Vast Woodlands Unearthed in the Flat Fens of Eastern England, Study Reveals

November 23, 2023

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By University of Cambridge

A recent study sheds new light on the history of the Fens, a low-lying, exceedingly flat landscape in eastern England now largely made up of agricultural fields. Researchers have discovered that the region was once a vast woodland teeming with large yew trees.

Researchers from the University of Cambridge have excavated hundreds of tree trunks that farmers unearthed while tending to their fields in Fenland. Their findings revealed ancient yew trees inhabited the area approximately 4,000 to 5,000 years ago.

The excavated trees hold invaluable information detailing what the Fens looked like thousands of years ago. These particular trees are often considered inconvenient when they interfere with farming machinery but their existence reveals much about Fenland's past.

Around 4,200 years ago, Fenland's yew woodlands underwent a sudden extinction as the trees fell into peat, naturally preserving them. The researchers speculate that a swift rise in sea levels in the North Sea flooded the region with salt water and resulted in the disappearing of the vast woodlands.

The ancient trees hold insights into the climate and environment, which could provide vital evidence supporting the theory of a significant climate event that coincided with other global events like a possible megadrought in the Middle East. This megadrought may have played a significant role in the collapse of Egypt's Old Kingdom. The researchers' findings were published in Quaternary Science Reviews.

Yew trees (Taxus baccata), which can grow up to 20 meters tall, are among the most ancient species in Europe. They're commonly found in Cambridge College gardens and southern England churchyards, but absent in the Fens, a marshy region in eastern England. Through the centuries, artificial drainage and flood protection measures have been put in place to transform the Fens into viable farmland.

Though the Fens is primarily composed of farmland today, 5,000 years ago it hosted a magnificent forest. While having to contend with large buried logs causing problems in farming can be troublesome for Fenland farmers, the unearthed wood provides a wealth of information for researchers.

The Cambridge team took samples from hundreds of logs that Fenland farmers had discarded, hoping to unlock the secrets they held within. The incredible preservation of these trees, some even appearing as if they were cut down recently, was a source of surprise for the researchers.

To understand the long-term impact of human-induced climate change and natural fluctuations, researchers require accurate evidence of past conditions. Trees play an essential role as they preserve past climates in their annual growth rings. However, such well-preserved specimens are rare, according to Professor Ulf Büntgen, the senior author of the study.

Remarkably, the Cambridge Tree-Ring Unit (TRU) found that some of the excavated yew trees were as old as 400 years at their time of death. The discoveries now offer a unique overview of the climate from 5,200 to 4,200 years ago, a time when Fenland was a woodland of yew and oak, entirely different in appearance compared to the present day.

'Finding these very old trees in the Fens is completely unexpected—it would be like turning a corner in rural Cambridgeshire and seeing an Egyptian pyramid—you just wouldn't expect it,' said Bebchuk. 'It's the same with nature—wood rots and decomposes easily, so you just don't expect a tree that died 5,000 or 4,000 years ago to last so long.'

Given that most of the Fens are barely above sea level, about 4,200 years ago, a sudden rise in sea level most likely killed the Fen woodlands. The period that the Fen woodlands died coincided with major climatic changes elsewhere in the world: at roughly the same time, a megadrought in China and the Middle East was a possible trigger of the collapse of several civilizations, including Egypt's Old Kingdom and the Akkadian Empire in Mesopotamia.

'We want to know if there is any link between these climatic events,' said Bebchuk. 'Are the megadroughts in Asia and the Middle East possibly related to the rapid sea level rise in northern Europe? Was this a global climate event, or was it a series of unrelated regional changes? We don't yet know what could have caused these climate events, but these trees could be an important part of solving this detective story.'

'This is such a unique climate and environmental archive that will provide lots of opportunities for future studies, and it's right from Cambridge's own backyard,' said Büntgen. 'We often travel all over the world to collect ice cores or ancient trees, but it's really special to find such a unique archive so close to the office.'

Journal information: Quaternary Science Reviews

Provided by University of Cambridge