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Forest response to climate changes in Atlantic Equatorial Africa during the last 4000 years BP and inheritance on the modern landscapes
Author(s) -
Vincens Annie,
Schwartz Dominique,
Elenga Hilaire,
ReynaudFarrera Isabelle,
Alexandre Anne,
Bertaux Jacques,
Mariotti André,
Martin Louis,
Meunier JeanDominique,
Nguetsop François,
Servant Michel,
ServantVildary Simone,
Wirrmann Denis
Publication year - 1999
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1046/j.1365-2699.1999.00333.x
Subject(s) - holocene , arid , climate change , pollen , geography , floristics , ecology , rainforest , ecosystem , physical geography , species richness , archaeology , biology
Summary This review paper synthesizes the recent published palaeoecological results obtained in Atlantic Equatorial Africa (ECOFIT program) on the history of forest ecosystems and inferred climate changes during the past 4000 years. Evidence are mainly provided by pollen analysis carried out at nine sites from Congo, Cameroon and Ghana, locally supported by macroflora remains, phytoliths, diatoms, δ 13 C and mineralogical data. At all the sites, except Lake Bosumtwi (Ghana), following a large expansion of rain and mesophilous forests until 3000 years BP , a major change is registered, affecting floristic composition, structure and geographical distribution. According to the hydrological sensitivity of the different sites, local openings of the forests with development of heliophilous formations and/or isolated enclosed savannas are observed at the most humid sites; complete disappearance of forested formations at the driest. The agreement between pollen records, hydrological and hydrobiological data definitely demonstrates that an arid event has been the primary driving factor of this change and is responsable for the main features of the modern landscapes in Atlantic Equatorial Africa. Moreover, the most recent palaeoecological data obtained in Congo (Lake Sinnda), indicate that this Late Holocene increasing aridity was of longer duration, from 4000 to 1300 years BP , and more progressive than previously inferred. A new expansion of forests is locally detected c. 900–600 BP despite increased human impact.