Ehtnobotany and Ecological Adaptation of the Black Plum (Vitex Doniana Sweet) to Climate Conditions in Benin, West Africa: Implications for Conservation and Domestication

Abstract

Climate change is projected to highly impact biodiversity components such as ecosystems and organisms. Through this work, Vitex doniana Sweet, one of the top ten priority species for domestication programs in West Africa was used to understand some of the mechanisms developed by plants to fit in various climatic environments. Uses values and perceptions of local people on climate change and its impacts on the biology and productivity of species were assessed through ethnobotanical survey. Ecology, structural parameters and the morphological variability of the species were assessed along transects within climatic zones of Benin. Radial growth and wood anatomical patterns of the species were studied in the two extreme (wet vs. dry) climatic zones using tree rings. Finally, impacts of current and future climates on the habitat suitability for cultivation and in situ conservation of the species were assessed through species distribution modelling using the Maximum Entropy algorithm (MaxEnt). The findings confirmed that V. doniana is an important agroforestry species diversely appreciated by local people depending on their ethnicity and age category. Shortening of rainy season’s length and temperature raising are the most reported perceptions on climate change. According to local people, these changes affect negatively the biology and productivity of the species. Regarding the ecology of the species, whatever the climatic zone, the species is more frequent in mosaics of croplands and fallows, and in areas close to river (less than 500 m). Structural parameters, mainly mean diameter (Dg) and basal area (Ba) of the species are under combined effects of climatic zone and land cover. The study revealed a relatively low climate-induced variability of morphological traits. Trees from the Sudanian region are the biggest, with fruits producing little pulp while individuals from the Guinean zone present a higher amount of pulp. Sudano-Guinean trees are the tallest with larger leaves. As far as the tree-ring analysis is concerned, trees from both climatic zones show common signal with a similar annual radial growth rate (0.8 cm/year). Vessels features vary significantly between stands with larger and more circular vessels in the Guinean zone. However, vessels are more abundant in rings from Sudanian trees. Finally, under current climatic conditions, about 85 % of Benin area is potentially suitable for the cultivation of V. doniana and, increase of 3 to 12 % of this habitat is projected under future climatic conditions for the year 2050. Moreover, a large proportion (76.28 %) of the national PAN was reported as potentially suitable for the in situ conservation of the species under current climate. This proportion is also projected to increase by 14 to 23 % under future climate. These findings highlighted some of the opportunities of integrating the black plum in the formal production systems of Benin and also its potentialities for ecosystem-based adaptation approaches implementation.