Impacts of type of fallow and invasion by Chromolaena odorata on weed communities in crop fields in Cameroon

In the humid forest regions of southern Cameroon in central Africa, sectoral and macroeconomic policy reforms introduced in the late 1980s have led to intensified land use, which in turn has resulted in, among other environmental consequences, shortened fallow systems dominated by the Asteraceae shrub, Chromolaena odorata (L.) King and Robinson, rather than by secondary forest species. A trial was established to determine the effect of shortened fallow duration and invasion by C. odorata on the weed flora in subsequent mixed food cropping systems. Plots were established in cleared 5- to 7-year-old fallow fields in which the vegetation was either dominated by C. odorata or not, and in which the dominant fallow vegetation in the previous crop–fallow rotation had been either C. odorata, forest, or herbaceous (not dominated by C. odorata). Cassava (Manihot esculenta Crantz), maize (Zea mays L.), and groundnuts (Arachis hypogaea L.) were intercropped and weed species were assessed 6, 14, and 30 weeks after crop planting. Soil analyses were conducted to assess the influence of edaphic traits on the distribution and abundance of dominant weed species. The results clearly indicated an enrichment of the weed flora with time after planting, but little difference between fallow histories. Two groups of weed species corresponded with soil characteristics: C. odorata, Cyathula prostrata, Mariscus alternifolius, Mikania cordata, Musanga cecropioides, and Trema orientalis were preponderant on soils with high clay, N, and C contents, and Ageratum conyzoides, Cyperus sp., Haumania danckelmaniana, Paspalum conjugatum, Pouzolzia guineensis, Richardia brasiliensis, Sida rhombifolia, Stachytarpheta cayennensis, Talinum triangulare, and Triumfetta cordifolia were preponderant on sandier soils with high pH, P, and Mg contents

Integrating Research Results into Decision Making about Natural Resource Management at the Forestagriculture Interface: a Case Study in the Congo Basin

Unlike Southeast Asia and the Amazon regions, where large-scale agricultural operations play an important role, most of the deforestation in the Congo basin is attributed to smallholder agriculturalists using extensive slash-and-burn techniques. Improved rural livelihoods are the key to poverty reduction and sustainability of landscape mosaics at the forest-agriculture interface of the Congo basin region. The issue has become more complex with globalisation and the situation therefore calls for an innovative approach that would look at trade offs between sustainability and productivity growth. On this basis, a collaborative partnership uniting research institutes, non-governmental organisations and universities members of the Alternatives to Slash-and-Burn national Consortium in Cameroon work with local communities to identify and develop policy, institutional and technological land-use options that can improve rural livelihoods while preserving the country's remaining forests. During the first three Phases of the programme (1994 to 2003), the global objective has been to: characterise and evaluate existing land use systems; modify or develop alternative technologies to the practice of slash-and-burn cropping system; identify, assess and design policy tools and mechanisms through which they could be implemented with the aim of protecting the environment by reducing the rate of deforestation. So far, the Project main outputs include: baseline environmental, agronomic, economic, and social datasets compiled and assessed in 6 landscape mosaics of the Forest Margin Benchmark; different resource management options for increased productivity of annual crop-based systems, perennial crop-based systems, and community-managed natural resource systems tested with farmers in the benchmark area; integrative landscape-level models and participatory community action methodologies developed; local capacity built in the use and interpretation of the models and methodologies and their outputs/outcomes; and mechanisms for policy formulation and dialogue improved at the local, provincial and national levels, targeting landscape mosaic and natural resources management.From the ASB experience, it is concluded that there is no single ‘best bet' solution to rural poverty alleviation at the forest-agriculture interface of Congo basin region. Only by integrating technology development, policies and institutional innovation can the question “are sustainable landscape mosaics feasible at the forest-agriculture interface in the Congo Basin region?” be addressed objectively

Influence of fallow landuse intensity on weed dynamics and crop yield in southern Cameroon

The influence of weeds community composition and dynamics on groundnuts intercropped with cassava was assessed in three different short fallow management systems, in the Forest Margins Benchmark Area of southern Cameroon (Central Africa). Fallow management intensities, indicated through differing fallow types, consisted of: recurrent Chromolaena odorata-dominated fallows (type I), C. odorata-dominated fallows that had been forest prior to the cropping phase (type II) and bush fallows not dominated by C. odorata that had previously been forest (type III). Weed species diversity, weed density and weed cover percentage were evaluated at six, 14 and 30 weeks after planting, in 30 mixed crop fields. Soil properties were determined at the beginning and at the end of the cropping period. Results showed that C. odorata thickets regulate the weed flora in natural short fallow-food crop farming systems of southern Cameroon. However, C. odorata seemed to have a detrimental effect on food crop productivity in 5-7 years old fallows. Cassava yields even appeared to be greater in recurrent fallow lands dominated by that asteraceous weed specie

