REVIEW OF BIOMASS AND VOLUME FUNCTIONS FOR INDIVIDUAL TREES AND SHRUBS IN SOUTHEAST AFRICA
Keywords:Above-ground woody biomass, individual trees, volume functions, east Africa, southern Africa
Estimation of biomass or volume of trees and shrubs is important in many contexts. Foresters and other natural resource managers in east and southern Africa have been faced with a double challenge in this respect: their fairest research institutions have been small and young, and their trees and shrubs are difficult to measure. A number of studies have been made in order to estimate biomass or volume of trees in this part of Africa. This review tries to bring together some of the findings of such studies in order to synthesize a few common principles and to make reliable functions more easily accessible to researchers and resource managers. A general conclusion appears to be that typical miombo trees have larger volumes for equal diameters than species typical in the drier southern woodlands. It is also noted that Pterocarpus angolensis takes an intermediary posititon. Inclusion of height in addition to diameter as independent variable does not increase the coefficient of determination very much. In some cases dbh alone gives an R2 of more than 0.95. This is due to the correlation between diameter and height. In practical inventories of volume or biomass where high precision is not required, economic considerations may, therefore, lead to the conclusion that measurement of height is unnecessary. One study suggests that diameter and crown width is a better pair of independent variables for total biomass of single trees than the traditionally used diameter and height.