ue9 cit\ue9es comme \ue9tant les esp\ue8ces dont la liti\ue8re des feuilles est valoris\ue9e. Les mesures r\ue9alis\ue9es in situ montrent que, les rendements du sorgho dans les champs ayant re\ue7u de la liti\ue8re foliaire de Vitellaria pour la premi\ue8re fois, ont \ue9t\ue9 inf\ue9rieurs \ue0 ceux des parcelles t\ue9moin. Par contre, les champs ayant re\ue7u cette liti\ue8re pendant trois ann\ue9es cons\ue9cutives ont \ue9t\ue9 plus productifs. Dans l\u2019optique de valider les savoirs locaux et d\u2019approfondir les connaissances sur l\u2019effet des liti\ue8res foliaires sur la fertilit\ue9 du sol, une \ue9tude scientifique sur leur caract\ue9ristique chimique et sur leur influence sur les param\ue8tres de fertilit\ue9 du sol, est \ue0 envisager

Les risques sanitaires lies a l\u2019utilisation des pesticides dans les bas-fonds rizicoles de la commune de dano, Province du Ioba Burkina Faso

Pesticides are an essential component of agricultural production techniques for pests and weeds control. In Burkina Faso, failure to observe good practices for pesticides use exposes farmers to health risks. The study presents health risks related to pesticide management in rice fields in Dano through a survey of 158 rice farmers working in inland valleys. Socio-demographic characteristics of farmers, the types of pesticides used and their effects on health were documented. Rice farming in Dano is mainly done by an ageing population with an average of over 50 years (60%). In addition, farmers\u2019 education level is low, with an illiteracy rate of 61 and only 32% of farmers attaining primary school education. Risky behaviours of pesticides use are common, especially inadequate of farmer protection, poor practices of storage and re-use of pesticide products. Twelve types of pesticides were identified, of which 40% are not officially registered. The main active components in herbicides are Glyphosate, Paraquat, Bensulfuron methyl and Bispyribac-sodium. Health risks of pesticide use reported by farmers included various poisoning symptoms. To mitigate pesticide poisoning prevalence associated with poor farming practices, awareness campaigns should be conducted to inform farmers to use pesticides safely.Les produits pesticides constituent de nos jours une composante essentielle des techniques de production agricole pour le contr\uf4le des ravageurs et des mauvaises herbes. Au Burkina Faso, le non respect des bonnes pratiques d\u2019utilisation des pesticides pose un v\ue9ritable probl\ue8me de sant\ue9 des populations. L\u2019\ue9tude pr\ue9sente les risques sanitaires de gestion des pesticides agricoles. Une enqu\ueate de terrain a \ue9t\ue9 r\ue9alis\ue9e dans la Commune de Dano aupr\ue8s de 158 producteurs rizicoles. Le questionnaire a port\ue9 sur les caract\ue9ristiques sociod\ue9mographiques des producteurs rizicoles, les types de pesticides utilis\ue9s et leurs effets sur la sant\ue9. L\u2019\ue9tude montre que la riziculture \ue0 Dano est une activit\ue9 principalement exerc\ue9e par une population vieillissante dont les plus de 50 ans repr\ue9sentent pr\ue8s de 60%. De plus, la population est analphab\ue8te \ue0 61% contre 32% des producteurs ayant fr\ue9quent\ue9 l\u2019\ue9cole primaire. Les mauvaises pratiques d\u2019utilisation des pesticides sont fr\ue9quentes et concernent surtout l\u2019insuffisance des \ue9quipements de protection individuels des producteurs, les pratiques de stockage et de r\ue9utilisation des reliquats de pesticides. Douze types de pesticides ont \ue9t\ue9 identifi\ue9s dont 40% ne sont pas homologu\ue9s. Les principales mati\ue8res actives dans les herbicides sont le Glyphosate, le Paraquat, le Bensulfuron methyl et le Bispyribac-sodium. Les effets sanitaires de l\u2019utilisation des pesticides sont ressentis par les producteurs agricoles \ue0 travers divers sympt\uf4mes des intoxications. Pour r\ue9duire la pr\ue9valence des intoxications aux pesticides, des campagnes d\u2019information et de sensibilisation doivent \ueatre men\ue9es \ue0 l\u2019endroit des populations et des producteurs pour une utilisation s\ue9curis\ue9e des pesticides

