Future Climate and Land Use Impacts on the Geographic Distribution and Conservation of Kigelia Africana in Benin, West Africa

Abstract

Kigelia africana (Bignoniaceae) is a Non-Timber Forest Products (NTFPs) that makes major contribution to the subsistence of West Africa household through their multiple purposes (medicinal, nutritional, economic and socio-cultural). However, these ecosystem services are threatened by climate and land use change. Data collection and household survey were performed in Benin, West Africa, to assess the species distribution and use. Current and future (CNRM-CM5 and HadGEM2-ES model base on RCP 8.5 by 2050 time horizons) climate data were retrieved from WorldClim, Soil layer from World Soil Database version 1.2 and Climate Change Initiative Land Cover (CCI_LC) maps of 1992, 2003 and 2015 from the European Space Agency (ESA). Additionally, MaxEnt species distribution modelling (SDM) was used to model species ecological niche in combination with a Geographic Information System (GIS). The modeled occurrence areas of K. Africana was implemented based on a total of 466 species records, from which 416 were collected on the field and 50 from the National Herbarium of Benin. Seventy one (71) households were interviewed using a semistructured questionnaire for ethnobotanical and socio-economic studies which were analysed using quantitative ethnobotanical methods. Principal Component Analysis (PCA) with R software was also applied to describe the use value and use forms of K. africana according to different tribes. The maps obtained from the model were overlaid on the existing protected areas network. The result depicted that 52% of the national area and 81 % of the national protected area network were found to be highly suitable for the cultivation and conservation of K. Africana and the greater part of the distribution of the species is expected to remain largely stable in Soudano-guinean zone and Guinean zone with some exception in the Soudanian zone. Despite the expansion and retraction in Kigelia africana species, the relationships with protected areas networks suggest that protected area networks of species distribution will also remain stable. All these corroborates with the assessment of CCI-LC map obtained. For the economic uses three categories were identified (Medicinal, Charcoal and Firewood).The result reflects that for K. africana medicinal use is more cited. The economical use value of the different parts of the K. africana, showed that the fruits (50 %) are sold more than the bark (29.17 %) followed by the leaf 16.67 % while the root has the lowest percentage of 4.17 %. Ethnobotanical Use Values (EUVt), the bark is more mentioned (100 %) by all the socio-cultural groups; the fruit 93%, leaf 86%, flower 14% and root 8% only in medicinal and magic uses; and contribution to yearly cash income ranging from 4.17 % to 50 %. Further development and research on K. Africana should be enhanced in order to conserve the genetic diversity within and among the population and also to expand the market channels to have more assess on the economic value of K. africana.