Cashew (Anacardium Occidentale L.) Cultivation in Togo (West Africa): Current and Future Distribution, Potential of Carbon Sequestration, and Analysis of the Interannual Variation of Carbon Isotope Ratio Regarding the Climatic Gradient.

Abstract

Cashew cultivation is gaining importance in Togo, as it has throughout Sub-Saharan Africa, due to recent trade developments in the two primary products: cashew kernels and cashew balm. The species' cost-effectiveness encourages producers to create new plantations in places that are not always conducive to its growth. Therefore, this study aimed to investigate (1) the assessment of the current distribution of cashew trees in Togo, (2) the prediction of the potential effect of climate change on the distribution of the habitat of Anacardium occidentale L. in Togo, (3) the evaluation of the organic carbon stock in the cashew plantations, in Togo regarding the climate gradient; (4) the examination inter-annual variability of carbon isotope ratios of cashew tree in the humid and dry cashew nut production zones with climatic parameters. The study used 2538 occurrence data and 17 soil and environmental parameters, HadGEM3-GC3.1-L and MIROC6 models to predict current and future appropriate habitats under two Shared Socioeconomic Pathways (SSP245 and SSP585) by 2050 and 2070. To measure carbon stock in the biomass, allometric equations were utilized and soil carbon stock was assessed using laboratory analysis. The climatic parameters were used to correlate with the δ13C values to be measured in the stem disks over a period of eight (08) years. According to the present model, 78.92% of Togo's topography is very favourable to sustainable cashew-growing practices. According to the MOROC6 Model, very favourable cashew nut production areas will be decreased to 5.24% in the SSP 245 scenario and altogether disappear with the SSP585 scenario by 2050. The Guinean zone has a higher soil carbon stock (86.89 ± 4.06 t C/ha) compared to the Sudanian zone (80.23 ± 3.78 t). The same trend can be observed in the various cashew tree components (trunk, branches and leaves), the tree trunk had 79% of the carbon stock, compared to 19% and 2% in the branches and leaves, respectively. One particular individual of cashew (BI) located in the dry cashew production zone (Soudanian climate) in Togo shows a positive and significative correlation between δ13C and temperature (r= 0.722; p<0.05), making it a useful proxy for temperature reconstruction