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Productivité Et Rôles Socio-Économiques Des Cultures Maraîchères Dans Les Communes De Tibiri Gobir Et De Madarounfa (Niger)
Get PDFLe maraîchage est une activité prépondérante qui prend de plus en plus de l’ampleur en milieu urbain et péri-urbain. Les communes urbaines de Madarounfa et Tibiri gobir ne sont pas en reste. Dès lors, l’objectif général de cette étude est d’évaluer la productivité et les rôles socio-économiques des cultures maraîchères sur les sites d’étude. La méthode de collecte des données a essentiellement concerné des enquêtes individuelles et des focus groupes sur chacun des deux (2) sites. Au total 50 producteurs ont été retenus sur chaque site. En vue de confronter les expériences des producteurs, des focus groupes ont été faits. Il ressort de cette étude que dix-huit (18) et dix-sept (17) cultures maraîchères sont pratiquées respectivement à Tibiri gobir et à Madarounfa. Les cultures les plus pratiquées à Madarounfa sont l’oignon avec une proportion de 23% suivi de la tomate (15%), le chou (15%) et de l’anis (15%). Par contre, dans la commune de Tibiri gobir c’est la tomate (28%) qui est la représentée puis viennent l’oignon (18%) et la citrouille (13%). En outre, les cultures qui ont eu les meilleurs rendements sont le manioc, l’oignon et la pastèque. Selon les résultats de cette étude, les cultures les plus rentables sont l’aubergine et dans une moindre mesure le melon, la citrouille, la pastèque, le manioc, l’oignon et le poivron. Ces cultures peuvent, en effet, procurer jusqu’à 500 000FCFA/ha/cycle. Le maraichage permet non seulement aux producteurs d’assurer leur sécurité alimentaire mais aussi le renforcement des relations sociales à travers des dons.
Market gardening is a predominant activity that is gaining more and more importance in urban and peri-urban areas and the urban communes of Madarounfa and Tibiri gobir are not to be outdone. Therefore, the main aim of this study is to assess the productivity and socioeconomic roles of market gardening at the study sites. The data collection method mainly concerned structured and semi-structured surveys. A total of 50 producers were selected on each site. In order to compare the experiences of producers, focus groups were held. Then, in order to compare the experiences of producers, focus groups were held. It emerges from this study that eighteen (18) and seventeen (17) vegetable crops are cultivated respectively in Tibiri gobir and Madarounfa areas. The most common crops in Madarounfa are onion with a proportion of 23% followed by tomato (15%), cabbage (15%) and anise (15%). On the other hand, in the municipality of Tibiri gobir it is the tomato (28%) that is represented, followed by the onion (18%) and the pumpkin (13%). On the other hand, the crops that have had the best yields are cassava, onion and watermelon. According to the results of this study, the most profitable crops are eggplant and to a lesser extent melon, pumpkin, watermelon, cassava, onion and peppers. These crops can, in fact, provide up to 500,000FCFA / ha. Market gardening not only allows producers to ensure their food security but also the strengthening of social relations through donations
Caractéristiques floristique et écologique des formations végétales de Gouré (Sud-est du Niger)
Get PDFThe present study aims to evaluate the characteristics of the vegetation of the department of Gouré. The data were collected using phytosociological surveys and dendrometric measurements in plots of 1000 m2 located in different units of land use (basins, dunes and shallows). A total of 56 surveys were conducted. The carried out phytosociological inventories showed the floristic richness with 81 species distributed in 68 genera and 29 families. A matrix made up of 81 species and 56 surveys, submitted to a Detrended Correspondence Analysis (DCA) and the Ascending Hierarchy Classification (CHA) discriminated three plant communities. It is about plant communities of Hyphaene thebaica and Amaranthus spinosus (G1); Acacia raddiana and Cenchrus biflorus (G2) and the grouping Leptadenia pyrotechnica and Aristida mutabilis (G3). In addition, therophytes followed by microphanerophytes are the dominant biological types. The Sudano-Zambezian and Guineo-Congolese-Sudano-Zambezian species are the dominant phytogeographic types. The Shannon diversity index varied from 3.13 to 5.16 bits and the Pielou equitability from 0.56 to 0,86. The diameter structure of woody stands shows that individuals of the Acacia raddiana and Cenchrus biflorus (G2) and Leptadenia pyrotechnica and Aristida mutabilis (G3) groups are dominated by small diameter individuals whereas the grouping with Hyphaene thebaica and Amaranthus spinosus (G1) are dominated by large subjects.
