Anne Fournier

“Ordinary biodiversity” in western Burkina Faso (West Africa): what vegetation do the state forests conserve?

The role of state forests in the conservation of the savannah environment of western Burkina Faso (West Africa) was assessed by considering the customary and fundamental biological components of plant diversity. The focus is on the “ordinary biodiversity” which constitutes the current environment of human populations and which generates their resources. Overall floristic composition, α, β, γ diversities and species accumulation curves of landscape units were compared inside and outside protected areas. Common species were identified according to their frequencies in landscape units and their local abundance. The occurrences of functional (life form, dispersion, etc.) and human-valued (current uses, potential threats, etc.) traits were compared. Current land uses outside protected areas have an unequal effect on the various components of plant diversity. Species richnesses and specific structures were all the more altered for woody species as agricultural pressure is high; conversely, they were maintained for herbaceous communities for which the proportion of wide-ranging species increased. The preservation of useful plant species on cultivated lands was obvious for woody species with edible fruits but less tangible for timber and service wood. It was deficient for species that furnish other non-wood products (e.g. leaves used as food or fodder), the conservation of which may be jeopardized where anthropic pressure is high. Given current land uses and dynamics, maintaining conservation areas in land use planning is crucial in order to preserve ordinary biodiversity.

Phenology of Woody Species Along the Climatic Gradient in West Tropical Africa

West tropical Africa (WTA) is known to be one of the most exposed regions in the world to climate change. The seasonality of rainfall and of atmospheric conditions, including a dry season lasting for several months in most of the area, strongly influences vegetation activity (Bourliere & Hadley, 1983; Breman & Kessler, 1995). Indeed, this region was already affected by severe and prolonged droughts in the 1970s-1980s. These events represent one of the major climate variations of the 20th century recorded at the global scale (Giorgi, 2002; Neelin et al., 2006; Redelsperger et al., 2006). The average annual rainfall deficit varied by ± 20% in higher rainfall zones and by 50% in lower rainfall zones. However, while these droughts were relatively uniform over most of WTA, the 1990–2007 period was characterised by a more complex pattern including large spatial variability (Lebel & Ali, 2009). Current projections of global change predict higher temperatures and lower rainfall, although opinions on temperatures are contradictory (Mearns et al., 2001; Haarsma et al., 2005; IPCC, 2007; Funk & Brown, 2009). More frequent extreme events are also expected in some parts of Africa (Hely et al., 2006; Frappart et al., 2009; Lebel & Ali, 2009).

Consequences of wooded shrine rituals on vegetation conservation in West Africa: a case study from the Bwaba cultural area (West Burkina Faso)

Anthropological contributions that challenge several common perceptions on sacred sites are still poorly taken into account in conservation and ecological studies. This paper aims at filling this gap and providing a better framework for biological studies. Local concepts of natural sacred sites and their ritual administration were studied and the ritual practices relating to the vegetation of these sites were analyzed in the Bwaba cultural area in West Burkina Faso. Our research shows that these ritual practices are much more diverse and fluid than might have been supposed. Protection ‘by tradition’ is thus rather different from what we call conservation. While vegetation does matter, its presence on sacred sites is not essential. In addition, under certain circumstances, sacred sites may be transferred or reproduced elsewhere. Attention is drawn to the inadequacy of ‘sacred woods’ as a category, in an ecological as well as an anthropological sense. Even if wooded shrines may contribute to biodiversity conservation as a side-effect of their religious purpose, the idea that they fundamentally are ‘endogenous’ nature conservatories must be disproved.

Groupements floristiques et capacité de régénération des espèces ligneuses des sanctuaires boisés dans l’aire culturelle bwaba (département de Bondoukuy, Ouest Burkinabé)

Résumé Afin d’évaluer l’intérêt des sanctuaires boisés pour la conservation de la flore ligneuse au sein de l’aire culturelle bwaba dans l’Ouest burkinabé, leur recensement exhaustif a été réalisé dans le département de Bondoukuy. Les investigations portent sur la répartition spatiale des sanctuaires, leur distribution de taille, leur flore, la densité de régénération de leurs espèces végétales. Elles portent aussi sur la variabilité des richesses spécifiques ? ? en fonction de la taille des sanctuaires et en fonction des groupements phytosociologiques mis en évidence. Ces travaux montrent que les sanctuaires boisés du département de Bondoukuy s’apparentent aux forêts sèches soudaniennes à Anogeissus leiocarpa et Diospyros mespiliformis; ils apparaissent comme des lieux de conservation d’espèces sensibles aux feux. Ils sont situés à proximité des lieux d’habitation et sont par ailleurs sujets à l’invasion par le neem, Azadirachta indica, qui appauvrit la flore forestière indigène. La flore des sanctuaires boisés apparaît ainsi menacée par l’anthropisation et la fragmentation des milieux ainsi que par leur sensibilité aux espèces invasives.