Abstract
Fossil phytolith assemblages from soils and lake sediments are widely used to reconstruct past vegetationpatterns and dynamics, especially in tropical environments where a phytolith index has been quantitativelycalibrated to estimate tree cover. Most calibration studies have focused on comparing phytolith assemblages inmodern soil with the present aboveground vegetation. However, little is known about phytolith taphonomyand the representativeness of phytolith assemblages and indices in lake sediments. The aim of this study is to im-prove the understanding of the composition of phytolith assemblages and their influx into recent lake sedimentsby comparing them with local land cover assessments. This study focused on three lakes in the Central AfricanRepublic located in savanna, forest–savanna mosaic, and forest. It appears that the local environment surround-ing the lake was critical for interpreting current and past assemblages, and the ratio of dicotyledon to Poaceaediagnostic phytoliths (the D/P index). The presence of a riparian forest in an open environment had no impacton phytolith assemblages or the D/P index, which instead reflected both the local and regional landscapes. Con-versely, contributions from a marsh, if present in a forested environment, completely dominated the phytolithrecords, which consequently reflected only the local environment of the lake. A high correlation between thePoaceae phytoliths influxes and the charcoal accumulation rates for the two lakes surrounded by a riparian foresthas also been found.Thisfinding,whichwasassociated with a highproportion ofburnedPoaceae phytoliths, pro-vides evidence that Poaceae phytoliths are mainly transported by wind in ash clouds produced byfires