Accurate and timely maps of tree cover attributes are important tools for environmental research and natural resource management. We evaluate the utility of Landsat 8 for mapping tree canopy cover (TCC) and aboveground biomass (AGB) in a woodland landscape in Burkina Faso. Field data and WorldView-2 imagery were used to assemble the reference dataset. Spectral, texture, and phenology predictor variables were extracted from Landsat 8 imagery and used as input to Random Forest (RF) models. RF models based on multi-temporal and single date imagery were compared to determine the influence of phenology predictor variables. The effect of reducing the number of predictor variables on the RF predictions was also investigated. The model error was assessed using 10-fold cross ). This mapping approach is based on freely available Landsat 8 data and relatively simple analytical methods, and is therefore applicable in woodland areas where sufficient reference data are available.

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RESUMELes aires protégées du Burkina Faso connaissent un phénomène d'anthropisation accrue. A cela s'ajoute l'effet des changements climatiques. Ainsi, ces facteurs ont des conséquences dont la baisse de la biodiversité. Cette étude a pour objectif principal d'analyser de la dynamique spatio-temporelle des savanes boisées. Elle a été conduite dans la forêt classée de Tiogo. Spatio-temporal dynamics of woody savannahs in the Tiogo protected area of Burkina Faso ABSTRACTThis study is a contribution to the analysis of the spatio-temporal dynamics of the savanna within protected areas. It was conducted in the classified forest of Tiogo in Central West of Burkina Faso. Images 1986 Landsat TM and ETM of 2010 have been used. Two land use maps of 1986 and 2010 respectively, were made with respect to three thematic classes defined. From these two land use maps, two maps of spatial P. BAZONGO et al. / Int. J. Biol. Chem. Sci. 9(4): 1983-2000, 2015 1984 distribution of woody savanna of 1986 and 2010 were generated. The mapping results reveal a sharp decline of woody savanna, declining from 35.17% in 1986 to 18.04% in 2010. During the same period, anthropization areas have increased of approximately 4.38% per year. Analysis of the spatial dynamics has shown fragmentation of savanna between 1986 and 2010. This fragmentation is due to anthropogenic activities, including logging and agricultural clearing. This is therefore a growing threat to the conservation of biodiversity in this classified forest if no action is taken to reverse the trends.

Les parcs agroforestiers occupent des superficies non négligeables au Burkina Faso. Mais, du fait de la pression foncière, ils subissent des formes d’exploitation qui menacent leur existence dans le moyen terme. Pour une gestion durable des parcs agroforestiers, leur connaissance sur le plan floristique s’impose. C’est ainsi qu’une étude floristique a été menée dans les parcs agroforestiers des forêts classées de Dindéresso et de Kuinima à l’Ouest du Burkina Faso. L’objectif est de contribuer à une meilleure gestion du peuplement ligneux des parcs agroforestiers. Pour ce faire, un inventaire forestier dans des placettes circulaires de 900 m² a été réalisé en vue d’établir la liste floristique, la diversité spécifique et d’apprécier l’état de la régénération et l’état sanitaire des peuplements ligneux. Au total, 27 espèces ligneuses réparties en 14 familles et 27 genres dans les parcs agroforestiers de Dindéresso et 27 espèces ligneuses réparties en 12 familles et 26 genres dans les parcs agroforestiers de Kuinima ont été inventoriées. La diversité spécifique de Shannon-Weaver est faible avec 1,80 bit pour les parcs agroforestiers de Dindéresso et 1,33 bit pour ceux de Kuinima. La régénération est beaucoup plus marquée par l’espèce Vitellaria paradoxa Gaertn.f. suivie de Anacardium occidentaleL. [cult.]. Les taux de régénération sont de l’ordre de 54,12% et 9,41% pour Dindéresso puis 35,64% et 26,60% pour Kuinima respectivement, pour Vitellaria paradoxa et Anacardium occidentale. L’appréciation de l’état sanitaire révèle que 49,85% des pieds de Vitellaria paradoxa inventoriés dans la forêt classée de Kuinima sont parasités. Par contre dans la forêt classée de Dindéresso, le taux de parasitisme des pieds de Vitellaria paradoxa est de 13,37%. Au regard de ces taux de parasitisme, il est plus que nécessaire de développer des stratégies de lutte contre ces plantes parasites. À court et moyen termes si rien n’est fait, ces parasites affecteront considérablement les capacités de cette espèce agroforestière à fournir des biens et services.

Most of the protected areas in Burkina Faso are affected by deforestation and forest degradation. This study is done in order to analysis the spatial and temporal dynamics of the classified forest of Koulbi and to identify the drivers of deforestation in the forest. For that, three Landsat images from 1986, 1998 and 2014 were exploited. The supervised classification based on the artificial neural network algorithm, under the ENVI software, was used. A transition matrix was established to analyze land use/land cover changes. The standardized precipitation index of 1985 to 2014 was used to access climate trend. Survey data from riverside villages and field observations were used to assess the human impact. The results show that between 1986 and 2014, the woodlands and tree savannas areas were reduced by 7% and 0.49% per year, respectively. However, substantial yearly increases in the areas of shrub savanna (2.8%) and agricultural fields (1.4%) were observed. During this period, the rainfall had a sharp trend towards aridity, with 18 years of drought against 12 years of humidity. This show that deficit of rainfall is increase. The socioeconomic survey revealed that the classified forest used to be highly occupied and 64% of the inhabitants were yam producers. Cattle breeders and gold diggers have also been observed. We conclude that human activities are the main cause of degradation of the vegetation cover of the Koulbi classified forest. And climatic factors to some extent. It will be necessary to take actions to better conservation.