A study of plant macrofossil taphonomy in lakes and rivers and its application for interpreting some Middle Pleistocene assemblages

The study of the processes involved in the production of a fossil assemblage from a living community is termed taphonomy. Consideration of these processes is important in palaeoenvironmental reconstructions from fossil assemblages. Taphonomic investigations of plant macrofossils were undertaken at a lake, two ponds, and along a river in southern Britain. The aims were to assess the effects of taphonomic processes operating on plant macrofossils, to determine which taxa were either under- or over-represented in fluvial and lacustrine sediments when compared to their abundance in the surrounding vegetation, and to apply the conclusions of the modern studies to the interpretation of some Middle to Late Pleistocene assemblages. \nLacustrine surface sediment samples were collected and analysed for potential plant macrofossils. Vegetation surveys around the lakes provided information on the abundance and distribution of plants. From the results it appears that potential plant macrofossils originated from plant communities in the immediate vicinity of the sites of deposition. The majority of plant material accumulated at the margins of the lake basin. Evidence from the investigation of a small pond suggested that plant material can be deposited on strandlines in the littoral zone. \nSome of the plant remains recovered from point bar sediments collected along the river appear to have originated from more distant sources. However, the majority of plant remains recovered from the fluvial sediments probably originated from local sources. Spatial and temporal variations occurred in the number of potential macrofossils deposited and in the taxa represented in the fluvial sediments. \nAs the modern investigations in both lacustrine and fluvial environments strongly suggest potential plant macrofossils were originating from predominantly local sources then Middle to Late Pleistocene assemblages only allow reconstructions of local vegetation. The modern investigations illustrated that it may not be taken for granted that the quantitative representation of a taxon in an fossil assemblage reflects its abundance in the past vegetation. Since there was large taxonomic variation in the modern sediment samples from one site it. is recommended that many samples be investigated when studying fossil sites to .obtain accurate reconstructions of past vegetation.