Fuel wood properties of six Tree species grown in Ethiopia.

In Ethiopia, the need to rank fuelwood species to specific requirements has necessitated the need for detailed analysis of biomass properties. Such analysis will help to identify desirable fuelwood properties. The objective of this study was to determine fuelwood properties such as moisture content (MC), ash content (AC), basic density (D) gross heat value (GHV) and fuel value index (FVI) for three Eucalyptus spp. and three Acacia spp. Fuelwood properties such as MC, D, AC, GHV and FVI of three plantation-grown Eucalyptus spp. were investigated. The species were E. globules Labill., E.grandis W.Hill ex Maid and E.saligna Sm. from the central highlands of Ethiopia. The indigenous trees of Acacia species investigated were A. abyssinica (Hochst. Ex Benth.), A. seyal( Del.) and A. tortilis (Forskk. Hayne) from western, southern and central acacia woodlands, respectively. The investigation was made on stem wood, branch, and foliage for sample trees selected randomly from respective forest stands. Moisture content was determined on green and air-dry basis in three replications. Basic density was determined for discs taken from three locations (bottom, mid- and top) by water displacement method. AC was determined by ASTME 1755 method. Gross heat value was determined by ASTM 2015 method on oven-dry basis. The results showed that the variation in MC (on green basis) in the components was highly significant (P0.001). The MCs of the components in increasing order are stem wood, branch and foliage. MC on air-dry basis for stem wood and branch did not vary significantly (P0.06). The variation in D for the species was highly significant (P0.001). The variation in AC of stem wood and branch of six species was significant (P0.05) whereas in foliage biomass the variation was highly significant (P0.001). The GHV of stem wood and branch did not show significant variation between species (P0.05) but in foliage, the variation was highly significant (P0.001). GHVs of the components in increasing order are stem wood, branch and foliage. Generally, the results revealed that GHV alone does not indicate the merits of desirable fuelwood qualities; therefore, FVI was calculated considering GHV, MC, and AC. The results revealed that FVI constitutes and adequate criterion for selecting and ranking fuelwood species. The species were ranked according to FVI descending order of desirable fuelwood properties; i.e. E. gloublus, E. grandis, E. saligna, A. tortilis, A. seyal and A. abyssinca.