Diospyro-Kyayetlia Senegalensis ord. nov. in the regional "Parc W" of river Niger

Les végétations arbustives des voisinages des cours d’eau ont été étudiées à partir de 34 relevés phytosociologiques réalisés entre septembre 2001 et décembre 2003, en utilisant la méthode phytosociologique de Braun Blanquet. Deux associations végétales en sont décrites: Feretio-Khayetum senegalensis et Celtido-Diospyroetum mespiliformis. Une alliance nouvelle et un ordre nouveau sont créés pour les regrouper. Il s’agit du Feretio-Khayion senegalensis et du Diospyro-Khayetalia senegalensis. Cet ordre rassemble les groupements vallicoles de la zone de transition soudano sahélienne et est considéré comme vicariante géographique du Pterygotetalia Lebrun et Gilbert 1954. Aussi, le Diospyro-Khayion senegalensis all. nov est consirédéré comme vicariante géographique du Khayo-Pterygotion Schmitz 1950 et du Psychotrio-Tecleion Schmitz 1971. Mots clés: Diospyro-Khayetalia senegalensis, Diospyro-Khayion senegalensis, Parc Régional du W du fleuve NigerThe shrubby vegetation close to water bodies was documented and analysed by 34 phytosciological observations, beginning September 2001 to December 2003; the Braun Blanquet phytoecological method was used. Two vegetative associations were depicted: Feretio-Khayetum senegalensis and Celtido-Diospyroetum mespiliformis. To regroup them, a new alliance and a new order were created. They consisted of Feretio-Khayion senegalensis and Diospyro-Kyayetalia senegalensis. This order assembled the in valley groupings of the transitional sudano sahelian zone and was considered as a geographic variance of Pterygotetalia Lebrun and Gilbert 1954. As well as the Diospyro-Khayion senegalensis all. nova was considered as a geographic variance of Khayo-Pterygotion Schmitz 1950 and of Psychotrio-Tecleion Schmitz 1971. Key words: Diospyro-Khayetalia senegalensis, Diospyro-Khayion senegalensis, W Regional Park of Niger Rive

Analyse De L’état De La Diversité Floristique Des Plateaux Suivant Un Gradient D’aridité Nord- Sud Dans La Réserve De Biosphère Du W Du Niger

Introduction: In Niger, the degradation of ecosystems leads to a loss of biodiversity and an increase in the adverse effects of climate change, especially in the ecosystems contracted from the plateaux of the Niger W biosphere reserve. Objective: The objective of this study is to characterize the spatial variability of the flora according to the north-south rainfall gradient of the reserve. Methodology: Phytosociological surveys, an ascending hierarchical classification and a canonical analysis of correspondences between plant groups and environmental factors. Results-Discussion: The 126 inventoried species have 88 dicotyledons, 28 woody species, and 98 herbaceous species. The most common families are: Poaceae (21.42%), Fabaceae (12.69%), Rubiaceae (7.14%) and Convolvulaceae (6.34%). The biological spectrum is dominated by therophytes then microphanerophytes. The world chorology is marked by African species followed by palaeotropics or pantropicales, and at the African level, Sudano-Zambezian species are the most frequent. The presence of intermediate species (GC-SZ and GC-SZ-SahS) is noted. From north to south, 3 groups of plants were highlighted: the group with Sida cordifolia and Guiera senegalensis whose phytodiversity is reduced; Group II consisting of the subgrouping with Combretum nigricans and Microchloa indica and the subgrouping with Combretum micranthum and Gardenia sokotensis floristically rich, with however a regeneration dominated by Guiera senegalensis; grouping with Loudetia togoensis and Acacia macrostachya, in good state of conservation. Conclusion: The study made it possible to characterize floristically the various landscapes along the rainfall and anthropic gradient. Thus, in view of the structures of the stands observed, the distribution of floristic diversity increases according to a gradient of decreasing aridity from the periphery to the internal part of the reserve. From the north to the south there is a degraded part, a part gradually invaded by Guiera senegalensis and another well preserved. This work, which provides an overview of the state of conservation of the floristic diversity of the Niger W Biosphere Reserve, allows taking appropriate measures to safeguard our plant resources

Diospyro-Khayetalia senegalensis ord. nov. dans le Parc Régional du W du fleuve Niger

The shrubby vegetation close to water bodies was documented and analysed by 34 phytosciological observations, beginning September 2001 to December 2003; the Braun Blanquet phytoecological method was used. Two vegetative associations were depicted: Feretio-Khayetum senegalensis and Celtido-Diospyroetum mespiliformis. To regroup them, a new alliance and a new order were created. They consisted of Feretio-Khayion senegalensis and Diospyro-Kyayetalia senegalensis. This order assembled the in valley groupings of the transitional sudano sahelian zone and was considered as a geographic variance of Pterygotetalia Lebrun and Gilbert 1954. As well as the Diospyro-Khayion senegalensis all. nova was considered as a geographic variance of Khayo-Pterygotion Schmitz 1950 and of Psychotrio-Tecleion Schmitz 1971.Les végétations arbustives des voisinages des cours d’eau ont été étudiées à partir de 34 relevés phytosociologiques réalisés entre septembre 2001 et décembre 2003, en utilisant la méthode phytosociologique de Braun Blanquet. Deux associations végétales en sont décrites: Feretio-Khayetum senegalensis et Celtido-Diospyroetum mespiliformis. Une alliance nouvelle et un ordre nouveau sont créés pour les regrouper. Il s’agit du Feretio-Khayion senegalensis et du Diospyro-Khayetalia senegalensis. Cet ordre rassemble les groupements vallicoles de la zone de transition soudano sahélienne et est considéré comme vicariante géographique du Pterygotetalia Lebrun et Gilbert 1954. Aussi, le Diospyro-Khayion senegalensis all. nov est consirédéré comme vicariante géographique du Khayo-Pterygotion Schmitz 1950 et du Psychotrio-Tecleion Schmitz 1971

