Contribution of archaeobotany to understand taphonomic phenomena. The case of a Preboreal palaeochannel of Autrecourt-et-Pourron (Ardennes, France)

Palaeoecology, through the analysis of the interactions between environmental factors and ecosystems, refines the knowledge of the structuring process of plant communities and helps to understand the complexity of past environments. However, it is necessary to analyse the taphonomic phenomena (deposition, conservation, degradation) affecting plant macrofossil assemblages in order to perform relevant palaeoecological analyses. Indeed, plant macrofossils may be under or over-represented in carpological assemblages, depending on the resistance of their cell membranes and the sedimentary condition deposits. For this reason, it is necessary to estimate the representative quality of the conserved part as a source of information. Like all archaeological documents, the plant archives are distorted by the processes of formation of the sedimentary levels and, ignore the diagenetic history of the sedimentary layers could lead to wrong palaeoecological interpretations. To this aim, we analysed plant macrofossils contained in the wet sediments of a Meuse palaeochannel (Autrecourt-et-Pourron, Ardennes, France). This archaeobotanical study of an oxbow lake dated to the Preboreal (11.7-10.7 ka cal. BP), provides a reference of a taphonomic referential according to a hierarchy of organic remain preservations. This framework successfully helped the palaeoecological interpretations of the Autrecourt-et-Pourron off-site, and it has brought robustness to environmental history reconstruction of the early Holocene in the Ardennes Meuse.