Ultrastructural observations of microbial succession and decay of wood buried at a Bronze Age archaeological site

Abstract

Buried archaeological wood is subject to microbial decay by bacteria and fungi. Little is known of the environmental conditions that affect and control the distribution and rate of microbial decay. In the UK in situ preservation is the preferred option for managing the archaeological resource. An understanding of the factors that influence microbial decay is therefore required. Samples of modern timbers were buried at a Bronze Age archaeological site for 550 days. Timbers were removed and investigated using light and electron microscopy. Decay was compared with environmental conditions of the burial environment. The decay types identified were soft rot, erosion and tunnelling bacteria. Bacterial decay occurred in samples buried under near anaerobic conditions. Soft rot decay was evident for samples buried under less anaerobic conditions. A combination of high water table, low pH, anaerobic conditions and high organic matter content of the soil were found to prolong the preservation of the timbers.