Firewood yield and profitability of a traditional Daniellia oliveri short-rotation coppice on fallow lands in Benin

Sub-Saharan Africa has a great diversity of local coppicing species which are exploited in traditional short coppice systems for firewood. Biomass yield and profitability of these systems as well as their responses to silvicultural improvement are little known. This study evaluated the firewood yield and the profitability of a traditional Daniellia oliveri short-rotation coppice on fallow lands in central Benin. Two weed management options were considered: (1) the weedy option, usually practiced by locals, which experienced grass competition and bushfires, and (2) the weed-free option, which consisted in periodic removal of grasses and other species. Destructive measurements and allometric equations were used to estimate biomass yield in 12 plots over 42 months. A cost-benefit analysis model based on the net present value and the benefit-cost ratio was used to compare the profitability of the two management options. Biomass accumulation rate averaged 1.08 ± 0.20 tonnes of dry matter ha−1 year−1 (t DM ha−1 year−1) in weedy conditions. Weed removal improved 3.5 times this rate in weed-free plots (3.83 ± 0.47 t DM ha−1 year−1). After 42 months, total biomass reached 3.67 ± 0.65 t DM ha−1 in weedy plots and 11.63 ± 0.76 t DM ha−1 in weed-free plots. Most of the biomass (≥88%) was marketable in local markets. Coppice exploitation was profitable after 24 months for both management options. Weed removal improved the profits three times. A sensitivity analysis showed that both options were still profitable with up to 25% increase of labour and transport costs, 25% decrease of biomass price and 12% increase of the discount rate.