The influence of C3 and C4 vegetation on soil organic matter dynamics in contrasting semi-natural tropical ecosystems

This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.Variations in the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated samples were used to assess the influence of C3 and C4 vegetation on SOM dynamics in semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. Differential patterns in SOM dynamics in C3/C4 mixed ecosystems occurred at various spatial scales. Relative changes in C/ N ratios between two contrasting SOM fractions were used to evaluate potential site-scale differences in SOM dynamics between C3- and C4-dominated locations. These differences were strongly controlled by soil texture across the precipitation gradient, with a function driven by bulk δ 13C and sand content explaining 0.63 of the observed variability. The variation of δ 13C with soil depth indicated a greater accumulation of C3-derived carbon with increasing precipitation, with this trend also being strongly dependant on soil characteristics. The influence of vegetation thickening on SOM dynamics was also assessed in two adjacent, but structurally contrasting, transitional ecosystems occurring on comparable soils to minimise the confounding effects posed by climatic and edaphic factors. Radiocarbon analyses of sand-size aggregates yielded relatively short mean residence times (τ ) even in deep soil layers, while the most stable SOM fraction associated with silt and clay exhibited shorter τ in the savanna woodland than in the neighbouring forest stand. These results, together with the vertical variation observed in δ 13C values, strongly suggest that both ecosystems are undergoing a rapid transition towards denser closed canopy formations. However, vegetation thickening varied in intensity at each site and exerted contrasting effects on SOM dynamics. This study shows that the interdependence between biotic and abiotic factors ultimately determine whether SOM dynamics of Published by Copernicus Publications on behalf of the European Geosciences Union. 5042 G. Saiz et al.: Influence of C3/C4 on SOM in tropical biomes C3- and C4-derived vegetation are at variance in ecosystems where both vegetation types coexist. The results highlight the far-reaching implications that vegetation thickening may have for the stability of deep SOM.UK National Environment Research CouncilAustralian Institute of Nuclear Science and Engineering (AINSE Ltd

The influence of C3 and C4 vegetation on soil organic matter dynamics in contrasting semi-natural tropical ecosystems

Variations in the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated samples were used to assess the influence of C3 and C4 vegetation on SOM dynamics in semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. Differential patterns in SOM dynamics in C3/C4 mixed ecosystems occurred at various spatial scales. Relative changes in C=N ratios between two contrasting SOM fractions were used to evaluate potential site-scale differences in SOM dynamics between C3- and C4-dominated locations. These differences were strongly controlled by soil texture across the precipitation gradient, with a function driven by bulk 13C and sand content explaining 0.63 of the observed variability. The variation of 13C with soil depth indicated a greater accumulation of C3-derived carbon with increasing precipitation, with this trend also being strongly dependant on soil characteristics. The influence of vegetation thickening on SOM dynamics was also assessed in two adjacent, but structurally contrasting, transitional ecosystems occurring on comparable soils to minimise the confounding effects posed by climatic and edaphic factors. Radiocarbon analyses of sand-size aggregates yielded relatively short mean residence times ( ) even in deep soil layers, while the most stable SOM fraction associated with silt and clay exhibited shorter in the savanna woodland than in the neighbouring forest stand. These results, together with the vertical variation observed in 13C values, strongly suggest that both ecosystems are undergoing a rapid transition towards denser closed canopy formations.However, vegetation thickening varied in intensity at each site and exerted contrasting effects on SOM dynamics. Thisstudy shows that the interdependence between biotic and abiotic factors ultimately determine whether SOM dynamics of C3- and C4-derived vegetation are at variance in ecosystems where both vegetation types coexist. The results highlight the far-reaching implications that vegetation thickening may have for the stability of deep SOM. © 2015, Copernicus Publications

Foliar trait contrasts between African forest and savanna trees: Genetic versus environmental effects

