Above-ground biomass and vegetation attributes in the forest-savannah mosaic of Togo,West Africa

Despite the increasing interest in the role of African savannah and woodlands on the global carbon cycle, little is known about the above-ground biomass (AGB) and the factors affecting it in these ecosystems in West Africa. We estimated AGB in different vegetation types of a forest–savannah mosaic in Togo, and we investigated the relationship between AGB, structural and diversity attributes. We also assessed the effects of using the ≥5 or ≥10 cm diameter threshold on AGB estimates. We sampled tree diameter, height and species of all trees ≥5 cm diameter following standardised protocols in 160 plots of 50 × 20 m (50 × 10 m for riparian). Above-ground biomass (AGB) (all trees ≥5 cm diameter) ranged from 6.2 Mg/ha in shrub savannah to 292 Mg/ha in riparian forest and showed significant differences between vegetation types. Differences in AGB were related to structural attributes, with little influence of diversity attributes. The effects of minimum tree diameter size (5 or 10 cm) on AGB estimates were negligible. At a landscape level, closed-canopy and open forests stored important quantities of carbon. We highlight the importance of the forest–savannah mosaic as a large carbon pool, which could be released if converted to another land cover type.