1. Early anthropogenic impact on Western Central African rainforests 2,600 y ago.
- Author
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Garcin Y, Deschamps P, Ménot G, de Saulieu G, Schefuß E, Sebag D, Dupont LM, Oslisly R, Brademann B, Mbusnum KG, Onana JM, Ako AA, Epp LS, Tjallingii R, Strecker MR, Brauer A, and Sachse D
- Subjects
- Africa, Cameroon, Humans, Time Factors, Archaeology, Climate Change, Ecosystem, Rainforest
- 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. [Formula: see text]
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. [Formula: see text]D 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., Competing Interests: The authors declare no conflict of interest.- Published
- 2018
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