Journal ArticleVariations in leaf mass per unit area (Ma) and foliar concentrations of N, P, C, K, Mg and Ca were determined for 365 trees growing in 23 plots along a West African precipitation gradient ranging from 0.29 to 1.62m a-1. Contrary to previous studies, no marked increase in Ma with declining precipitation was observed, but savanna tree foliar [N] tended to be higher at the drier sites (mass basis). Generally, Ma was slightly higher and [N] slightly lower for forest vs savanna trees with most of this difference attributable to differences in soil chemistry. No systematic variations in [P], [Mg] and [Ca] with precipitation or between trees of forest vs savanna stands were observed. We did, however, find a marked increase in foliar [K] of savanna trees as precipitation declined, with savanna trees also having a significantly lower [K] than those of nearby forest. These differences were not related to differences in soil nutrient status and were accompanied by systematic changes in [C] of opposite sign. We suggest an important but as yet unidentified role for K in the adaption of savanna species to periods of limited water availability; with foliar [K] being also an important factor differentiating tree species adapted to forest vs savanna soils within the 'zone of transition' of Western Africa.Natural Environment Research Council TROBIT Consortium projectRoyal Society - University Research Fellowshi

A Randomized Trial to Assess the Impact of a Package of Diagnostic Tools and Diagnostic Algorithm on Antibiotic Prescriptions for the Management of Febrile Illnesses Among Children and Adolescents in Primary Health Facilities in Burkina Faso.

BACKGROUND: Low- and middle-income countries face significant challenges in differentiating bacterial from viral causes of febrile illnesses, leading to inappropriate use of antibiotics. This trial aimed to evaluate the impact of an intervention package comprising diagnostic tests, a diagnostic algorithm, and a training-and-communication package on antibiotic prescriptions and clinical outcomes. METHODS: Patients aged 6 months to 18 years with fever or history of fever within the past 7 days with no focus, or a suspected respiratory tract infection, arriving at 2 health facilities were randomized to either the intervention package or standard practice. The primary outcomes were the proportions of patients who recovered at day 7 (D7) and patients prescribed antibiotics at day 0. RESULTS: Of 1718 patients randomized, 1681 (97.8%; intervention: 844; control: 837) completed follow-up: 99.5% recovered at D7 in the intervention arm versus 100% in standard practice (P = .135). Antibiotics were prescribed to 40.6% of patients in the intervention group versus 57.5% in the control arm (risk ratio: 29.3%; 95% CI: 21.8-36.0%; risk difference [RD]: -16.8%; 95% CI: -21.7% to -12.0%; P < .001), which translates to 1 additional antibiotic prescription saved every 6 (95% CI: 5-8) consultations. This reduction was significant regardless of test results for malaria, but was greater in patients without malaria (RD: -46.0%; -54.7% to -37.4%; P < .001), those with a respiratory diagnosis (RD: -38.2%; -43.8% to -32.6%; P < .001), and in children 6-59 months old (RD: -20.4%; -26.0% to -14.9%; P < .001). Except for the period July-September, the reduction was consistent across the other quarters (P < .001). CONCLUSIONS: The implementation of the package can reduce inappropriate antibiotic prescription without compromising clinical outcomes. CLINICAL TRIALS REGISTRATION: clinicaltrials.gov; NCT04081051

The influence of C₃ and C₄ vegetation on soil organic matter dynamics in contrasting semi-natural tropical ecosystems

Variations in the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated samples were used to assess the influence of C3 and C4 vegetation on SOM dynamics in semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. Differential patterns in SOM dynamics in C3/C4 mixed ecosystems occurred at various spatial scales. Relative changes in C / N ratios between two contrasting SOM fractions were used to evaluate potential site-scale differences in SOM dynamics between C3- and C4-dominated locations. These differences were strongly controlled by soil texture across the precipitation gradient, with a function driven by bulk δ13C and sand content explaining 0.63 of the observed variability. The variation of δ13C with soil depth indicated a greater accumulation of C3-derived carbon with increasing precipitation, with this trend also being strongly dependant on soil characteristics. The influence of vegetation thickening on SOM dynamics was also assessed in two adjacent, but structurally contrasting, transitional ecosystems occurring on comparable soils to minimise the confounding effects posed by climatic and edaphic factors. Radiocarbon analyses of sand-size aggregates yielded relatively short mean residence times (τ) even in deep soil layers, while the most stable SOM fraction associated with silt and clay exhibited shorter τ in the savanna woodland than in the neighbouring forest stand. These results, together with the vertical variation observed in δ13C values, strongly suggest that both ecosystems are undergoing a rapid transition towards denser closed canopy formations. However, vegetation thickening varied in intensity at each site and exerted contrasting effects on SOM dynamics. This study shows that the interdependence between biotic and abiotic factors ultimately determine whether SOM dynamics of C3- and C4-derived vegetation are at variance in ecosystems where both vegetation types coexist. The results highlight the far-reaching implications that vegetation thickening may have for the stability of deep SOM. Â © Author(s) 2015

