La dynamique spatio-temporelle de l'occupation du sol et les facteurs de dégradation ont été analysés à partir des images Landsat de 1972, de 1990 et de 2008, de la télédétection et d'un système d'information géographique (SIG), dans le Parc National du W et sa périphérie dans le Nord-Ouest du Bénin. L'objectif de la présente étude est d'une part d'analyser la dynamique de l'occupation du sol entre 1972 et 2008, et d'autre part, de déterminer les facteurs de dégradation du couvert végétal. Des enquêtes socioéconomiques ont été réalisées dans les villages riverains du Parc National du W. La classification supervisée par maximum de vraisemblance a été appliquée. Deux matrices de transition ont permis de mettre en évidence les conversions subies par les différentes unités d'occupation du sol. Les formations forestières ont régressé de 22,70% à 17,00% entre 1972 et 2008. Les forêts galeries dégradées quasi inexistantes en 1972 se sont reconstituées à partir de 1990 et sont passées de 0,60% à 2,85% en 2008. Quant aux forêts denses ainsi que les forêts claires et savanes boisées, elles ont subi une régression en terme de superficie (0,23% en 1972 à 0,09% en 2008 et de 17,90% à 12,91% respectivement). Par contre, les savanes arborées et arbustives ont connu une légère diminution (73% en 1972 à 66,65% en 2008) tandis que les mosaïques de champs et jachères ont connu une augmentation de leur superficie (1,38% en 1972 à 13,97% en 2008), soit plus de 10 fois leur superficie initiale de 1972. La démographie, l'agriculture et le surpâturage sont les trois principaux facteurs de dégradation du Parc National du W et de sa périphérie.

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Background. Ethnobotanical knowledge on four herbaceous species, Acmella uliginosa (Sw.) Cass., Momordica charantia L., Phyllanthus amarus Schumach. & Thonn., and Scoparia dulcis L., in Benin was investigated. Methods. Herbal medicine traders in six different markets were interviewed using a semi-structured questionnaire. The linear regression test was performed to check for the influence of respondent’s age on ethnobotanical uses they hold. Relative frequency citation, fidelity level, use value, and Rahman similarity index were calculated to assess the diversity of medico-magic knowledge. The Informant Consensus Factor is not applicable in this study since we are dealing neither with the diversity of medicinal plants used by a community of people nor with a great number of plant species used for medicinal purposes, nor the diversity of plant species used in the treatment of a specific or group of ailments. Results. The respondent's age did not influence the ethnobotanical uses they hold on the species. All thirty-six informants surveyed traded Phyllanthus amarus Schumach. & Thonn., Momordica charantia L., and Scoparia dulcis L., and the majority traded Acmella uliginosa (Sw.) Cass. The respondent's age does not influence the diversity of ethnobotanical uses they hold on the study species. Purchase in traders’ own markets was the predominant source of Phyllanthus amarus Schumach. & Thonn., Momordica charantia L., and Scoparia dulcis L. while Acmella uliginosa (Sw.) Cass. was mostly purchased in other more distant markets. A noticeable proportion of traders also collect Phyllanthus amarus Schumach. & Thonn. and Momordica charantia L. from wild populations. Phyllanthus amarus Schumach. & Thonn. was the species most demanded by customers followed by Momordica charantia L. Traders confirmed the scarcity of all species in recent years and climate change and destruction of natural habitats for logging were the most cited causes. The entire plant of Phyllanthus amarus Schumach. & Thonn. was used mainly to treat malaria, diabetes, and constipation, and decoction with oral administration was the most frequent preparation for malaria treatment. To treat diabetes, informants mixed Phyllanthus amarus Schumach. & Thonn. with Momordica charantia L. used as a decoction with oral administration. Momordica charantia L. was also used to treat measles and chicken pox. Acmella uliginosa (Sw.) Cass. and Scoparia dulcis L. were mostly used for their spiritual use for luck, predominantly by chewing fresh leaves or flowers, and by bathing with the ground plant mixed with soap, respectively. Overall, Momordica charantia L. had the greatest use value followed by Phyllanthus amarus Schumach. & Thonn. The majority of traders do not plant the species. Conclusions. The harvesting and trade of the species threaten their natural populations and urgent tools, including in situ and ex situ conservation, are needed to ensure their long-term sustainable exploitation.

Savannahs are widespread vegetation type in Sudanian zone of Africa. As protected areas are often assumed to be the best way to conserve biodiversity, we assessed the effectiveness of the Pendjari Biosphere Reserve in Benin, for maintaining savannah woody species composition, diversity and structure. Square plots of 900 m 2 were randomly established in protected and surrounding unprotected savannahs, and all woody species (dbh ! 1 cm) were recorded and identified. Species composition, Importance Value Index, densities, basal area and diversity indexes were assessed in relation to conservation status. The results showed that DCA based on presence/absence species data did not separate clearly protected savannahs from unprotected ones. However, some species were prominent in unprotected savannahs while others showed the same scheme in protected ones. Diversity indexes indicated a good distribution of species in the two savannah types. The woody density showed a higher value in protected than unprotected savannah at shrub layer level. The basal area was significantly higher in the protected savannah than unprotected one at the two woody layer levels. It can be concluded that biodiversity conservation in surrounding unprotected areas should be of great importance to increase biodiversity conservation by protected area whether specific actions were implemented.

Bananas and plantains production is an important income source for millions of small farmers. The increased demand for bananas and plantains on national and international market would justify its value chain development. However, its value chain faces several constraints, of which production and marketing turn out to be the most important. This study aimed at determining and analyzing the constraints related to Bananas and Plantains value chain and showing the gaps between agroecological and agricultural practices used by farmers in southern Benin. Characterization was carried out on the seed production systems, agricultural practices, bananas and plantains production, fruit availability and commercialization constraints with farmers using individual and focus groups surveys. Bananas and plantains seedlings production and acquisition varied according to production areas. Their seedlings self-production was widespread in production areas and 26 cultivars have been identified as major. The availability of these cultivars varied across time and production areas. There were significant negative effects of agricultural practices on major banana pest's presence. Bananas and plantains production was limited by 12 factors, from which banana plants fall related to the wind, lack of financial support to irrigate banana fields, climate changes, no availability of cultivable How to cite this paper: Dassou, A.G.,

Nitrogen fertilization and nutrient removal are some of the greatest challenges associated with the production of bioethanol from corn grain in the United States. The project was conducted in Missouri from 2008 to 2009 in a silt loam soil to determine the effect of N fertilization on the nutrient removal by corn grain. Corn grain removed 31 to 201 kg N/ha, 10 to 102 kg K/ha, 3 to 20 kg P/ha, 0.6 to 11 kg Ca/ha, 0.7 to 2.7 kg Fe/ha, 0.045 kg Mn/ha, and 0.003 kg Cu/ha, depending on the N rate. Our results suggest that as farmers add N to their soil to improve the grain or starch yield, they will also be increasing the nutrient removal, therefore affecting the fertility of their fields if the nutrient removal is not offset.

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Variation of Loranthaceae impact on Vitellaria paradoxa C. F. Gaertn. fruit yield in contrasting habitats and implications for its conservation.