Biomass yield and energy value of some fast-growing multipurpose trees in Nigeria

The above-ground biomass yield of seven-year-old trees of Gliricidia sepium, Gmelina arborea and Leucaena leucocephala grown for fuel production were assessed. The combustion properties of the fuelwood and charcoal produced from the trees (moisture content, density, percentage fixed carbon, volatile matter, micro-elemental composition and heat of combustion) were determined. There were significant differences in the above-ground biomass and the charcoal yield from the various species. The stand biomass was 37.4 t/ha for Gliricidia sepium, 85.6 t/ha for Gmelina arborea and 46.2 t/ha for Leucaena leucocephala. The charcoal yield (range 25–42%) was highest in Leucaena leucocephala. The average heat of combustion of charcoal, 33.25 MJ/kg, was higher than that of wood, 21.6 MJ/kg. Gmelina arborea gave the greatest energy yield per hectare due to its high stand biomass.