Keywords: Floristic diversity, biological and phytogeographic types, plant communities, demographic structure, GouréLa présente étude vise à évaluer les caractéristiques de la végétation du département de Gouré au Niger. Les données ont été collectées au moyen des relevés phyto-sociologiques et des mesures dendrométriques dans des placettes de 1000 m2 reparties dans des unités d’occupation des terres (cuvettes, dunes et bas-fonds). Un total de 56 relevés a été réalisé et 81 espèces réparties dans 68 genres et 27 familles ont été inventoriées. L’analyse Factorielle des Correspondances Détendancées (AFCD) et la Classification Hiérarchique Ascendante (CHA) a permis de discriminer trois groupements végétaux. Il s’agit du groupement à Hyphaene thebaica et Amaranthus spinosus (G1); le groupement à Acacia raddiana et Cenchrus biflorus (G2) et le groupement à Leptadenia pyrotechnica et Aristida mutabilis (G3). Par ailleurs, les Thérophytes suivies des microphanérophytes sont les types biologiques dominants. Les espèces Soudano-Zambéziennes et Guinéo-Congolaises-Soudano-Zambéziennes sont les types phytogéographiques dominants. L’indice de diversité de Shannon varie de 3,13 à 5,16 bits et l’équitabilité de Pielou de 0,56 à 0,86. La structure en classes de diamètre des peuplements ligneux montre que les individus des groupements (G2) et (G3) sont à dominance d’individus de faible diamètre tandis que le groupement (G1) sont à dominance de gros sujets.
Mots clés: Diversité floristique, types biologiques et phytogéographiques, groupements végétaux, structure démographique, Gour
Biodiversity and Structure of Woody Plants of Sahelian Rangelands of Baban Rafi, Niger
No full textThe present study investigates the importance of harvesting regimes and natural disturbances on the diversity, the population structure and the regeneration trends of the woody plant species of Sahelian rangelands and their implication for sustainable browsing management. Woody plants data was collected in 42 plots established in the interval of 500 m, along transects distant of 500 m, in the direction South-west and North-east of the study area. In each plot, height and diameter at breast height of each individual mature tree and shrub (diameter < 4 cm), and the number of seedlings (diameter > 4 cm) were recorded. A total number of 21 plants species were recorded, with low values of the Shannon-Weaver (H’) index and the evenness of Piélou (E) indicating very low diversity of rangelands. Analysis of size classes distribution of diameters and heights of the whole vegetation and the three dominants species revealed high density of juveniles, relating to stable populations. The juvenile plants represented more than 80 of the vegetation with diameters and heights respectively lower than 6 cm and 2.5 m, indicating shrubby vegetation. Combretum micranthum, Guiera senegalensis and Combretum nigricans which have the highest values of IVI, have also the greatest rates of seedling and vegetative propagation densities. Stable populations with strong capacity of regeneration under harsh area and high human pression such as logging and grazing can be related ecological success. Management practices that promote plantations or managing natural regeneration of such species can facilitate fast secondary succession towards desirable condition.</jats:p
Succession des communautés végétales des jachères protégées en zone sahélienne: cas de Banizoumbou (Niger)
Get PDFObjectif: L’importance de la perturbation (en durée ou en intensité) semble décisive pour déterminer l'état de la végétation et la dynamique successionnelle. L’objectif de la présente étude est d'examiner les variations des paramètres écologiques des champs et des jachères protégées de Banizoumbou.Méthodologie et résultats: Les relevés phyto-sociologiques ont été réalisés selon la méthode sigmatiste de Braun-Blanquet (1932). L’échantillonnage a été effectué sur la base de types des systèmes, ainsi les jachères et les champs ont fait l’objet d’inventaire suivant 6 transect, des placettes de 1000 m2 équidistantes de 500 m ont été placé. Ainsi au total 33 relevés ont été effectués dont 18 dans la jachère et 15 relevés dans le champ. Il ressort de l’étude que la diversité dépend de stade successionnel même à l’intérieur d’un même type d’occupation. L’analyse des indices montre qu’en plus des jachères, les champs sont aussi d’importantes sources de biodiversité. Ainsi l’indice de diversité de Shannon évolue en fonction de l’âge de jachère