Is the Decline in Rainfall the Main Cause of Selective Mortality of Pterocarpus Lucens in Northern Burkina Faso?

Introduction: Pterocarpus lucens has ecological and socio-economic importance for arid and semi-arid zone of West Africa. Unfortunately, in recent decades its selective mortality has been noted in sub-Sahelian zone. Declining of groundwater levels, anthropogenic pressure on species and termites are cited as causes. Although these natural and anthropogenic disturbances seem pertinences, this study aimed to analyze intrinsic physiological responses of this species to adapt to its environment condition that is becoming increasingly arid. Materials & Methods: Leaves water potential (Ψ) with its attributes (predawn water potential (Ψb), midday water potential (Ψm) and the range (ΔΨ) between (Ψb) and (Ψm)) were measured in two sites with contrasted water conditions using pressure chamber. Complementary variable such as water content (WC) and water relative content (RWC) were measured and analyzed. Results: Results showed that Midday and predawn water potential were significantly lowest (P <0.001) in Dori than Tougoury and diurnal range of individual shrubs in Dori showed no significant relaxation (P> 0.05). Conclusion: These results suggest that the species is experiencing unfavorable water conditions at the Dori site and could partly explain its selective mortality. Further studies will be necessary to determine other factors and their impact on the phenomenon.