The influence of C₃ and C₄ vegetation on soil organic matter dynamics in contrasting semi-natural tropical ecosystems

Variations in the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated samples were used to assess the influence of C3 and C4 vegetation on SOM dynamics in semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. Differential patterns in SOM dynamics in C3/C4 mixed ecosystems occurred at various spatial scales. Relative changes in C / N ratios between two contrasting SOM fractions were used to evaluate potential site-scale differences in SOM dynamics between C3- and C4-dominated locations. These differences were strongly controlled by soil texture across the precipitation gradient, with a function driven by bulk delta 13C and sand content explaining 0.63 of the observed variability. The variation of delta 13C with soil depth indicated a greater accumulation of C3-derived carbon with increasing precipitation, with this trend being also strongly dependant on soil characteristics. The influence of vegetation thickening on SOM dynamics was also assessed in two adjacent, but structurally contrasting, transitional ecosystems occurring on comparable soils to minimise confounding effects posed by climatic and edaphic factors. Radiocarbon analyses of sand-size aggregates yielded relatively short mean residence times (T) even deep in the soil, while the most stable SOM fraction associated to silt and clay exhibited shorter T in the savanna woodland than in the neighbouring forest stand. These results together with the vertical variation observed in delta 13C values, strongly suggest that both ecosystems are undergoing a rapid transition towards denser closed canopy formations. However, vegetation thickening varied in intensity at each site and exerted contrasting effects on SOM dynamics. This study shows that the interdependence between biotic and abiotic factors ultimately determine whether SOM dynamics of C3- and C4-derived vegetation are at variance in ecosystems where both vegetation types coexist. The results highlight the far-reaching implications that vegetation thickening may have for the stability of deep SOM

Structural, physiognomic and above-ground biomass variation in savanna-forest transition zones on three continents - How different are co-occurring savanna and forest formations?

Through interpretations of remote-sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity) in Africa, South America and Australia. Woody plant leaf area index variation was related to tree canopy cover in a similar way for both savanna and forest with substantial overlap between the two vegetation types. As total woody plant canopy cover increased, so did the relative contribution of middle and lower strata of woody vegetation. Herbaceous layer cover declined as woody cover increased. This pattern of understorey grasses and herbs progressively replaced by shrubs as the canopy closes over was found for both savanna and forests and on all continents. Thus, once subordinate woody canopy layers are taken into account, a less marked transition in woody plant cover across the savanna-forest-species discontinuum is observed compared to that inferred when trees of a basal diameter > 0.1 m are considered in isolation. This is especially the case for shrub-dominated savannas and in taller savannas approaching canopy closure. An increased contribution of forest species to the total subordinate cover is also observed as savanna stand canopy closure occurs. Despite similarities in canopy-cover characteristics, woody vegetation in Africa and Australia attained greater heights and stored a greater amount of above-ground biomass than in South America. Up to three times as much above-ground biomass is stored in forests compared to savannas under equivalent climatic conditions. Savanna-forest transition zones were also found to typically occur at higher precipitation regimes for South America than for Africa. Nevertheless, consistent across all three continents coexistence was found to be confined to a well-defined edaphic-climate envelope with soil and climate the key determinants of the relative location of forest and savanna stands. Moreover, when considered in conjunction with the appropriate water availability metrics, it emerges that soil exchangeable cations exert considerable control on woody canopy-cover extent as measured in our pan-continental (forest + savanna) data set. Taken together these observations do not lend support to the notion of alternate stable states mediated through fire feedbacks as the prime force shaping the distribution of the two dominant vegetation types of the tropical lands