Mid to Late Holocene vegetation dynamics in the Itombwe Mountains of DR Congo

Aim: The early to mid-Holocene was a time of profound social, ecological and environmental change across equatorial Africa: settled agrarian and pastoral societies emerged and were established quickly across much of Eastern Africa, new technologies were developed, and various complex societies emerged. However the long term social and ecological history of the Democratic Republic of the Congo (DRC) remains largely unknown. The ecosystem dynamics of the Itombwe Massif forest are explored through a palynological analysis of the sediments of Lake Lungwe in the Itombwe Natural Reserve. Location: Lake Lungwe, South Kivu, Eastern DRC, Albertine Rift Time period: Mid to late Holocene Taxon: Vascular plants Methods: A sediment core of 575 cm was collected using a Russian manual corer and conventional 14C dating of the sequence sampling was performed. Results: Radiocarbon dating shows that the pollen data extends from 6729 ± 30 BP through to the present day. Our pollen record demonstrates two major ecosystem shifts. The mid Holocene was characterized by dense Afromontane forest with two dry periods characterized by increased presence of Juniperus and the expansion of Olea and Podocarpus: taxa better adapted to dry climatic conditions. From around 3500 yr BP there is an increase of Ericaceae together with Cyperaceae; again indicative of a drier, more open ecosystem. Main conclusions: In the uppermost samples, dating to the last 500 years, there is a sustained presence of Hagenia and Asteraceae pollen suggests that anthropogenic activities have become increasingly important in shaping forest composition.