Pierre Deschmaps (CEREGE)
(ECCOREV)
(Université de NGaoundéré)
(Université de Dschang)
(UMR PALOC – IRD - MNHN)
(LGLTPE - Ecole Supérieure de Lyon)
(University of Potsdam)
(GFZ–German Research Centre for Geoscience)
The forest block of Central and West Africa has experienced several crises during the Holocene marked by phases of expansion and contraction sue to environmental changes and population increase. Whilst these ecological / environmental alternations have so far been attributed to climate oscillations, several studies have recently suggested that humans have been active agents of these transitions.
The CALAKÉ project is part of a project that aims to provide high-resolution, quantitative time series of climate, vegetation, and human activity proxies in order to elucidate the drivers of the hydrological and environmental changes that have affected Central Africa in recent times. It focuses on several lacustrine systems from the Cameroon volcanic line and is devoted to the characterisation of the present-day hydrological, hydrogeochemical and sedimentological functioning of these hydrosystems. It relies on coring and on measuring the fate of inorganic and organic tracers in sedimentary sequences.
First investigations on the Barombi Mbo, a volcanic lake located Southwest Cameroon, showed that:
- abrupt environmental disturbances affected the rainforest during the Holocene. Carbon and hydrogen isotopic signatures of long-chain alkanes in leaf waxes independently document both vegetation and hydrological changes.
- prominent and abrupt vegetation change between 2600 and 1950 cal y BP
- ths rainforest crisis was not associated with any significant hydrological change.
Regarding the present-day anthropization of the Barombi watershed a hydrological, geochemical and isotopic survey was carried out at several lakes as well as a first seismic-reflexion and coring operation in this area.