Microbial decay of waterlogged archaeological wood found in Sweden Applicable to archaeology and conservation

Waterlogged archaeological wood suffers from microbial degradation. Sections from 92 archaeological samples from seven marine and terrestrial sites in Sweden were investigated using light- and electron microscopy to determine the major forms of microbial decay. Decay was related to sample age, wood species and environmental factors. The results confirmed earlier observations that erosion bacteria were the main degraders of archaeological waterlogged soft- and hardwoods, whereas soft rot and tunnelling bacterial decay were less frequently observed. Characteristic slime material, derived from attack by erosion bacteria and left behind in the cell lumen, may affect the penetration of consolidants used to conserve waterlogged archaeological wood. Advanced decay by erosion bacteria had only a slight effect on the original colour, form and appearance of the wood. Different oxygen levels influence the type of microbes and the extent of decay. Examining the decay can reveal a great deal about the past history of a site and provide valuable information to archaeologists.