Biology, Ecology and Dynamics of African Hackberry [Celtis toka (Forssk.) Hepper & J.R.I. Wood] in two Climatic Zones in Burkina Faso (West Africa)

Abstract

Climate change is defined as a change in the weather pattern of a location or region that devastates land, and terrestrial ecosystems and exacerbates human food insecurity. These changes have a significant impact on many people who are thought to be disproportionately vulnerable to the effects of climate change. To cope with and mitigate the effects of climate change, rural communities relied on forests, mainly multipurpose plants such as Celtis toka, for goods and services. The current study on Celtis toka, a threatened species in Burkina Faso, was conducted in this context. The main goal was to contribute to the best knowledge of Celtis toka biology, ecology, and threat factors in order to ensure its conservation and sustainable management under climate change and land use change in the Sudanian region of West Africa. Especially, the study aimed to (i) assess the traditional knowledge and management practices of Celtis toka, (ii) to analyse the impacts of land use and climate on the diversity, structure, and regeneration of Celtis toka natural stand, (iii) to determine the effects of climate on tree ring growth, wood anatomical patterns, and aboveground carbon stock, (iv) predict the impacts of climate change on the geographical distribution of Celtis toka. The method consisted of surveying 405 respondents in a semi-structured interview, forest inventories in 129 plots, tree ring analysis and species distribution modelling. Ethnobotany demonstrated that Celtis toka is a multiuse tree overharvested in Burkina Faso for mystic (11.62%), food (27.89%), fodder (18.97 %), and medical (14.92 %) uses. Overall, 290 woody species from 113 genera and 105 families were investigated in Celtis toka’s natural stand habitats. The diameter (adult) and the height (juveniles) class distribution showed the populations of Celtis toka are unstable due to overexploitation, lack of regeneration, fire, and animal grazing. Tree-ring analysis discovered distinct growth ring boundaries. Tree ring chronology showed that climate change may affect the growth of Celtis toka. Aboveground biomass (51.44 ± 6.87 to 69.21 ± 13.38 Mg/ha) and carbon stock (25.72 ± 3.43 to 34.60 ± 6.69 Mg/ha) differ significantly (P < 0.05) across the climatic zone and land use type designating that climate and land use type impact the carbon storage. Under current climatic conditions, about 54.77 % of Burkina Faso area was suitable for the conservation of Celtis toka. Under both emission scenarios, all climate models predicted a decrease in the extent of suitable habitats of Celtis toka at the horizons 2041-2060 and 2081-2100. Suitable areas are predicted to decrease from 20.65 % to 27.81 % under the scenario ssp245 and from 48.07 % to 48.83 % under ssp585 in 2041-2060. By 2081-2100, the ssp245 predicts drastic changes in the species' spatial patterns, with habitat loss ranging from 25.26 % to 47.85 % while the ssp585 projected a loss of suitable area from 53.27 % to 54.37 %.