5000-year-old forest found under the Fens

The discovery of preserved wood by farmers in the east of England has led Cambridge scientists to determine the presence and fate of an ancient forest...

Will - Great scientific tales often come from unusual places or accidental discoveries. Just ask Alexander Fleming. And this tale of ancient trees is no different. This story begins with a lone, brave traveller, wading through harsh conditions and trying to garner sympathy by saying something like, 'I'm in the cold winds of the Fens, in the east of England.’

Brave Traveller - I'm in the cold winds of the fences in the east of England to watch a mystery unravel, usually known for being a place that is flat and somewhat featureless, unidentified and strangely shaped. Wood has been piling up on farmland in this area after being ploughed out of fields. I'm here to speak to one of the people that has been amassing a sizable collection.

Chris - I'm Chris Beever, farm manager for J.G farms managing land in this area around the other side of Boston.

Will - When I heard about this story originally and I was told that there was some mystery wood being unearthed on farms in this area, I was expecting one or two trees. This is an insane amount of wood in front of us. Just how much do you think there is?

Chris - There'll be at least 70 tonnes here. Yeah. Dragged out over a lot of years.

Will - Is it just a case of it turning up in the soil as you plough?

Chris - Basically? Yes, it does tend to move around there. So deep cultivations do pull it out, but then if we can't pull it out the first year, generally we'll mark it and go back the second year. Just being aware of where it is and it normally moves in the soil. And it's nothing but a pain.

Will - It's something I feel like we should appreciate is that there is fascinating scientific value to this, but from a practical farming side, <laugh>, this is not what you want at all.

Chris - No, no. It is just difficult to deal with on a day-to-day basis, we'll go round autumn cultivations and then we'll have to go round and pick up the bog oak trees, heap them up again. And then spring cultivation is exactly the same. It's

Will - Almost good that it turned out to be so old and unusual because otherwise this would be utterly <laugh>, utterly pointless.

Chris - Yeah, I mean there must have been some value in it, but it's a question of realising the value of it.

Will - What did you think it was when you first saw it? Did you just assume there was no real significance to it?

Chris - Everyone calls it bog oak. We know it's old. Yeah, we don't know if there's any real value in it. But at the actual age, no one was really interested.

Will - I assume it wasn't a direct line of communication with you, but did you get in contact with the university? Did the university get in contact with this group of farmers and, and how was this relationship established?

Chris - Yeah, I assume my predecessor got in contact with Tatiana about this and yeah, then she got in contact with me eventually.

Tatiana - So very luckily, one of the farmers contacted the department saying that, 'Hey guys, I have lots of wood here on the edge of my field. Is there any interest?'

Will -
This is Tatiana Bebchuk. She's a PhD student at the University of Cambridge's Department of Geography and was one of the people tasked with unlocking the secrets of this dead forest.

Tatiana - Luckily my supervisor gets very excited when he hears about the wood, so he went to the field, took a sample of the wood because he had no idea of how old it is. When the results came back, he was even more excited because it turned out that it's around 5,000 years ago when these trees were growing.

Will - Trees are very useful for telling us the recent history of the climate. Since they grow more in warmer, wetter years, the rings are further apart when you look at a cross section of the trunk. So what kind of snapshot do these preserve trees give us about the fences 5,000 years ago?

Tatiana - Since we find so many trees, it means that there were woodlands. The species that we find are yew trees and oak trees. We then see that these trees established themselves in the area around 5,200 years ago and they were growing in favourable, for them, conditions. However, we do see that some of the trunks have what is called adventitious roots. So roots that are produced when a tree starts to be buried. So it means that while these trees were growing, something was going on in the landscape, in the topography, right? Then we see that all these trees die and they get preserved. So altogether we kind of can bring these pieces of puzzle and reconstruct the environmental story, which for us now looks like this area is very flat and is basically situated at the sea level, it was very much affected by sea level. So if the sea level rises, rivers don't have as much flow to pass the water to the sea so that it gets flooded with freshwater and under fresh water logging conditions. Peat starts accumulating, so that's what was burying the trees. But then the question remains what actually killed the trees. And as we see that these trees produce adventurous roots, it means that they were not killed by peat. They could overcome it. So our current hypothesis is that these species are intolerant to salt water and salt aerosols. So the rapid sea level rise or increased storminess could lead to decline of the trees.

Will - On a geological timescale, sea levels rise and fall all the time. What do you think drove this one in particular and was there anything significant about it?

Tatiana - So I can't yet <laugh> say what drove this sea level rise, but we do see some interconnections on a global scale between the disappearance of these trees and some other major climatic events. 4,200 years ago when these trees disappeared, we know that there was a mega drought in Asia and the Middle East, which potentially led to the collapse of three major civilizations such as the Old Kingdom in Egypt, Harappa in India, and Mesopotamia. So we can kind of see that there are these teleconnections and we just have to explore if that's what was in 4,200 years ago.

Will - It is remarkable to think that relatively recently, the flat featureless fences were a sprawling forest of oaks and elms. But mega droughts, rising sea levels, collapsing civilizations. Sounds familiar, doesn't it? Should we continue to burn fossil fuels and allow climate change to shape our weather systems and landscapes, areas such as the Fens, a place of home, food, and wildlife, could well find themselves in very deep water.