Identification of ancient charcoal fragments in Central Africa: meeting the challenge of species diversity

Fossil pollen and charcoal fragments are preserved in lake sediments, in forest soils and in ancient human settlements. As such, vegetation history is remarkably well archived. However, Central African vegetation history has been poorly documented. Central African palaeovegetation reconstructions are based mainly on pollen analysis, while the charcoal archive remains hardly explored. Nevertheless, ancient charcoal analysis has proven worthwhile in temperate regions. One of the main challenges for charcoal identification in tropical regions is species diversity. Therefore we developed and present a transparent charcoal identification protocol within an umbrella database of species names and metadata, compiled from the on-line database of wood-anatomical descriptions (InsideWood), the database of the worldU+2019s largest reference collection of Central African wood specimens (RMCA, Tervuren, Belgium) and inventory and indicator species lists. This database covers more than 2900 Central African woody species, which is a large fraction of the total woody species richness of Central Africa. The protocol starts with an anatomical query within this database, focussing on genus rather than species level and proceeds with automatic extension and reduction phases taking into account metadata on (1) availability of thin sections within the reference collection, (2) species distribution and (3) synonymy. The protocol ends with a comparative microscopic study of wood reference thin sections and charcoal anatomy. The protocol has been optimised for the Mayumbe region (DRCongo). We present first identification results from several radiocarbon dated charcoal collections (8000 - 200 cal yr BP), sampled in systematically excavated profiles in the Mayumbe forest. Identification results are mutually consistent. Also, these identification results are consistent with vegetation history based on palynological research within and around the research area. As such, anthracology complements palynology and a combination of both can lead to stronger palaeobotanical reconstructions.

Publication year:2012