New results of bacterial degradation in wood
New findings reveal that bacterial degradation is a major threat to the wooden cultural heritage located in water or in soils. As a result of this research it is now known that if wood is well conserved it can last centuries and retain its strength. However in the presence of fungal activity, bacterial wood degradation will be more aggressive, an issue believed to be underestimated in Germany, Great Britain and Italy. The research found that foundation piles that have been in service for approximately 100 years and are situated below groundwater level show indications of bacterial decay. This decay begins in the outermost layer, where it was most commonly found, before it works its way towards the centre. The study revealed that certain timber species used for piles were more resistant to decay than others. Spruce appeared to be more resilient to bacterial degradation than pine sapwood or alder. Pine heartwood also appeared to be quite resistant. Despite the resilience of certain timber species, location also played a critical role in the development of bacterial degradation. This explained why Spruce, with its high resistance factor, was found to be seriously degraded at certain sites. Results indicate that soil type and pollution were major factors to bacterial degradation. The study shows that a correlation exists between the level of nitrogen/phosphorus existing in the wood and the degree of degradation. Wooden piles found in permeable soil, such as sand, showed higher instances of severe bacterial attack compared to wooden piles found in non-permeable soils such as clay and peat. The same however could not be said for archaeological wood. In contrast, degradation in archaeological wood occurred slower in sandy soils than it did in peat. The study also found no correlation between bacterial degradation and age. The structural integrity of wood is important to archaeologists as it allows them to recognise the original sample shape and size. The study concluded that the impact of bacterial degradation in wood is underestimated in Europe and especially in the field of archaeology.
