Biomass determination of fuelwood trees and bushes of Botswana, Southern Africa

In order to establish a relation between tree fresh biomass and tree dimensions, samples of 14 tree species indigenous to Botswana were measured, cut and weighed. The relation best suited to the indirect estimation of total tree fresh weight was the regression between tree fresh weight and stem basal area at ankle height (5–10 cm above ground level). The regression curves of the 14 tree species overlay in a narrow band. On the basis of the measured data points of all 14 tree species a single regression curve is calculated: the combi-line. The combi-line satisfactorily describes the relation between stem basal area and fresh weight for most trees. A comparison of the combi-line with some tree species from elsewhere in Africa, India and Europe shows that the combi-line also describes, to a large extent, the basal area-fresh weight relation for those trees.