et de champ, mais toute fois il évolue beaucoup plus rapidement au niveau de jachère que le champ. La densité moyenne de la zone d’étude est de 260 individus par hectare dont Guiera senegalensis représente plus de 70%. La hauteur moyenne, le diamètre moyen, la densité moyenne et le recouvrement moyen les plus élevés sont observés au niveau des jachères.Conclusion et application of résultats: la présente étude a montré que la variation de la diversité végétale est une fonction de l’âge aussi bien au niveau des champs que les jachères. Ainsi la diversité évolue plus rapidement au niveau des jachères.Mots clés: Succession des communautés végétales, jachères protégées de BanizoumbouEnglish AbstractObjective: The importance of disturbance (duration or intensity) seems decisive in determining the state of vegetation and successional dynamics. The purpose of this study is to study and examine variations in the floristic richness, diversity and production of protected fallow land in Banizoumbou.Methodology and Results: The phyto-sociological surveys were carried out according to the sigmatist method of Braun-Blanquet (1932). Sampling was carried out on the basis of land use types, so fallows and fields were inventoried following 6 transect, 1000 square meter equidistant plots of 500 m were set. A total of 33 surveys were carried out, including 18 in the fallows and 15 in the fields. Our findings show that diversity depends on the successional stage even within the same type of land use. Analysis of the indices shows that in addition to fallow land, fields are also important sources of biodiversity. Thus, Shannon's diversity index increases according to the fallow and field age, but this increase is much higher in the fallows in than the fields. The results reveal also that average density of the study area is 260 individuals per hectare, of which Guiera senegalensis represents more than 70%. The mean height, mean diameter, average density and highest average cover were observed at fallow land.Conclusion and Application of results: The present study showed that variation in plant diversity is a function of age at both field and fallow land. Thus diversity evolves more rapidly at fallow land.Keywords: Succession of plant communities, protected fallow land of Banizoumbo
Assessment of Drought Characteristics under Changing Climatic Conditions using SPI and SPEI Indices in Semi-Arid Environment of Southeastern Niger
No full textIn the sahelian zone where 80% of the populations rely on rainfed-agricultural activities for their livelihood, drought episodes had significant socio-economics and ecological impacts. In recent decades, there has been an increase in the intensity, frequency and severity of drought occurrence mainly attributed to climate change. Thus, the main objectives of this study were: i) to understand drought multi-scale patterns and trend; ii) to assess drought duration, frequency and temporal extent over Mainé-soroa and Diffa located in the lake chad basin. To achieve these objectives standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) at 1, 3, 6, 9, 12 and 24-month timescales were employed for the stations of Mainé-soroa and Diffa. Stations’ monthly rainfall, air minimum and maximum temperature spanning 1950-2009 and 1988-2017 respectively for Mainé-soroa and Diffa were used for the analysis. The Mann–kendall trend test was performed and revealed negative SPEI and SPI trends in the station of Mainé-soroa. Results indicate a significant negative SPI-12 and SPI-24 trend (p-value < 0.05), while no trend was detected in the rest of the time-scale series. The absolute value of declining trend was gradually increasing when SPEI was calculated with more lagged months. Meanwhile, at the Diffa station both SPEI and SPI showed positive trends. The pettitt\u27s t-test on the SPEI series indicated particularly 1968 as the change point detected for three time scales including spei-9, SPEI-12, and SPEI-24. Drought frequency generally increased in Mainé-soroa over the period of 1950–2009. SPEI appear to be the most powerful tool of monitoring drought in semi-arid environment in the context of climate change. To build resilience to drought and cope with its effects in the area we stress the importance of the establishment of early risk identification and advices framework at local level such study should be extended to lake chad basin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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