Title
Vegetation changes during the past 1300 years in western equatorial Africa: A high-resolution pollen record from Lake Kamalété, Lopé Reserve, Central Gabon
Author(s)
Ngomanda A., Chepstow-Lusty A., Makaya M., Schevin P., Maley J., Fontugne M., Oslisly R., Rabenkogo N., Jolly D.
Published
2005
Publisher
Holocene
Abstract
Vegetation changes during the past 1300 years are reconstructed in western equatorial Africa using a high-resolution pollen record from Lake Kamalété. This small marshy basin (c. 5-7 ha) is located in forest-savanna mosaic in Lopé Reserve (0°43'S, 11°46'E), central Gabon. The Kamalété pollen data show the persistence over the past 1300 years of a relatively stable forest-savanna mosaic, associated with significant changes of the forest component. Three successive stages of forest dynamics occurred. First, at 1325 cal. BP, moist semi-evergreen rainforest existed around the catchment of Lake Kamalété. However, it appears from the consistent presence of > 70% Gramineae pollen that the site was always primarily in savanna. Secondly, from c. 1240 to 550 cal BP, a noticeable increase in shade-intolerant plant species indicate openings in the rainforest canopy. The persistence of gap-colonizer species, such as Macaranga, Tetrorchidium and Musanga for several centuries in the rainforest, is explained by recurring canopy disturbance associated with shifts in available moisture. These hydrological changes may be related to a succession of longer and more severe dry seasons than observed today. Thirdly, at 550 cal BP, mature forest was re-established, corresponding to progressive savanna colonization by forest pioneer species such as Aucoumea klaineana, Lophira alata and Fagara macrophylla. This new phase of forest expansion coincided with a marked lithological change, indicating an increase in lake-level. It is concluded that the major vegetation changes observed are due to climatic variability, and anthropogenic action had limited influence. © 2005 Edward Arnold (Publishers) Ltd.
Keywords
climate change; Holocene; paleoclimate; palynology; savanna; vegetation history; Africa; Central Africa; Eastern Hemisphere; Gabon; Lope Reserve; Ogooue-Ivindo; Sub-Saharan Africa; World; Aucoumea klaineana; Fagara macrophylla; Lophira alata; Macaranga; Musanga; Poaceae; Tetrorchidium
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PUB12299