Distinguishing the Signs of Fungal and Burial-Induced Degradation in Waterlogged Wood from Biskupin (Poland) by Scanning Electron Microscopy.

Abstract

A scanning electron microscopy (SEM) investigation of pine (Pinus sylvestris) and oak (Quercus sp.) wood samples exposed to various types of natural degradation is presented with the aim of discussing the correct identification of multiple degradation signs in waterlogged wood. This is part of an experiment performed at the archeological site of Biskupin (Poland) to evaluate the dynamics of short-term wood degradation during reburial and the suitability of excavated wood as substrate for the fungal attack. The final aim is to support and inform the in situ conservation strategy currently applied to archeological woods. To replicate the burial conditions, wood samples were put into lake water and peat. The samples were removed from the burial environments after 4, 6, 8, and 10 years, and then exposed to laboratory-controlled attack by a brown rot fungus Coniophora puteana and a white rot fungus Coriolus versicolor. SEM images were acquired for all samples before and after the fungal attack. The results showed a slight degradation occurred in the burial environments (soft rot and bacteria). In addition, both typical and previously neglected features of fungal attack were observed, highlighting that the extent of the fungal decay varies according to the previous degree of wood degradation. Some comparisons are provided with archeological wood samples from the Biskupin site.