Browsing by Subject "WEST-AFRICA"

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  • Fobissie Blese, Kalame; Kanninen, Markku Tapani; Etongo, Daniel (Viikki Tropical Resource Institute, University of Helsinki, 2016)
    VITRI Brief
  • Flamant, Cyrille; Deroubaix, Adrien; Chazette, Patrick; Brito, Joel; Gaetani, Marco; Knippertz, Peter; Fink, Andreas H.; de Coetlogon, Gaelle; Menut, Laurent; Colomb, Aurelie; Denjean, Cyrielle; Meynadier, Remi; Rosenberg, Philip; Dupuy, Regis; Dominutti, Pamela; Duplissy, Jonathan; Bourrianne, Thierry; Schwarzenboeck, Alfons; Ramonet, Michel; Totems, Julien (2018)
    The complex vertical distribution of aerosols over coastal southernWest Africa (SWA) is investigated using airborne observations and numerical simulations. Observations were gathered on 2 July 2016 offshore of Ghana and Togo, during the field phase of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa project. This was the only flight conducted over the ocean during which a downward-looking lidar was operational. The aerosol loading in the lower troposphere includes emissions from coastal cities (Accra, Lome, Cotonou, and Lagos) as well as biomass burning aerosol and dust associated with long-range transport from central Africa and the Sahara, respectively. Our results indicate that the aerosol distribution on this day is impacted by subsidence associated with zonal and meridional regional-scale overturning circulations associated with the land-sea surface temperature contrast and orography over Ghana and Togo, as typically observed on hot, cloud-free summer days such as 2 July 2016. Furthermore, we show that the zonal circulation evidenced on 2 July is a persistent feature over the Gulf of Guinea during July 2016. Numerical tracer re-lease experiments highlight the dominance of aged emissions from Accra on the observed pollution plume loadings over the ocean, in the area of aircraft operation. The contribution of aged emission from Lome and Cotonou is also evident above the marine boundary layer. Given the general direction of the monsoon flow, the tracer experiments indicate no contribution from Lagos emissions to the atmospheric composition of the area west of Cotonou, where our airborne observations were gathered. The tracer plume does not extend very far south over the ocean (i.e. less than 100 km from Accra), mostly because emissions are transported northeastward near the surface over land and westward above the marine atmospheric boundary layer. The latter is possible due to interactions between the monsoon flow, complex terrain, and land-sea breeze systems, which support the vertical mixing of the urban pollution. This work sheds light on the complex - and to date undocumented - mechanisms by which coastal shallow circulations can distribute atmospheric pollutants over the densely populated SWA region.
  • Etongo, Daniel; Djenontin, Ida Nadia S.; Kanninen, Markku; Glover, Edinam K. (2017)
    Empirical ethnobotanical studies in Burkina Faso and the Sahel apply unmodified use-value methods, which often fail to capture uses of plants within and across categories. These methods mask both the relative uses and local people's 'true' knowledge of plant species. This study addresses these methodological weaknesses by assessing plant use-values within and across eight use categories for livelihood values and their potentials for environmental protection among 48 informants, selected through a stratified random technique. The research is twofold: (1) to document and identify the conservation status of plant species and (2) to assess local knowledge and perceived importance of the most easily found plant species in relation to informant's age, gender, ethnicity, and location. Seventy-three plant species belonging to 24 families were recorded on fields, fallows, and forests. The most easily found 30 species belonged to 14 families of which Combretaceae, Mimosodeae, Caesalpinioideae, and Anacardiaceae dominated. Results show that Adansonia digitata, Parkia biglobosa, Vitellaria paradoxa, and Balanites aegyptiaca were more valued for livelihood benefits, while A. digitata, Tamarindus indica, and Ficus thonningii received more value for their potentials in environmental protection. Local knowledge was unevenly distributed and showed significant differences at the 0.01 % level among gender, age, ethnicity, and study village. The relative importance of plant uses goes beyond nutrition and potentials in environmental protection and can provide valuable information for creating local markets for such goods. Three species belonging to different families were identified as vulnerable and considered priority for conservation. The design of conservation and development projects should consider creating opportunities for knowledge sharing that will not only improve knowledge but provide better understanding of local priorities based on sociocultural and economic factors.
  • Liu, Jinxiu; Heiskanen, Janne; Maeda, Eduardo Eiji; Pellikka, Petri K. E. (2018)
    West African savannas are subject to regular fires, which have impacts on vegetation structure, biodiversity and carbon balance. An efficient and accurate mapping of burned area associated with seasonal fires can greatly benefit decision making in land management. Since coarse resolution burned area products cannot meet the accuracy needed for fire management and climate modelling at local scales, the medium resolution Landsat data is a promising alternative for local scale studies. In this study, we developed an algorithm for continuous monitoring of annual burned areas using Landsat time series. The algorithm is based on burned pixel detection using harmonic model fitting with Landsat time series and breakpoint identification in the time series data. This approach was tested in a savanna area in southern Burkina Faso using 281 images acquired between October 2000 and April 2016. An overall accuracy of 79.2% was obtained with balanced omission and commission errors. This represents a significant improvement in comparison with MODIS burned area product (67.6%), which had more omission errors than commission errors, indicating underestimation of the total burned area. By observing the spatial distribution of burned areas, we found that the Landsat based method misclassified cropland and cloud shadows as burned areas due to the similar spectral response, and MODIS burned area product omitted small and fragmented burned areas. The proposed algorithm is flexible and robust against decreased data availability caused by clouds and Landsat 7 missing lines, therefore having a high potential for being applied in other landscapes in future studies.
