A quantitative description of woody plant communities that aimed at aiding studies on grass–tree competition interactions, bush encroachment and estimation of food to browser herbivore species, was proposed during 1989. It evolved as the BECVOL-model and differs from other methods by being able to provide estimates for both complete plants and plant portions. The previous model provides estimates of leaf volume and leaf dry mass only and this limitation regarding estimates of the browseable component of woody plants are addressed by including the edible shoots. The need for accurate estimations of the wood component is also addressed. Complete trees of a number of savanna tree species were harvested and separated into specific biomass fractions, dried and weighed: leaves, shoots and stems in three diameter classes (<0.5 cm, >0.5–20 cm and <20 cm). Regression analyses were applied with the plant dry mass fractions as dependent variables and spatial canopy volume as the independent variable. Highly significant regressions (P < 0.001) were achieved with the curvilinear regression models (exponential and multiplicative) that yielded the highest correlation coefficients. Once incorporated into the BECVOL 3-model, these regression equations will enable a complete quantification of the aboveground biomass of woody plants within specific height strata.
Keywords: allometric, biomass, browse, modelling, savanna
African Journal of Range & Forage Science 2014, 31(2): 179–186