Nanna Bjerregaard Pedersen

When buried in waterlogged, oxygen-poor environments such as bogs, marine and lake sediments, urban layers, and coastal deposits, wooden objects can survive for thousands of years. 

However, the wood is colonised by erosion bacteria, which slowly hollow out the cell walls and remove the structural carbohydrates that give wood its strength. What remains is a fragile but remarkably detailed cellular skeleton that retains the original shape and cultural information of the object. 

The preservation depends on skilled conservation, which stabilises the deteriorated material and ensures its long-term accessibility for research, exhibition, and future generations.

My research has elucidated, and continues to explore, how bacterial degradation alters wood anatomy and cell wall chemistry in waterlogged archaeological wood, and how these changes affect material performance. 

By combining microscopy with advanced chemical imaging and analytical techniques, I investigate how decay progresses within individual wood cells and which cell wall components are lost during the degradation process. 

The findings improve our ability to assess preservation state, predict long-term stability, and develop more effective conservation strategies for waterlogged archaeological wood.

Archaeological sites in Greenland are often considered exceptionally well preserved because low temperatures and permafrost limit biological activity. 

However, climate change is altering these preservation conditions. As permafrost thaws, increasing volumes of soil become seasonally thawed, forming the active layer where the presence of oxygen and water promotes microbial activity. 

Together with researchers from the National Museum of Denmark, the University of Minnesota, and the Norwegian Institute of Bioeconomy Research, I investigated how wood-degrading fungi affect archaeological wood in these active-layer soils. 

Svalbard’s iconic cable car pylons are among the most visible reminders of the Arctic coal-mining era that once transported coal across the landscape around Longyearbyen. 

Built from untreated timber and exposed to some of the world’s harshest environments, many of these structures have survived for more than a century. 

We have investigated more than 20 cable car pylons spanning more than a century in age to understand how wood-decaying fungi affect their long-term preservation.

We have examined how fungal wood decay develops in different parts of the structures and assessed the long-term decay risks. We found that the timber is remarkably durable—but far from immune to decay. 

The most severe deterioration occurs where the wood meets the ground. Although the structures may appear well preserved, hidden decay in these critical load-bearing elements can significantly weaken the stability of the entire construction. 

As climate conditions change, understanding the role of fungi is becoming increasingly important for conservation planning, restoration priorities, and the sustainable management of Arctic cultural heritage. 

The research project was funded by Norwegian Research Council, hosted by the Norwegian Institute of Bioeconomy Research, and carried out in collaboration with the Royal Danish Academy and several Norwegian heritage partners, including Norwegian Institute for Cultural Heritage Research.