Late-Glacial Paleograssland Communities In Tropical West Africa
by
Kristina Beuning
Wesleyan University
Coauthors: Jessica Scott (Wesleyan University), Michael Talbot (University of Bergen), Daniel Livingstone (Duke University)

Isotopic and morphological analysis of late-glacial organic remains from Lake Bosumtwi, Ghana provide a comprehensive, multi-proxy method for characterizing paleograssland communities surrounding the basin. Carbon isotopic analysis of the bulk lake sediment offers an important first-order approximation of the relative abundance of C3 vs. C4 plants surrounding a basin. However, such analysis does not directly address paleograssland composition, as contributions from arboreal C3 plants may hinder interpretation. Comparison of the bulk sediment carbon isotopic signal with carbon isotopic values of grass cuticle extracted from the same sediments allows evaluation of the integrity of the bulk sediment carbon isotopic signal as a record of paleograssland composition. Concomitant analyses of pollen as well as grass cuticle morphology further refine reconstructions of vegetation composition and allow not only recognition of grassland vs. non-grassland communities, but in the case of grass-dominated ecosystems also provides information regarding specific grass taxa present on the landscape. The Lake Bosumtwi sediments contain abundant, well-preserved cuticle, particularly during the Last Glacial Maximum interval. Earlier studies of cuticle in this sedimentary section suggested the presence of exotic grasses, including possible montane species, no longer found in the region. This new study provides considerable refinement of the previously rather rudimentary data.

Date received: March 30, 2001

Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cagc-86.