Comparaison de signaux anthracologiques Holocènes issus de différents types d’archives en Allemagne : vers une reconstitution plus précise de l’histoire des incendies ?

Abstract

Anthracology permits the reconstruction of both history and dynamics of past ecosystems based on various types of carbonized indicators. Various anthracological approaches allow the quantitative and/or qualitative analysis of the recording of those indicators, in various preservation contexts. Therefore, the relevance and significance of a chosen anthracological approach to a specific problematic, are directly related to the type of archive that have preserved on a long term scale the records. Consequently, the strategy for sampling and analysis will depend largely on the type of available archive. For instance, the spatial resolution of a signal would notably depend on the lake size and catchment area feature. In addition, the size of the carbonized pieces would have a role in the spatial resolution of the analyzed anthracological signal. The larger a carbonized piece, the most local its significance. Thus, the macroscopic and microscopic charcoal assemblages are commonly distinguished, and interpreted as having various spatial resolutions. Therefore, the analytical protocol must be adapted to the desired, or needed, spatial resolution. We postulate here that the comparative analysis of anthracological records, consisting of piece assemblages of various sizes, and sampled from various types of archives, allows one to improve the reconstruction of fire signals. To demonstrate that hypothesis, we compared anthracological assemblages from various archive types on two investigation areas in Germany. On each of those areas, we quantitatively and qualitatively analyzed charcoal records from sampled soils, and/or continental sediment sequences, and from peat sequences. We extracted the micro-, macro- and mega-charcoal assemblages. With the support of radiocarbon dating and of age/depth models, we observed synchronous and asynchronous patterns in the various signals analyzed, which highlight the utility and efficiency of such a complementary multi-proxy approach.