Ecological and Conservation Patterns of Wild Palm Species in the Context of Climate Change in Burkina Faso (West Africa)

Abstract

Wild palms occur in tropical and subtropical regions where people use them for many purposes. Despite their low diversity in semi-arid and arid areas, they highly contribute to the livelihoods of local people. Therefore, the overexploitation and climate change threaten palms in arid and semi-arid areas. This study investigates the ecological and conservation patterns of wild palm species under current and future climatic conditions in Burkina Faso in order to propose sustainable management strategies for their conservation. The methods consist in a combination of individuals’ interviews (258 people surveyed), inventories (in 120 plots), direct observations, species distribution modelling and climate niche factor analysis. The interview reported the importance of seven palms species in Western Burkina Faso. The importance of wild palm species depends on socio-cultural factors such as ethnic group, gender and age category. Wild palms that are considered useful are the one benefiting much of conservation care (e.g. Borassus akeassii and Elaeis guineensis). The inventories showed that Borassus akeassii, Elaeis guineensis, Phoenix reclinata and Raphia spp. had instable populations in Western Burkina Faso. A diversity of trees species co-occurred with palms with a significant lowest diversity in Borassus akeassii habitats (30 species) compared to Eleais guineensis (97 species), Phoenix reclinata (63 species) and Raphia spp. (73 species). More than half (65%) of Phoenix reclinata juveniles come from tillering, while Borassus akeassii, Elaeis guineensis and Raphia spp. are regenerated only by seeds. The morphological assessment suggests that another species of Raphia, co-occurs with Raphia sudanica in Western Burkina Faso. This may increases the flora of native palms of the country to eight (8), including two species of Raphia. The species distribution models identified water related variables such as precipitation and topographic position index as determinant variables of palms distribution in Burkina Faso. The potential suitable areas of wild palms were comprised between 10 and 15 % of the country and are located in the Sudanian climatic zone under current climatic conditions. Climate change may induce range expansion (up to 28.51%) or contraction (up to -16%) depending on the palm species, global circulation models and climatic scenarios. The climate change vulnerability assessment indicates that Borassus akeassii is less vulnerable to climate change than Elaeis guineensis, Phoenix reclinata and Raphia sudanica.