Fuel value indices of selected woodfuel species used in Masindi and Nebbi districts of Uganda

Abstract

Biomass currently meets more than 97% of the total energy requirements in Uganda. However, contrary to this heavy reliance on biomass, there is paucity of information regarding the fuel value indices (FVIs) of woodfuel species used in different locations of the country such as Masindi and Nebbi districts. This study therefore sought to identify ten woodfuel species commonly used by the communities in these two districts and examine their FVIs from basic properties, namely; moisture content, density and gross calorific value. A semi-structured interview using a checklist of guiding questionnaire was conducted to generate a woodfuel species list. The familiarity index (FI) was calculated for each species and then used to rank ten commonly used species for further analysis. The moisture content, density and gross calorific value of the selected species were determined in triplicate. The FVI of each species was then determined from these basic properties. One-way ANOVA, Pearson product moment correlation, and Spearman rank correlation coefficient analyses were performed in SPSS ver.16.0 to examine the variation and relationship of variables. Ten woodfuel species belonging to seven families and eight genera were identified as commonly used species. Combretum collinum was mentioned by every respondent as a suitable woodfuel species. A significant variation in moisture content and density was recorded among the species (F ( df = 9) = 92.927, p = 0.0001) unlike in gross calorific value (F ( df = 9) = 1.400, p = 0.253). There was a positive correlation between density and gross calorific value (r = 0.895, n = 30, p = 0.0001) and a negative correlation between moisture content and gross calorific value (r = −0.518, n = 30, p = 0.003). The FVIs obtained ranged from 1.10 in Ficus natalensis to 13.09 in Albizia grandibracteata. There was also a positive relationship (rho = 0.62) between FVIs and FIs using Pearson rank correlation coefficient. Moisture content and density are important properties in the selection of woodfuel species than gross calorific value. On the proposition of the FVIs, A. grandibracteata is a suitable woodfuel species than F. natalensis. These findings fit well into the ongoing efforts by Government and Civil Society Organizations to encourage woodlot management to ensure the sustainability of woodfuel in the country.