Xylic substrates at the fossilisation barrier: oak trunks (Quercus sp.) in the Holocene sediments of the Labe River, Czech Republic

Sediments of the Holocene floodplain of the Labe River (central Bohemia) provided an accumulation of oak trunks (Quercus sp.) bearing relatively rich and diverse assemblages of borings. Among the recognised morphotypes of borings, four can be attributed to insect feeding, one resulted probably from an enzymatic fungal activity, and the last one is probably a mammal ‘scratch’. The borings record three phases of activity: (1) on living trees, (2) on dead trees before their burial by sediment, and (3) on exhumed trunks (i.e., during the last several years). Generally, the wood mass comes mostly from live, ‘healthy’ floodplain forests, which shows that these were affected by extremely large floods during certain intervals in the Holocene. The borings found support the idea of erecting terrestrial wood ichnofacies, but the Holocene material itself is not suitable for this purpose.