  • Sell, Mila; Vihinen, Hilkka; Gabiso, Galfato; Lindström, Kristina (2018)
    This article describes the process and analyses the results of a project in Ethiopia establishing an innovation platform (IP) as a tool for co-creation from an innovation systems perspective. The results are encouraging, suggesting positive effects both on yields, but more importantly on the capacity and role of participants as communicators and agents of change in the community. The IP seems promising in creating new networks and modes of communication. The importance of good facilitation, commitment by all members from the start, and feedback loops driving the process was found to be essential.
  • Toure, Ibrahim; Larjavaara, Markku; Savadogo, Patrice; Bayala, Jules; Yirdaw, Eshetu; Diakite, Adama (2020)
    Land degradation (LD) in Mali is prevalent and leads to an enduring environmental and humanitarian crisis. Farmers' ecological knowledge has proven to be a valuable tool in addressing its challenges. How farmers perceive LD affects how they deal with induced risks, and their responses to these perceptions will shape restoration options and outcomes. Therefore, this study assessed farmers' perceptions of LD along a climatic gradient in three regions of Mali. We interviewed 270 farmers, and we analyzed their responses using descriptive statistics and Spearman rank‐order correlation. We found that the respondents were aware of LD and have identified its key indicators and its impacts on their livelihoods. Moreover, we found that farmers' perceptions are not influenced by gender, age, or education level, but rather by agricultural training, participation in agricultural labor, the practice of fallowing, shortage of firewood, livestock, household size, appearance of some plant species and famine. Additionally, farmers' perceptions of LD vary along the climatic gradient as they correlate to different variables in each agro‐ecological zone. LD's impacts, however, decrease in severity along the north–south gradient, although they are linked to the same variables. As LD is seen through a reduction of ecosystem services provisioning capacity because of the local communities' heavy dependence on natural resources, actions should be geared towards agronomic and vegetative land management options. Such actions should prioritize context‐specific soil and water conservation techniques and proven indigenous practices.
  • Etongo, Daniel; Djenontin, Ida Nadia S.; Kanninen, Markku; Kalame, Fobissie (2015)
    Climate variability and change significantly affect smallholder farmers' food security and livelihoods in sub-Saharan Africa. Tree planting is one of the measures promoted by development programs to mitigate and adapt to climate change. Tree planting is also believed to positively contribute to livelihoods. This paper examines factors influencing smallholders' tree planting activities in four villages in the Ziro province, Southern Burkina Faso. Furthermore, it analyses the challenges encountered and willingness to continue tree planting under current tenure arrangements. The data was obtained through key informants, household interviews, focus group discussions, and field observations. Results indicate that the majority of farmers interviewed planted Mangifera indica (50%), Anacardium occidentale (32%) and Moringa oleifera (30%). In a number of trees planted, Eucalyptus camaldulensis, Mangifera indica and Anacardium occidentale dominated. Tree planters were mainly farmers who held large and old farm areas, were literate and relatively wealthy, had favorable attitudes toward tree planting, and with considerable years of participation in a farmers' group. The main reasons for planting trees included income generation from the sale of tree products, access to markets and local support for tree planting. Preference for agriculture, tenure insecurity and lack of sufficient land were the main reasons cited for not planting trees. Farm households that were relatively poor, had smaller workforces and smaller farm sizes were not willing to continue tree planting. To effectively engage farmers in tree planting and to make it more attractive, policies are needed that address tenure insecurity for migrants, enable better access to markets, and support fair pricing structures for wood and other tree resources.
  • Selier, Sarah-Anne Jeanetta; Slotow, Rob; Di Minin, Enrico (2016)
    Unprecedented poaching levels triggered by demand for ivory in Far East Asia are threatening the persistence of African elephant Loxodonta africana. Southern African countries make an important contribution to elephant conservation and could soon become the last stronghold of elephant conservation in Africa. While the ecological factors affecting elephant distribution and densities have extensively been accounted for, there is a need to understand which socioeconomic factors affect elephant numbers in order to prevent conflict over limited space and resources with humans. We used elephant count data from aerial surveys for seven years in a generalized linear model, which accounted for temporal correlation, to investigate the effect of six socioeconomic and ecological variables on the number of elephant at the country level in the Greater Mapungubwe Transfrontier Conservation Area (GMTFCA). Important factors in predicting elephant numbers were the proportion of total land surface under cultivation, human population density and the number of tourists visiting the country. Specifically, elephant numbers were higher where the proportion of total land surface under cultivation was the lowest; where population density was the lowest and where tourist numbers had increased over the years. Our results confirm that human disturbance is affecting elephant numbers, but highlight that the benefits provided by ecotourism could help enhance elephant conservation. While future studies should include larger areas and more detailed data at the site level, we stress that the development of coordinated legislation and policies to improve land-use planning are needed to reduce the impact of increasing human populations and agriculture on elephant.