Variation in fuelwood properties and correlations of fuelwood properties with wood density and growth in five tree and shrub species in Niger

Abstract

Information about variation and correlations of fuelwood properties and growth is needed in order to recommend species and sites for fuelwood production in a changing climate in Africa. We investigated the effects of site variables (land use, soil, terrain), geographical coordinates, and mean annual rainfall on fuelwood properties (volatile matter, fixed carbon, ash content, moisture content, gross calorific value, gross calorific value per cubic metre, and fuel value index) of Combretum glutinosum Perr., Combretum micranthum G. Don., Combretum nigricans Lepr. ex Guill. & Perr., Guiera senegalensis J.F. Gmel., and Piliostigma reticulatum (DC.) Hochst. and correlations of fuelwood properties with wood density and growth (height, stem diameter, and ring width) in Niger. We hypothesized that wood density, fixed carbon, and gross calorific value were positively correlated with one another and that fixed carbon and gross calorific value were positively correlated with growth. Most effects of site variables, geographical coordinates, and mean annual rainfall on fuelwood properties differed among species. Fuel value index was greater on rocky soils than on sandy soils. Wood moisture content of three species was greater in drier locations than in more humid ones. Correlations of fuelwood properties with wood density and growth differed among species. Based on this and previous research, we recommend parkland agroforests and sites with rocky soils and higher mean annual rainfall for fuelwood production.