1. Early anthropogenic impact on Western Central African rainforests 2,600 y ago.
- Author
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Garcin, Yannick, Deschamps, Pierre, Ménot, Guillemette, de Saulieu, Geoffroy, Schefuß, Enno, Sebag, David, Dupont, Lydie M., Oslisly, Richard, Brademann, Brian, Mbusnum, Kevin G., Onana, Jean-Michel, Ako, Andrew A., Epp, Laura S., Tjallingii, Rik, Strecker, Manfred R., Brauer, Achim, and Sachse, Dirk
- Subjects
ANTHROPOGENIC effects on nature ,RAIN forests ,HOLOCENE Epoch ,PALEOHYDROLOGY ,FORESTS & forestry -- Environmental conditions - Abstract
A potential human footprint on Western Central African rainforests before the Common Era has become the focus of an ongoing controversy. Between 3,000 y ago and 2,000 y ago, regional pollen sequences indicate a replacement of mature rainforests by a forest-savannah mosaic including pioneer trees. Although some studies suggested an anthropogenic influence on this forest fragmentation, current interpretations based on pollen data attribute the "rainforest crisis" to climate change toward a drier, more seasonal climate. A rigorous test of this hypothesis, however, requires climate proxies independent of vegetation changes. Here we resolve this controversy through a continuous 10,500-y record of both vegetation and hydrological changes from Lake Barombi in Southwest Cameroon based on changes in carbon and hydrogen isotope compositions of plant waxes. δ
13 C-inferred vegetation changes confirm a prominent and abrupt appearance of C4 plants in the Lake Barombi catchment, at 2,600 calendar years before AD 1950 (cal y BP), followed by an equally sudden return to rainforest vegetation at 2,020 cal y BP. δD values from the same plant wax compounds, however, show no simultaneous hydrological change. Based on the combination of these data with a comprehensive regional archaeological database we provide evidence that humans triggered the rainforest fragmentation 2,600 y ago. Our findings suggest that technological developments, including agricultural practices and iron metallurgy, possibly related to the large-scale Bantu expansion, significantly impacted the ecosystems before the Common Era. [ABSTRACT FROM AUTHOR]- Published
- 2018
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