Évaluation de Stocks de Semence de Diospyros mespiliformis Hochst. ex A. Rich. (Ebenaceae): Une Espèce en Forte Régression au Niger

Les graines sont les éléments indispensables dans la dispersion et le renouvellement des individus d’une espèce. De la qualité et surtout de la quantité de ses graines dépendent la dynamique d’une population surtout ligneuse. L'objectif est d'évaluer les stocks des semences de D.mespiliformis dans les sols afin de contribuer à la maîtrise des contraintes liées à sa régénération naturelleAinsi un échantillon de 265 arbres adultes dans les zones de présence de l’espèce a été pris pour cette étude le long de quatre cours d’eau du Niger (Dargol, Goulbi N’kaba, Goulbi Maradi, Gouroubi). L’évaluation des stocks de graines du sol révèle 42 graines/m2 avec le pourcentage de graines pleines variant entre 73,98 % à Goroubi et 95,94% dans les champs dunaires de Goulbi Maradi. Au total, 83 % de graines récoltées sont pures avec une viabilité moyenne de 95 %. Ce stock est nécessaire et est suffisant pour assurer la dynamique progressive de population de l’ébène d’Afrique.   Seeds are indispensable in the dispersal and renewal of a particular species. The quantity and quality of these seeds depend on the dynamics of a predominantly woody population. The objective is to assess seed stocks in soils so as to contribute to the knowledge of the difficulties related to natural regeneration of D. mespiliformis. A sample of 265 adult trees were taken from the species for this study along four rivers of Niger (Dargol, Goulbi kaba, Goulbi Maradi, Gouroubi). The evaluation of the soil seed stocks reveals 42 seeds/m2 with the percentage of full seeds varying between 73.98% in Goroubi and 95.94 % in the dune fields of Goulbi Maradi. 83% of seeds harvested are pure with an average viability of 95%. This stock is necessary and sufficient to allow the progressive population dynamics of african ebony

Vegetation and plant diversity pattern study of Central Eastern Niger grasslands

Vegetation and plant diversity patterns of Central Eastern Niger grasslands were investigated following phytosociological methods. Vegetation data collected on 76 plots by using the Braun-Blanquet’s (1932) coverabundance scale were analyzed through five multivariate analyses (TWINSPAN, NMS, DCA, ISA and MRPP) in order to distinguish and to describe plant communities. Alpha diversity (H’, E and R) was also used to describe these communities. A total of 162 species belonging to 37 families and 104 genera were identified. Dominant families were the Poaceae (18%), Leguminosae-Papilionoideae (8%), Convolvulaceae (7%) and Leguminosae-Caesalpinioideae (4%). Life forms were dominated by Therophytes (59%) and Phanerophytes (27%), whereas the most prominent geoelements were of the Soudano-zambesians-saharo-sindians (33%), Soudano-zambesians (25%) and Guineo-congolian-soudano-zambesians (25%) types. In total, five plant communities were identified on the basis of environmental gradients and species composition. The environmental parameters that favorably influence these plant distributions are topography, moisture, texture and land use (fallow, pasture). Importantly, each of these communities seems to correspond to a particular wildlife habitat. These habitats shelter their own species that may be seen as a keystone species.Keywords: Multivariate analysis, vegetation communities, characteristic species, Central East grassland, Nige

Effet De Prétraitements, De Substrats Et De Stress Hydriques Sur La Germination Et La Croissance Initiale De Diospyros Mespiliformis Hochst. Ex A.DC

This study is on the seeding and the initial growth of a food species, Diospyros mespiliformis, in Niger. Diospyros mespiliformis is an overexploited food species in Niger. The aim of this study is to determine the optimal conditions for germination and seedling growth of this species. In doing so, seed germination tests were conducted in petri dishes laboratory and seedling growth survey respectively. Also, the nursery was done using bags. The treatments involve the seed staying in warm water for 1, 3, 5, 7 days; scalding; and mechanical scarification. In the nursery, the substrates used are alluvial soil and alluvial soil mixed in 1/4, 1/3, and 1/2 of organic manure. As a result, the growth monitoring is done on plants kept in the shade. Others were exposed to the sun for 12 months by applying water stress (watering every day; 2 and 1 times per week; and without watering). Thus, the germination capacity is 55, 4% without treatment and it reached 74% by scalding. The conservation makes it reduce to 43% after 6 months and 25% after 1 year. In the nursery, the emergence rate is 52,8 % in alluvial soil, but it reduced to 10% in the substrate (soil 1/2 and 1/2 fertilizers). D. mespiliformis growth is slow during cold weather and becomes fast during hot weather. When the weather is shady or sunny, this species supports four months of drought by developing a significant root system. D. mespilformis can be used for afforestation