Are the wooden remains of the Lusatian culture settlement at Biskupin safe? Decomposition of archaeological oak wood samples during a 10-year experiment

Abstract

A study was made of the decomposition of oak wood samples deposited in different environments on the Lusatian culture site in Biskupin, Poland. Waterlogged archaeological wood samples were examined after 10 years of deposition in peat, sand or mineral soil or in a water-filled trench. Wood decay was evaluated on the basis of wood mass loss, sample volume loss, physical properties (maximum water content, basic density, porosity) with and without mineral compounds, chemical composition (holocellulose, cellulose, pentosans, lignin, substances soluble in 1% NaOH, 95% ethanol and hot and cold water, and ash content) and microscopic observations. The oak wood was found to be least degraded in the strongly reducing waterlogged peat in which the preserved remains of wooden constructions of the Biskupin settlement are deposited. Nevertheless, even in this near-anaerobic environment, wood decomposition was significant. The loss of wood mass was about 8–10%, whilst the decrease in the cellulose content ranged from 14 to 16%. To preserve the remains of the Biskupin settlement for future generations, it is proposed to consider excavating some of the wood for conservation and exhibition under controlled museum conditions.