Conservation because it pays: shaded Cocoa agroforests in West Africa

The shaded cocoa cropping system found throughout West Africa but particularly well represented in Cameroon and Nigeria is a sustainable agricultural land use system that provides relatively high values of environmental services. The paper describes and quantifies some of its non-cocoa economic and environmental values and examines the economic logic underlying smallholder management. Estimates of these values are developed from field surveys and on-farm research conducted with cocoa producers in West Africa over the last four years. The secondary products evaluated include the fruits of shade trees commonly associated and occupying the mid and upper canopy such as the African plum (Dacryodes edulis) and ndjassang (Ricinodendron heudolotii) along with introduced fruit species such as citrus and avocado. The nutritional contribution of selected associated species such as the bush mango, avocado, wild oil palm (Elaeis guineensis), and African plum is also examined. Timber is another economically important component of the upper canopy, with some species managed and maintained at densities above those found in primary and secondary forests for local exploitation in rural construction. Many medicinal plants are also maintained in the cocoa farm, which often serves as an in-situ herbal pharmacy for the household. The environmental and ecological benefits of these systems include habitat conservation, climate change mitigation, hydrological cycling and watershed protection. The degree to which these services are provided depends in large part on the type and degree of shade maintained as well as their spatial coverage in the landscape. An econometric model of the determinants of shade level explores some of the driving forces behind shade management in Côte d’Ivoire, Ghana, Nigeria, and Cameroon. We conclude by arguing that because of the significant public goods associated with this land use system that there is a need for directed efforts to publicly support the development and maintenance of shaded systems

Drivers of Store Brand Choice Over National Brands in Times of Crisis: Effect of Marketing Variables and Socio-Demographics

International audienc

C55 - Contrôle de qualité des comprimés de diclofénac de sodium 50 mg commercialisés à Yaoundé dans le circuit licite et illicite

Introduction : De nombreux médicaments sur le marché sont contrefaits et les anti-inflammatoires non stéroïdiens n’échappent pas à la règle. Ce travail avait pour objectif de contrôler la qualité des comprimés de diclofénac de sodium 50 mg commercialisés dans la ville de Yaoundé dans le circuit licite et illicite. Matériel et méthodes : Les échantillons ont été collectés par une méthode aléatoire simple dans le circuit licite et illicite. Les contrôles effectués comprenaient : le contrôle de l’emballage du médicament, le contrôle visuel, l’uniformité de masse, la friabilité, la désagrégation, l’identification et le dosage du principe actif des comprimés. Résultats : Un total de 24 échantillons de diclofénac de sodium a été collectés dont 12 prélevés du circuit licite, tous constitués des comprimés gastro-résistants, et 12 prélevés du circuit illicite 2 lots constitués de comprimés gastro-résistants, 5 lots de comprimés pelliculés et 5 lots de comprimés nus. Sur 24 échantillons analysés, 10 échantillons étaient conformes et provenaient tous du circuit licite. Tous les échantillons analysés étaient conformes à 100% en ce qui concerne le contrôle visuel, le contrôle de l’uniformité de masse et le contrôle de la friabilité. La totalité des échantillons analysés a révélé la présence du diclofénac de sodium. Les non-conformités observées sur l’ensemble des échantillons étaient de quatre types : le défaut de l’emballage des médicaments (2 échantillons sur 12 soit 16,67% dans le circuit licite versus 12 échantillons sur 12 soit 100% dans le circuit illicite), le défaut de la désagrégation des comprimés (1 échantillon sur 12 soit 8,33% dans le circuit licite versus 2 échantillons sur 12 soit 16,67% dans le circuit illicite), le sous dosage (0% dans le circuit licite versus 3 échantillons soit 25% dans le circuit illicite), le surdosage en principe actif (0% dans le circuit licite versus 1 échantillon soit 8,33% dans le circuit illicite). Conclusion : La non-conformité touche à la fois le circuit licite et illicite. La plupart des échantillons du secteur illicite sont non conformes. Toutes ces non-conformités exposent la population aux échecs thérapeutiques et la survenue de nouvelles pathologies