Woody charcoal with traces of pre-charring decay from the Late Oligocene (Chattian) of Norken (Westerwald, Rhineland-Palatinate, W Germany)

Abstract

A variety of traces of pre-charring decay are described from coniferous charcoals from the Norken locality, stratigraphically positioned within the Breitscheid Formation (Late Oligocene, Chattian) of the Westerwald area (Rhineland-Palatinate; W Germany). The traces include three-dimensionally preserved as well as collapsed fungal hyphae, collapsed filamentous structures (maybe related to ascomycetes), so-called shot-like holes of different diameters in cell walls of tracheids, as well as crater-like structures on the surface of tracheid walls. The latter occur on tracheids with bordered pits, in the direct vicinity of charred phloem (so far only rarely reported from pre-Quaternary charcoal). These observations, together with evidence that some of the charcoal fragments originated from wood that dried out prior to charring, point to a surface fire as the most likely source of the charcoal, although it cannot totally be ruled out that (partly) dead but still standing trees were affected during a crown fire. The data from the Late Oligocene of Norken provide further evidence that pre-Quaternary charcoal can be used as an additional, so far largely underutilized source for additional information about plant–microorganism interactions in deep time.