The sustainable management of tropical timber stocks relies to a large extent on the accurate estimate of the available volume of commercial tree species. Therefore, given the current state of fragmentation and degradation of West African forests, the use of non-destructive methods such as volume equations should be encouraged to determine timber stocks. All requirements should be considered and applied when appropriate to stop using inaccurate equations that has often led decision-makers to misjudge the real potential of west-African managed forests and increase the threat to sustainable timber production. For this purpose, this study aims to improve the accuracy of volume estimations of standing tree in both natural forest-stands and plantations. We calibrated volume equations in a Bayesian framework by using 18864 volume measurements of 24 commercial tree species, covering a large part of the Sudano-Guinean zone of West Africa, from Sierra Leone to Ghana. We consider bole volume in relation to (i) tree species variability, (ii) forest type (natural vs planted) and (iii) climatic factors including annual rainfall, seasonality, and maximum temperature. It is found that bole volume varies widely between commercial tree species and with temperature, suggesting that forest management programs that do not account for interspecific tree variability and annual maximum temperature are unlikely to be sustainable and reliable for assessing and predicting timber stocks in West Africa.
Keywords : Bole volume equation, Commercial tree species, Climate effects, Bayesian modelling, West Africa.