The abundance of charcoal fragments emphasizes the assumption of huge palaeofires in the mixed moist semi-evergreen rainforest of the northern republic of Congo

in Damblon, Freddy (Ed.) Proceedings of the Fourth International Meeting of Anthracology (2013)

In this paper, we study the origins of the northern Congo Republic rainforests. Macroscopic charcoal fragments were systematically recorded through auger investigations and pits observations in four ... [more ▼]

In this paper, we study the origins of the northern Congo Republic rainforests. Macroscopic charcoal fragments were systematically recorded through auger investigations and pits observations in four forest types: the open canopy Marantaceae forest, the dense forest with Marantaceae, the Gilbertiodendron dewevrei forest and the Triplochiton scleroxylon forest. In addition, the charred Elaies guineensis seeds were distinguished from the other charcoals in the pits. Ten selected charcoals, including charred E. guineensis seeds, were dated by AMS. Abundance of charcoal fragments in the soils at various depths indicated several episodes of fires in the region. A dryer climatic phase, between 2320 and 1330 BP, associated with a large scale human occupation related to the important harvesting of oil palm nuts, could explain the widespread Marantaceae forests. Recent slash-and-burn shifting cultivation, c. 200 BP, would allow T. scleroxylon installation. Implications for forest management are discussed. [less ▲]

Recent disturbances in the Congo Basin : an anthracological contribution to vegetation reconstructions

Poster (2012, March 01)

In contrast to the well-known vegetation history of the northern hemisphere, few is known about past vegetation change in Central Africa. However, recent palaeoecological and biogeographical studies ... [more ▼]

In contrast to the well-known vegetation history of the northern hemisphere, few is known about past vegetation change in Central Africa. However, recent palaeoecological and biogeographical studies suggest that early human disturbances had a substantial influence on Central Africa vegetation patterns, particularly allowing the expansion of light-demanding species. This interesting hypothesis is the basis of one of the main research questions of the ERA-net BIODIVERSA CoForChange project: what was and is the relationship between (increasing) human activity and vegetation change? A recently developed protocol for the identification of ancient Central African charcoal fragments opened the door for vegetation reconstructions with a high spatial and taxonomical resolution. Therefore, we chose to study macro-charcoals from pedoanthracological profiles situated in N Congo and SE Camero0n. In total, 48 taxa were found in nine radiocarbon dated profiles. At the moment, three taxa have been identified down to species level. First, we found numerous fragments of Gilbertiodendron dewevrei under a current monodominant forest of G. dewevrei (40 cm depth, 1421-1327 cal. BP). This seems to confirm the presumption that monodominant forests of G. dewevrei, shade-bearer species, are relatively stable. Second, we evidenced the lack of Triplochiton scleroxylon charcoals under a T. scleroxylon stand, which could confirm the hypothesis of the recent nature of those stands. Finally, our results suggest that taxonomic diversity of charcoal findings in open canopy Marantaceae forests is greater than in dense forests. Pterocarpus soyauxii and Millettia drastica have been found under an open Marantaceae forest at 40 cm depth (1184-1055 cal. BP). The abundance of the light-demanding species P. soyauxii appears to be decreasing over time (levels 20 to 40 cm depth) to the benefit of giant herbs. Anthracology in Central Africa is on the rise and the first results of the CoForChange project are promising. More identifications will follow, resulting in a better understanding of the evolution of Central African forests. [less ▲]

A commented checklist of woody plants in the Northern Republic of Congo

in Plant Ecology and Evolution (2012), 145(2), 258-271

Soil seed bank characteristics in Cameroonian rainforests and implications for post-logging recovery

in Ecological Engineering (2011)

The soil seed bank is considered as an important component for resilience of climacic vegetation. No investigation has ever been conducted in Central African rainforests regarding this topic. We studied ... [more ▼]

The soil seed bank is considered as an important component for resilience of climacic vegetation. No investigation has ever been conducted in Central African rainforests regarding this topic. We studied the soil seed bank characteristics in relation to the standing vegetation in three Cameroonian forest zones with different disturbance regimes. There was no significant difference between sites in terms of density of the seed bank. But dissimilarities of the floristic compositions between sites were high. Overall, seeds came from 43 species including three commercial tree species. Whereas the seedlings emerging from soil samples mostly came from weedy and short-lived pioneer species, climax species predominated in the extant vegetation, leading to a very weak similarity between soil seed flora and the surrounding vegetation. Canopy openness could significantly affect the species richness of soil seed stocks but not the seed density. These results show that the soil seed bank contribution to the resilience of mature tropical forests is low. In particular, very few timber tree species could benefit from soil seed stocks for their regeneration. Therefore, the development of enrichment techniques including use of the soil seed bank as a source of tree regeneration in such a context would be irrelevant. [less ▲]