Patterns of above-ground biomass and its environmental drivers: an analysis based on plot-based surveys in the dry tropical forests and woodlands of southern Africa

In this paper we present an estimate of above-ground biomass (AGB) in the dry tropical forests and woodlands of southern Angola, western Zambia, northern Namibia and northern Botswana. Furthermore, we investigated the environmental variables infl uencing the spatial distribution of AGB. We compiled data from 498 vegetation plots and forest inventories covering seven vegetation types. The dataset contained measurements of 8803 individual trees belonging to 167 diff erent species. The frequency of the trees per diameter at breast height (DBH) classes indicated healthy community structures with all vegetation types of miombo (Zambia and Angola), Baikiaea (Angola and Namibia), Baikiaea-Combretum, mopane, and Terminalia showing high number of trees in the smaller classes. We used two regional allometric equations developed for the miombo woodlands by Ryan (2011) and Chidumayo ( The highest AGB was recorded in the miombo woodlands of Zambia (median = 82.2 t/ha), followed by the dense Baikiaea-Combretum woodlands in Angola (median = 61 t/ha) and the Angolan miombo woodlands (median = 60.4 t/ha). Using generalized linear models, we analysed the relationship of AGB and environmental variables. Mean annual precipitation had the highest predictive power, explaining almost two thirds of the variance. Our conclusion was that, at regional scale, climate is a key driver of vegetation patterns, and biomass is no exception. There is a high local variability, however, that cannot completely be explained by gridded environmental datasets.